I'm starting to plan for this years winter projects. One thing that I want to repair is my odometer. It hasn't worked since I bought the car. I done a forum search and can't seem to find specific instructions. I've even checked Barry K's site. My car is a 63, but I'm pretty sure that the cluster is 65. I know how to remove the cluster,I'd just like some specific instructions/pictures on how to replace the odometer.

 

Send to John Wolf in Ohio, 1-888-309-0453

 

First you need to determine the year of the cluster. 63 will have a brushed aluminum cone in the center of all gauges, 64 with have a "stepped" black cone in the center of all gauges, 65-67 will have flat gauge faces.

There is a 99% chance that your odometer operates fine, it's the speedo head and its odometer drive gears that have worn out. The easiest and cheapest way to fix this is to buy a new head from just about any Corvette vendor and swap them out.

With as difficult as it is to remove the cluster (yes it has to come out), I would do all of the other things one should do while its out; bulbs, new tach head, any small gauge that needs replaced, lense replacement, etc etc

good luck!

 

I agree. But would suggest you find and restore the correct cluster, prior to further investment. Al W.
pAl W.

 

The cluster has been restored. All wiring and bulbs have been replaced. I know, I should have done the odometer then. I'm positive that it's not a 63 cluster. Pretty sure that it's 65. My speedo is also off. I assumed that was because a prior owner changed the rear end ratio and didn't make a corresponding change to the speedometer. I tested it with a GPS. When it reads 50 mph, I really doing 70 mph. Tach reads 2500 rpm. It isn't always 20 mph off. 55 mph is actually 80 mph. 60 is about 92. Low speeds are only 5-10 mph off.

 

The speedo inaccuracy problem can be fixed by replacing the plastic drive gear in the trans. with the correct one for the new rear end ratio. It's a 10 minute job.

Jim

 

I"ve heard that that's a pretty simple job. I really don't know what the current ratio is. I planned on pulling the gear and see what's in there now . Maybe I could get lucky and get the proper replacement.

 

Jack it up, rotate the rear wheel until it turns one complete time. Keep track of the amount of drive shaft rotation it took for this to happen and do the division. You can thus calculate the ratio. Then buy a plastic gear to match that ratio.

 

Ren,

Mentioned above, but again ou need to find the ratio out and then make sure you have the right gears.

Here is a copy from a thread I did a while back explaining why the odometer stops but the speedo keeps going. I can fix this, but you'll still need to make sure you have the correct gear in the tranny.

It sounds to me like your first worm and magnet bushing is taking a dump on you.

Over time this bushing will wear out and cause a miss-alignment condition between the first worm (A) and the second worm (B). (The second worm drives the odometer assembly). When the second worm wears out as shown in the right hand side of the picture, the speedo keeps working but the odometer will stop turning.

I think what has happened is the second worm is wearing out (at point B) and when it came to the stress of turning all the numbers on the odometer wheel it finally tanked. This in turn is causing stress on the first worm (which drives the speed cup the needle is attached to) at Point A and B and is causing it to bind and jump.

The first worm has to turn regardless of what the other parts are doing. If the second worm is locked up from the odometer turn, it will cause interference with the first worm and thus your jumping condition.

If I'm right, the speedo will need to come out of the car for repair!

Hope this makes sense.

Willcox


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