uscgjason Posted June 6, 2014 Share Posted June 6, 2014 Hi All, Is there anyway to find out what rear gearing is in the rear differential of a 1956 Pontiac without taking the cover off? Thanks for any helpJason Link to comment Share on other sites More sharing options...
Guest Posted June 6, 2014 Share Posted June 6, 2014 If you have a car with a posi or limited slip rear, jack up the car and get both rear tires off the ground. Now put your jackstands under the axle. Make a line on the pinion yoke and onto the rear end with chalk or a grease pencil. Do the same to the tire on the car, so you can see when the tire has rotated exactly one turn. Now count the number of turns of the driveshaft that it takes (use your chalk marks) to make the rear tire turn one complete rotation. (Transmission needs to be in nuetral or out of gear.) If your car has an open rear, jack up only one rear tire and leave the other on the ground. Now put a jackstand under the lifted side. Turn the tire and again count the number of turns of the driveshaft, but this time you must turn the tire two full rotations. So: Posi: Jack both wheels off the ground. Turn one wheel 1 complete turn. - Count the turns on the drive shaft. Non-posi: Jack one wheel off the ground. Turn the wheel 2 complete turns. - Count the turns on the drive shaft. If it takes about 2 and three-quarters turns, it's around a 2.73 gear ratio. If it's a little more than 3, you have 3.08s. If it takes about 3 and a quarter turns of the driveshaft, you have 3.23 or 3.25 gears. Very close to 3 and three-quarter turns, 3.70 or 3.73 gears. This method won't work very well on a posi that's worn-out and won't spin both tires equally. Link to comment Share on other sites More sharing options...
uscgjason Posted July 24, 2014 Author Share Posted July 24, 2014 Thanks!! Link to comment Share on other sites More sharing options...
Guest Posted July 24, 2014 Share Posted July 24, 2014 Here are the codes stamped on the diff.1956 Code 3.08 0 3.23 9 3.42 8 3.64 6 3.90 4 Link to comment Share on other sites More sharing options...
PONTIAC1953 Posted July 25, 2014 Share Posted July 25, 2014 Here are the codes stamped on the diff.1956 Code 3.08 0 3.23 9 3.42 8 3.64 6 3.90 4 you'll find that looking at the 7 o'clock position on the rear end housing, a square looking pad where the single digit number is stamped, most likely you'll find a 0, 9, or 8.charles coker1953 pontiac tech advisortech advisor coordinatorpontiac oakland club int'l Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now