Hey guys, I am at work right now and I only have about an hour left to work on my car. I am trying to set my pinion angle. I have a Spohn adjustable torque arm. I called Spohn and got the procedure from them. Looking at a magnetic angle finder from the drivers side of the car I have a positive 1 degree on the driveshaft, and negative 3 degrees on the flat spot of the torque arm where it mounts to the rear end. Now here is the formula that I have to calculate.....
TPA=DS-PA

TPA is total pinion angle
DS is driveshaft pinion angle
PA is pinion angle measured at the base of the driveshaft where it bolts to the rear end yoke

Anyway, when you plug in the numbers I get...

DS of 1 minus -3=4

So my pinion angle is 4 positive?!?!?!

How is this possible?? From what I know you want to rear end to point down so that under load when the pinion angle goes positive the angle would be 0 and there is no bind. Help me out with this!!!

 

Well that sounds like you measured, read, and calculated properly. ...and yes, the +4 is not what you want. You're looking for about -1 or -2, give or take. Lot's of people seem to like 0 as well. Either way, +4 is way high.

.....but that's the point of having it be adjustable. Just adjust it.

 

Well, after some confusion about basic mathematics, I finally came to the conclusion that I was looking at the formula properly. My original formula with the numbers plugged in was 1-(-3) did in truth end up being +4 because two negatives equals a positive. Anyway, I did some reverse mathematics and came up with setting the rear end to +3. This way....
1-(+3)=-2

So now my pinion angle is set to -2 and I feel pretty confident that is where I want it. I have a 1998 Pontiac Trans Am with a BMR adjustable transmission mounted torque arm, and I also have that set to -2 and have no problems with it. The only differences that I see are HP and TQ levels(the T/A has only 350HP and maybe 350TQ whereas the camaro has 500HP/500TQ), and the fact that the torque arm on the T/A mounts to the transmission tailshaft(which does have extra movement due to the polyurethane mount unilike the camaro which the torque arm bolts to the crossmember). I guess the only thing I can do is take it to the track hen I get everything done and see how she 60fts. Then, maybe give it 1 more negative degree and take it to -3 and see if the 60ft. changes.