The Big Mopar 8 3/4 Video! How To Rebuild Your Center Section, Identify Suregrip Carriers, And More
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- เผยแพร่เมื่อ 26 ม.ค. 2024
- On today's episode, we dive into the Chrysler 8 3/4 differential. It's like a Ford 9", but less Fordy. We go over assembly and setup of the 8 3/4, and take a look at the different components and case types found in muscle car era Mopar axles.
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The tool for measuring pinion depth is fairly simple, but you can often get away without it. I use a piñon bearing, honed out for a slip fit, to select shims and then double check with a new bearing, pressed on the pinion gear. The shims for Dana rears have shims that are made to go behind the pinion bearing race. You can choose the proper diameter of these, in place of the shims that go on the pinion gear. The concept for setting backlash and side bearing preload is also fairly simple. Have one adjuster all the way nearly out, no contact with the side bearing and tighten the other side adjuster to seat that side bearing. Then back out the tight one and tighten the other side adjuster to seat that side bearing. Then tighten the ring gear side adjuster for zero backlash, with the non-ring gear side adjuster backed out or just barely touching, no pre-load. At this point you don't want pre-load on the bearings, but ring gear side has to be tight enough to eliminate backlash, just tight enough for that. At this point, the ring gear side adjuster is done. Then tighten the non-ring gear side adjuster for proper backlash. This will pre-load the side bearings and spread the case slightly. Lacking a dial travel indicator, this adjustment is about two spanner wrench holes of tightening on the non-ring gear side adjuster, after contact with the seated bearing. To recap, the ring gear side adjuster is set to zero backlash with the gears and no pre-load and no tightening after zero backlash is a achieved. Then the non-ring gear side adjuster is tighten to set the gear backlash. This will also pre-load the side bearings. The non-ring gear side adjuster pushes the ring gear away from the pinion gear, while pressing against both side bearing, for their pre-load.
Excellent walk through. I’m going to pin it so I can find it later for reference. Thanks.
I had so many questions about rebuilding my 489 to put taller gears in. You answered so many of them and confirmed a few of my suspicions! Thank you, you rock!
Most of this stuff is way over my head mechanically, but I still find it interesting to see how this is all done. Also the reason why I respect anyone that can do this kind of thing.
When I first got into mechanic work, I also thought this was rocket science. It isn’t quite that - but there are a couple things you have to get right or it goes badly. I’ve done well enough so far. Haha.
Never expected to learn this much about diffs. Plus, that's way more tools than the average guy like me will likely ever own (I'm jealous). Good video
My '71 came with a 741 carrier with 2.76 gears; I was going to use either a 489 or 742 with 3.23 gears (got both used but in great shape. ) But since I'm putting in an OD transmission I may find happier gears to use and would have to rebuild one of them so its great to have this video lined up.
Wow. I thought they were done with the 741 by 71. My 66 Coronet with a 273 has a 741 with 2.94 gears . My 74 Charger has a 318 with a 489 case and 2.76 gears.
If you go OD that opens up options on the gears for sure. I have the 3.23's in my 72 Challenger with a TF727 behind a stroked, roller EFI LA and
honestly with the TF727 it's a great ratio. I drove my Challenger home 250 miles all on the turn pike and highways and it was a really nice drive
I wasn't cranking a ton of RPM to go 70mph.
@@IhateTH-cam I asked Jamie before, he thought 3.55s would be good. Honestly I could run 3.73 or 3..91, or even 4.10s which might be a lot of fun even (or especially) with a mild 318, and still have a final drive ratio (with 4.10s) of 2.82:1, right between the available 2.76 and 2.94 gearsets behind a 727. Its up to what I have or maybe can find since I would really prefer OEM gearsets. All my bargain pickups years ago ended up being 3.23s. But with all three carriers I can even set up "quick change" units with a range of gears. Options. We like them.
My brother and I changed a cone posi on his 70 Dart Swinger 340 back around 1973. He was 19 and I was 21. It was quite easy. Ran great and no noises. Never took the pinion gear out as it wasn't leaking. No bearings either. Just the carrier. Probably about a two hour job including taking the tires on and off. Rebuilt a 273 in 24 hrs too. Rings and bearings. That included yanking the engine in and out and starting it. Had to get the cherry picker back in 24 hrs! Mopars are easy to rebuild and repair.
Good video! I had 3 489 center sections 323 highway 456 st 1/4 513 1/8 mile for my 67 Cuda mild 70 340 11/1 4spd, solid lifter, ported J heads, Holley 780 4150, sub frame con, adj pinion snubber, SS prings. Some how I cracked the caps on the 456 gear center section after words I made cap straps. Really enjoy your videos as myself or family owned most of the cars you show including the Studebaker except the 300's.
I learned how to rebuild several of the cone clutch type Sure-Grips. I'd have a machinist friend cut 0.100" off the outer side of each cone clutch, then make up several spacers (looked like a doughnut when finished being made) from random pieces of sheet metal in thicknesses like .020" or .030", then reassemble with a combination of spacers until I got it right, minimal gear lash, for full tooth engagement. They worked great after that. All the ones I did were in 489 cases.
Bro, see you understand how to set up a diff.. You're the only guy on here including the dude who did the video that actually noticed his teeth were wearing way off and needed pinion depth shims..
Pre-Internet, I used to machined 0.020" off the backside of the cone gears. This just kept them from bottoming out and allowed the comes to work again. More recently, I've seen on the Internet, people machining 0.040" from each and adding 0.040" hardened shim stock to the springs, to increase the spring pressure. I wouldn't use plain sheet metal, as it will wear more quickly and might break up. The reason I removed 0.020" off the cones was to keep them from bottoming and with that small amount, when the cones further wore down, 0.020" would be the wear limit, allowing the gears themselves to survive, with their new wear pattern. I ran them on circle track racing and would get about one season out of them and would fix up another one for the next season. It doesn't matter how much you take off of the gears, as they can only go as far as the cones allow. Any additional amount would be to allow for wear, but when they wear farther than that, the gear engagement and gear wear become iffy.
I was always told to find someone who knew about them and avoid a lot of troubles, did learn a bunch from this video, thanks for sharing your knowledge!
Thanks Jamie lm fascinated by work i could watch it all day
I used the service manual to set carrier bearing preload and it howled like crazy. I’m Leary about doing another one. Nice job.
I have always used blue grease to check final gear lash. Never cared for the yellow paint they came up with in later years. Note though 489 cases are super strong so but so is the 742. The differnce is the pinion shaft thickness. The 489 has a fatter shaft thus why it takes more abuse. However i have yet to break a 742 pinion yet. Saying yet so i dont jinks myself. If you have a auto 742 works great. If you have a stick and love burnouts 489 is what i was told. I have beat both into the ground. However the only one i ruined was a 489 case go figure. Now if your pinion goes back into the ring gear the word carnage comes to mind. There will be loud noises you can clearly hear and feel from the drivers seat. You may poop your shorts too. But most times you will blow a u joint over a pinion. Only talented guys get to distory a chunk. 😂
I love your videos, but I enjoy these tech videos the most. It's how I found your channel long ago. I'm trying to do more and more things by myself at home instead of paying someone else to do it. That being said, I am still scared of all that is required to set up an 8 3/4, including the tools I'd need to purchase to complete the task. I don't have a press. Right now I'd still rather keep multiple 3rd members on hand with different ratios to swap in and out when I want a gear change. BUT... I did learn what those " buttons" (9:51) are that fell out during my last swap.
Thank you for sharing your knowledge 🙏 Jamie
In my opinion 323 is a good ratio for daily driving . Had this ratio in most of my 🇦🇺Chargers. Valiants owned 2 / 68 383 pillares Dodge phoenix With that diff that always looks bigger then a 9 inch 👍🏻had 2 / 66 Dodge phoenix with a similar diff both poly 318 but man did they pull strong 💪 . The ground would shake under those boys and would leave two black long lines no worries man those motors sounded like they came of a NASCAR track not sure what my old boss did with them but they were MOPAR heaven . Great clip 👍🏻🇦🇺.
AWESOME....MOPAR 4 EVER.
I hang the transmissions at my job at the truck plant. Part of said job is measuring the backlash on those transmissions that have a PTO to install. Pretty similar to what you did. All in all, that didn't look too bad, with some "special" tools. Nice work.
Nothing I'd rather do on a rainy Saturday than look at rear ends.
😅
Great video on the 8 3/4. Thank you!!
Next video from DDG: Rebuilding and upgrading your A727 or A904.
Appreciate the knowledge that you have bestowed, hope to tear into the Diff on my forward look car.
It’s on the list! And much like the four speed video, it will largely be a learning experience for me.
@@DeadDodgeGarage Likewise, i've got my Pushbutton A727 all disassembled right now, first time for me too. hope to get it rebuilt and back on the road soon!
Once again, very well, executed and detailed video Jaime
This was great information! Keep doing what you’re doing brother, it’s very appreciated
It's a shame all rear axles aren't a drop out style. So much easier than setting pinion preload under the car and set backlash under the car with shims. One trick I did setting pinion preload/torque on my 9" was to use the press to hold the pinion flange secure to the press plate and torqued it. It didn't move a bit and I used a couple pieces of 4x4 to protect the ring gear and used the press to press the ring gear onto the carrier and it also held it securely to tighten the ring gear bolts. Way easier than when I did the 8.8 in my grand marquis, that was a PITA under the car.
Awesome video, so glad that it's not just me having issues with interpreting the paint patterns.
No, it has never made sense to me, ever. Haha.
Very informative thanks
Thank you and good content....
Awesome vid. Now I'll be able to rebuild the 8 3/4 in my 300. Now I will wait for you to do a full 440 rebuild :)
I already did that! It’s been a year or so.
Good info. Thanks!
I was missing your videos. Showed up right on time 😃
I wish this had come out a week sooner! Just had to do my drop-in and was trying to figure out reusing the crush sleeve on the 489. Turns out "yeah its no big deal" when using the original R&P. To be fair, you can reuse whatever crush sleeve was with the diff and alter the preload with the shims in the pack.
Yes, very true. Adding shim allows you to crush the sleeve further. I probably could have included that. The general consensus always seems to be “crush sleeve bad” so I kind of focused on that side of the equation. I like the crush sleeve, personally.
@@DeadDodgeGarage Thank you for this vid though. Put my mind at ease after the fact for sure. Im still a little scared about my condition of the cone pack. Some nasty chunks missing from a few of the 'threads' but worse case scenario is she gets welded, haha!
I love sandblasting. It's so satisfying 😊
Great Video !
Thx Jamie
Worked at a Jeep dealership some years back. They were having a lot of bearing failures. Never enjoyed rebuilding the rears.
Perfect timing
Ooooohhhh?!
Another fabulous how to video. The only thing that could have been better is the camera work. You really need a camera man or uhh.. person? I love to see all the intricate details of a procedure. I need to change my gears. I have a 489 housing. And allegedly I have a fairly new Yukon unit in it. I want to go from 3.73 to something more highway friendly. I might attempt it this summer. But I would much rather pay someone else to do it that has all the proper tools. Anyway keep up the good work!
Fair enough. Yeah, I need to go get my tripod. I left it in the shop we painted the Barracuda in, so that’ll give you an idea of how long I’ve been without it. Haha.
Mmmm, 90w.
Good vid!
It's nice seeing someone do it correctly, unlike me who would use the impact and just wing it till it feels good to me 😂
That’s how it’s done with the crush sleeve! Haha.
Jaime looking for an eight and three-quarter for my 75D 100 I heard that some 8 3/4 will fit like out of a bodies for a wider tire in the rear. Another great video. Thanks.
I’ve heard the same, but I don’t know which housing works the best. I’ve never done that setup in a truck before.
Great instruction!
Have you any experience with Eaton limited slip, the gear style?
Not at all - yet…
Pretty okay timing
If you say so 😅
@@DeadDodgeGarage Someone’s gotta keep you humble
Now I await the day you get into the dreaded Chrysler Dana 44 front axle 😅
Been needing to find a hub seal kit for it
Funny enough, we actually did bearings and axle joints on one, and I got a little bit of footage, but it didn’t seem like enough for a whole video. That will probably get rolled into the next Trail Duster video.
@@DeadDodgeGarage Fuckin mint, ive been hurting on my W100
I watch some TH-cam mechanics, this channel separates pros from amateurs...good work, im not sure if it's my Mopar Bias showing but your making the Jr mechanics look bad chief 😂😂. Cheers
Hey, hopefully they can learn something here. Haha. I started out as one of them too… and I had to goof this up a couple times to figure it out. Thanks!
@@DeadDodgeGaragebro no offense but how can you do a video making all these kids think you know your stuff when you can't even get your back lask pattern correct? I have never seen someone leave it with the teeth wearing that far off? Was barely touching the tooth?
Get your pinion depth correct and your patterns will be Cresent right in the center everytime. Make a setup bearing set so you set your shims and isn't difficult to correct it. Keep in your box.. sorry but that diff will wear out way sooner then correct pattern.
@@michellebaxter1403 Anyone who's on TH-cam looking for someone who knows everything is doing the wrong thing. I am fully self taught and untrained. I have made that as clear as I can. I have had zero luck attempting to get a readable pattern with gear paste. No pattern I have ever gotten even remotely resembled any of the examples in mesh charts. So I just don't bother. If it was good enough for the factory, if it was fine for fifty years, it's fine for me now. Sorry, and goodbye.
the #2 diff. is stronger, the pinion bearings are wider with greater load capacity.
Swapping a LSD from another 8.75 (one of those old late 50s you mentioned) should go the same right? My open 3.23 is a 489 from a D100, other than the crush sleeve making the install different, the LSDs are swappable between housings are they not? I’ve done the 9.25 and 44 in my Ramcharger but not a 8.75 yet.
As far as I know, any of the various carriers are essentially interchangeable - but I don’t know that for sure on earlier housings, and I do know that there is at least a center button difference in the older style 8 3/4 carrier (in axles with threaded nuts on the axle shafts and separate flanges) that would prevent it from being a direct swap.
That Petty blue Charger speaks to me.
It’s really cool! It has a drivetrain again as of Thursday! So there will be updates coming on that.
@@DeadDodgeGarage Sweet. I’m a Petty fan since the 70s when he raced this body style. I have a bone stock 74 with 49k miles. It’s a time capsule if you need to know anything about them. I can take pics and send them to you.
I got two 80s model Fifth Avenues with a 318 they look nice but kinda slow of course 😂. should i get one of these and if I did would it fit or should I just rebuild and upgrade the diff that's in one of them already?
The 8 3/4 axle housing was long gone by the time those cars were built, so there is no housing that fits right in that car. One could be adapted, but generally speaking there is no point - unless you’re going to make a bunch of horse ponies.
Woot!!
Do you have a break in procedure for new gears and sure-grip?
I’m sure there is supposed to be one, but I don’t know what it would be.
Do you know if the prebuilt third members that mancini racing sells are any good ? I can't see me doing all of that and not screwing it up.
I haven’t used one, but I’d trust Mancini.
Mancini racing has always done right by me. I've seen many others come and go over the years but Mancini is still kickin'.
I need to swap out the center in my 72 Challenger because it still has a spool in it from it's past life as a drag car. I found
complete new centers on ebay using Yukon cases with Eaton Tru Track helical limited slips for approx $1400.
I was just going to swap the centers and then sell my spooled 323 center. Have you had or has anyone here had any
experience with those helical LSD's? Are they ok for the street or should I just go with a clutch type? Also does anyone
know, are those Yukon nodular iron centers as good as factory?
Thanks in advance and as always, awesome video!
Personally, I haven’t dealt with any of that aftermarket stuff, so I have nothing useful to contribute. This carrier cost us under $500. There are actually cheapo units on eBay for like $300-350. I’ve never tried one of those either… yet… the clutch type makes sense to me.
@@DeadDodgeGarage Thanks for the reply! I think the high cost is because they're using brand new castings and that Eaton diff is a bit more pricey. I will look for units that
have clutch type in them. I've never had one of those helical gear setups but I've had lots of clutch type and never had issues with them. I know I could do this a lot cheaper if I did the work myself but honestly I don't have the tools and I've never set up the back lash so I will spend a little more to not have to deal with that part. :)
This spool has to go though... I had a pro street 71 Big Block Demon years ago and that made sense to have a spool but the Challenger has been redone from the ground up to handle and my friend just never cracked the rear open to swap it back to LSD. I do love the 8.75 rear end design it always made so much sense (that and the 9") over non pumpkin types. Like you said, you can have numerous centers all ready to go.
@@DeadDodgeGarage Oh I also forgot to add... I can smell this video.... Ugh the smell of gear oil is the worst! LOL
I was pumping gear oil out of my differential in my 72 Barracuda, and the plastic stem fell in, l just looked at ur video to see what I'm dealing with and it looks like it's going to have to stay. My question is do u think this is going to effect the differential being left in there. Thank You
It won't be fun to remove the wheels, brakes, axle shafts, and gear chunk just to get that out. Leaving it in there is not at all ideal - but, on the other hand, it's a piece of plastic. The worst that could happen is it gets caught in the gears, in which case it will probably get shredded to pieces without causing any real harm. What is most likely to happen is it sits where it fell and does nothing. If I were in your position, I would ignore it until such a time as the differential starts making horrible noises. It probably never will.
@@DeadDodgeGarage Thanks for ur reply, it looks like l might take that trip to the Puget Sound after all, this was going to keep me from taking my Car. There's a part will it will drive me nuts that it's in there , but what r u going to do.Thanks for ur reply, Great Channel btw.
You weren’t specific about the side bearing preload. This is determined by total turning torque of the assembled unit. Great video tho. I built countless diffs in Jeeps. They were setting them up too tight from the factory and bearings were failing like crazy. Good times…..
Had race from my demon diff explode while removing, dug 2 pieces out of thumb,1 remains.😮
😮 dang…
What bearings are on the new power lock number
I have no idea.
As I get older.... I desire taller gears. True.
Well that's way more complicated than I ever knew.
I could’ve made the explanation a lot simpler, but that’s not how I operate 😅
Lmho great job
It’s just missing the front pinion support like in the 9 inch ford for ultimate strength
Yep. The 9” definitely wins for strength.
You reuse old bearings that you grind inside the race.. get them correct with shims reassemble with new bearings.
Ok
So my 73 8 3/4 has cone?
It sure ought to
👍🏻🇦🇺
I've learned that I never want my rear end to fail 🤣 And if it does, this video will get a lot of views as I try to fix it. I'm a slow learner....
Use a punch to remove the ring gear, through the ring gear bolt holes. Easy peasy.
Smart!
I have a 69 Dodge charger, with a 408 stroker. It has a rear Gear ratio In the twos, What would be a good year combination that would be fun on the street and drink a shit ton of gas
Wow. Haha. 3.23 is a good compromise, that’s what I’ve got in my ‘68. Very pleased with the performance and acceptable highway cruising. A 3.55 would tilt that toward better burn outs and in town fun, but a little worse on the highway.
Thank you!! Think I’m gonna lean towards the better burnouts! lol. I think 3:91 would be to steep because I live 30 miles from town where the fun is.
Love your videos!!
Indifferent 😮😊tyall 😂.
What lol
If this is the big MOPAR, what happened to the Dana?
In the muscle car era, this was the bread and butter medium to highish performance axle in Mopars. The Dana 60 was reserved for Hemi and 440 four speed Charger R/Ts and other specially optioned muscle era Mopars. In the 70s, Chrysler developed their own 9 1/4 axle for heavy duty and truck use, which strongly resembles a Dana design. Of course horsepower was basically gone by then, and the Dana 60 left the building anyway. The Dana 44 could also be found in the front of trucks.
Get some one to hold the camera!
But then I’d have to have someone with me all the time. Yuck! 😅
Diffs... ugh!
I watched this once again Anyone watching this dont ever just skip the last step because this guy is either to lazy or to ignorant to get right.. Notice how he explained all steps in detail minus the one he doesnt know how to get correct and is the most important guage of your overall gear setup.. So his wear pattern is way way off.. your pinion and ring gear should leave a pattern right on the center of your ring gear like a half circle. Shouldnt be to low or to high dead center of each tooth on both sides.. He doesnt even explain what your measuring or how to correct it. You can either spin the gears with your drill while with gloves on holding some pressure against ring gear hence creating a load!
If this isnt correct, the difference is astronomical to longevity of the diffs life.. There are a million diagrams online that explain how to correct it wherever your wear pattern is. No one ever gets it perfect first try.. I do this professionally.
So the reason his is off is because his pinion depth is off. Was most likely off from factory with same shim the 1 right behind the pinion teeth. Behind the bearing. As long as preload and backlash are to spec then its the shim for his depth.
And you can adjust those carrier adjusters in and put all day long but wont get it correct until his pinion is at correct depth.
No, that’s not what I’m here to explain. I even explained why I essentially never mess with pinion depth. I’m glad you know what you’re doing. I am super happy for you!
booo put a dana 80 under it
😭
3rd member rebuild vid. Channel "pillar" or "filler"? You're channeling someone's 9th grade shop teacher here, sir. Not funny. Too informative!
You’re probably right. Haha. There are different types of videos, and a channel like mine kind of needs all of them to be successful. This is an “evergreen” video, meaning people will find it and reference to it for years to come. I wanted to actually get the details right so I tried to focus on that. Way back at the very beginning of the channel, my main focus was electrical guide videos. I’ve done other more technical stuff like this over the years too. We probably return to your regularly scheduled programming today.
I so enjoy your jokes, sometimes I forget you have a purpose. 😎