tranny speedo gear
Thread Starter
1st Gear
Joined: May 2008
Posts: 1
Likes: 0
tranny speedo gear
I have a 71' Stingray with a Lt1 automatic the problem is the speedometer at 50mph it is showing about 65 and at 65 apox 85. I pulled the gear out and its dark green with 42 teeth running 235X60x15 tires. I have no idea of the exact gear ratio of the rear. Can any one give me a direction as to what color gear I should try? Thanks Tag
Burning Brakes
Joined: Dec 2005
Posts: 992
Likes: 56
From: Baldwinsville, NY
Speedo Gears
All the Corvette Parts Vendors Sell that stuff. Try this link:
http://www.zip-products.com/Zip/sear...=false&GiftID=
http://www.zip-products.com/Zip/sear...=false&GiftID=
Melting Slicks
Joined: Aug 2004
Posts: 2,914
Likes: 229
From: Oakbank Manitoba
You need to count the teeth on the other gear in the tranny. Jack the car up and spin both back wheels one revolution while counting how many times the driveshaft turns to get the gear ratio. You also need the diameter of the back wheels the are being used. There are calculators on the web that will tell you exactly which gear you need based upon the number of teeth on the other gear and tire diameter and gear ratio. TCI website has a good calculator.
Last edited by KENS80V; Jul 16, 2008 at 04:05 PM.
Burning Brakes
Joined: Oct 2006
Posts: 1,044
Likes: 0
From: Henrico VA
I am running a few different speeds with my GPS and seeing what I get. I will graph the data points and use the slope as my gear that I will order. I believe that will provide the best accuracy.
Melting Slicks
Joined: Aug 2004
Posts: 2,914
Likes: 229
From: Oakbank Manitoba
Check out this website for great info. www.tciauto.com then click on "technical info" near the bottom. Next click on "calculations and specifications". This is a handy calculator that works great. Your tire size 235/60/15 has a total diameter of 26.1 inches.
These calculators are very accurate ....you just need to provide the drive gear teeth size, tire diameter and lastly gear ratio.
These calculators are very accurate ....you just need to provide the drive gear teeth size, tire diameter and lastly gear ratio.
Last edited by KENS80V; Jul 16, 2008 at 04:06 PM.
