86 951 Driver

My odometer quit working a few weeks ago. I finally got some time to tear into it. Upon my inspection everything appears to be fine. No broken gears, and the odometer works fine by hand. What else would stop the odometer from working?

stujelly

same here, curious what it might be

HICKS

Me too. Mine was a broke ODO gear at first, then like 300 miles later it stopped again. I found a known working cluster and switched them out, and the ODO still doesnt work. I gave up for now...

86 951 Driver

Someone mentioned it could be the motor that went out. I don't know if there is a replacement for that or not.

Jay W

I put a new gear in mine and it stopped again the next day. Took it back apart and everything looked fine. On closer inspection I found there was left to right free play in the group of number wheels. So what happened was all the number wheels slid to the one hundred thousand side and left just enough room between the drive gear and the first number wheel. That bit of room allowed the gear and the number wheel to bind and it stopped the odometer.
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. It has been good for 50,000 miles.

This was from an 88, the early ones have a different gear slipping issue that a bit of super glue fixes up.

Kona

Have the same issue on my 86 951. Post pictures if someone has a fix

TexasRider

How about the shaft or the sender from under the car . I dont have the diagram here, but that might need to be cleaned or replaced.

HICKS

The one that goes inside the trans? Has a plug on top, and a plastic gear inside?
I picked a used one up to try, but still havent put it in yet. If the speedo works just fine will it effect the odo? When that part fails, is it all or nothing?

TexasRider

Yes that one on the tranny. Just for a lack of other places to look. I was also thinking the speedo was giving trouble - but nobody above said that.

It at least seemed like a part not checked on the above posts. Although as you say, if the speedo works correctly, than it would seem to rule it out. I dont know that they have any related function . Or not.

Scott at Team Harco

I've been having a similar problem on my S2.

The odo stopped working earlier this year. Speedo is fine. The tach was also normally non-functional - but that's a diferent issue.

Had assistance (meaning he did all the work) from Brian (from SC) at 944Fest. He replaced the bad odo gear. The odo stopped working on the way home from the Fest!

I swapped in the old cluster from my 85.5 to get a functioning tach and odometers. This one had a non-functioning fuel gauge. But at least the tach worked and so did the odo (for a while).

Only got about 62 miles on that odo before it stopped working.

Just recently took delivery from Brian of a complete S2 cluster with everything working. Got all of 0.2 miles before the odo stopped!

What the hell is going on? I noticed in another post that there are two capacitors on the circuit board that may become overloaded at 15 volts. Anyone care to speculate on this being my problem? Maybe an alternator that is not properly regulated?

I can live without working odos - but I'd rather not.

86 951 Driver

Took my gauge cluster to a local place in town. They said it is a board in the speedometer that went bad. It will cost $285 for the board.

Any ideas on what I should do?

doabarrelroll

Ok, I ran into a similar problem with my speedometer. After some research, it turns out a number of the 911 guys from this period have experienced similar problems.

If you look at the board that controls the speedo, there is more than likely a shorted resistor on it. My only thought at the moment is that it is due to additional wiring added to the car for additional gauges, etc. Anyways, I have some pictures to show what I'm talking about here.

The first thing to replace is the black capacitor on the upper left. It's a 47 uF, 16V piece. Turns out, there is about 15V going through this thing at any given time, and in some cases, causes the resistor in this picture to fry. Go to RadioShack and get a 47uF 35V capacitor ($1.49), and the 33 ohm resistor ($1.49). When it's finished it should look like this. I have soldered very few things in my time and I found this to be very basic.

If you're looking for an additional board, it is the same for all 944's, so, you can hit the yard to find a spare. For about less than $15, you can have a working speedo.

HICKS

You say this fix is for the speedo, will it also fix the odometer?

Scott at Team Harco

Small update to my problem: The primary odo started working yesterday (maybe the day before). Anyway, I have tallied about 150 miles since it stated working again. If it continues to work - I'll be quite happy with this.

xsboost90

alot of times you just slap a new odo gear in there and dont blow out the debris from the old odo that shattered to pieces. Then small bits get lodged in the gears eventually and stop it from working- you pull it apart and they fall out- then it works again. I always blow mine out with compressed air when i do a new gear.