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No, this was at the thumb nut where the cable sleeve connected to the speedo head, not the tripometer for the warning light.

The tripometer you show had a safety wire tying the screw to one of the posts, not a seal. There was originally a cover that would enshroud that assembly to prevent joe average from getting in there and tinkering, yet still allow for cable changes. (you can see the broken tabs where it used to be under that rivet to the lower left in your pic, meaning since joe couldn't figure out how to get in, he broke the cover off)
 

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Discussion Starter #42
Gee-whiz! I wonder what they were after, breaking the cover off? There's not much you can do to the thing even without the cover. When I found the "hidden" reset switch for the engine check light, I was trying to figure out how to get inside the box. I imagined it was some circuit board inside with a pulse counter that latched when it got to a preset number of pulses. I figured it was just a matter of looking up the IC to see which pin cleared the reset and I'd be free of that evil red light, but as it turned out I never had to go further than removing that silver cap and pressing the button underneath it.

Here is the back (case) of my speedo housing. The two bolts with the apparent holes for a seal are on either side of the thumb nut that secures the speedometer cable to the case. I didn't notice if there was something on the thumb nut for a seal to attach to.
 

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81 spider veloce speedo works SOMETIMES!

Greetings all

OK, I can relate to the desire to hammer-fix my speedo. This evening we traced the connections to determine if they were good or bad. Coonector to rear of speedo was not fully threaded. With that corrected and the second connection was solid we gave it a shot and ran it against a GPS & another vehicle - city & highway. It worked (actually quite well) for all of 15 minutes. Then back to on and off. Any thoughts? My initial impression (hope) is that the original cable may have been damaged due to the poor initial fit. Any other thoughts? I plan to pull a new cable tomorrow... but if that fails, what are the resorces out there for new or rebuilt speedos? I've hit a few dead ends. :

Thanks
 

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81 spider veloce speedo works SOMETIMES!

Greetings all

OK, I can relate to the desire to hammer-fix my speedo. This evening we traced the connections to determine if they were good or bad. Coonector to rear of speedo was not fully threaded. With that corrected and the second connection was solid we gave it a shot and ran it against a GPS & another vehicle - city & highway. It worked (actually quite well) for all of 15 minutes. Then back to on and off. Any thoughts? My initial impression (hope) is that the original cable may have been damaged due to the poor initial fit. Any other thoughts? I plan to pull a new cable tomorrow... but if that fails, what are the resorces out there for new or rebuilt speedos? I've hit a few dead ends. If all else fails there is always duct-tape and the GPS.

Thanks
 

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Hopefully tonight I will post some of the pictures that I took as I disaasembled my 82 Speedo. I did not take it to the same point as OLEO Spot due to rivets vs screws and the fear of breaking the needle. I have the problem that Partridge describes. If I ever get finished fixing all the other stuff that I own that keeps breaking I might be able to get my car on the road and see if cleaning and lubing the back end of the speedo fixed my problem. I know that the cables are good, the sending unit is good etc since I have had them all apart and the tripometer always works whether the speedo works or not. My thought is the lubricating oil dries up and becomes sticky causing the problem. I could feel this when I turned the connection by hand. I do not have the problem of the needle being off the stop pin. It rests against it with some tension from the spring.
 

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Discussion Starter #46 (Edited)
From what I've read and from what I've seen of my own speedo, if the odometer and tripometer both seem to work (they both roll over one mile when one mile is travelled) then it must not be your cable. The end of the cable is keyed (square in cross-section as I recall) and slips into a mating receptacle as the thumb screw is tightened down onto the back of the speedometer. That receptacle has a pinion-type gear on it, whose teeth engage a worm gear, and the worm gear drives another gear which turns all of the other gears on the odometer and tripometer. It's a mechanical connection straight through, gear teeth meshing with other gear teeth.

For the needle it's not the same. You start from the same point, the key of the speedometer cable mating with the receptacle, but the receptacle's shaft (that the pinion gear is mounted on to) has the center of the two-lobed magnet pinned to its far end. All mechanical to this point, but then the magnet has no physical connection to the cup it "sits" in. It does not touch the cup at any point, but relies on the magnet's field lines to "drag" the cup with the magnet as it spins. Picture a 5-gal paint bucket with a hand drill powered paint stirrer in the middle of the bucket. As the paint stirrer turns you see a whirlpool-like effect in the paint. The stirrer is only pushing the paint that is in actual physical contact with it, but that paint is "dragging" the paint next to it. That paint travels at a slightly slower speed because of the paint's viscosity, which both provides the drag that makes the molecules want to keep up with each other and the lubrication, if you will, to allow it to slip some. As you move out further from the stirrer, the revolving paint is moving slower, until the outermost paint seems to be sitting still because of the friction with the inner surface of the bucket. If you placed the bucket on something like a lazy-susan (turntable mounted on ball bearings), the bucket would actually spin, too, from the drag of that outermost ring of paint. The magnet and cup work more or less the same way as the stirrer and the bucket and the magnet's field lines acting as the paint. The cup is restrained from following the magnet around and around by the watch spring mounted to a shaft that is stuck to the middle of the cup. The needle is press-fit onto the end of that same shaft. The faster the magnet is made to revolve on its axis (from the turning of the speedometer cable), the more drag on the cup, which is then able to more overcome the resisting force of the spring, rotating the shaft and turning the needle further in its arc.

Unless the speedometer cable's key is able to slip (rounded corners on either the outside of the key or the inside of the receptacle?), then I would think that (working my way out from there):
1) The magnet has become unpinned from its shaft
2) The distance between the magnet and the cup have increased
somehow to where the magnet has little or no drag effect on
the cup
3) The cup has become unpinned from its shaft
4) The spring tension has increased to the point that it is stronger
than the drag effect of the magnet on the cup (unlikely).

From some of the readings, there is an adjustment mechanism (screw or stem) that can change the gain (increase or decrease the magnet's drag on the cup) by mechanically decreasing or increasing the distance between the magnet and the cup. That may be the purpose of the watch stem-like thing that I found hidden beneath the speedo's face plate on mine. If my speedo's problem was that it was off different amounts at different speeds I would put on my big girl panties and either find a way to tweak that stem or find a way to disassemble my speedo even further to figure out what the heck that stem was connected to. But knowing that curiosity killed the cat, and more importantly that I have enough stress in my life (I recently had to lay-off half my department, and today I learned that the company is being reorganized and my department and I will be reporting to a new boss) without euthanizing my speedo, I'm not going to do either one of those.

Rivets, hunh? I'd say "go for it" and drill them out, but who wants to chance metal shavings in all of those plastic gears?
 

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I like your analogies of the working of the Speedo. I also spent quite a bit of time learning how they work but I was not willing to start drilling out riveted parts but I will need to look at my phots to see how mine is different than yours. I should know once I try it whether my issue is #1 or 3 whereby I will send it to have it rebuilt or whether it is #2 and I may have solved it. The odd characteristic of mine and many others who have posted problems is that the speedo works perfectly sometimes (mostly when it first used) then after a short period of time it drops to zero and stays there and the tripometer continues to work just fine. Sort of led me to the cup and magnet parts as well. It could be that friction holds the parts (cup to shaft or magnet to its shaft) together until they warm up. However this issue has been present for quite a number of years so I would think that if they were unpinned they would wear themselves so loose that they never would work. What I am hoping is that somehow the cup had extra drag as a result of the old lubrication that keeps it from following the magnet or that the clearances changes due to the build up. My unit is put back together and is back in the car so I just need to get to try it.
 

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Carnitasboy
What issue do you have? The speedo reading 10 mph at stop or it working then dropping to zero? Sorry that I've confused this thread by adding another issue/problem into an interesting tear down
 

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Carnitasboy
What issue do you have? The speedo reading 10 mph at stop or it working then dropping to zero? Sorry that I've confused this thread by adding another issue/problem into an interesting tear down
I have the speedo reading 10-15MPH over what I am actually traveling and at stop. I did also recently notice that there is a noise coming from the speedo sometimes. Like there is not enough grease in the speedo cable? Probably a different issue, but could be related.
 

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Here are a couple pictures of my 82 speedo. There was no obvious easy way to split the inner mechanism in half to get at the magnet and cup. I took one picture with the pointer gently lifted over the stop to see where it would naturally come to rest.
 

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Discussion Starter #52 (Edited)
Spidryell, yours is only three years older than mine, but there are some major differences in how it is constructed. On mine it is obvious how to make the next disassembly step because you can see where the pot metal "upper" piece (that has the speedo cable connection) joins to the white plastic body that houses the odometer gears and cup, and there are two screws that secure the pot metal to the plastic. There is also a brass plate sandwiched in between the pot metal and the plastic.

In the first picture below I've separated the pot metal/brass plate portion (showing the magnet freed from the cup). The second picture shows the other half with the cup facing you and the brass shaft removed. The red arrow shows how that shaft goes back. The third picture is a close up and looking into the empty shaft hole. The arrow points to the protruding other end of the watch stem. I can't tell that the watch stem does anything but thread (if that) through the plastic so it doesn't look as if it either adjusts the spring or the cup. I'd say maybe that it was an artifact from an earlier version of speedo, but there is Spidryell's only a couple of years previous and it has major changes to it so I doubt seriously Jaeger would make all of those changes and leave a non-functional brass bolt.
 

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Discussion Starter #53
Update:
After I took the pictures below I made a rough guess as to where the needle should mount and stuck it back on. As it turns out I shouldn't have bothered, but I'll get to that. I put the pieces of the upper assembly (pot metal, geared shaft, brass plate and magnet with its shaft) back together and then screwed that back onto the plastic lower body. Then I put that assembly back into the case taking several tries to stab the tripometer cable receptacle hard-mounted on the case into its key on the assembly. Put the two bolts back to secure the case to the assembly. I then took that (leaving the glass face, bezel, and trim piece off) and reattached it back into the binnacle.

For those of you who might forget to mark which of the wires is the fan indicator bulb, switch the ignition on (don't crank), turn the fan button on, and then touch the black ground wire to each of the bulbs. The one that lights up is obviously the one. I also screwed the odometer cable on but just fed the tripometer cable through the back hole and let it dangle. The object was to get the speedo back into the console as fully connected as it needed to be to test it on the road, but knowing it would have to come right back out.

Next I plugged my GPS into the lighter socket and wedged it between the two binnacles and left the house. I found out right away that I didn't have the needle in the right spot because it didn't even start to lift off the needle stop pin until 30 mph. I stopped and pulled the needle back off its post (the benefit of not putting the glass and all back on). Then I maintained as steady a 30 mph as I could according to the GPS and pressed the needle back on to where it indicated 30 mph. I ran at various speeds and stopped at several stop lights and determined that I got the needle about 3 to 4 mph low. I pulled it back off and tried again going 50 mph and now I'm happy to say that my speedo is reading only about 1/2 mph off at all speeds (in the 15 to 60 range, anyway) so unless I goof up when I take it back out, put it completely together, and install it back into the binnacle I'm ready to claim success! :D

I'm pretty sure that my odometer and tripmeter worked, too. My only doubt is that I took some more pictures (not yet posted) of the upper assembly in pieces and partially reassembled and realized as I was about to post them that the brass shaft (that mates to the pinon gear) was in backwards. I think I realized that when I tried to get every thing back together, but the nagging doubt makes me question if the odometer was doing right. I'll check the odometer's function tomorrow and match it against the GPS distance, and then pop it open regardless and take correct pictures to post.

A word of caution is probably in order. Driving in even the very light traffic that I was, at night, trying to coordinate keeping a steady speed on the GPS, splitting your focus between the road, the GPS, and stabbing the needle back onto its tiny post, and not get run over or go into a ditch carries a certain risk to it. The longer, straighter, devoid of stops and other traffic you can pick your road, the better.
 

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Discussion Starter #54
You just gotta laugh. This morning I was anxious to drive my Alfa into work so that I could do some more checking of the speed and odometer reading against the GPS...and the car wouldn't start. It would crank, and act like it was going to turn over, and even cleared its throat a bit. I gave it ten minutes and then had to jump ship and drive my mother-in-law's Maxima in to work. Didn't seem to be a battery problem or a fuel problem, she was just being ornery. I guess I'll spend my work breaks today checking out some other threads instead of this one.
 

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great thread

Gentlemen

I have been following this thread with interest for two of the same problems; noisy speedo and incorrect readings. I have an '85 veloce and the speedo cable broke shortly after I purchased it. The reason was obvious, the housing got pinched against the frame when the wheels were turned to full lock. I installed a new one-piece cable (as it had when I bought it) and got lots of noise from the speedo head, needle bounce and a reading 10 mph over actual as confirmed by my GPS.

So, to the chase. The cable needed more and better greasing than I had previously applied - it now has white lithium which has cured the noise and needle jumping. I followed the instructions on pulling the head apart to reposition the needle, and of course, broke the pointer in so doing. Now it is all back together with epoxy and my speed is about 3-4 mph too low across most of the "city" speeds but very close at highway speeds. I doubt that I will take it apart again as there are other areas that need attention - who knew that a 25 year old car would require as much maintenance as a 25 year old mistress??

Steve
 

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A follow up. Speedo stopped working a few days ago, but if I hit the brakes really hard, it sometimes works for the rest of the day! ***????? Oh, and I am frustrated, too.
 

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Vibration!

I never knew of a VW Passat that had a problem with the Speedo?:confused:
Just kidding, check your cable connections. If all else fails, let me know. I still have one or two good speedo' on the shelf.
Ray:)
 

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Robert, I feel your pain. My children will need corrective eye surgery to repair all the damage done by eye rolling.

Is there a chance that my issue is in the trans drive end? I made sure that the cable is seated all the way in, but I have seen some threads about the drive parts failing. How to assess this possibility and can it be repaired while trans still in car?
 

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Speedo Trans gear assembly

I believe you can remove it without taking out the transmission. I've taken out several from different cars, but usually when the transmission is on the bench. The gear assembly is held in with two 10mm bolts and pulls straight out. There are at least ( if I recall correctly) two different version, due to different rear ends or tire sizes (14" vs. 15") you just need to count the # of teeth on the gear, I think there may even be a number stamped on it if I recall. I think I may have one, not 100% sure.
Ray:)
 
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