Babaron

Hello. My brother in law has a '60 base engine vette with powerglide and has asked me the following question:

My speedometer on my C1 does not work. It seems that the cable turns counterclockwise instead of clockwise. I tried spinning it with a drill and it works fine. So it looks like the issue is from the plastic drive gear installed on the transmission or the gear on the spline. Attached are the photos of both.

Since I am pretty ignorant on this issue, I am hoping someone here can offer some advice.

Thanks in advance.

Ron

CANDA

The plastic gear is a speedometer drive gear. The color of the gear is based on the ratio of the rear end. In my 62 I have a 3.31 ratio so my speedo gear color is "natural" which looks like whitish clearish color. Your photo is showing Red so I am assuming you have a 3.55 or a 3,70 rear ratio. The gears are different to allow for the different things that will affect your speedo reading such as changing the ratio of the rear end or the size of the tires. This info is posted in a thread by "Hitch" that notes the color variations.
https://www.corvetteforum.com/forums...edometer+gears In my 62 I have an aluminum powerglide that the plastic drive gear is in series with. Not sure about the iron powerglide but I would assume a similar setup.
I am not sure about the other gear but you have come to the right place for answers. Is there a chance the metal gear was placed on the shaft upside down. I am assuming the metal gear matches up with the plastic drive gear. Thanks good luck.

davekp78

Doesn't matter which way the drive gear is installed.
When you say the cable spins clockwise, do you mean looking at it from the speedometer end? If so, it is correct. If you are spinning the cable from the trans end with an electric drill, the drill must be run reversed- as if you are backing out a bound up drill bit from a hole.
The drive gears, and driven gears come in 2 different diameters. A smaller drive gear with a smaller driven gear won't work.

Babaron

Thanks for the info, guys.

It looks like he needs to confirm his axle ratio. I believe that would be stamped on the rear dif. If he determines that the drive gear he has is the wrong one, where would be a good place to buy the proper one?

Thanks!

Ron

buns

Some drive and driven gear info here:


http://chevellestuff.net/tech/speedo.htm

CANDA

Most of the corvette parts places have them just search speedometer drive gear and the various types will come up. Here is a link for Corvette Central. Good luck
http://www.parts123.com/corvettecent...size=50&page=1