I knew this would be your favorite! The TH400/425 SP is a honey of a transmission - which is why so many non-GM manufacturers made this their transmission of choice. Adam, I hope you do a video on the great GMC motorhomes of the early/middle 1970's.
The TorqueFlite was not just used by Chrysler; it was adopted by luxury automakers Monteverdi, Facel Vega, Bristol, Aston Martin, Maserati, and Jensen, as well as domestic rival AMC and commercial-vehicle makers International Harvester, Land Rover, Iveco, Karrier, Matbro, Stonefield, Sirmac, Boss Motor, and Mitsubishi.
When I worked at a Dodge dealership, I had a customer call and ask if I had a starter in stock for an Aston Martin. I reminded them that he had called a Dodge dealership. His reply was that it took the same starter as a 440 engine. The reason was that his relatively new Aston Martin had a TorqueFlite transmission to which the starter bolted.
I am a GM guy but also bit of a Mopar guy too. I'd have to rate the 727 Torqueflite nose to nose here. Both great transmissions and pretty much bulletproof. My dad bought a brand new 1966 Buick Riviera with the 425 Nailhead and the TH400 with the switch pitch convertor. That car was amazing! I drove it in the mid 70's in my High School years.
The 727 Torqueflite was stronger and smoother in some respects than the TH400. A lot of international companies used them along with Chrysler engines ( Jensen, Bristol, Monteverdi and others )
I love how you suffer with the wind and your hair blowing all over the place to give us the facts about these great transmissions. Another great one thanks!
Not surprised this is your favorite, it's very possibly my favorite as well. Just an excellent transmission that fit perfectly the era of big block, full size luxury cars that GM did so well with during the mid 60s- early 70s. Really was the golden era of GM imo, and the th400 was a big part of that excellence.
TH400 also used in Humvees until 4L80E. When the Hummer was armored-up (which it was not originally designed to) and you added additional weaponry, etc.... it became very heavy. To move it meant the 19 year old just floored the 6.2/6.5 diesel and held it there. The TH400/4L80E took that punishment in all kinds of environments including 120 degree desert!
Ford's philosphy with the C-6 was that more positive shifts would result in less wear. My dad was taught this in Ford transmission school. As a Ford service manager, he heard some complaints from owners that didn't like it compared to the smoother-shifting GM transmissions.
Your right, the three kings of automatics: Turbo 400, 727 and C-6. The three kings of manual transmissions are the: Top Loader Ford, Chrysler A833 and GM's M23 'RockCrusher. Thanks for posting, very enjoyable.
The TH400 is a bulletproof and very reliable. It was the main transmission found in several gm muscle cars and gm personal cars as well as several foreign brands. Proof of its clever conception and durability
Hey Adam. Growing up as a kid we had a 66 Cadillac with 390 v8 and a 400 Turbo-Hydra Matic. The best shift I have ever felt in my life to date and I'm now 60 years old. Nothing will ever replace it.
I own a 66 Cadillac Calais, it has the 429. My dad had a 65 sedan Deville it too was a 429. To my knowledge the 390 was last used in 64. The 429 replaced it and the 429 was replaced by the 472 in 68 which was bumped to 500 in 1970. 472 disappeared after 74 and the 500 was gone by 77
@@tonykramer4976 Hey Tony. I was not aware the usa is different from Canada. I also saw I GM build on a 68 caddy where the usa uses leaf springs in the rear of the 68 caddy. Unheard of here in Canada. I Grose to put leaf springs in any caddy.
My Father had a 1965 Wildcat and a 1967 LeSaber, both with the Super Turbine 400 with the dual pitch converter. The Wildcat was especially quick off the line. The LeSaber was repaired by someone who didn't know what he was dealing with and left the connector off the throttle linkage. When it was replaced properly it was SO MUCH better! I understand that some drag racers liked to get these converters and install them with a manual switch on the dash so when they made a run they could set it for best acceleration. It was really like having two different levels of passing gear.
I will say that my parents' 1965 Country Squire survived many, many neutral drops that I subjected it to as a teenager just fine. Long live the Cruise-o-Matic, with its rough 2-3 shifts and all!
The Ford C-6 is superior to the GM Turbo Hydramatic 400..This is why.. The lugs in the case that retain the snap ring on second gear tend to blow out of the case, rendering the case junk, this was an issue on Turbo 400s made before 1987 when GM revised the case design. The C6 and Torqueflite never had such issues. This guy simply doesnt have all the information.
That is great! I remember doing neutral drops in my parent's cars a lot when I was 16 to impress my buddies. I watched a friend of mine drop a driveshaft out of 58 Chevy wagon doing that. Those were the good old days. Can you even do a neutral drop in a modern car?
The 1965 Chrysler 426 Hemi Cornet with the 727 Torqueflite is the Best 727 Torqueflite ever made. It shifted at 7000 rpms Factory Bone Stock 1-2 &2-3 Full Auto left in Drive. Check Out Jay Leno's 1966 426 Hemi Cornet 727 Auto with 3.23 Posi. He is Street Racing on Los Angelous Freeways with doing 100 -130 mph Blowing Everyone's Doors Off Late Model ! !
I like to comment on the Chrysler torqueflite Transmissions from the sixties and seventies and I understand these are a legendary tranny with reliability and practically Bulletproof.
Great presentation. If I remember correctly this transmission was originally known simply as Turbo Hydramatic. I think it only became known as Turbo Hydramatic 400 in 1969 when the turbo 350 was introduced. Similarly, General Motors transit buses only became known as “Old Look” once the “New Look” (a.k.a. Fish Bowl) buses were introduced in 1959.
Rebuilding automatic transmissions 46 years ,and you are very correct 👍 I find it almost impossible to find a better 3 speed ,, and the 425 would put me out of business because I've only rebuilt 5 of them in my life EDWARDS BROTHERS TRANSMISSION IN ROANOKE RAPIDS NC ..
my late maternal grandmothers used 1979 Cadillac Coupe Deville she drove when I was a little girl it was that car that made me fall in love with Cadillac had this transmission and rode smooth as silk
My 73 Caprice had the thm400 and it was indeed reliable and smooth. It almost let me down once in super freezing cold weather, did nothing when shifted into drive. I just backed it in the driveway again and let the engine warm up for a few minutes, then it worked fine. I took the car in to have the tranny serviced, but it had almost 200K miles on it. The honest transmission shop pulled the tranny apart just a bit to have a look, said every thing looked fine and I/they shouldn't fool with it. So, I agreed to let the car warm up on cold days and never had any further problems. Sure wish I could have kept that old Chevy, but New England rust got the best of it. I would also agree that the temp/AC/control system was second to none as well. Instant heat, defrost, and AC so cold that it had to be cycled on/off with the vent even on the hottest of days.
We had two fullsize GM vans at one time. One was a '85 Chevy Van 20 with a TH350 and 5.7L V8, and the other was an '84 GMC Vandura 20 with a TH400 and 5.7L V8. The older '84 was always a bit faster and peppier driving hard and towing, and just that bit smoother shifting when taking the family to church. I miss those vans. Was a great time to be a kid and go camping and travelling all over.
I miss my van too. Wish I had kept it. What a gem. '77 Chevy w/ small block 400 4bbl, THM 400, & factory A/C with the old "A-6" compressor. Blew enormous amount of the coldest air I've ever experienced! It was the one ton version with the true truck axle (had to unbolt & pull axle shafts to pull the brake drums) &, of course it was "posi" besides. Had to be a super heavy vehicle. (estimate it could have been 6000lb empty) As such it could still manage (by handheld stopwatch, starting from idle, not revved) 0-30 in 3 sec & 60 in 9. And although the steering was "vague" the heavy duty suspension & big "anti-roll" bars actually made surprisingly fun driving on country roads. Should have never left it go!
When i was a kid my dad had a 73 chev class C motorhome with 350 and turbo 400. Interior looked tasteful with charcoal and ivory cabin color with light wood tone, also had frigidaire ac … about as nice as you could get trim wise in a GMC. I loved it when he would drive it briskly because that drivetrain combo sounded and felt amazing. I didnt realize then the overbuilt quality of everything there at the time. Fond memories
Yes, yes, the switch turbo 400! I owned a 1967 Buick GS 400 and experienced that pitch switching. I had to do research on it to figure out that it was not defective. What a great transmission it was.
Thank you for this video Adam. I know I repeat myself a lot about the entertaining and educational value of your videos, however, let it be also said that they are also good as a reference (go to) when needed. I am currently interested in a 66 Olds that has a 425 TH400 and this video really helped to reassure me of the (TH400) quality. You also spoke on another video about a replacement trans filter and that was very good to know. Thank you! Cheers 😊
Great video and great tranny choice, too! I worked at Hydra-Matic (Willow Run) and I actually bid the production labor for the assembly of the prototype replacement for the THM 400 back in the late 1980s. It was the 400-R2 with a dual stator converter and a 4th gear. GM was trying to retire the THM 400 and produce a lighter 4 speed version, but even with cars becoming smaller trucks were still a serious consideration as were GM's outside customers (Rolls-Royce in particular). This thing supposedly climbed Pike's Peak heavily overloaded and the converter did not stall. Sadly GM went the cheap route and this wonderful concept transmission never went to production. Rolls-Royce and others would NOT accept the 700-R4 or the 200-4R On a side note: Not sure if fact or fiction, but the "buzz" at Hydra-Matic was that the THM 350 (I believe actually designed by Chevrolet Division) used in the Caprice at that time and while Chevrolet still controlled the calibration of the transmission was actually made to flare on shifts to attempt to sell Caprice owners that it shifted as smooth as a Cadillac. Well, soft calibration and flares = clutch wear and the ones of the late 1970s usually died before 90,000 miles. Who cared! A rebuild then was about $350! Oh the good old days when you could maintain and repair a car cheaply! But the 1970s also brought Frankensteins! GM started using just about all division engines across platforms and many were pissed that they paid for a Buick only to find it had a Chevy motor in it! I also saw the GM restructuring where the company made so many mistakes. Hydra-Matic eventually came under Powertrain. I saw the failed Pontiac Fiero redesigned into a decent car produced for only 1 year and scrapped (The Fiero GT). GM also turned the THM 325 into a 4-speed for one year and the fuel economy of the resized land yachts of the late 1970s into mid 1980s (FWD) with a small V8 actually got respectable fuel economy and would push you back into the seat if you hit the gas (albeit not much back force, but a bit of a relief from the Malaise days of gutless engines). So after building a great transmission for ONE YEAR they scrapped the platform entirely! I remember, too, seeing thousands of brand new THM 325 4L transmission sent to scrap vs. sold because of surface rust on the stamped steel brackets holding the torque converter in place. GM was the KING of wasting money and resources back then! Needless to say I bailed and never looked back! And YES: Our plant also produced the THM 200C. It was for gutless cars and was not one of GM's better ideas. I believe it actually started as a THM 180 and was always meant to be light duty. The 700-R4 was produced in Toledo at the time and went into cars with a bit more power. The 200-4R was produced in Western Michigan then as well and I believe ended up in the Camaros and Firebirds of the late 1980s. Once the cars started producing decent power GM had to hand weld the lugs to the converters vs using the spin weld like on the 200C. They sheared off! Don't get me started on the Cadillac V7-5-3... Uncle had one. More time in the shop than in the driveway! He ditched it and got a Fleetwood Brougham with a 4100 in it, but I thought it was a six, not a V-8... I'm still not sure to this day. But I do recall driving across Alligator Alley back in the day when it was a two-lane hwy only and if you planned on overtaking a slow vehicle ahead you needed a pair of binoculars to spot any potential oncoming traffic as you'd need a LOT of time to pass! Seem to recall watching the gas gauge drop about as quickly as the speedo rose! He finally bought a Rolls-Royce and told GM to PHUCK AUF! Also while at Hydra-Matic I remember all the Pontiac Grand Am 3.0 engines with no heat treating of cam lobes. Around that time I was stupid enough to buy a 1986 C Platform Buick Electra T-Type. Oh that 440-T4! Put THREE of them in the car in less than 10k miles! The 3.8L of that time had carbon issues causing stall issues too... that was the WORST car I ever owned! GM Hydra-Matic actually had to work with outside companies to ramp-up rebuilds of all the 440 T4s failing it was that bad! The 440-T4 was produced in Warren, MI at the time. I bought the '86 Electra under the GM employee program. We got huge discounts (18% typically). The only condition was that you had to keep a car for 12 months in your name before transferring title. I sold the Electra in 10 months and LOST my Employee Discount as a result. So I bought a used Mercedes 450SE in Florida and a brand new Jeep Comanche Chief in 1987! On both I affixed "Real Americans Buy Whatever They Want" Bumper Stickers...and drove either proudly into the salaried parking areas! But none of the GMs I ever owned were as much fun as the X Car of the early 1980s. Mine was a Pontiac Phoenix LJ with the 2.8L Chevy motor. It was fun in slippery surfaces hitting the brakes because almost always you'd do donuts unintentionally (well, for most unintentionally... I turned it into a fun pursuit)... Pontiac: We build excitement! Yeah... the excitement of braking and when you're done facing 180 degrees from where you started! Love that one time on 441 south of Miami during a downpour where I decided NOT to run the light... BIG MISTAKE! After 2 360s and 1 180 I ended up facing North! Turned around and continued South... but at least I did stop before the cross traffic started! Oh GM: Your Olds 350 Diesel KILLED the passenger car market here for diesels! I suspect it even hurt Mercedes to some extent. Lest we forget the "wonderful" BMW Diesel back then that even made the 350 Olds look good! But funny: Had a fraternity brother who came from Western Michigan. Family owned a farm and they had a Delta 88 (1978 I believe) with the 350 Olds Diesel. He was driving it at school and it had almost 250k miles on the odometer. I think the trick with the Olds 350 diesel was long driving cycles vs. short. Being rural it got a lot of miles each run and this seemed to contribute to its durability... I can only speculate. But thinking of Big Rigs always idling and rarely ever shut-off it does make sense. It was no powerhouse however. My 1977 Buick Electra Park Avenue with the Buick 350 and THM 350 would leave it in the dust! Now to the 1973-1975-1/2 models! Nippon Steel. Defective! ALL GM Cars from this era rusted-out in 3 years or more. How sad GM didn't verify the quality of the supplies it purchased. I suspect the Japs knew this and sabotaged what was left of GM's reputation. Smart move on the Japs part! Lazy and predictable response from a once great US Giant on the way down. My family was part of a lawsuit collective action, but GM had lawyers and all lost. Well, Did we? I won't buy their crap anymore! BTW: For you FORD Fans out there: Ford bought the same steel, but not nearly to the extent GM did! Chrysler never did, but Chrysler is an entirely different matter in this time frame. They had just recovered from a near death experience.
@@motoxdudeNV-UT oh, the storys you could tell! I have an '85 FWD Olds 98 4.3 V6 deeeezel... And many Corvairs, and a 1st gen BMW V12, and 2 '66 Toronado's, and a last last '78 Eldo, and several 6.2 and 6.5 Suburbans and on and on...
@@CORVAIRWILD Some good, some not so good... in the end we all hope we can choose! But today's consumer is a willing livestock accepting his/her path to slaughter! I'm 59 and younger are NOT taught to question. They are taught to Obey and Comply! Just shut-up and BUY IT! It's "New and Improved"! That's all you need to know!
I have the TH400 in my 1970 Pontiac Catalina which I still drive in the summer. The car has nearly 300k miles and the transmission has never been out of the vehicle. I put a TransGo shift kit in it in the mid 70's and the shifts are still quick and crisp.
Since I have a '67 Eldorado, I got a switch-pitch (SP) THM-425 for free! Well … not exactly. My car had been sitting, unattended, in a storage facility for 10 years. I'm not sure any transmission can endure drying out for that long. Still, it lasted for a few years before failing on me. In an all-time first, the mechanic who rebuilt it *thanked* me for the "opportunity" to work on the esteemed THM-425 (particularly from an Eldorado). But he still charged for the parts and labor. 😊 One aspect of the Toronado/Eldorado system that has become problematic is the durability of the Quadrajet-mounted switch that is used to control the transmission. That plastic-and-metal switch - mounted just above the extremely hot intake manifold - deteriorates more quickly than any other component. As a result, a new THM-425 switch is Unobtainium. Mine crumbled to bits a few years ago. To replace that switch-pitch controller, I bought a home-made controller from a savvy switch-pitch enthusiast that uses a combination of engine vacuum and a timer to control the SP stator. One of this post-GM-design quirks is that, if the car idles at a stop light for more than about 12 seconds, the timer in the switch-pitch controller shifts the stator from high to low stall. If you don't have your foot on the brake, this means that the Eldorado starts to move forward, even if you're pointed uphill. It's as if the car says "OK. We've been sitting still long enough. Let's go!" In normal operation, as you point out, you can't really feel the car go through the gears (and switch-pitch phases). All you can sense is that the engine always seems to be ready to go whatever speed you prefer, thanks to the THM-425's ability to keep the engine in its happy zone. I think that the switch-pitch was doomed by its own smoothness of operation. It would be tough for the typical car buyer to feel the difference between a SP and a SP-free THM 4xx. Given that practical outcome, I could see why GM beancounters would say, "If the public can't feel the difference, why spend money on it?" Another great chat. Thanks!
With the help of a friend, we converted my 66 Fleetwood from carb to throttle body fuel injection off a 91 Chevy. One of the challenged became how to activate the switch pitch converter and the downshift solenoid since the linkage and everything was different now. I put on my thinking cap and ended up using a microcontroller that reads the throttle position sensor voltage and based on the programming I set up, activates those solenoids. The nice thing is I can change whenever the solenoids are activated. The downside is there is more wiring.
@@clarkinthedark1 I did similar to this on my 68 Toronado. I didn't know I had a switch pitch until I pulled the converter to swap it. I used a cheap pressure switch that I hillbilly mounted to the gas petal. I then have it go to a relay with a small electric motor that activates the solenoid. Works but I want to make a not as ghetto one next time I pull the transmission. I have a offy single carb tunnel ram on it with a basset scoop. I can't really figure a way to make it not giant and messy at the carb.
So much fun to learn more about these things know more history. My 1964 Bonneville has a TH400 and it is next to perfect. A once took the filter to a place in Charlotte NC to see if I could get one and it stoped the place. All the old guys came out of the back and said CAREFULLY clean that filter and put it back in. I will say that I don't like the way the dip stick tube goes into the pan as it tends to drip, but I have found a way to stop that. I also found the O rings going to the cooling tubes tend to weep but that is an easy fix by removing the plate and fitting new rings. I once had a 1962 TBird and it shifted so hard. By the time I got it the reverse shaft was broken. It also did the Ford going into gear at idle from P without asking! I had the beast rebuilt and put the detent fix on the shifter. I also found in the TBird that a direct shift into R from P was very hard and that quickly going past R and going in from the right it was smoother? It just worked but that car is gone. It was a triple black convertible and to be honest I was glad to see it go. I love my Bonneville. We had a 1965 conv Bonnie when I was a boy but I like the 1964 better. Your information is just great and I hang on every word! You have really informed me about all of this on many levels. I saw the band Liquid Velvet in Chapel Hill NC at a place called The Cave too! Bobby
I worked at a Chevy dealer in the 70's. When I went to Hydramatic training we were told 400's were bench tested at the end of assembly and the 350's were not. That explained why you rarely saw a 400 in for any service but the shop always had 350's in for problems. I had several 400's in cars and they were always dependable. They just needed to be serviced regularly.
Hi Adam, Another fantastic video! Thanks so much! I'm no transmission expert and frankly never gave too much thought to automatics. This is not because I prefer to drive stick shifts (although this preference clearly has an influence), but rather because the function of an automatic is so mysterious to me still. I know how combustion and compression work, carburetors, venturi tubes, distributors, turbos, superchargers, alternators, cam shafts, slide valves, and so on. But how shift mechanisms work, and the most mysterious of all, the torque converter, has always been a mystery. I don't suppose you'd do a video about that, would you? Perhaps your other fans are much more knowledgeable than I. The "switch pitch" is fascinating and remarkable simple and innovative. In principle, I get it. But the rest is Greek (and I read Greek, so that tells you how mysterious it is to me). But thanks so much. Loving this series. And I hope you'll occasionally go back to these topics and go into even more detail, where you find there's more of a story to tell. Fantastic series (porch chat) to get us through the gloom and doldrums of winter until you get back to the feature cars. Fantastic! Thanks again!
I have always heard good things about the THM-400. Most of my GM vehicles have had the THM-350, which I've always been happy with. I have a GM car with a switch pitch ST-300. I've also owned many Chrysler 727s and 904 automatics - never had any problems with those.
I have a TH400 in my 68 Chevelle so as I started watching the video I was like Adam please say the TH400! So I was happy to hear your pick! Yes, it is very solid and shifts so smoothly.
I was just watching a video about a bloke in the UK who somehow installed an RR Meteor 27L tank engine in a Rover SD1 street car. This engine can output almost 2000 Nm (1500 lb ft) at something like 2500 RPM. My first thought was what kind of transmission is he using? Turns out he used a TH 400 with a weird torque converter. The back axle was taken from a 70's F-150. Truly a Frankenstein vehicle. :D
I have a 1932 Ford 3 window in which I installed a 401 Nailhead with a Super Turbine 400 and a 3.25 ratio Ford 9 inch with a Detroit Locker. Have the switch-pitch switch on a switch panel in the cab. At the drag strip, I have run a 13.2 with street tires. Use the high stall to get off the line but have to switch to low stall pretty quickly to limit wheel spin. I believe the Turbo Hydramatic 400 replaced the Dynaflow in Buicks (an ahead of their time CVT transmission using the varying torque converter pitches as a substitute for changing gear ratios in the tranny-although Dynaflows did have a low and a high ratio in the tranny). The Dynaflows were smooth with no shifting through the rpm range but were inefficient. Some 1964 Buicks came equipped with the THM400 with electronic passing gear with only with one electrical terminal on the transmission-no switch pitch. Then I believe in 1965-1967 Buick added the switch pitch feature which added a second electrical terminal to the transmission. The SP300 was used in smaller Buicks and was a Powerglide with the switch-pitch feature. The Super Turbine 400 transmission works beautifully and I believe is a work of industrial art.
Love the bulletpfoof TH400. I own a '70 Olds 442 with a 455 and a TH400. I freshened up the drivetrain a number of years back and added a 2500 stall converter, a real nice enhancement to that torque monster. I worked at a full repair garage during college in the late 1970's. We had many GM TH350 failures usually in half ton trucks. I remember the shop owner would convert them over to a TH400. I have no menory of him ever rebuilding a TH400. I will say from my experience the TH350 in a passenger car was very reliable. My Mother's '69 Camaro went 225K miles before she sold it with the original TH350 still in good working order.
The TBH 400 had an excellent, smooth shifting design as compared to previous GM automatics. The difference between our '62 and '65 Pontiac Bonneville was major. At that time the power steering changed to variable ratio and the driving experience was a huge improvement.
Remember the Slim Jim ? I bought a 1964 Grand Prix with a 389 . It ws starting to slip when I bought it . I put a junk yard unit in on my back with a floor jack . We did a lot of stupid stunts in that car . It would dig deep ruts in someone's front lawn !
Mate, I'm a mechanic in Australia of 25 years. I've been watching your vids since you kicked off and I've learnt so much! Even though we've got a LOT of your engineering over here, I have to say I'm glad we didn't get all these weird-ass front wheel drive setups that you guys have. 😅 Keep up the great vids. 👍 Rob.
Rolls Royce used the GM turbohydromatic bought in unmodified from the 1960s to 1990s. I owned a 1978 Rolls Royce Silver Wraith that needed a new transmission. The Rolls Royce dealer quoted me $15000 for one (this was in 1991). I found a mechanic who got a brand new transmission from Chevrolet and it dropped right in to the Rolls Royce with zero modification. Cost $350.
Don't forget the 4L80E from 1991-2013?, its basically a 400 with an overdrive added as you know. I liked the ones with straight cut planetarys, reminds me of the old "rock crusher" manual trans!
GMC's 400 & Chrysler's 727 were great, owning many! However Ford's C6, I believe,was the only one allowing a start in 2nd gear? Great on slippery surfaces!
Back in the day we used TH350 usually because they were everywhere, cheap and there is 30hp less parasitic loss over TH400. 455's and 454 gotta have Th400, the Th350 could stand up to most 400.
Very informative and accurate review or the THM 400. I had a 68 Buick GS 400 with the THM 400. I use to street race it and manually shift the tranny. I would get a peel of rubber when I shifted into 2nd gear. The car was completely factory stock. I put 51,000 miles on the car, I never changed tranny fluid or filter and it never leaked or had any problems such as slipping. I agree with you that the THM 400 is a fantastic piece of engineering, reliability and durability.
My first car was a 67 Coupe DeVille. It would really launch when you asked it to! I was driving the best transmission ever, and just took it for granted as a kid. Well, not really I loved that car!
I ran a switch pitch 400 in my '73 Buick Regal behind a 455 Buick,deleted the throttle switch and put a toggle switch on the dash,my secret weapon,it was a blast to drive and blew off quite a few unsuspecting corvette,barracudas and others
The first year units were a bit different from the rest. They used a Powerglide shift quadrant, PRNDL, even though it is a 3 speed. You can shift it manually, but you have to rock the shift lever back and forth between low and drive to shift it. Start in LOW / 1st, move to DRIVE to catch 2nd and pull lever back to LOW. When ready for 2 - 3 shift, move lever back to DRIVE. 55 - 57 TBirds were similar, except on those if you start off in DRIVE, it starts in 2nd gear. To shift those AND utilize all 3 speeds, you drive it just like the early TH400. For the 65 models, GM went to the familiar 3 speed quadrant that they used for years.
Another great video! Thank you Adam. The 400 is a very good trany no doubt. Back in the 80’s in our locale which is ag based we saw a lot of 4x4 trucks pulling anhydrous ammonia tanks. The 727 and 400 did a great job, however on wet years when pulling got really tough, only the C6 consistently withstood overheating until the fluid dumped out the dipstick. And this frequent happened so indeed the C6 was tough. Smooth shifting would go to the 400 Turbohydramatic indeed but hardcore abuse I think the C6 gets the nod.
The best automatic transmissions I believe were the GM Turbo 400,the Chrysler 727 Torqueflite, & the Ford C 6 Trans. They were pretty bullet proof & I'm pretty sure that AMC vehicles used Chrysler Torqueflites also!!!
I know the guy that did the final inspection on those GMC motorhomes and he currently has one he is restoring himself and said that there is an annual meet up and parts swap amongst the owners of them. His name is John Metts and lives in Potosi, Wisconsin. My uncle owned a 1967 Riviera before I was born that he bought new. I owned a 1974 Riviera myself. The Riviera, Toronado, and El Dorado were called the E body, the Electra 225 and similar were the A body, and the Le Sabre and similar were the B body (at least for the 1971-1976 years) and the Monte Carlo, Regal, Cutlass Supreme, Gran Prix, and Malibu were G body from 1973 to 1988, not sure before and after.
One of the strengths of the transmission is the full round case. It isn't open at the bottom. Also, it uses clutches to apply all gears with the exception of manual low and reverse. The forces inside the case are forward and rearward. Ford transmissions, C6 and C4, have open cases and in high load situations applying the intermediate band tends to spread the case. Chrysler side stepped this somewhat by having the intermediate servo applied through a lever arrangement. The 400 is a really great transmission. I have one, with a switch pitch, behind a 401 Buick in my 1928 Model A. Under light throttle it is hard to tell when it shifts.
Hay Adam Looks like you found something alot of ppl like your talk on best of worst of. I watch all your stuff , your voice and mannerisms fo it for me very nice energy. Love.your channel
The GM Turbo 400 Transmission is so Good with an Aftermarket Reid Case and a few Billet Steel parts upgraded it's good for 2000 Hp. A few more Aftermarket parts with stock Planetary gearsets retained it's good for 5000+ Hp.
The Chrysler 727 was well known to be the strongest transmission at the time. So much so they had kits to put one behind any Chevy, Ford, Jeep etc. no modifications needed, you could go straight to the track. Today the ZF8 is by far the best, also found in Chrysler products
Loved my 1976 Chevy C250 with 350cu engine and THM400 trans..... what a serviceable heavy duty beast with 8' bed! But just 3 speeds sucked... should have gotten a GEARVENDOR OD............. I sure miss that truck
I am using a GM Turbo 400 from a 1988 Chevy P30 Butternut Van delivery Truck Bone Stock in my 1963 Pontiac Grand Prix with the Pontiac 455 520 Hp Hp 500ft/lbs engine I built for it. It spins to 7000 rpms. I modified the Governor for 6500 rpm full auto 1-2 & 2-3 upshifts with a B&M TH400 Governor Recalibration kit. Hasn't failed any the Turbo 400. Using a TCI Chevy Turbo 400 to BOP Pontiac V8 Steel Transmission adapter plate. A Hughes 2500 HD Pontiac V8 455 Torque converter with a Heavy Duty Sprag inside full Torrington needle bearings and furnace brazed Full the turbine and stator fins.
On THM400, center support wore case. It would then move in case and cause hollow bolt to break. Then first to second shifts were slow. Had 84 3/4T Suburban and needed to get the trans rebuilt.
I have a 1973 GMC motorhome and have modified the THM425 for the switch pitch. I've changed the diffy to a smaller numerical ratio (taller gears less RPM) and use the switch pitch for steep grades and passing. If one were to make these mods, a larger trans cooler is needed. It's been working perfectly for about 20 years.
Back in the day alot of Buick guys would put these in their drag cars but would put the control on the shifter with A button switch. And it would stall up in the 3 and 4 thousand range.
Th400s were used in bread vans with either the 6.2/6.5gm turd diesel or the 4b Cummins. Seen em in both. Some of em have a fancy finned converter cover vs the standard stamped steel one.
The Super Turbine 400 was developed by Buick to replace the TwinTurbine Dynaflow for the 1964 model year. It was only used in Buick in '64 except for one Cadillac model.
I remember reading about the 1966 Oldsmobile Toronado using a chain drive between the torque converter and the transmission. To see it at 3:27 was fascinating. Imagine close to 500 FT-LBS of torque being transfered through that! What type of maintenance was required for that chain? Lubrication schedule? Replacement? Or was no service required and lasted the life of the car?
It was a robust heavy chain - this is why this transmission was equally reliable in the GMC motorhomes of the early/middle 1970's. Also, they were used reliably in a few oddball exhibition and drag cars with north of 1,000 hp.
The chain in the TH425 is ridiculously strong. Look up the Hurst Hairy Olds for more proof. For those who have never heard of this car, it was a 66 442 with twin Toronado drive trains. It had 2 supercharged 425 olds engines, each making about 1700hp, with Toronado transaxles. It was famous for doing 4 wheel 1/4 mile long burnouts. It was a handful to drive, it was wrecked several times. If the chain can handle a supercharged 1700hp, your not going to break it on the street.
Did I call it or what? The Super Turbine 300 also had a switch pitch, but alas it was a 2 speed. Most people erroneously call them Powerglides. The switch pitch was used in Olds and Buick, but the Pontiac 300, did not. (no, your 1965 GTO with a 2 speed is NOT a powerglide, it is a Super Turbine 300).
The TH 400 was even used in 3 ton trucks according to a friend who is a great mechanic. I got my TH 400 serviced (oil and filter) and I never had any problems. I even towed a holiday trailer with the 427 and TH 400. We put on over 115,000 miles on the car and it was sold to a relative. I later had a 1978 Olds with the 403 engine. It was nothing like the 427. The 1978 Olds was replaced with a 1980 Olds with a 350 engine. It was special ordered to be our trailer car. However, when I went to undercoat it, I discovered that it had a 200 transmission. Imagine, putting in a 200 transmission in a trailer vehicle. My mechanic friend said the 200 transmission had some parts akin to an apple juice can. I phoned my GM dealer and he said that he had a 1980 Olds station wagon ordered for trailering that was due in a couple weeks. He was fair to me and we picked up the station wagon in a couple of weeks. It had the TH 350 transmission. The 350 engine was the Oldsmobile engine but it was barely satisfactory in pulling a trailer, especially in the mountain passes around Radium, BC. I was starting to realize that there were other manufacturers besides GM.
I would like to say they are indestructible. But I actually broke one in my 72 Grand Prix 455. I was 16 years old. And beat it badly. Along with 100k miles. It finally said "I give up"! Got a rebuilt replacement for 325.00. This was in 1981. Much better times indeed.
Power glide 2 speed , loved them , 1st gear good for 110 mph then you grab 2nd gear , so smooth and so prompt too , very tough reliable and can handle big power
my Dad had Pontiac wagons and Chryslers - the 727 was better than the GM hydramatics the 1965 New Yorker could be push started because the 727 was so over engineered Hemmings actually recommends replacing the GM transmissions w/ the 727 for added "durability" "The A-727 was one of Chrysler's most versatile workhorses for over 30 years, and its strength and ability to handle high-performance power with ease made it a popular choice with many other manufacturers. Finding a replacement unit for your car, whether it is a Mopar, AMC or International, should be an easy task, and adapting an A-727 to your GM car can add durability to any automatic drivetrain."
Imagine if they brought this technology back for the modern ones. They can make these anemic 4 cylinders (which I’d never drive) actually have some pickup, especially with modern fluids and technology being around now. Well done on this series!
My first car in high school was a '65 Olds 98 with a 425 V8 and TH400. It was a solid drivetrain pulling around a heavy car. When I see the crazy horsepower ratings on stuff like Hellcats I wonder how robust the transmissions are in those cars. I have not had very good luck with Mopar transmissions in cars with just average horsepower.
The Hellcat Drag Racers were and still are Turbo 400 swapping out thier 8-speeds. Also a Turbo 400 weighs 135 lbs only. They improved the Later 8-speeds in the Dodge Demons has a Factory Trans Brake for front wheels off the ground launches on the Streets.
They all had there problems and good thing they did kept me employed, THM 400 would always come in with forward clutches burnt, Back then transmissions would usually show up with about 60-80 thousand miles in need of an overhaul ,to make them really last a trans go shift kit would be installed, Variable pitch two wire 400 was not around that long only saw a few come into the shops in Boston then they disappeared , most modern transmissions will get double that but thousands of dollars to rebuild them when they fail. retired trans builder
How often did you see the intermediate snap ring blow out of the case on 400s? I ve had a few of them. Trans Go at one time sold a super heavy duty snap ring that would minimize the issue, but not until the redesigned case was introduced (Chevy bellhousing only) in the late 80s did the problem entirely disappear.
@@donreinke5863 A few, not that many ,that snap ring came in the shift kits and needs to be indexed in the case. rear planet pinions digging into the carrier housings in heavy weight applications.
Please explain the Chevrolet Turbo-Glide transmission when you get a chance. One of the first non-belt CVTs? Progressive? Obviously a failure in the market at the time. Rushed into production? First GM aluminum auto trans case? A necessary prequel to the buttery smooth Turbo-hydromatiscs to follow? Thanks for all the info you provide.
I remember all the car magazines in the 80s talking about torque steer in transverse fwd cars, and how it was nearly impossible to handle over 200hp or lb.ft torque [can't remember which]. meanwhile, these TH425 cars had no such problem with double the torque and power.
The switch pitch was used in dynaflo as well? I had a '63 LeSabre for a short period of time and found the transmission to be surprisingly good. Not Turbohydramatic good, but better than expected.
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I knew this would be your favorite! The TH400/425 SP is a honey of a transmission - which is why so many non-GM manufacturers made this their transmission of choice. Adam, I hope you do a video on the great GMC motorhomes of the early/middle 1970's.
I'm a 57 years old GM car guy.... I enjoy watching and listening to your videos..... you know your stuff....
The TorqueFlite was not just used by Chrysler; it was adopted by luxury automakers Monteverdi, Facel Vega, Bristol, Aston Martin, Maserati, and Jensen, as well as domestic rival AMC and commercial-vehicle makers International Harvester, Land Rover, Iveco, Karrier, Matbro, Stonefield, Sirmac, Boss Motor, and Mitsubishi.
Didn’t the vector W8 use it as well?
They have a really good
When I worked at a Dodge dealership, I had a customer call and ask if I had a starter in stock for an Aston Martin. I reminded them that he had called a Dodge dealership. His reply was that it took the same starter as a 440 engine. The reason was that his relatively new Aston Martin had a TorqueFlite transmission to which the starter bolted.
I am a GM guy but also bit of a Mopar guy too. I'd have to rate the 727 Torqueflite nose to nose here. Both great transmissions and pretty much bulletproof. My dad bought a brand new 1966 Buick Riviera with the 425 Nailhead and the TH400 with the switch pitch convertor. That car was amazing! I drove it in the mid 70's in my High School years.
I have always understood that the 727 Torqueflite is first rate.
727 was the choice on the drag strip - bulletproof
Yeah I agree the 727 is incredibly strong and reliable and Is say the best. Just dont try to run it without the kickdown hooked up:)
727 was 1 real good Tran too.
The 727 Torqueflite was stronger and smoother in some respects than the TH400. A lot of international companies used them along with Chrysler engines ( Jensen, Bristol, Monteverdi and others )
I love how you suffer with the wind and your hair blowing all over the place to give us the facts about these great transmissions. Another great one thanks!
Not surprised this is your favorite, it's very possibly my favorite as well. Just an excellent transmission that fit perfectly the era of big block, full size luxury cars that GM did so well with during the mid 60s- early 70s. Really was the golden era of GM imo, and the th400 was a big part of that excellence.
TH400 also used in Humvees until 4L80E. When the Hummer was armored-up (which it was not originally designed to) and you added additional weaponry, etc.... it became very heavy. To move it meant the 19 year old just floored the 6.2/6.5 diesel and held it there. The TH400/4L80E took that punishment in all kinds of environments including 120 degree desert!
Ford's philosphy with the C-6 was that more positive shifts would result in less wear. My dad was taught this in Ford transmission school. As a Ford service manager, he heard some complaints from owners that didn't like it compared to the smoother-shifting GM transmissions.
Your right, the three kings of automatics: Turbo 400, 727 and C-6. The three kings of manual transmissions are the: Top Loader Ford, Chrysler A833 and GM's M23 'RockCrusher. Thanks for posting, very enjoyable.
T 10?
You’re forgetting the sm465
I think the np 1ton four speed should be in the top 5.
@@michaelking550 my dad put a t-10 behind his 71 402 Cheyenne Super and exploded 2nd gear and destroyed the case.
M-22 not M-23, T-10 is junk,
The TH400 is a bulletproof and very reliable. It was the main transmission found in several gm muscle cars and gm personal cars as well as several foreign brands. Proof of its clever conception and durability
Hey Adam. Growing up as a kid we had a 66 Cadillac with 390 v8 and a 400 Turbo-Hydra Matic. The best shift I have ever felt in my life to date and I'm now 60 years old. Nothing will ever replace it.
66 Cadillac would have had a 429
@@tonykramer4976 66 caddy had both 390 cid and 429cid
One had the distributor at the front the other at the back of the motor.
I own a 66 Cadillac Calais, it has the 429. My dad had a 65 sedan Deville it too was a 429. To my knowledge the 390 was last used in 64. The 429 replaced it and the 429 was replaced by the 472 in 68 which was bumped to 500 in 1970. 472 disappeared after 74 and the 500 was gone by 77
@@tonykramer4976 Hey Tony. I was not aware the usa is different from Canada. I also saw I GM build on a 68 caddy where the usa uses leaf springs in the rear of the 68 caddy. Unheard of here in Canada. I Grose to put leaf springs in any caddy.
A727's were used by some other manufacturers as well.
A lot of the British coach cars of the 60s and 70s used these due to their reliability.
My Father had a 1965 Wildcat and a 1967 LeSaber, both with the Super Turbine 400 with the dual pitch converter. The Wildcat was especially quick off the line. The LeSaber was repaired by someone who didn't know what he was dealing with and left the connector off the throttle linkage. When it was replaced properly it was SO MUCH better! I understand that some drag racers liked to get these converters and install them with a manual switch on the dash so when they made a run they could set it for best acceleration. It was really like having two different levels of passing gear.
Between my dad and I we had five THM-400's, four Pontiac 400s and a Cadillac 472. Never had one fail.
I will say that my parents' 1965 Country Squire survived many, many neutral drops that I subjected it to as a teenager just fine. Long live the Cruise-o-Matic, with its rough 2-3 shifts and all!
The Ford C-6 is superior to the GM Turbo Hydramatic 400..This is why..
The lugs in the case that retain the snap ring on second gear tend to blow out of the case, rendering the case junk, this was an issue on Turbo 400s made before 1987 when GM revised the case design.
The C6 and Torqueflite never had such issues.
This guy simply doesnt have all the information.
That is great! I remember doing neutral drops in my parent's cars a lot when I was 16 to impress my buddies. I watched a friend of mine drop a driveshaft out of 58 Chevy wagon doing that. Those were the good old days. Can you even do a neutral drop in a modern car?
@@uhplumber5962 Sure you can! Search "neutral drop" on TH-cam to see hundreds of them.
The 1965 Chrysler 426 Hemi Cornet with the 727 Torqueflite is the Best 727 Torqueflite ever made. It shifted at 7000 rpms Factory Bone Stock 1-2 &2-3 Full Auto left in Drive.
Check Out Jay Leno's 1966 426 Hemi Cornet 727 Auto with 3.23 Posi. He is Street Racing on Los Angelous Freeways with doing 100 -130 mph Blowing Everyone's Doors Off Late Model ! !
I like to comment on the Chrysler torqueflite Transmissions from the sixties and seventies and I understand these are a legendary tranny with reliability and practically Bulletproof.
I think it and the TH400 at the top of the heap there.
Drag racers loved Torqueflites.
Torqueflites were simpler to rebuild
Great presentation. If I remember correctly this transmission was originally known simply as Turbo Hydramatic. I think it only became known as Turbo Hydramatic 400 in 1969 when the turbo 350 was introduced. Similarly, General Motors transit buses only became known as “Old Look” once the “New Look” (a.k.a. Fish Bowl) buses were introduced in 1959.
Rebuilding automatic transmissions 46 years ,and you are very correct 👍 I find it almost impossible to find a better 3 speed ,, and the 425 would put me out of business because I've only rebuilt 5 of them in my life EDWARDS BROTHERS TRANSMISSION IN ROANOKE RAPIDS NC ..
my late maternal grandmothers used 1979 Cadillac Coupe Deville she drove when I was a little girl it was that car that made me fall in love with Cadillac had this transmission and rode smooth as silk
My 73 Caprice had the thm400 and it was indeed reliable and smooth. It almost let me down once in super freezing cold weather, did nothing when shifted into drive. I just backed it in the driveway again and let the engine warm up for a few minutes, then it worked fine. I took the car in to have the tranny serviced, but it had almost 200K miles on it. The honest transmission shop pulled the tranny apart just a bit to have a look, said every thing looked fine and I/they shouldn't fool with it. So, I agreed to let the car warm up on cold days and never had any further problems. Sure wish I could have kept that old Chevy, but New England rust got the best of it. I would also agree that the temp/AC/control system was second to none as well. Instant heat, defrost, and AC so cold that it had to be cycled on/off with the vent even on the hottest of days.
Yeah, wish we could have that 73 Caprice back, but in convertible form...
We had two fullsize GM vans at one time. One was a '85 Chevy Van 20 with a TH350 and 5.7L V8, and the other was an '84 GMC Vandura 20 with a TH400 and 5.7L V8. The older '84 was always a bit faster and peppier driving hard and towing, and just that bit smoother shifting when taking the family to church. I miss those vans. Was a great time to be a kid and go camping and travelling all over.
I miss my van too. Wish I had kept it. What a gem. '77 Chevy w/ small block 400 4bbl, THM 400, & factory A/C with the old "A-6" compressor. Blew enormous amount of the coldest air I've ever experienced! It was the one ton version with the true truck axle (had to unbolt & pull axle shafts to pull the brake drums) &, of course it was "posi" besides. Had to be a super heavy vehicle. (estimate it could have been 6000lb empty) As such it could still manage (by handheld stopwatch, starting from idle, not revved) 0-30 in 3 sec & 60 in 9. And although the steering was "vague" the heavy duty suspension & big "anti-roll" bars actually made surprisingly fun driving on country roads. Should have never left it go!
When i was a kid my dad had a 73 chev class C motorhome with 350 and turbo 400. Interior looked tasteful with charcoal and ivory cabin color with light wood tone, also had frigidaire ac … about as nice as you could get trim wise in a GMC. I loved it when he would drive it briskly because that drivetrain combo sounded and felt amazing. I didnt realize then the overbuilt quality of everything there at the time. Fond memories
Yes, yes, the switch turbo 400! I owned a 1967 Buick GS 400 and experienced that pitch switching. I had to do research on it to figure out that it was not defective. What a great transmission it was.
These lived on as Allison 4spd in heavy duty/commercial applications into the millennium
Adam... These videos are great really appreciate you braving the weather were having this year to bring them to us... Thank You keeping them comming.
Thank you for this video Adam. I know I repeat myself a lot about the entertaining and educational value of your videos, however, let it be also said that they are also good as a reference (go to) when needed. I am currently interested in a 66 Olds that has a 425 TH400 and this video really helped to reassure me of the (TH400) quality. You also spoke on another video about a replacement trans filter and that was very good to know. Thank you! Cheers 😊
Great video and great tranny choice, too! I worked at Hydra-Matic (Willow Run) and I actually bid the production labor for the assembly of the prototype replacement for the THM 400 back in the late 1980s. It was the 400-R2 with a dual stator converter and a 4th gear. GM was trying to retire the THM 400 and produce a lighter 4 speed version, but even with cars becoming smaller trucks were still a serious consideration as were GM's outside customers (Rolls-Royce in particular). This thing supposedly climbed Pike's Peak heavily overloaded and the converter did not stall. Sadly GM went the cheap route and this wonderful concept transmission never went to production. Rolls-Royce and others would NOT accept the 700-R4 or the 200-4R
On a side note: Not sure if fact or fiction, but the "buzz" at Hydra-Matic was that the THM 350 (I believe actually designed by Chevrolet Division) used in the Caprice at that time and while Chevrolet still controlled the calibration of the transmission was actually made to flare on shifts to attempt to sell Caprice owners that it shifted as smooth as a Cadillac. Well, soft calibration and flares = clutch wear and the ones of the late 1970s usually died before 90,000 miles. Who cared! A rebuild then was about $350! Oh the good old days when you could maintain and repair a car cheaply! But the 1970s also brought Frankensteins! GM started using just about all division engines across platforms and many were pissed that they paid for a Buick only to find it had a Chevy motor in it!
I also saw the GM restructuring where the company made so many mistakes. Hydra-Matic eventually came under Powertrain. I saw the failed Pontiac Fiero redesigned into a decent car produced for only 1 year and scrapped (The Fiero GT). GM also turned the THM 325 into a 4-speed for one year and the fuel economy of the resized land yachts of the late 1970s into mid 1980s (FWD) with a small V8 actually got respectable fuel economy and would push you back into the seat if you hit the gas (albeit not much back force, but a bit of a relief from the Malaise days of gutless engines). So after building a great transmission for ONE YEAR they scrapped the platform entirely! I remember, too, seeing thousands of brand new THM 325 4L transmission sent to scrap vs. sold because of surface rust on the stamped steel brackets holding the torque converter in place. GM was the KING of wasting money and resources back then! Needless to say I bailed and never looked back!
And YES: Our plant also produced the THM 200C. It was for gutless cars and was not one of GM's better ideas. I believe it actually started as a THM 180 and was always meant to be light duty. The 700-R4 was produced in Toledo at the time and went into cars with a bit more power. The 200-4R was produced in Western Michigan then as well and I believe ended up in the Camaros and Firebirds of the late 1980s. Once the cars started producing decent power GM had to hand weld the lugs to the converters vs using the spin weld like on the 200C. They sheared off!
Don't get me started on the Cadillac V7-5-3... Uncle had one. More time in the shop than in the driveway! He ditched it and got a Fleetwood Brougham with a 4100 in it, but I thought it was a six, not a V-8... I'm still not sure to this day. But I do recall driving across Alligator Alley back in the day when it was a two-lane hwy only and if you planned on overtaking a slow vehicle ahead you needed a pair of binoculars to spot any potential oncoming traffic as you'd need a LOT of time to pass! Seem to recall watching the gas gauge drop about as quickly as the speedo rose! He finally bought a Rolls-Royce and told GM to PHUCK AUF!
Also while at Hydra-Matic I remember all the Pontiac Grand Am 3.0 engines with no heat treating of cam lobes. Around that time I was stupid enough to buy a 1986 C Platform Buick Electra T-Type. Oh that 440-T4! Put THREE of them in the car in less than 10k miles! The 3.8L of that time had carbon issues causing stall issues too... that was the WORST car I ever owned! GM Hydra-Matic actually had to work with outside companies to ramp-up rebuilds of all the 440 T4s failing it was that bad! The 440-T4 was produced in Warren, MI at the time. I bought the '86 Electra under the GM employee program. We got huge discounts (18% typically). The only condition was that you had to keep a car for 12 months in your name before transferring title. I sold the Electra in 10 months and LOST my Employee Discount as a result. So I bought a used Mercedes 450SE in Florida and a brand new Jeep Comanche Chief in 1987! On both I affixed "Real Americans Buy Whatever They Want" Bumper Stickers...and drove either proudly into the salaried parking areas!
But none of the GMs I ever owned were as much fun as the X Car of the early 1980s. Mine was a Pontiac Phoenix LJ with the 2.8L Chevy motor. It was fun in slippery surfaces hitting the brakes because almost always you'd do donuts unintentionally (well, for most unintentionally... I turned it into a fun pursuit)... Pontiac: We build excitement! Yeah... the excitement of braking and when you're done facing 180 degrees from where you started! Love that one time on 441 south of Miami during a downpour where I decided NOT to run the light... BIG MISTAKE! After 2 360s and 1 180 I ended up facing North! Turned around and continued South... but at least I did stop before the cross traffic started!
Oh GM: Your Olds 350 Diesel KILLED the passenger car market here for diesels! I suspect it even hurt Mercedes to some extent. Lest we forget the "wonderful" BMW Diesel back then that even made the 350 Olds look good! But funny: Had a fraternity brother who came from Western Michigan. Family owned a farm and they had a Delta 88 (1978 I believe) with the 350 Olds Diesel. He was driving it at school and it had almost 250k miles on the odometer. I think the trick with the Olds 350 diesel was long driving cycles vs. short. Being rural it got a lot of miles each run and this seemed to contribute to its durability... I can only speculate. But thinking of Big Rigs always idling and rarely ever shut-off it does make sense. It was no powerhouse however. My 1977 Buick Electra Park Avenue with the Buick 350 and THM 350 would leave it in the dust!
Now to the 1973-1975-1/2 models! Nippon Steel. Defective! ALL GM Cars from this era rusted-out in 3 years or more. How sad GM didn't verify the quality of the supplies it purchased. I suspect the Japs knew this and sabotaged what was left of GM's reputation. Smart move on the Japs part! Lazy and predictable response from a once great US Giant on the way down. My family was part of a lawsuit collective action, but GM had lawyers and all lost. Well, Did we? I won't buy their crap anymore! BTW: For you FORD Fans out there: Ford bought the same steel, but not nearly to the extent GM did! Chrysler never did, but Chrysler is an entirely different matter in this time frame. They had just recovered from a near death experience.
I never understood GM making the Fiero a proper sports car for ONE year.
Wonderful write up!
@@CORVAIRWILD Thank You!
@@motoxdudeNV-UT oh, the storys you could tell! I have an '85 FWD Olds 98 4.3 V6 deeeezel... And many Corvairs, and a 1st gen BMW V12, and 2 '66 Toronado's, and a last last '78 Eldo, and several 6.2 and 6.5 Suburbans and on and on...
@@CORVAIRWILD Some good, some not so good... in the end we all hope we can choose! But today's consumer is a willing livestock accepting his/her path to slaughter! I'm 59 and younger are NOT taught to question. They are taught to Obey and Comply! Just shut-up and BUY IT! It's "New and Improved"! That's all you need to know!
I have the TH400 in my 1970 Pontiac Catalina which I still drive in the summer. The car has nearly 300k miles and the transmission has never been out of the vehicle. I put a TransGo shift kit in it in the mid 70's and the shifts are still quick and crisp.
I like how you transitioned from featuring those amazing survivors to porch talks when the cars should be away from the salty roads.
Yes. Needed something else while the roads are salty.
Since I have a '67 Eldorado, I got a switch-pitch (SP) THM-425 for free! Well … not exactly.
My car had been sitting, unattended, in a storage facility for 10 years. I'm not sure any transmission can endure drying out for that long. Still, it lasted for a few years before failing on me. In an all-time first, the mechanic who rebuilt it *thanked* me for the "opportunity" to work on the esteemed THM-425 (particularly from an Eldorado). But he still charged for the parts and labor. 😊
One aspect of the Toronado/Eldorado system that has become problematic is the durability of the Quadrajet-mounted switch that is used to control the transmission. That plastic-and-metal switch - mounted just above the extremely hot intake manifold - deteriorates more quickly than any other component. As a result, a new THM-425 switch is Unobtainium. Mine crumbled to bits a few years ago.
To replace that switch-pitch controller, I bought a home-made controller from a savvy switch-pitch enthusiast that uses a combination of engine vacuum and a timer to control the SP stator. One of this post-GM-design quirks is that, if the car idles at a stop light for more than about 12 seconds, the timer in the switch-pitch controller shifts the stator from high to low stall. If you don't have your foot on the brake, this means that the Eldorado starts to move forward, even if you're pointed uphill. It's as if the car says "OK. We've been sitting still long enough. Let's go!"
In normal operation, as you point out, you can't really feel the car go through the gears (and switch-pitch phases). All you can sense is that the engine always seems to be ready to go whatever speed you prefer, thanks to the THM-425's ability to keep the engine in its happy zone.
I think that the switch-pitch was doomed by its own smoothness of operation. It would be tough for the typical car buyer to feel the difference between a SP and a SP-free THM 4xx. Given that practical outcome, I could see why GM beancounters would say, "If the public can't feel the difference, why spend money on it?"
Another great chat. Thanks!
With the help of a friend, we converted my 66 Fleetwood from carb to throttle body fuel injection off a 91 Chevy. One of the challenged became how to activate the switch pitch converter and the downshift solenoid since the linkage and everything was different now. I put on my thinking cap and ended up using a microcontroller that reads the throttle position sensor voltage and based on the programming I set up, activates those solenoids. The nice thing is I can change whenever the solenoids are activated. The downside is there is more wiring.
@@clarkinthedark1 I did similar to this on my 68 Toronado. I didn't know I had a switch pitch until I pulled the converter to swap it. I used a cheap pressure switch that I hillbilly mounted to the gas petal. I then have it go to a relay with a small electric motor that activates the solenoid. Works but I want to make a not as ghetto one next time I pull the transmission. I have a offy single carb tunnel ram on it with a basset scoop. I can't really figure a way to make it not giant and messy at the carb.
So much fun to learn more about these things know more history. My 1964 Bonneville has a TH400 and it is next to perfect. A once took the filter to a place in Charlotte NC to see if I could get one and it stoped the place. All the old guys came out of the back and said CAREFULLY clean that filter and put it back in. I will say that I don't like the way the dip stick tube goes into the pan as it tends to drip, but I have found a way to stop that. I also found the O rings going to the cooling tubes tend to weep but that is an easy fix by removing the plate and fitting new rings. I once had a 1962 TBird and it shifted so hard. By the time I got it the reverse shaft was broken. It also did the Ford going into gear at idle from P without asking! I had the beast rebuilt and put the detent fix on the shifter. I also found in the TBird that a direct shift into R from P was very hard and that quickly going past R and going in from the right it was smoother? It just worked but that car is gone. It was a triple black convertible and to be honest I was glad to see it go. I love my Bonneville. We had a 1965 conv Bonnie when I was a boy but I like the 1964 better. Your information is just great and I hang on every word! You have really informed me about all of this on many levels. I saw the band Liquid Velvet in Chapel Hill NC at a place called The Cave too! Bobby
A 64 with the Turbo 400? Must have been swapped in, as that car came with the old 4 speed Hydramatic.
This is an excellent series.
I worked at a Chevy dealer in the 70's. When I went to Hydramatic training we were told 400's were bench tested at the end of assembly and the 350's were not. That explained why you rarely saw a 400 in for any service but the shop always had 350's in for problems. I had several 400's in cars and they were always dependable. They just needed to be serviced regularly.
Guess they made a choice to save money
Hi Adam, Another fantastic video! Thanks so much! I'm no transmission expert and frankly never gave too much thought to automatics. This is not because I prefer to drive stick shifts (although this preference clearly has an influence), but rather because the function of an automatic is so mysterious to me still. I know how combustion and compression work, carburetors, venturi tubes, distributors, turbos, superchargers, alternators, cam shafts, slide valves, and so on. But how shift mechanisms work, and the most mysterious of all, the torque converter, has always been a mystery. I don't suppose you'd do a video about that, would you? Perhaps your other fans are much more knowledgeable than I. The "switch pitch" is fascinating and remarkable simple and innovative. In principle, I get it. But the rest is Greek (and I read Greek, so that tells you how mysterious it is to me). But thanks so much. Loving this series. And I hope you'll occasionally go back to these topics and go into even more detail, where you find there's more of a story to tell. Fantastic series (porch chat) to get us through the gloom and doldrums of winter until you get back to the feature cars. Fantastic! Thanks again!
Back in the 60's Jim Hall used the Turbo Hydramatic 425 transmission in his Chaparral race cars!
I have always heard good things about the THM-400. Most of my GM vehicles have had the THM-350, which I've always been happy with. I have a GM car with a switch pitch ST-300. I've also owned many Chrysler 727s and 904 automatics - never had any problems with those.
I have a TH400 in my 68 Chevelle so as I started watching the video I was like Adam please say the TH400! So I was happy to hear your pick! Yes, it is very solid and shifts so smoothly.
Underrated channel. I love the porch chats! Fun to hear your take on the good/bad. Even the ugly! Well done as usual
I was just watching a video about a bloke in the UK who somehow installed an RR Meteor 27L tank engine in a Rover SD1 street car. This engine can output almost 2000 Nm (1500 lb ft) at something like 2500 RPM.
My first thought was what kind of transmission is he using? Turns out he used a TH 400 with a weird torque converter. The back axle was taken from a 70's F-150. Truly a Frankenstein vehicle. :D
I have a 1932 Ford 3 window in which I installed a 401 Nailhead with a Super Turbine 400 and a 3.25 ratio Ford 9 inch with a Detroit Locker. Have the switch-pitch switch on a switch panel in the cab. At the drag strip, I have run a 13.2 with street tires. Use the high stall to get off the line but have to switch to low stall pretty quickly to limit wheel spin. I believe the Turbo Hydramatic 400 replaced the Dynaflow in Buicks (an ahead of their time CVT transmission using the varying torque converter pitches as a substitute for changing gear ratios in the tranny-although Dynaflows did have a low and a high ratio in the tranny). The Dynaflows were smooth with no shifting through the rpm range but were inefficient. Some 1964 Buicks came equipped with the THM400 with electronic passing gear with only with one electrical terminal on the transmission-no switch pitch. Then I believe in 1965-1967 Buick added the switch pitch feature which added a second electrical terminal to the transmission. The SP300 was used in smaller Buicks and was a Powerglide with the switch-pitch feature. The Super Turbine 400 transmission works beautifully and I believe is a work of industrial art.
I really enjoy these porch chats!!! Thank you once again!!! 👍👍
Love the bulletpfoof TH400. I own a '70 Olds 442 with a 455 and a TH400. I freshened up the drivetrain a number of years back and added a 2500 stall converter, a real nice enhancement to that torque monster. I worked at a full repair garage during college in the late 1970's. We had many GM TH350 failures usually in half ton trucks. I remember the shop owner would convert them over to a TH400. I have no menory of him ever rebuilding a TH400. I will say from my experience the TH350 in a passenger car was very reliable. My Mother's '69 Camaro went 225K miles before she sold it with the original TH350 still in good working order.
The TH350 is a fine transmission, but it is not for engines larger than about a 380 or so.
My brother used the 400 on his '53 ratrod pickup behind a 327 V-8. Sat for two years and needed a rebuild. Still, a great Tranny. Took a beating.
The TBH 400 had an excellent, smooth shifting design as compared to previous GM automatics. The difference between our '62 and '65 Pontiac Bonneville was major. At that time the power steering changed to variable ratio and the driving experience was a huge improvement.
Remember the Slim Jim ? I bought a 1964 Grand Prix with a 389 . It ws starting to slip when I bought it . I put a junk yard unit in on my back with a floor jack . We did a lot of stupid stunts in that car . It would dig deep ruts in someone's front lawn !
Mate, I'm a mechanic in Australia of 25 years. I've been watching your vids since you kicked off and I've learnt so much!
Even though we've got a LOT of your engineering over here, I have to say I'm glad we didn't get all these weird-ass front wheel drive setups that you guys have. 😅
Keep up the great vids. 👍
Rob.
Thx!
Rolls Royce used the GM turbohydromatic bought in unmodified from the 1960s to 1990s. I owned a 1978 Rolls Royce Silver Wraith that needed a new transmission. The Rolls Royce dealer quoted me $15000 for one (this was in 1991). I found a mechanic who got a brand new transmission from Chevrolet and it dropped right in to the Rolls Royce with zero modification. Cost $350.
Don't forget the 4L80E from 1991-2013?, its basically a 400 with an overdrive added as you know. I liked the ones with straight cut planetarys, reminds me of the old "rock crusher" manual trans!
I had a 97 GMC 3/4 ton with a 7.4 and the 4L80E. Great transmission!
GMC's 400 & Chrysler's 727 were great, owning many! However Ford's C6, I believe,was the only one allowing a start in 2nd gear? Great on slippery surfaces!
Great video. Would be interested in your comments on the TH 350 vs 400 transmissions. I had several TH 350s over the years, they were rock solid IMO.
They were great trannys. Just not as robust as 400s.
Back in the day we used TH350 usually because they were everywhere, cheap and there is 30hp less parasitic loss over TH400. 455's and 454 gotta have Th400, the Th350 could stand up to most 400.
In anything but a big block the turbo 350 is more than sufficient 💪👍🔥 !
Very informative and accurate review or the THM 400. I had a 68 Buick GS 400 with the THM 400. I use to street race it and manually shift the tranny. I would get a peel of rubber when I shifted into 2nd gear. The car was completely factory stock. I put 51,000 miles on the car, I never changed tranny fluid or filter and it never leaked or had any problems such as slipping. I agree with you that the THM 400 is a fantastic piece of engineering, reliability and durability.
My first car was a 67 Coupe DeVille. It would really launch when you asked it to! I was driving the best transmission ever, and just took it for granted as a kid. Well, not really I loved that car!
I ran a switch pitch 400 in my '73 Buick Regal behind a 455 Buick,deleted the throttle switch and put a toggle switch on the dash,my secret weapon,it was a blast to drive and blew off quite a few unsuspecting corvette,barracudas and others
Had two Oldsmobiles with these! Bulletproof!😉
I adapted the turbo 400 to fit behind the small block Chevy in my 2001 s10
The first year units were a bit different from the rest. They used a Powerglide shift quadrant, PRNDL, even though it is a 3 speed. You can shift it manually, but you have to rock the shift lever back and forth between low and drive to shift it. Start in LOW / 1st, move to DRIVE to catch 2nd and pull lever back to LOW. When ready for 2 - 3 shift, move lever back to DRIVE. 55 - 57 TBirds were similar, except on those if you start off in DRIVE, it starts in 2nd gear. To shift those AND utilize all 3 speeds, you drive it just like the early TH400. For the 65 models, GM went to the familiar 3 speed quadrant that they used for years.
I had a th400 in my 70 olds 442. Never had a minute's problem with it and as far as I know it's probably still working to this very day.
I would love to hear your take on the A727 and A904 TorqueFlites!
Another great video! Thank you Adam. The 400 is a very good trany no doubt. Back in the 80’s in our locale which is ag based we saw a lot of 4x4 trucks pulling anhydrous ammonia tanks. The 727 and 400 did a great job, however on wet years when pulling got really tough, only the C6 consistently withstood overheating until the fluid dumped out the dipstick. And this frequent happened so indeed the C6 was tough. Smooth shifting would go to the 400 Turbohydramatic indeed but hardcore abuse I think the C6 gets the nod.
C6 is by far the strongest of the 3
The best automatic transmissions I believe were the GM Turbo 400,the Chrysler 727 Torqueflite, & the Ford C 6 Trans. They were pretty bullet proof & I'm pretty sure that AMC vehicles used Chrysler Torqueflites also!!!
I know the guy that did the final inspection on those GMC motorhomes and he currently has one he is restoring himself and said that there is an annual meet up and parts swap amongst the owners of them. His name is John Metts and lives in Potosi, Wisconsin. My uncle owned a 1967 Riviera before I was born that he bought new. I owned a 1974 Riviera myself. The Riviera, Toronado, and El Dorado were called the E body, the Electra 225 and similar were the A body, and the Le Sabre and similar were the B body (at least for the 1971-1976 years) and the Monte Carlo, Regal, Cutlass Supreme, Gran Prix, and Malibu were G body from 1973 to 1988, not sure before and after.
One of the strengths of the transmission is the full round case. It isn't open at the bottom. Also, it uses clutches to apply all gears with the exception of manual low and reverse. The forces inside the case are forward and rearward. Ford transmissions, C6 and C4, have open cases and in high load situations applying the intermediate band tends to spread the case. Chrysler side stepped this somewhat by having the intermediate servo applied through a lever arrangement.
The 400 is a really great transmission. I have one, with a switch pitch, behind a 401 Buick in my 1928 Model A. Under light throttle it is hard to tell when it shifts.
Hay Adam
Looks like you found something alot of ppl like your talk on best of worst of.
I watch all your stuff , your voice and mannerisms fo it for me very nice energy.
Love.your channel
Thx!
Don't forget the TH450. Motorhome and heavier truck chasis had them. Great Video.
Plate C
The GM Turbo 400 Transmission is so Good with an Aftermarket Reid Case and a few Billet Steel parts upgraded it's good for 2000 Hp.
A few more Aftermarket parts with stock Planetary gearsets retained it's good for 5000+ Hp.
The Chrysler 727 was well known to be the strongest transmission at the time. So much so they had kits to put one behind any Chevy, Ford, Jeep etc. no modifications needed, you could go straight to the track. Today the ZF8 is by far the best, also found in Chrysler products
Landrover zf8 is lovely
I have to agree with your choice, had one in a '70 Gran Prix with a posi rear end.
Loved my 1976 Chevy C250 with 350cu engine and THM400 trans..... what a serviceable heavy duty beast with 8' bed! But just 3 speeds sucked... should have gotten a GEARVENDOR OD............. I sure miss that truck
I am using a GM Turbo 400 from a 1988 Chevy P30 Butternut Van delivery Truck Bone Stock in my 1963 Pontiac Grand Prix with the Pontiac 455 520 Hp Hp 500ft/lbs engine I built for it.
It spins to 7000 rpms.
I modified the Governor for 6500 rpm full auto 1-2 & 2-3 upshifts with a B&M TH400 Governor Recalibration kit.
Hasn't failed any the Turbo 400.
Using a TCI Chevy Turbo 400 to BOP Pontiac V8 Steel Transmission adapter plate.
A Hughes 2500 HD Pontiac V8 455 Torque converter with a Heavy Duty Sprag inside full Torrington needle bearings and furnace brazed Full the turbine and stator fins.
I loved this transmission-it was in my 66 Starfire and NEVER let me down.
On THM400, center support wore case. It would then move in case and cause hollow bolt to break. Then first to second shifts were slow. Had 84 3/4T Suburban and needed to get the trans rebuilt.
as I'm from the UK I don't know all the cars you mention , but I love hearing about them.
I have a 1973 GMC motorhome and have modified the THM425 for the switch pitch. I've changed the diffy to a smaller numerical ratio (taller gears less RPM) and use the switch pitch for steep grades and passing. If one were to make these mods, a larger trans cooler is needed. It's been working perfectly for about 20 years.
Has any shop needed to work on it- rebuild, gaskets or seals?
Back in the day alot of Buick guys would put these in their drag cars but would put the control on the shifter with A button switch. And it would stall up in the 3 and 4 thousand range.
Th400s were used in bread vans with either the 6.2/6.5gm turd diesel or the 4b Cummins.
Seen em in both.
Some of em have a fancy finned converter cover vs the standard stamped steel one.
The Super Turbine 400 was developed by Buick to replace the TwinTurbine Dynaflow for the 1964 model year. It was only used in Buick in '64 except for one Cadillac model.
I remember reading about the 1966 Oldsmobile Toronado using a chain drive between the torque converter and the transmission. To see it at 3:27 was fascinating. Imagine close to 500 FT-LBS of torque being transfered through that!
What type of maintenance was required for that chain? Lubrication schedule? Replacement? Or was no service required and lasted the life of the car?
No maintenance, it was lubricated by ATF.
@@edwardpate6128 So it was completed enclosed and submerged in ATF ?
It was a robust heavy chain - this is why this transmission was equally reliable in the GMC motorhomes of the early/middle 1970's. Also, they were used reliably in a few oddball exhibition and drag cars with north of 1,000 hp.
No Maintenance. No replacement. Very strong.
The chain in the TH425 is ridiculously strong.
Look up the Hurst Hairy Olds for more proof. For those who have never heard of this car, it was a 66 442 with twin Toronado drive trains. It had 2 supercharged 425 olds engines, each making about 1700hp, with Toronado transaxles. It was famous for doing 4 wheel 1/4 mile long burnouts. It was a handful to drive, it was wrecked several times.
If the chain can handle a supercharged 1700hp, your not going to break it on the street.
Did I call it or what? The Super Turbine 300 also had a switch pitch, but alas it was a 2 speed. Most people erroneously call them Powerglides. The switch pitch was used in Olds and Buick, but the Pontiac 300, did not. (no, your 1965 GTO with a 2 speed is NOT a powerglide, it is a Super Turbine 300).
Torqueflyte A-727!
The Rolls Silver Shadow had it behind a V12 it was such an awesome thing to see an American tranny behind the refined and elegant v12
The TH 400 was even used in 3 ton trucks according to a friend who is a great mechanic. I got my TH 400 serviced (oil and filter) and I never had any problems. I even towed a holiday trailer with the 427 and TH 400. We put on over 115,000 miles on the car and it was sold to a relative. I later had a 1978 Olds with the 403 engine. It was nothing like the 427. The 1978 Olds was replaced with a 1980 Olds with a 350 engine. It was special ordered to be our trailer car. However, when I went to undercoat it, I discovered that it had a 200 transmission. Imagine, putting in a 200 transmission in a trailer vehicle. My mechanic friend said the 200 transmission had some parts akin to an apple juice can. I phoned my GM dealer and he said that he had a 1980 Olds station wagon ordered for trailering that was due in a couple weeks. He was fair to me and we picked up the station wagon in a couple of weeks. It had the TH 350 transmission. The 350 engine was the Oldsmobile engine but it was barely satisfactory in pulling a trailer, especially in the mountain passes around Radium, BC. I was starting to realize that there were other manufacturers besides GM.
Legendary th400 transmission
I would like to say they are indestructible. But I actually broke one in my 72 Grand Prix 455. I was 16 years old. And beat it badly. Along with 100k miles. It finally said "I give up"! Got a rebuilt replacement for 325.00. This was in 1981. Much better times indeed.
The W55 and W56 transmission is my favorite transmission. Literally never seen one break
Power glide 2 speed , loved them , 1st gear good for 110 mph then you grab 2nd gear , so smooth and so prompt too , very tough reliable and can handle big power
The 4L80 is its sibling and I loved my 400's in my old dump trucks, then I got 4L80's in dump trucks and pickups they became my favorite by far!
Great transmission.
Another interesting episode. The TH400 is probably the most reliable part in my Jag-u-ar XJ-S 😂
my Dad had Pontiac wagons and Chryslers - the 727 was better than the GM hydramatics the 1965 New Yorker could be push started because the 727 was so over engineered Hemmings actually recommends replacing the GM transmissions w/ the 727 for added "durability" "The A-727 was one of Chrysler's most versatile workhorses for over 30 years, and its strength and ability to handle high-performance power with ease made it a popular choice with many other manufacturers. Finding a replacement unit for your car, whether it is a Mopar, AMC or International, should be an easy task, and adapting an A-727 to your GM car can add durability to any automatic drivetrain."
Imagine if they brought this technology back for the modern ones. They can make these anemic 4 cylinders (which I’d never drive) actually have some pickup, especially with modern fluids and technology being around now. Well done on this series!
It was used in a Jeep as well, when equipped with Quadra Trac.
My dad owned an automatic transmission shop when I was a kid. One of the best was the 727 torqeflight.
My first car in high school was a '65 Olds 98 with a 425 V8 and TH400. It was a solid drivetrain pulling around a heavy car. When I see the crazy horsepower ratings on stuff like Hellcats I wonder how robust the transmissions are in those cars. I have not had very good luck with Mopar transmissions in cars with just average horsepower.
The Hellcat Drag Racers were and still are Turbo 400 swapping out thier 8-speeds. Also a Turbo 400 weighs 135 lbs only.
They improved the Later 8-speeds in the Dodge Demons has a Factory Trans Brake for front wheels off the ground launches on the Streets.
I’ve had my 400 since 1988 in a 66 c10 and when I got it it had a 2-3 slip
With regular service it hasn’t changed a bit
They all had there problems and good thing they did kept me employed, THM 400 would always come in with forward clutches burnt, Back then transmissions would usually show up with about 60-80 thousand miles in need of an overhaul ,to make them really last a trans go shift kit would be installed, Variable pitch two wire 400 was not around that long only saw a few come into the shops in Boston then they disappeared , most modern transmissions will get double that but thousands of dollars to rebuild them when they fail. retired trans builder
How often did you see the intermediate snap ring blow out of the case on 400s? I ve had a few of them. Trans Go at one time sold a super heavy duty snap ring that would minimize the issue, but not until the redesigned case was introduced (Chevy bellhousing only) in the late 80s did the problem entirely disappear.
@@donreinke5863 A few, not that many ,that snap ring came in the shift kits and needs to be indexed in the case. rear planet pinions digging into the carrier housings in heavy weight applications.
Please explain the Chevrolet Turbo-Glide transmission when you get a chance. One of the first non-belt CVTs? Progressive? Obviously a failure in the market at the time. Rushed into production? First GM aluminum auto trans case? A necessary prequel to the buttery smooth Turbo-hydromatiscs to follow? Thanks for all the info you provide.
Loved my 1990 Suburban 4x4 2500.... My favorite body style and the front grille treatment 454 TB and TH400 only thing more reliable is a rock.
I remember all the car magazines in the 80s talking about torque steer in transverse fwd cars, and how it was nearly impossible to handle over 200hp or lb.ft torque [can't remember which]. meanwhile, these TH425 cars had no such problem with double the torque and power.
The switch pitch was used in dynaflo as well? I had a '63 LeSabre for a short period of time and found the transmission to be surprisingly good. Not Turbohydramatic good, but better than expected.
Yup, the 55 and later DynaFlow had Switch-Pitch, but since it only came into play when you floored it, it was still Dynaslow in most situations.
I prefer Allison transmissions. Although your old school choices are a solid.
Allison makes awesome trans. They weigh almost twice the 400 though and can’t really be revved very high.