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Odo intermittant... gears?

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Old 02-06-2016, 01:48 PM
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FeralComprehension
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Default Odo intermittant... gears?

Hi all,

My odometer has gone intermittant; yesterday it registered

Last edited by FeralComprehension; 02-06-2016 at 01:50 PM. Reason: post issues
Old 02-06-2016, 01:51 PM
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less than 20 miles on a 100 mile+ round trip. Speedo works fine.

I searched the other odo threads and read about gear failure, but those all seemed to imply that the odo stopped completely. Mine works.... sometimes.

Anyone else seen this and fixed it with a gear transplant?
Old 02-06-2016, 02:21 PM
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abarthguy
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You may have one or two plastic teeth left on the gears, but they need replacing....
Best to send the speedo out to one of the pro shops. Easy and not much $$
Old 02-06-2016, 02:31 PM
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jpar
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Originally Posted by FeralComprehension
less than 20 miles on a 100 mile+ round trip. Speedo works fine.

I searched the other odo threads and read about gear failure, but those all seemed to imply that the odo stopped completely. Mine works.... sometimes.

Anyone else seen this and fixed it with a gear transplant?
Same thing happened to mine last year, yours will probably fail completely pretty soon. I used these guys.http://www.odometergears.com/product...1-964+89-93/70 There are step by step instructions, it's really not that difficult.
Old 02-06-2016, 03:05 PM
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Earlydays
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Originally Posted by jpar
Same thing happened to mine last year, yours will probably fail completely pretty soon. I used these guys.http://www.odometergears.com/product...1-964+89-93/70 There are step by step instructions, it's really not that difficult.
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Old 02-06-2016, 11:11 PM
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Good to know, thanks!
Old 12-22-2016, 03:27 PM
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John McM
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Was this fixed?

I have two 964s. The odometer stopped in the first one, which turned out to be the classic missing teeth on the gear.

When I bought my second one, it had what I thought was a stopped odometer so I took it in for the gear replacement. The repairer sent it back with a note that the gear teeth were fine and he'd given it a lube. Now it's become intermittent.

The speedo works as normal, as does the spoiler suggesting that the input to the gauge is working. Before I send it back in I thought I'd research this more. Has anyone else fixed an intermittent odometer where the speedo is working normally, and what fixed it?

Last edited by John McM; 12-22-2016 at 08:37 PM.
Old 12-22-2016, 08:57 PM
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Interesting excerpt from a thread on a 944 Intermittent Odometer

What I found was that the stack of number wheels in the odometer had lots of end play on the small shaft that they all spin on. Every so often they would slide far enough away from the drive gear, that they would totally dis-engage. Make a turn and she would start working again.
The solution was to take a small (1/8" diameter) plastic tube and cut about 1/16" of length (mini donut).
I then split the tube down one side with a razor so that it could be opened up like a "C". Making so that I can just snap it on to the end of shaft. Thus pushing the number wheels against the drive gear. Kind of like a thrust shim if you will.
Old 12-22-2016, 11:11 PM
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Actually... no, it wasn't, and my odo is partially disassembled as we speak.

The first time I tore it down I did in fact find that the replaceable gears were shot. $50 later (yow) I figured I was back in biz. After a quick test to verify function I buttoned it back up and drove on.

Only to have it go intermittent ~50 miles later.

Re-reading the instructions for gear install I found the bit about making sure to blow the unit out with compressed air. "Don't skip this step," they say. "It's really important." Since I didn't recall having done that before I tore the odo down again and shot it out with shop air. Used a dental pick to gently remove some hardened lube from some of the gears. Tested it. For 100 miles. Worked great.

And then it quit again.

I'm off next week, and am intending to look again. I'll look for the endplay described above and try a similar solution if I find it.
Old 12-23-2016, 08:53 AM
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http://www.odometergears.com/product...1-964+89-93/70

I just replaced mine 2 weeks ago, it's a very easy fix
Old 12-24-2016, 03:50 PM
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You read the part where the gears were replaced and it didn't cure the issue, right?
Old 12-24-2016, 05:47 PM
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Very keen to see what you find. The odometer from the car with the already repaired gear is doing it as well. Makes you wonder how many cars out there have the same problem. Reliance on odometer readings might be misplaced. A dirty little secret.
Old 12-24-2016, 07:31 PM
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Trying to muster the motivation to look at it tonight. Think another cider will help?
Old 12-26-2016, 04:57 PM
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Originally Posted by FeralComprehension
Trying to muster the motivation to look at it tonight. Think another cider will help?
Evidently not! My two 1990 C4s wait with bated breath for your insights
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Old 12-26-2016, 09:20 PM
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I didn't find any end play of note; it really looked impossible for the gears to slide so far out of position that they'd disengage.

I did find one pin on the odo motor that had a less-than-perfect solder joint which I touched up with the iron:





Looks better here:



There was also a rough spot on the main board that I went after as well: (Sorry- no after shot).





I haven't tested it yet; get back to you.

Last edited by FeralComprehension; 01-01-2017 at 05:25 PM. Reason: grammar improvement


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