[redlightning]

I just bought an 80 camaro that was an unfinished project.I got it running but the speedo is not working.
I have it up on jack stands.The speedo gear is not turning.It is brown and I can see the gear inside is red.
Should these two colors match up enough to turn the speedo gear.
The reason I ask is the guy I got it from had the trans "rebuilt".I found the gear in some bolts he had given me for the car.So I don,t even know if it is close to the right gear.
It is a th350 with 3.55 gears(he had them installed also).




On a side not here.I have not owned a chevy in over 20 years.I got a good deal on this one.Rebuilt 350 041 heads,flat top pistons,mild cam.It,s a fun car.It may wind up on ebay so I can finish my 56 ford but I might just keep it.

[jimfulco]

Assuming your brown gear is ~3/4" in diameter, the red gear has 10 teeth, and the brown one has 18. What you have is a 1.8:1 ratio, which would be used with some serious highway gears, or some seriously large tires.

With 3.55 gears, you'd need 39.8" tires to make the speedo right. Got clearance?

With 26" tires, you'd need 2.32 gears to make it right. No fun in my book.

Take your tire diameter and rear end ratio to www.novaresource.org/speedo.htm and use the formula to calculate what speedo gear ratio you need. Then use the chart to find what gear combos will give you the ratio closest to that. Gears are cheap at the Chevy place, or you can get them online.

It's possible that the drive gear (the red one) is not firmly attached to the tailshaft itself. There's a small metal clip that holds the gear to the shaft, and if it's broken, the shaft can slip inside the gear, and the brown gear won't turn like it should.

[redlightning]

FIXED. I pulled the gear out of the trans and took it to a local trans shop and told them what the problem was.I showed the gear to one of the older guys there and he said," That looks like a Buick gear".He gave me one for chevy.I got it in and it works.


Jimfulco,Thanks for the link.