I am trying to make sure that the front and rear U-Joint angles are w/in spec after my 700R4 to T5 swap. The GM Service manual (pg. 1986 4A-7 Figure 4A-6) says that the angles should 1.1* front and 1.5* rear.

My question is: Are these angles a maximum or am I supposed to have these exact numbers?

Thanks
Dale

 

Those are usually maximum. The smaller the angle. the less wear and tear in a u-joint.

The front angle is hard to change. You have to raise or lower the back of the tranny to change it.

The rear angle is set by adjusting the pinion angle. Factory setting is usually close to zero degrees however under accelleration, the pinion will rise up creating positive pinion angle. Set the pinion down 1-2 degrees. Factory rear suspension gives no adjustments of pinion angle. You'll need an adjustable torque arm.

 

I'm glad to hear that! With two shims at the tranny, I can get the angles pretty close to zero.

Just after the swap I did not put any shims in and I *think* that led to the demise of my extension housing bushing. Hopefully this fixes it.

Thanks
Dale

 

86,

Zero would be good, but you have to consider the flex of the bushings on the torque arm and LCAs while under extreme torque. This will change the drive line angle, and at a time when you need the greatest efficiency from the U-joints. 1½° is probably considering the slight rise of the axle (and therefore, driveshaft at the front) when the torque is slapped to the rear axle. I would tend to maintain the 1/1½° specs for that reason, or even increase it slightly it the car sees a lot of track action.

If you want to emulate the twist and weight transfer, check the angle with a full load of fuel and about 600 pounds of dead weight in the rear of the car (for weight transfer).