odometer question

paul571 · 11-12-2003, 09:36 PM

Hello all,

I need some help. On the way home today, I noticed the odometer and the trip odometer stopped working for 15 miles or so. Then it would start working again. Mind you while all this was happening, the speedometer was working just fine. I believe this just happened today. Because I always zero out my trip odometer to track my MPG, which I have did last night after topping her off. Could I have loosened a gear in the gauge or could this be something else.

I appreciate any help.

Paul

CarreraS2 · 11-12-2003, 09:43 PM

I think the little gear inside the speedo that drive the odo is slipping on its shaft.

Happened in my 914. I took it apart, glued the gear onto the shaft with some superglue (after first roughing it up a bit), and it worked fine for years after that.

aigel · aigel's Garage

Palo Alto Speedometer will rebuild the unit for around $120. http://www.paspeedo.com/
Opening the speedo for servicing is a major pita. It isn't made for easy access, naturally. I think once you have it open, it is an okay project. Wayne's 101 project book has it in there.

G

CarreraS2 · 11-12-2003, 11:02 PM

I think you have it backwards!

It's actually a piece of cake to get the speedo open.

You simply pry up the bezel from the back side. Comes right off. Takes maybe 10 minutes if you are being super careful. 5 minutes if you are not.

Of course, a speedo shop will put a new bezel on, and it will look like new. If you reuse the old bezel, it will be apparent that the speedo was opened, but only if you pull the speedo out of the dash and pull back the rubber sealing ring to see the backside of the bezel. Some of the paint will likely be chipped a bit and it won't be 100% smooth. Not visible from the front when installed, though.

Getting to the gear and getting a drop of glue down in the right spot is the tricky part.

It's all do-able. But it also isn't a bad deal to just have a shop like PA Speedo do it. Depends on how cheap you are!

derkpitt · derkpitt's Garage

I just did the gear replacement in my 88 Speedo.
In was a major PITA!!!!!!!!!!!!!!!!!!!!
The trip now works, but the speed is not.
In the electronic Speedo the gears are very difficult to get at.
I would not do it again, ever.
Send it out to a shop in FL called,
Ice Cold Auto Air
1526 E Colonial Dr, Orlando, FL 32803
Phone: (407) 896-4661

VaSteve · 11-13-2003, 04:30 AM

I have a question: I test drove an 80 SC the other day. The Tach did not work and niether did the Odo. However the speedometer did work. I thought these were unrelated.

My brother (self proclaimed expert on everything) said that the VDOs tend the flake out if you reset the trip Odo in motion - it breaks off the gears or something.

How would this be related to the Tach though?
I'm not buying that car, I'm just curious.
Thanks
Steve

Thomas Owen · 11-13-2003, 06:43 AM

I have had 2 repaired with broken gears because I could not find a source for the gear. About 8 months ago (approx.) someone posted a thread about finding a source for the gears and they were inexpensive. Keep searching the archives...
Good luck,

sammyg2 · 11-13-2003, 07:11 AM

I've replaced the gear on two different electric speedos, took me about 1/2 hour each. I paid $40 each for the gears, there is a cheaper source but I don't have it handy.

The gears get old and crumbly and literally fall apart. It shows up more often when the odo is reset while in motion because that puts a little more stress on the old gear. With a new gear you can reset it any time without damaging it (supposedly).

There is no reason why replacing the gear would effect the speedo unless something else got messed up during installation.
It is also unrelated to the tachometer, two different issues at work there.

vinny c · 11-13-2003, 10:16 AM

Try www.odometergears.com. Gears are $25.

Vince

paul571 · 11-13-2003, 10:44 AM

Thank you all for your insights. I will take the speedo out tonight and see what I can find out. I will keep you all posted.

Any do's and don'ts on removing the speedo?

Once again, thanks for all the help.

Paul

sammyg2 · 11-13-2003, 11:40 AM

I believe there is an article written by Wayne in the technical article section, it covers disassembling a pre-electric speedo but much of it still pertains.
mark all wiring or take a digital photo, be very careful removing the bezel and glass, be very careful removing the needle and note the position before removing it, take another picture of the internals just in case, take your time and have plenty of lighting, wear magnifying glasses if your eyes are getting as old as mine

that's all i can think of.