I have a T-56 with a Spohn crossmember and torque arm. I lost the instructions on how to find the proper angle, and was wondering if any one knows how to figure it out. I remeber my total angle should be -1, but that's all I remember. Thank you in advance.

 

With the car sitting in its normal position (i.e. flat on the ground, or at least flat ane level on something) measure the driveshaft angle, and measure the angle of the top of the diff housing on top of the pinion. You want 1 degree less on the rear than the DS; so if the DS is at 5 degrees with respct to the ground, you'd want the rear to be at 4. You can get an angle checker at Sears.

 

Sorry, but that is wrong.

You need to match the diff pinion anlge to the same exact reading as the TRANS OUTPUT SHAFT (not the drive shaft), then lower the front of the diff to -1* from the matched reading. This compensates for thrust and will even the out under a load to cancel out any bad harmonics that develop from unmatched angles.

RB, the reason why your method is wrong is because the car can be raised or lowered and need different pinion angles. The angle the diff is at when the car is at stock height is not the same angle needed if the car is lowered 2 inches. When the car is lowered, the pinion (front of the diff) needs to be raised slightly to be rematched with the trans output shaft angle.

Hope this helps.