Odometer fix not permanent with new gear

[Awaino]

Hello All, I recently did the odometer fix with the new gear. The first time it worked for 16 miles. I took it all back apart and checked for small pieces, etc. I found nothing. I could turn the motor and drive the gears in the odometer with no binding or catching. I put it all back together last night and it was working. I drove to work this morning and it stopped working after 8 miles. Could it possibly be the motor not working? I am scratching my head on this.

By the way, the speedometer and tachometer needle mess-up was $90 (with shipping) for two needles. Expensive mistake. D'oh!

[JK McDonald]

Hey Awaino - There have been a couple of instances similar to yours where after the new odometer gears were installed the tumblers suddenly stopped again. There is a good write-up on installing an additional very small washer on to the odometer drum during reassembly to keep all the gear teeth tight and synch'ed. The description on sizing the washer is toward the end of the procedure.

To get the speedometer/odometer back together only to have it stop working once again is really aggravating. I had the same thing happen but mine had quit a second time because of the destruction of another brittle gear that I should have replaced during the initial tear down.

1984 ODOMETER REPAIR PROCEDURE

Good Luck, Michael

[SanDiego928]

That is an outstanding repair procedure. I am thinking of selling my 928 but after reading I may want to keep it so I can try to fix my odo.

[Awaino]

I did everything except that washer. I shall try it again this weekend....

[Mrmerlin]

the washer will usually cure the odometer from jamming
A hint try backing up in a parking lot about 300 feet ,
this might unjamb the drive gears

[MPDano]

Originally Posted by Mrmerlin

the washer will usually cure the odometer from jamming
A hint try backing up in a parking lot about 300 feet ,
this might unjamb the drive gears

Doing this in Los Angeles will most likely get you shot by LAPD

Maybe put on jack stands and do this to be safer?

[tmpusfugit]

There are several things that can cause a odometer to stop working shortly after replacing the drive gear besides the documented binding of the odometer drive drum referred to in the write up. Specifically:
1) drive gear being larger in diameter than the old gear, usually no more than .010-.015" larger. This leads to the worm gear on the stepper motor binding on the new drive gear shortly after installation. Solution is to place a thin washer under the stepper drive motor foot to lift it ever so slightly removing the bind on the worm/drive gear. I recommend just a slight amount of white grease on the worm to smooth things out a bit
2) the new drive gear is too tight on the shaft, or the shaft is rusty/clogged with old lube and debris, requires cleaning and in some cases a pass through the center hole of the gear with a proper sized drill bit.
3) the gear itself is too "long" meaning that when the e ring is installed it clamps down the gear and binds it up. The over all gear stack can be reduced in height with judicious application of a file to the end of the stack.
4) some of the gears have had "flash" on the backside from the molding process, I think the removal is covered in the write referred to by previous responses in this thread.

I have seen or had all these problems in the 14 or so odometers I have replaced gears in, so it is not unlikely that one of these is your problem more so than the of needing a washer in the drive drum assembly (never had to do that, yet)

[Yoni_d]

I can only say that I have the exact same problem When I took it all apart the reason for the problem was that the step motor was pressing the gear to much. I added a small washer to keep the worm away from the gear and it worked perfectly...mmm...for 200km and then it stuck again

I will try adding the washer to the drum and hope it will solve it.
So frustrating...

[unL33T]

I have the same problem. I've probably pulled mine apart and unbound it 4 times since I first replaced the gear years ago when I got the car. I've shimmed one gear with a very thin washer, cleaned everything several times, tried to file off some of the extra bits left from moulding, applied grease, but I'm going to have to go through that procedure and try a few more things. Quite frustrating but at least I've done it so many times now that I can get it out, working, and reinstalled in about half an hour.

[unL33T]

After reading that write up you guys with the older models have a much harder time with that repair. I have about half as many steps on my 87.

[Awaino]

I have not gone back in to look at it again yet. Working on getting the fuel lines ordered and replaced currently. It is on the list though...

[mazdaverx7]

Pull the speedometer unit from the cluster assembly and check the circuit board for burnt resistors or capacitors. These can commonly fail rendering the entire unit non functional. Recently had to replace two resistors and two capacitors on one of my 944's.