Found my repair thread from 2007 on the old NARP site, but can't link to it for some reason
So I just cut & pasted it here:
Posted: Sep 3 2007, 06:25 PM
Group: 914 Fan
Posts: 1,103
Member No.: 476
Joined: 15-December 06
My '76 BMW's odometer stopped many years ago at around 83k miles. The ODO stopped working on my wife's 914 (before we acquired it), and I always wanted to know what made them tick ... or 'stop ticking' to be more precise.
George H. gave me a Silver Dot speedo the other day, and unfortunately, the ODO and Trip Counter didn't work on it either ... so today I took it apart.
It kind of looks like a cross between a clock and a music box inside. The speedo cable drives a small magnetized flywheel. The flywheel spins inside a thin metal cup that is connected to the pin of the indicator needle. There is a shaft with a worm gear that is driven from inside the flywheel shaft housing, which drives another shaft that the plastic odo number wheels ride on.
This where I found the problem with the ODO and Trip Counter.
On the extreme right hand side of the 'ODO number wheel cluster', there is a pot-metal wheel that should be held tightly on the shaft so it rotates with the shaft (whereas the number wheels 'float' on the shaft). It looks like this wheel was originally pressed on or a friction fit, and eventually just wore the shaft or the bore on the wheel unsure.gif
I disassembled the cluster enough to remove the metal wheel, and scribed several linear impressions to create a splined shaft where the metal wheel resides. I reassembled the cluster, and the wheel needed a little bit of a push to get it back onto the shaft (which was my theory and goal).
I reassembled the speedo unit, re-greased the gears and shafts, then tested it using a cordless drill motor (with a tip from an old speedo cable in the chuck).
The Speedo, ODO and Trip Counter are working again smile.gif
NOTE: Make sure you spin the speedo in reverse (counter clock-wise) ...
In lieu of taking pix, I drew a little diagram. The diagram will make more sense once you look at an actual disassembled speedo: