C6-13thPilotCar

On my 1962 Corvette I have changed my stock 4.56 rear to a 3.70.
The 4.56 spedo setup has drive 6T/ driven 20T spedo gear setup. From searching I found info and charts for the stock drive - driven gear ratio for 3.70. It is drive 8T/ driven 22T.

My question is that I am running P215/70-14 tires on my 3.70 rear end. Their dia. is 25.9 in. I believe that the stock 15in tires had a dia. of 27.1in. Are the gears for the 3.70 the best choice or is there a different drive/drive setup I should use. Any help would be appreciated as I now have the transmission apart and want to get the best setup for the spedo gears.

midyearvette

i hope this helps but as you know, the driven gear size sets the speedo needle....did your 456 gear have an accurate reading??....best to check it with a gps....if you are reading too fast, then go with a larger driven gear to slow it down and visa-versa....i have found that each tooth is 4-5 mph either way, but don't hold me to it!......

tach drive 61

I just took out my 370 gears and put 308 ham and must live with speedo being off , or pull of tail on trans and change plastic ring on main shaft , i tried 18 tooth brown gear in place of green 23 tooth no good , so while it is apart do it right good luck

vetrod62

Use this.

http://www.stl-vettes.com/65Vette/GearCalc.htm

C6-13thPilotCar

Thanks that answered my question. You guys are great with helping others.