Odometer Drive Gear Worn

[Kevpix]

Hi Guys, sorry for all the questions. I've found out why the odometer in the speedo isn't working. The worm gear below the rotating magnets has dried out and worn. I have a new worm shaft on order but it could be difficult to replace. It looks like one end is supported by a bush. I'm hoping the bush will knock out and I can reuse it.
Any tips from somebody who has done this job would be most welcome.

 

[TimP]

Hi Kevpix,
I did a similar repair on my '72 a year or so back which I posted about on the '72 Corvette - Restoration Updates' pages in the 'Your Projects' section.

Its on the bottom of page 4 and the top of page 5 (jan 2021). There's probably a way to link to it but I'm not sure how.

I might have some more pics if you need them - I don't post them all - although I think your one may be a little different than the one I have. I needed to replace the plastic odometer drive gear as it was chewed up due to a seized mechanism.

Hope this helps.

Tim

 

[teamzr1]

Try this Tim
Tim's Restore

 

[Kevpix]

Hi Tim. Found your restoration project. It was a great read although I only got as far as the speedo bit, saving the rest for another day.
How did you remove/replace your worm drive? I see your original was plastic and replaced with steel. My new worm drive should arrive tomorrow, er, today!
Time for bed said Zebedee.

 

[TimP]

I've gone through my other pictures and unfortunately none of mine show the key piece - the second worm retainer.

However, I did find this page on Wilcox which shows it quite well. The second worm (which I think is the one you are replacing) has a retainer which is removed and the worm is fed through that and the far end goes into a bushing and then the retainer is replaced, keeping the worm in place

1953-1977 Corvette Speedometer Odometer. Why they stop working

At the top there is a photo that shows an exploded view with the main casting showing the retainer removed and the hole where the worm slides through. A picture of the retainer is shown on the right.

Hope this helps!

Tim

 

[Kevpix]

TimP. It helped very much, thankyou. What they called a retainer I called a bush and it tapped out easier than expected.

 

[Kevpix]

My C3 is back on the road with a working odometer, which will keep my insurance company happy.
It was quite a task to get the dash and speedo out, made easier by taking the steering column out. The new second worm didn't cure my problem as the first worm was also worn (as you would expect but thought I could get away with it). I never did find a source for the first worm drive but trawling through the internet I discovered that the rev counter had the same magnet rotor/first worm drive assy. Obviously the worm drive (which drives the odometer and trip in the speedo) isn't required in a rev counter so is unused. I dismantled the RC and pressed out the rotor/worm drive assy and swapped it for the worn speedo rotor/worm drive assy. Now speedo/odometer and RC are working fine. Thanks for your help guys.

 

[johng]

That's a good piece of lateral thinking