Pete, you make this old guy of 70 feel like a kid again. Would have loved to be in your shop classes. You have the patience of a Saint and I, for one, truly appreciate your work. Thank you for sharing. Mike, Charlottesville, VA
You so remind me of my late grandfather. I could sit and listen to him and his stories all day long. I owe so much of my "real life" education to him and my late father. You are now my continuing "real life" educator. My wife knows when I grab the IPad that I am headed to "school" in my office. Keep doing what you are doing. Great stuff Mr. Pete.
Amazing. It's quite complicated; I guess I'll never look at another speedometer the same way again. Most of the objects we commonly use are far more complicated/complex that we realize and appreciate. We are just looking "at the tip of the iceberg." Thanks for giving us a peek at how thing work.
This brought back memories of when I was a teenager and got hold of a speedometer out of a '49 Chevy truck and took it apart. Pretty much the same. Thanks for the video!
I'm so glad I found this channel, you have no idea how much I appreciate videos like these. The world needs more talented and passionate teachers like yourself. Keep up the great work!
Thanks for this demonstration. I never took one apart, basically I knew how it worked but nothing better than see the real thing. I appreciate the work you had to put into the preparation, it was very enjoyable, so thanks again Bob
I've always had a fascination with how things work, more so with mechanical devices rather than digital. I've wondered many a time how the constant rotation the cable could translate to the needle. Always figured had something to do with friction. Thank you sir for what you do! I appreciate the in depth explanation!
very interesting video Mr. Pete. First time I ever heard Renault Dauphine and Geraldo mentioned in the same conversation!!! I always enjoy your videos. Jim
Thank you from Manchester, UK. I can honestly say that this is the best TH-cam video I have ever watched. Your knowledge, your patience and your humility inspire me.
I was riding the bus, looked over at the speedometer, wondered how in god's name it works, and now I'm half an hour later with way more than just simple information. I absolutely love hearing stories and hearing you talk to your audience as if we're casual friends in the shop there with you. That you for the video :)
Thanks Mr. Pete I was looking forward to you doing this. Lots of good stuff you touched on here. Wish you could have spent some more time on the Eddy Current principles but the odometer was great and amazingly complex for a counter of the day. I won't go into all the physics about Eddy currents but your previous video with dropping a magnet through a tube reflects the same principles. They are used in all kinds of mechanisms from braking to linear motors and MagLev systems today. The history goes back to Babbage and trains in the early 1800's but the speedo is credited to Otto Shultze in 1902. I was graced to learn more, after my father back when I was a kid, to apprentice/working with a Carb and Speedo guy who was in his mid 60's in the early 80's and about to retire. He passed on so much to me and grateful for that, as I am to you for all that you bring forward. Dad used to say about people like you and he, that; "His little finger forgot more than most people know." Also there were several cup styles I saw, from cup shaped to conical...and some anti-rollback mechanisms for the counters, to prevent the dishonest from their trickery. en.wikipedia.org/wiki/Eddy_current en.wikipedia.org/wiki/Speedometer th-cam.com/video/otu-KV3iH_I/w-d-xo.html Thought this would ring a bell. Many Thanks, Mr. Pete! ~PJ
yeah - ' clocking ' used to be done quite a lot here in UK too when I was a teenager . A way of telling if it had probably been done was that the numbers didnt line up properly in the window good vid thanks
I think my dad, an auto mechanic, told me about the spinning magnets inside when I was about 8 years old, too. I kept waiting for you to explain why the speedometers in old cars sometimes have a tendency to bounce wildly at slow speeds. It has always been my suspicion that problem is due to the cable needing lubrication wherein the cable’s driven end connected to the transmission turns at a constant rate but the opposite end connected to the speedometer stops and starts in a herky-jerky motion.
Pretty impressive engineering and mechanics that went in to this back in the day. It's also amazing how far technology has come. Thanks for the video. Just out of the blue, I was wondering how a speedometer worked and now I know.
Awesome job-video-editing-narrating! I took so many things apart as a kid, good thing my brain wasn't held in by screws! I never got to see the inside of a real speedometer. I had a old Suzuki four wheeler with a stock speedo and I used to spin it backwards. Thanks for all you do!
This was a great video, MrPete, thanks! I took one apart on a 90's pontiac and when I put it back together the numbers would skip from ...38 to ...49! So I was looking out for that here, the row of numbers you show at 26:50 started with 35... But the correct row was the one starting with 24... It was a headache getting it to line up again! But it had to be done, the original speedo broke and the replacement one had too low mileage.
+mrpete222 you really are a wonderful man, I mean that. thank you for the fascinating videos, and the generosity of your time to make them. I watch your videos with a box of popcorn rather than the tripe that is TV! My first ever car was an old Mini (30 odd years ago), and at some point the speedometer cable wore out, so I had to replace it. Bloody hands, much cursing, and of course no internet in those days, we relied on good old fashioned books. Anyway, this reminded me of that, although I had no idea about the intricacy of the odometer. Really interesting stuff.
Very cool dissection. It would be cool to see you take apart a chronometric speedometer. They work like clocks. The speed updates in intervals rather than the fluid movement that the magnetic ones have.
Aaaamen to under dash misery! You described it perfectly. Still have scars from our '69 Fury...always an air conditioner switch. I've been trying to place those stylized digits; first remembered them as GM, but comments about Dodge reminded me of my grandfather's late 50s Plymouth, and I think that's the match. Mopar used red for high beam in the 60s, but those lights could be oil and generator. Doubt it would lack a beam indicator, though. Europe was different; our '64 VW already had a blue beam indicator (with green OP and red gen). I knew you were going to say, "I'll call him Don to protect the innocent." No, "...'cause it's his name!" lol Someone mentioned old cars smelling alike. It's largely the seat foam, but the VWs have a unique smell. Fun memories.
Thank you for the explanation sir. I have a mechanical tach in my airplane that reads 100rpm low so I am trying to figure out whether I can have it re-calibrated and your video is most helpful with understanding how these eddy-current indicators work.
I realy enjoyed this one. I had torn an old speedometer apart as a kid and figured out how they work a long time ago. You are correct that it was at one time not a crime to alter the odometer record. It only became a crime after the value of used cars had risen enough that it went from being a couple hundred bucks more to several thousand more for a low miles car. After it became a crime the manufacturers of speedometers installed a scribe mechanism inside the odometer so if it was rolled backwards while the unit was assembled it would score a mark in the center of the numbered wheel, leaving a visual indicator of tampering. An acquaintance of mine owns a garage. He is in his 80s now and still works every day. He told me that his business was at one time a certified speedometer repair shop and he did the majority of speedometer "repairs" for the car dealerships in nearby Youngstown, Ohio. I have worked on many, many cars in my life. I have only had to replace one speedometer ever. And that was in an '88 Chevy Cavalier. My guess is the little magnet likely came detached from the speed cup. I have had several apart for classic cars. Simply clean, oil, sometimes repaint the needle and reassemble them and they are good for another 40 plus years. All the best! Mike
You might add a link to your magnet experiments. The eddy currents (and the induced counter magnetic field) that drag the aluminum cup around are the exact same as the effects that cause the magnet to drop so slowly through the copper tube. You can see the same effect in reverse when you move the needle by hand and release it - the needle returns to zero quite slowly. In this case it is the aluminum cup rotating in a fixed magnetic field.
Thank you very much for this detailed video which allows us a quick travel in the past in order to discover old (but very smart !) mechanism ! Happy that you mentioned a famous car from my country : Renault Dauphine :)
Some speedos (like those for an Opel GT) have a mark and a corresponding rpm noted on the dial face that allows you to calibrate the unit on a bench. I was able to verify that the unit on my car would have been accurate if the wheels/tires were stock, but they were smaller, so the unit read high. Wish I still had that car!
Great video!! I always wondered how a speedo worked,....and now I know, magnets,.....I worked at a juice bottling plant, and the bottle capper chucks had magnetic clutches and worked sorta kinda on principle like a speedo.
I know very well about working under the dash. I worked a couple months at a car stereo shop in the 2nd part of the 70's when everybody and their mother were buying C.B. radios for their vehicles. (remember the song "Convoy"?). We also installed after-market cruise controls. There was a box you mount under the hood with a linkage that went to the carb. It also had 2 shafts on it, an input and output. We removed the cable from the back of the speedometer and the tranny. The cruise kit came with a couple shorter cables. One attached from the tranny to the input shaft of the box. The other cable went from the output shaft of the box to the back of the speedometer.
P.S. Moving the odometer back reminds me of the beginning of the movie "Used Cars". It is a hilarious movie starring Kurt Russell. Also had 'Lenny' and 'Squiggy' (from "Laverne & Shirley" - not a big fan of that show), and Al Lewis (grandpa from "The Munsters"). A must see movie with a little gratuitous nudity.
My first "car" was a 1947 Willys Jeep, CJ-2A. It had two identical looking dimmer switches on the floorboard. The one on the left -was- a dimmer switch, the one slightly to the right and above the accelerator pedal was the starter switch. That way you could crank the engine over with the toe of your right shoe and pump the accelerator pedal with the heel of your right shoe, at the same time! Good memories!
Grandpa Cocky remember my band teacher told me a story from the days of vacuum operated wipers He had to stop going uphill in the rain driving a Chevy pickup once because the wipers would literally stop as the engine would be pulling too much air under load
I was at a gas station in Maryland that had a dynamometer that was used to calibrate the Prince Georges County Police speedometers. I remember used car dealers putting Motor Honey in the engine and sawdust in the differential.
Howdy Pete, I've always sorta known how the old speedos worked, but never saw the innards to know for certain. Your video 'splained it all...THANKS!Also, you said you had a Renault Dauphine way back when and, as a fellow who turned wrenches on 'anything foreign' (back when anything imported WAS foreign) in the later '60's, there was an in-trade saying we used to describe the Dauphine. It was that the French captured Dr. Ferdinand Porsche, and forced him to design a car as good as the VW. The result was the ever-popular Renault Dauphine, which was known as "Porsche's Revenge".They weren't great cars, nor were they lousy cars but, like all French cars...they were inexpensive (spelled c-h-e-a-p) and tres comfortable!And there you have it...please keep 'em coming...Mark in Modesto
There is a stigma attached to odometer readings. Someone wrote down the mileage wrong on my Supra, probably getting my oil changed or some minor repair, and it completely destroyed it's value from an appraiser. It wasn't because it was too high or too low, but that it wasn't chronological.
I replaced the speedo in my XY Falcon (Aussie car) which was in mph with a unit from a later build (same model) that was in kph. The original speedo had given up the ghost. When I was doing it, I pulled the new speedo apart and it was a very easy task to rearrange the odo dials to 00000. I didn't do it to rip anyone off mind you, but I just thought I'd try. The car was about 26 years old when I sold it and the odos only went to 99999 so it had clocked over about four times regardless. I told the guy who later bought it off me that it was a non original speedo and to ignore the odo.
Cool vid Mr.Pete.Even before you asked,I thought it was a Chrysler product because of the different size zeros.If we knew we would be selling a car,we would just disconnect the cable at the head to stop putting miles on "the clock".
I had a '61 Olds, F-85, that had that cup come loose on it's shaft, and caused it to peg while moving in the drive way. I took it out and apart and managed to re-anchor the cup (can't remember how though). After that it would show approximately half of your actual speed, so I think they were calibrated by adjusting the cup to increase or decrease the amount of "drag" the magnet had on it. 215 ci aluminum block V-8, with a Hydra-matic 3 speed, no torque converter (the old whiplash shift automatics). They had a lot of snap, and could get as much as 20 mpg on the highway, which was pretty good considering the weight of the car. If I could find one of those engines in good shape, I'd be tempted to try fitting it into my S10....
I remember when I first learned about how speedometers work, back in my school days. I thought that was just the neatest idea, with the magnet and cup arrangement.
Green and Red lights: Green - alternator, Red - Oil. Green showed the Alt. was putting out current, Red would come on if no oil pressure. The two lights would come one when you first started your car (to let you know they were working). Just an old Ford boy here.
Hi Mr. Pete You speak of the cable being driven from the transmission. I wonder how many remember the dust cover of the front wheel bearing on V W's was the driving force for their speedometers?
I found that video to be very educational. I specifically wanted to know, how the speedometers of cars worked at the era, when no electronics was used in cars. Also, please do understand that Your videos have a very important archival value, because the younger generations just do not have the need, nor the opportunity, to know about those old systems from their practical experience, a lot like is the case with computer museums, where the old timers explain to the modern generation, how those computers worked that were used before the birth of the modern generation. An interesting property of the mechanical instrumentation is that it can not be hacked in, it does not have any software security flaws. Thank You for the nice video.
You mentioned the older car dealerships replacing certain interior parts to make the car look newer than it actually was, most used car dealerships now do sort of the same thing, but they do it by covering the plastic engine covers and hoses with tire shine. The half worn tires also get a good coat of the same, while the dash and interior all get armor-all.
What would make the speedometer stop working when the odometer still works? The pin is in place, spring is in place- just won't work. The magnet spins- It's a 1950 Chevy truck. Any thoughts or suggestions as to what I should look for to fix this? Anything that would cause the magnet not to spin the cup holding the pin?
Many old cars did not have separate turn signal indicators. Just one light that blinked no matter which side you had on. The operator was expected to know which one he had turned on. I've still got an old vehicle or two that do just that. So that's correct, the red is the high beam, the green is the signal. Thanks for the great video Mr. Pete!
Yes! Another Tubalcain cutaway!! That old speedometer causes another lamentation about when things were built to last; coincidentally I have a much more modern electronic speedometer apart in front of me at the moment. There are still gears in it because even though the speedo is electronic the odometer and tripodometer are analog driven from an electric motor. Of course all of the gears are plastic and one as small as the pinion gear in this video is broken. Replacement for the tiny plastic gear is $25. :( Turns out this is a common problem for many 90's vehicles.
My '74 VW Beetle had a double-ender arrow in the bottom center, it worked just as you described. Except the high beams would show blue. I think you had to remember to turn off the turn signal too. That was the first car I had with just symbols for everything, the oldsmobile i learned to drive on had words for everything that lit up. Why does every old car made in USA has the same smell?
in the past I have got my dremel out drilled a small hole through the spline and cracked gear and glued a pin(needle) through it never to happen again. Think it was a commodore many years ago.
Do you remember how some speedometer needles would bounce? I wonder if a weakening magnet was the cause of that? I remember the peg to keep the needle from going further. 120 mph on a speedometer was alot for old cars. My dad had an '84 Z28 that only went up to 85 mph.
Where did you get the cut away diagram of the speedometer at the end of the video? I haven't been able to find anything like that! Any hints or links are appreciated. rtc
MrPete, if the part number on the back of your speedometer is 18778A, you have a 1955 Dodge speedometer. If it is 14195A it is a 1956 Dodge speedometer. As I recall, Stewart Warner made Ford speedometers, not Autolite. (See partsfromthepast.com under Chrysler). When I was a boy, my father had an auto repair shop next door to a used car lot. He did touchup and small repairs for many of the used car lots in town. There was a man all the used car dealers called to turn back speedometers. I remember him because he was a paraplegic who had hand controls in his own car. At 12 years old, I was very impressed with his car. There was also a man they would call "re-groove" the tires. I watched him many times using what looked like a big electric soldering iron with a little metal loop at the end to deepen the grooves so the tires looked almost new. He got 25 cents for each tire. The strange part was, the owner of the lot was one of the more honest dealers in town. So much for honesty.
Back when I as a 16 year old back in the early 70s, my Dad would keep tabs on how many miles we would drive on a Friday night. After one night of putting on many extra miles driving some girls home from all over the county, I decided to roll back the odometer by at least 150 miles. I removed the speedo cable from the transmission of the 1966 Ford Galaxy 500 and hooked up the only drill available, which was Dad's 1/2" Montgomery Ward. I hooked up the drill and was quite disappointed when it would only run at 40mph. I had limited time, so I gave up on the project, and by chance, Dad never did check it that day.
Ok, the math.... You would have to travel @ 1037 mph BACKWARDS to match the dremals 15,000 rpms and it would take you a little over 6 hours to get the OD to read zero LOL !!! For the mph, i took the reference 1200 rpm drill that ran at 83 mph, divide 1200 / 83 = 14.46 rpm per mph, divide 15000 / 14.46 = 1037 mph. For the time, i timed how long it took for the OD to go down by 1 mile when you was running it with the dremal and that took approx. 6.3 secs, 6.3 * 3496(original miles on OD) = 22025 / 60 = 367 minutes / 60 = 6.1 hours... Tah-dah !!!!
I was wondering how many turns of the rear shaft it takes to advance the odometer by 1 mile. Going by Mark's figures, the dremel took 6.3 secs to move the odometer 1 mile. If the dremel is turning at 15,000 rpm's divided by 60 comes to 250 revs per sec. In 6.3 sec's, the dremel would have turned 1575 times to move the odometer 1 mile (or 157.5 turns per 10th mile). A more accurate method would be to count the teeth on the gears and figure the gear ratio accordingly.
Yeah, the dremal was not spinning the OD at 15,000 rpm but I would think the drills rpm would closer to accurate. Could probably time 1 mile while running the drill to get a more accurate figure on rpm at OD
I tried to get a reading when tubalcain used the drill. I watched the tenths dial as the bottom of the numbers just disappeared from the display window. I stopped the video at 4:51 just as the 8 disappeared and at 4:56 when the 9 did. That's 5 sec's at 1200 rpm for a tenth mile or 50 sec's per mile. 1200/60=20 rev's per sec. times 50 sec's = 1000 turns per mile. One full turn of the gear on the end of the odometer advances the readout by 1 mile making the ratio of the input shaft to the odometer 1000:1
Pete, you make this old guy of 70 feel like a kid again. Would have loved to be in your shop classes. You have the patience of a Saint and I, for one, truly appreciate your work. Thank you for sharing. Mike, Charlottesville, VA
You so remind me of my late grandfather. I could sit and listen to him and his stories all day long. I owe so much of my "real life" education to him and my late father. You are now my continuing "real life" educator. My wife knows when I grab the IPad that I am headed to "school" in my office. Keep doing what you are doing. Great stuff Mr. Pete.
Keep teaching, TUBALCAIN, this is a great history lesson in how things work, and you never know who you may inspire
Amazing. It's quite complicated; I guess I'll never look at another speedometer the same way again. Most of the objects we commonly use are far more complicated/complex that we realize and appreciate. We are just looking "at the tip of the iceberg." Thanks for giving us a peek at how thing work.
This brought back memories of when I was a teenager and got hold of a speedometer out of a '49 Chevy truck and took it apart. Pretty much the same. Thanks for the video!
I'm so glad I found this channel, you have no idea how much I appreciate videos like these. The world needs more talented and passionate teachers like yourself. Keep up the great work!
Thank you very much, I appreciate this, comment
@@mrpete222
I am here from the future to take care of 'extra credit'.
⏳🚜
Thanks for this demonstration. I never took one apart, basically I knew how it worked but nothing better than see the real thing. I appreciate the work you had to put into the preparation, it was very enjoyable, so thanks again
Bob
I've always had a fascination with how things work, more so with mechanical devices rather than digital. I've wondered many a time how the constant rotation the cable could translate to the needle. Always figured had something to do with friction. Thank you sir for what you do! I appreciate the in depth explanation!
very interesting video Mr. Pete. First time I ever heard Renault Dauphine and Geraldo mentioned in the same conversation!!!
I always enjoy your videos.
Jim
Thank you from Manchester, UK.
I can honestly say that this is the best TH-cam video I have ever watched.
Your knowledge, your patience and your humility inspire me.
Thank you very very much
I was riding the bus, looked over at the speedometer, wondered how in god's name it works, and now I'm half an hour later with way more than just simple information. I absolutely love hearing stories and hearing you talk to your audience as if we're casual friends in the shop there with you. That you for the video :)
Thank you very much
Thanks Mr. Pete I was looking forward to you doing this. Lots of good stuff you touched on here. Wish you could have spent some more time on the Eddy Current principles but the odometer was great and amazingly complex for a counter of the day. I won't go into all the physics about Eddy currents but your previous video with dropping a magnet through a tube reflects the same principles. They are used in all kinds of mechanisms from braking to linear motors and MagLev systems today.
The history goes back to Babbage and trains in the early 1800's but the speedo is credited to Otto Shultze in 1902. I was graced to learn more, after my father back when I was a kid, to apprentice/working with a Carb and Speedo guy who was in his mid 60's in the early 80's and about to retire. He passed on so much to me and grateful for that, as I am to you for all that you bring forward. Dad used to say about people like you and he, that; "His little finger forgot more than most people know."
Also there were several cup styles I saw, from cup shaped to conical...and some anti-rollback mechanisms for the counters, to prevent the dishonest from their trickery.
en.wikipedia.org/wiki/Eddy_current
en.wikipedia.org/wiki/Speedometer
th-cam.com/video/otu-KV3iH_I/w-d-xo.html Thought this would ring a bell.
Many Thanks, Mr. Pete! ~PJ
Thank you, Mr.Pete! Really enjoy the old stuff...
I’m starting to wonder- how did they manage to have a flexible cable rotating at several thousand times a minute without it twisting?
The cable did not turn very fast not several thousand RPMs and we'll lubed right Mr.Pete?
The cable was wound with at least a double helix, with each helix successive wrapped in opposing directions
@@SuperWhoremuffin By the way, they were extremely hard to cut with a pair of diagonal pliers. You damn near needed bolt-cutters to do it.
I was wondering about this only a few days ago; wonderful timing Mr Pete.
Thank you for sharing! :)
yeah - ' clocking ' used to be done quite a lot here in UK too when I was a teenager .
A way of telling if it had probably been done was that the numbers didnt line up properly in the window
good vid thanks
I always learn something new from your videos!
I think my dad, an auto mechanic, told me about the spinning magnets inside when I was about 8 years old, too. I kept waiting for you to explain why the speedometers in old cars sometimes have a tendency to bounce wildly at slow speeds. It has always been my suspicion that problem is due to the cable needing lubrication wherein the cable’s driven
end connected to the transmission turns at a constant rate but the opposite
end connected to the speedometer stops and starts in a herky-jerky motion.
yes--needs lube-cable is windin & unwinding
Interesting to watch as always. Thank you
Pretty impressive engineering and mechanics that went in to this back in the day. It's also amazing how far technology has come. Thanks for the video. Just out of the blue, I was wondering how a speedometer worked and now I know.
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Awesome job-video-editing-narrating! I took so many things apart as a kid, good thing my brain wasn't held in by screws! I never got to see the inside of a real speedometer. I had a old Suzuki four wheeler with a stock speedo and I used to spin it backwards. Thanks for all you do!
Speedometer is from a 1955 - 1956 Dodge.
Love thevideo,and the history lesson.Keep up the great work.
This is so interesting, tons of extra information. I like this style of video very much thank you for putting in the time
This was a great video, MrPete, thanks! I took one apart on a 90's pontiac and when I put it back together the numbers would skip from ...38 to ...49! So I was looking out for that here, the row of numbers you show at 26:50 started with 35... But the correct row was the one starting with 24... It was a headache getting it to line up again! But it had to be done, the original speedo broke and the replacement one had too low mileage.
Thank you! I always wondered about this. And now I know more than I did!
Thank you very much for, taking the time to post this video..
Mr. Pete, always interesting, never boring!
+mrpete222 you really are a wonderful man, I mean that. thank you for the fascinating videos, and the generosity of your time to make them.
I watch your videos with a box of popcorn rather than the tripe that is TV!
My first ever car was an old Mini (30 odd years ago), and at some point the speedometer cable wore out, so I had to replace it.
Bloody hands, much cursing, and of course no internet in those days, we relied on good old fashioned books.
Anyway, this reminded me of that, although I had no idea about the intricacy of the odometer. Really interesting stuff.
Very nice topic and explanation! Nicely done. I enjoyed your video, thank you, Sir.
Best regards, Rob
LOL! "They are of course totally honest at modern dealerships." I was giggling till you got it open. :)
What a great video. I appreciate your attention to detail.
Always have been fascinated by mechanical stuff like this.
Very cool dissection. It would be cool to see you take apart a chronometric speedometer. They work like clocks. The speed updates in intervals rather than the fluid movement that the magnetic ones have.
Aaaamen to under dash misery! You described it perfectly. Still have scars from our '69 Fury...always an air conditioner switch. I've been trying to place those stylized digits; first remembered them as GM, but comments about Dodge reminded me of my grandfather's late 50s Plymouth, and I think that's the match. Mopar used red for high beam in the 60s, but those lights could be oil and generator. Doubt it would lack a beam indicator, though. Europe was different; our '64 VW already had a blue beam indicator (with green OP and red gen).
I knew you were going to say, "I'll call him Don to protect the innocent." No, "...'cause it's his name!" lol
Someone mentioned old cars smelling alike. It's largely the seat foam, but the VWs have a unique smell. Fun memories.
Thank you for the explanation sir. I have a mechanical tach in my airplane that reads 100rpm low so I am trying to figure out whether I can have it re-calibrated and your video is most helpful with understanding how these eddy-current indicators work.
Worthwhile. Dated; yes, but still worthwhile. Thanks, Tubalcain!
I realy enjoyed this one. I had torn an old speedometer apart as a kid and figured out how they work a long time ago. You are correct that it was at one time not a crime to alter the odometer record. It only became a crime after the value of used cars had risen enough that it went from being a couple hundred bucks more to several thousand more for a low miles car. After it became a crime the manufacturers of speedometers installed a scribe mechanism inside the odometer so if it was rolled backwards while the unit was assembled it would score a mark in the center of the numbered wheel, leaving a visual indicator of tampering. An acquaintance of mine owns a garage. He is in his 80s now and still works every day. He told me that his business was at one time a certified speedometer repair shop and he did the majority of speedometer "repairs" for the car dealerships in nearby Youngstown, Ohio. I have worked on many, many cars in my life. I have only had to replace one speedometer ever. And that was in an '88 Chevy Cavalier. My guess is the little magnet likely came detached from the speed cup. I have had several apart for classic cars. Simply clean, oil, sometimes repaint the needle and reassemble them and they are good for another 40 plus years.
All the best!
Mike
You might add a link to your magnet experiments. The eddy currents (and the induced counter magnetic field) that drag the aluminum cup around are the exact same as the effects that cause the magnet to drop so slowly through the copper tube.
You can see the same effect in reverse when you move the needle by hand and release it - the needle returns to zero quite slowly. In this case it is the aluminum cup rotating in a fixed magnetic field.
Thank you very much for this detailed video which allows us a quick travel in the past in order to discover old (but very smart !) mechanism ! Happy that you mentioned a famous car from my country : Renault Dauphine :)
👍👍
Thanks for the video. Always wondered how the needle was linked to the shaft is such a way the needle didn't just spin around.
Some speedos (like those for an Opel GT) have a mark and a corresponding rpm noted on the dial face that allows you to calibrate the unit on a bench. I was able to verify that the unit on my car would have been accurate if the wheels/tires were stock, but they were smaller, so the unit read high. Wish I still had that car!
Great video!! I always wondered how a speedo worked,....and now I know, magnets,.....I worked at a juice bottling plant, and the bottle capper chucks had magnetic clutches and worked sorta kinda on principle like a speedo.
I know very well about working under the dash. I worked a couple months at a car stereo shop in the 2nd part of the 70's when everybody and their mother were buying C.B. radios for their vehicles. (remember the song "Convoy"?). We also installed after-market cruise controls. There was a box you mount under the hood with a linkage that went to the carb. It also had 2 shafts on it, an input and output. We removed the cable from the back of the speedometer and the tranny. The cruise kit came with a couple shorter cables. One attached from the tranny to the input shaft of the box. The other cable went from the output shaft of the box to the back of the speedometer.
P.S. Moving the odometer back reminds me of the beginning of the movie "Used Cars". It is a hilarious movie starring Kurt Russell. Also had 'Lenny' and 'Squiggy' (from "Laverne & Shirley" - not a big fan of that show), and Al Lewis (grandpa from "The Munsters"). A must see movie with a little gratuitous nudity.
I really like analog things like a speedometer, this video is pretty good at showing how does it works and the parts it has. Very Great video!!!!
Thanks
I can remember a floor mounted high-beam switch!
My first "car" was a 1947 Willys Jeep, CJ-2A. It had two identical looking dimmer switches on the floorboard. The one on the left -was- a dimmer switch, the one slightly to the right and above the accelerator pedal was the starter switch.
That way you could crank the engine over with the toe of your right shoe and pump the accelerator pedal with the heel of your right shoe, at the same time! Good memories!
Grandpa Cocky remember my band teacher told me a story from the days of vacuum operated wipers
He had to stop going uphill in the rain driving a Chevy pickup once because the wipers would literally stop as the engine would be pulling too much air under load
@@TreeTop1947 i have a willys but it's a work in progress
I was at a gas station in Maryland that had a dynamometer that was used to calibrate the Prince Georges County Police speedometers.
I remember used car dealers putting Motor Honey in the engine and sawdust in the differential.
The precision of the odometer drums and especially the pinion gear casts is amazing considering the age of the component. Thanks for the video!
thanks Mr Pete for the great video.
excellent video, learned something new today
Ahh I really thought there was a good chance no videos would exist on this pretty random and obscure topic, so thank you for this!
I'm glad you like it
Really robust speedometer internals, so cool!
Nicely done.
Howdy Pete, I've always sorta known how the old speedos worked, but never saw the innards to know for certain. Your video 'splained it all...THANKS!Also, you said you had a Renault Dauphine way back when and, as a fellow who turned wrenches on 'anything foreign' (back when anything imported WAS foreign) in the later '60's, there was an in-trade saying we used to describe the Dauphine. It was that the French captured Dr. Ferdinand Porsche, and forced him to design a car as good as the VW. The result was the ever-popular Renault Dauphine, which was known as "Porsche's Revenge".They weren't great cars, nor were they lousy cars but, like all French cars...they were inexpensive (spelled c-h-e-a-p) and tres comfortable!And there you have it...please keep 'em coming...Mark in Modesto
This is great. Thanks Lyle
Brilliant...thanks for the video.
Probably the only complete and precise video on a speedometer
Thanks
This is so handy I am forever taking things apart to see how it works so thanks great vid
Thanks
thank you for your video, it was very informative!!!
this was like getting a lesson from my old man, very good, this was a fun watch
😀
There is a stigma attached to odometer readings. Someone wrote down the mileage wrong on my Supra, probably getting my oil changed or some minor repair, and it completely destroyed it's value from an appraiser. It wasn't because it was too high or too low, but that it wasn't chronological.
Good video and thanks for sharing.
Thankyou Sir you had my full attention wish my teacher in UK had half your knowledge in M.V.T
Thanks
Great explanation!
Thanks! I showed this to my 9 y/o son for part of his home school math. Odometers are helpful in understanding number systems and combinatorics.
That's great, I am always glad when our young person watchers
I replaced the speedo in my XY Falcon (Aussie car) which was in mph with a unit from a later build (same model) that was in kph. The original speedo had given up the ghost. When I was doing it, I pulled the new speedo apart and it was a very easy task to rearrange the odo dials to 00000. I didn't do it to rip anyone off mind you, but I just thought I'd try. The car was about 26 years old when I sold it and the odos only went to 99999 so it had clocked over about four times regardless. I told the guy who later bought it off me that it was a non original speedo and to ignore the odo.
very interesting, thanks
1062.5 mph great videos Tubalcain thankyou
Cool vid Mr.Pete.Even before you asked,I thought it was a Chrysler product because of the different size zeros.If we knew we would be selling a car,we would just disconnect the cable at the head to stop putting miles on "the clock".
I had a '61 Olds, F-85, that had that cup come loose on it's shaft, and caused it to peg while moving in the drive way. I took it out and apart and managed to re-anchor the cup (can't remember how though). After that it would show approximately half of your actual speed, so I think they were calibrated by adjusting the cup to increase or decrease the amount of "drag" the magnet had on it.
215 ci aluminum block V-8, with a Hydra-matic 3 speed, no torque converter (the old whiplash shift automatics). They had a lot of snap, and could get as much as 20 mpg on the highway, which was pretty good considering the weight of the car. If I could find one of those engines in good shape, I'd be tempted to try fitting it into my S10....
Thanks for this video!
How did they calibrate the spedometer.
Thanks for the video.
we use to have a name for people that clocked cars.. (cowboys).... Thanks for sharing sir enjoyed that very much....
I remember when I first learned about how speedometers work, back in my school days. I thought that was just the neatest idea, with the magnet and cup arrangement.
Yes
Green and Red lights: Green - alternator, Red - Oil. Green showed the Alt. was putting out current, Red would come on if no oil pressure. The two lights would come one when you first started your car (to let you know they were working). Just an old Ford boy here.
Hi Mr. Pete You speak of the cable being driven from the transmission. I wonder how many remember the dust cover of the front wheel bearing on V W's was the driving force for their speedometers?
I thought all the old cars were driven via front hub cable? But then I cut my teeth on an old VW Beetle so that was all I knew.
Thanks for posting this....
Agree wholeheartedly about working under the dash. My 1972 LeMans was a torture chamber.
Super video 👍
I found that video to be very educational. I specifically wanted to know, how the speedometers of cars worked at the era, when no electronics was used in cars. Also, please do understand that Your videos have a very important archival value, because the younger generations just do not have the need, nor the opportunity, to know about those old systems from their practical experience, a lot like is the case with computer museums, where the old timers explain to the modern generation, how those computers worked that were used before the birth of the modern generation. An interesting property of the mechanical instrumentation is that it can not be hacked in, it does not have any software security flaws. Thank You for the nice video.
Thank you, I never thought of it that way. But it is a museum of sorts
You mentioned the older car dealerships replacing certain interior parts to make the car look newer than it actually was, most used car dealerships now do sort of the same thing, but they do it by covering the plastic engine covers and hoses with tire shine. The half worn tires also get a good coat of the same, while the dash and interior all get armor-all.
how would you like to be the mold maker that made the die cast molds.
Good video !
Thanks always wandered. I always imagined they made the modern ones (not electronic) tamper resistant.
What would make the speedometer stop working when the odometer still works? The pin is in place, spring is in place- just won't work. The magnet spins- It's a 1950 Chevy truck. Any thoughts or suggestions as to what I should look for to fix this? Anything that would cause the magnet not to spin the cup holding the pin?
I would bet the car dealers are not any noticeable amount different than they ever were. Keep on keeping on.
Kurt Russel, Used Cars?
Many old cars did not have separate turn signal indicators. Just one light that blinked no matter which side you had on. The operator was expected to know which one he had turned on.
I've still got an old vehicle or two that do just that.
So that's correct, the red is the high beam, the green is the signal.
Thanks for the great video Mr. Pete!
Yes! Another Tubalcain cutaway!!
That old speedometer causes another lamentation about when things were built to last; coincidentally I have a much more modern electronic speedometer apart in front of me at the moment. There are still gears in it because even though the speedo is electronic the odometer and tripodometer are analog driven from an electric motor. Of course all of the gears are plastic and one as small as the pinion gear in this video is broken. Replacement for the tiny plastic gear is $25. :(
Turns out this is a common problem for many 90's vehicles.
My '74 VW Beetle had a double-ender arrow in the bottom center, it worked just as you described. Except the high beams would show blue. I think you had to remember to turn off the turn signal too. That was the first car I had with just symbols for everything, the oldsmobile i learned to drive on had words for everything that lit up. Why does every old car made in USA has the same smell?
in the past I have got my dremel out drilled a small hole through the spline and cracked gear and glued a pin(needle) through it never to happen again. Think it was a commodore many years ago.
That's how my '61 Plymouth Valiant is - a red dot for the high beams, and a green double-ended arrow for the turn signals.
i had a 65 Pontiac Grand Prix the high beam indicator was a Indian head with 2 feathers sticking up ..... cars used to have carachter
Thank you, very precision for mass production
Yes
Tubslcain rocks!
Thanks for that video I’m so thankful that I can just search something on the internet and learn
😀
Do you remember how some speedometer needles would bounce? I wonder if a weakening magnet was the cause of that?
I remember the peg to keep the needle from going further.
120 mph on a speedometer was alot for old cars. My dad had an '84 Z28 that only went up to 85 mph.
Good video.
great video
Where did you get the cut away diagram of the speedometer at the end of the video? I haven't been able to find anything like that! Any hints or links are appreciated. rtc
MrPete, if the part number on the back of your speedometer is 18778A, you have a 1955 Dodge speedometer. If it is 14195A it is a 1956 Dodge speedometer. As I recall, Stewart Warner made Ford speedometers, not Autolite. (See partsfromthepast.com under Chrysler).
When I was a boy, my father had an auto repair shop next door to a used car lot. He did touchup and small repairs for many of the used car lots in town. There was a man all the used car dealers called to turn back speedometers. I remember him because he was a paraplegic who had hand controls in his own car. At 12 years old, I was very impressed with his car. There was also a man they would call "re-groove" the tires. I watched him many times using what looked like a big electric soldering iron with a little metal loop at the end to deepen the grooves so the tires looked almost new. He got 25 cents for each tire. The strange part was, the owner of the lot was one of the more honest dealers in town. So much for honesty.
Cool, I had always assumed it used something like the governor on a steam engine. Not so.
Back when I as a 16 year old back in the early 70s, my Dad would keep tabs on how many miles we would drive on a Friday night. After one night of putting on many extra miles driving some girls home from all over the county, I decided to roll back the odometer by at least 150 miles. I removed the speedo cable from the transmission of the 1966 Ford Galaxy 500 and hooked up the only drill available, which was Dad's 1/2" Montgomery Ward. I hooked up the drill and was quite disappointed when it would only run at 40mph. I had limited time, so I gave up on the project, and by chance, Dad never did check it that day.
Haha. Geraldo should open this!
the red and green could very well be turn signals, boats have red and green to indicate left and right sides at night
Ok, the math....
You would have to travel @ 1037 mph BACKWARDS to match the dremals 15,000 rpms and it would take you a little over 6 hours to get the OD to read zero LOL !!!
For the mph, i took the reference 1200 rpm drill that ran at 83 mph, divide 1200 / 83 = 14.46 rpm per mph, divide 15000 / 14.46 = 1037 mph.
For the time, i timed how long it took for the OD to go down by 1 mile when you was running it with the dremal and that took approx. 6.3 secs, 6.3 * 3496(original miles on OD) = 22025 / 60 = 367 minutes / 60 = 6.1 hours...
Tah-dah !!!!
Very interesting mathe--I hope everyone reads your comment
I was wondering how many turns of the rear shaft it takes to advance the odometer by 1 mile. Going by Mark's figures, the dremel took 6.3 secs to move the odometer 1 mile. If the dremel is turning at 15,000 rpm's divided by 60 comes to 250 revs per sec. In 6.3 sec's, the dremel would have turned 1575 times to move the odometer 1 mile (or 157.5 turns per 10th mile). A more accurate method would be to count the teeth on the gears and figure the gear ratio accordingly.
Yeah, the dremal was not spinning the OD at 15,000 rpm but I would think the drills rpm would closer to accurate. Could probably time 1 mile while running the drill to get a more accurate figure on rpm at OD
I tried to get a reading when tubalcain used the drill. I watched the tenths dial as the bottom of the numbers just disappeared from the display window. I stopped the video at 4:51 just as the 8 disappeared and at 4:56 when the 9 did. That's 5 sec's at 1200 rpm for a tenth mile or 50 sec's per mile. 1200/60=20 rev's per sec. times 50 sec's = 1000 turns per mile. One full turn of the gear on the end of the odometer advances the readout by 1 mile making the ratio of the input shaft to the odometer 1000:1
Nicely done. In practice though, I would be concerned the speedo gears would not hold up to the excessive RPM and blow apart.