1 FMF

iTrader: (1)

have an s60 axle 3.73 ratio installed with umi adjustable long torque arm going to the tail shaft of the 6-speed transmission, poly bushing that comes with the tq arm. i'm in the process of setting pinion angle. I have a digital inclinometer that does 0.1° accuracy. Right now everything is installed and pinion angle is set close. i was thinking about deflection in regards to setting however many degrees of downward angle of the rear axle pinion to compensate for the tendency of the axle to roll upwards under load. everyone here says 2° down, or -2°.
I don't plan on racing the car any time soon, only the occasional pedal to the floor getting on the highway. with the rear tires on rhino ramps so i can get under the car, front tires on ground, i measure the angle of the rear axle from the umi torque arm mount. to simulate a load i put a floor jack under the torque arm bracket on the axle and pushed up a little, i am only measuring 0.3° to 0.5° upward change before the body starts to raise. so i am thinking setting a -2° pinion angle is way overkill and that i shouldn't set it to more than -0.5°. what do you think for street use? are these beefy aftermarket torque arms with the poly bushing that strong?
once again for right now i'm looking for the best setting so there is ZERO vibration driving the car on the highway, which i assume at a constant speed below 90 mph there is not much load on the axle making it want to roll pinion angle upward?

poltergeist 02

iTrader: (65)

I think the factory set them at -2 with the stock torque arm. I have my rear set at -2 and I have zero vibration up to 100mph (I have not gone faster than that with it yet). I have also heard that you should take the angle of the transmission, match the rear end angle to the trans and then compensate for deflection (-1 to -2 degrees).

SSellers

Correct. If you draw a line through your transmission output shaft it should be parallel to a line drawn through your pinion. Pinion angle is the angle of the pinion with respect to the output shaft of the trans. I have run two degrees down and zero degrees (parallel) without vibration in a street car. More than two degrees down is typical for drag cars so the pinion will climb towards parallel.

farmington

iTrader: (14)

pinion angle is the angle between the DRIVESHAFT and the companion flange on the rear end. The factory set them at 0 degrees. -2 degrees is essentially a race setting and -1 is better for street driving.