Hi all,

So My odometer has been acting up. I took out the cluster and sure enough the main lil gear was toast, swapped that out, cleaned 'er up and got about 250 miles before it stopped working. Took it back out and noticed there was still some dirt, so i cleaned again and it worked for about 57 miles.

Now I currently have it out and all the gearing looks good, everything is tight and moving fine. Doesnt seem to be any excessive play. The speedo works fine so i know it's not the cable.

My question is regarding the worm gear, when you turn it by hand should there be any resistance? I can feel almost an indent? Like you turn it a quarter turn and you can feel it. But i dont know if thats normal or if it should be as smooth as all the other gears.

Trying to decide if I should take a chance on a used cluster on ebay and swap out the speedo. Unless anyone could point me in the direction of a place that sells the motor that turns that worm gear......

Help? lol


Thanks guys,

I'm rolling in my ol mans C4 while my dash is apart so i guess it's not so bad

 

what year car? early dash or late dash?

 

Ha, Sorry, that might be helpful

1985.5 944 NA

So the late dash.

 

I have the same problem. I have replaced the gear twice and the longest it has worked is about 2500 miles. I've considered sending it in to VDO for a overhaul.

 

the motor is a stepper, it should have a definite cogging feel as you rotate it. I have done several of these, some of the replacement gears were not well made, and sometimes a little piece of the old gear is stuck in the gear teeth of one of the remaining gears and forcing it will destroy the new gear (been there, done that). Take your time, clean each gear completely, regrease, reassemble - inspect the new gear carefully to make sure the teeth aren't damaged (the teeth on the small drive gear on the new gear are what gets messed up, not the part that mates with the worm gear). it is very important to carefully get all the junk out of the gear train and also to make sure that the numbers and the little pawls don't get misaligned.

 

I had the same problem, replaced the gear, took it apart several times, would always stop working after a bit. Finally solved it by doing this:

"I ended up getting a thin piece of wire from a bread tie and wrapping it around the number wheel axle on the hundred thousand side, which took out the tiny bit of free play at the gear end." credit to Jay W

 

My odometer stopped working, thought it was "the gear" replaced it, and it worked for a little while longer and stopped. Took it all apart again, and upon closer inspection, it was another gear that had several damaged teeth, that once they came up, the odometer would stop working. Had to find another odometer, and scavenge the needed gear. So far so good. Not sure if it was shoddy reassembly or the other gear just failed.

 

Also, don't reset the odometer while the car is moving.

 

that is an old wife's tale - I've looked carefully at the mechanism, there is no way that resetting the odometer while the car is moving or not moving could cause the gear damage, please don't propagate that story - I know it's all over the web, but it's just plain not correct. If you don't believe me, take an odometer assembly apart and examine the mechanism and identify the causal mechanism for inducing a failure by actuating the reset on the 85.5 and later cars (I haven't inspected the earlier ones recently). the failure is caused by the disintegration of the soft plastic gear due to the specific plastic that was selected for the gear.

 

This is true. And most people first experience that fault when they reset while moving. And so it continues.

 

+1 on Noble - the device uses a solenoid to reset. My question has always been, why didn't they use the same plastic on the toothed gear that they used for all the other plastic gears in there? When I took mine apart, the toothed gear was like mush, and everything else looked brand new.

 

I think the soft plastic on the gear was to prevent hearing a click as the stepper actuated, but the only way to know for sure would be to find an engineer from VDO that was there and working on the assembly at the time. The soft plastic gear is common in many cars of the period with VDO gauges, so there was probably some specific reason.

 

Maybe it's the engineered "weak point", so that if something gets jammed, it's the only thing that gives, leaving the rest intact.