I can not find what the stock pinion angle is on my RS. Any one have any rough ideas as to what it may be. I will be doing my transplant soon and that will involve a new tranny. Now i haven't measured but I've been told a driveshaft will need to be istalled. I want to make sure I get the geometry as close to stock as I can. Not even sure if it will change but just asking anyway

 

Does it matter what is the spec?

Never done it before, but I figured you just match the driveshaft angle to whatever the angle is on the transmission side. Equal and opposite angles result in smooth rotation of driveshaft.

 

Pinion angle is roughly 2° between the axis of the pinion and the axis of the drive shaft. Drive shaft goes upward from the pinion.

Ideally you want the pinion axis and the transmission axis parallel, but slightly offset, such that the u-joints are at an equal angle at both ends of the shaft. Something in the 1½ - 2° range is usually about best. If you can imagine looking at the whole setup from the side, a line though the trans shaft pointing a smidge above the pinion shaft, but parallel to a line through the pinion. Not sure what it is at the trans end in stock trim.

 

You may have worn parts, but it can be measured with a smartphone app. or an angle finder is cheap. Measure the driveline and trans. while you're under there.

 

These attachments might help.

 

Pretty certain factory angle is 0

most adjustable torque arms recommend -2 to -4* angle (pinion rotated down)

Hope that helps

 

Remove the driveshaft. Put an angle finder (or JMD suggestion of phone app) on the yoke of the rear end and find the angle. Put the angle finder again on the engine's balancer or crank pulley and take 3 measurements and find the average. Now that you know the engine's and the rear end's drive line angle you can adjust the rear end's angle as needed.

 

Forgive me if my thinking is wrong, but you can't just put an angle finder against surfaces around the car and read off the angles directly. This is because you're reading the angles with respect to the level of the ground.

The angle you're looking for is the angle with respect to the chassis; the chassis might be on ground (or on stands) that has a slight slope.

If the car is nose up on a +2 degree slope, and (as yet unknown) the yoke is pointing upwards at 2 degrees, the angle finder will read +4 degrees. The slope of the ground needs to be accounted for.

 

the slope of the ground is irrelevant because you're comparing the angles of the pinion and trans yoke with respect to each other.

 

BINGO!