CORSA SPEEDOMETER MAINTENANCE AND REPAIR

[bbodie52]

The Monza speedometers are less prone to input bearing failure. The Corsa with the extra trip odometer tends to wear out.

I don't believe the internal trip meter drive adds significantly to the stress on the main Corsa speedometer drive cable. There is a small internal gear drive that tends to wear out and fail as the original factory gear grease fades away!

https://www.youtube.com/watch?v=ypTQkiYSGSg


See the attached CORSA article for a complete description of the problem...

[66vairguy]

The Monza speedometers are less prone to input bearing failure. The Corsa with the extra trip odometer tends to wear out.

I don't believe the internal trip meter drive adds significantly to the stress on the main Corsa speedometer drive cable. There is a small internal gear drive that tends to wear out and fail as the original factory gear grease fades away!

Corsa Speedo Quote.jpg

I agree the input cable does not see much additional rotational resistance when the Corsa model speedometer is in good working order compared to the Monza model speedometer. The problem is either a lack of lubrication at the input shaft bushing, or the bushing is worn to the point it binds. When badly worn it can cause the spinning magnet on the input shaft to strike the needle shell and BANG the needle breaks off. Not common, but it happens.

As shown in the CORSA speedometer picture 11, the main input shaft and intermediate gear fail on the Corsa speedometer. This almost never happens on the Monza speedometers. Once the Corsa speedometer input shaft and intermediate shaft wear out, they start to produced excess side loading on the main input shaft bushing (the input shaft turns 825 rotations for EVERY mile). I've fixed four Corsa speedometers using the Monza speedometer main frame and input shaft with a reproduced intermediate gear (not sure if they are still sold). You have to modify a few things and you MUST use the other Corsa model parts. The bar magnet MUST be recalibrated. This was decades ago when my local speedometer shop had the equipment to calibrate the magnetic field. When he was done the speedometers read accurately. The fellow was knowledgeable and gave me some good tips. He was old back then and I suspect he is not working now. Now it is hard to find a shop that repairs/calibrates the old mechanical speedometers.