OK, i installed my BMR adjustable torque arm today and I didnt get any directions with it...none needed really for the install....but!

the car is up and jack stands suspended on the body and the rear is hanging down and the fronts are hanging also.....do I have to adjust the pinion while the suspension is loaded? or can I do it the way it sits now? if it does have to be loaded how do I do that and still be able to crawl under the car? Load the rear under the axle and have the fronts sitting on the ground?

also where do I put the pinion indicator? and whats the best setting for a car with almost an inch drop?

thanks!!!

 

Now I could be completely wrong on this, as I use a non-adjustable arm, but when doing lift and lowering kits with trucks, the idea is to always match the angle of the first u-joint to avoid vibration, if possable. If it is a slight angle, this is no problem, our cars are almost all matched that way from the factory. Figure the less the angle, the less wear you will have on the u-joint, and the less the chance of an unwanted vibration.

On a slightly related tangent, there are two schools of thought on driveshaft angle in the off road world, which may or may not be relavent here. With 4" of lift, or a "mild" lift, many mechs will not adjust from the factory pinion setting to keep the angle balance relatively equal (say the yolk at the transfer is at 30* down, the yolk at the pinion will be 30* up) to avoid vibrations. Unfortunitly, when the suspention cycles, this can lead to extreme angles in the joints. The way I prefer to do it is at ride hight, have the rear joint at 0* (pointing directly in a straight line up to the X-fer), that way as the suspention cycles, it will still be well within the normal articulation range of the u-joint. But, this does carry the side effect of an unbalanced shaft, and typically leads to vibration, but with 35" tires, everything vibrates.

Back to point: as far as setting the angle, you want to do it at regular ride height, which means supporting the weight of the car by the axle, putting your jackstands under the axle tube. I dont know where else you would put them, but in any case, as long as the axle is supporting the weight of the car, you can adjust the pinion angle as if the car were on the ground. Hope this helps,

 

I have the Spohn adjustable torque arm and his instructions call for the car to have the weight on the suspension. Steve also recommends having the pinion angle set at -1 degree for street driving for lowered cars. I used a set of ramps under the front wheels and the rear axle sitting on jackstands to get the job done.

 

I know this post is old but I was wondering what the setting was for a NON lowered car. I have the adjustable torque arm also and since putting it on I have had a vibration. I had the driveshaft balanced and its still there. Also where do you put the angle finder at to get the correct reading.

 

Hopefully, I an help you out a bit. I too, have the BMR adjustable torque arm on my 1998 Trans Am Ram Air, so it is the same suspension. First thing, the best way to do it is to get the car on a drive on style lift so that all the wheels are on the ground how she would sit while driving. Next thing is to take the angle finder and put it on the bottom of the tranmission tail shaft where the driveshaft comes out. The angle finder should be magnetic so just write down the reading. Next, put the angle finder on the bottom of the rear differential, where the pinion goes in and write down that number. The difference between the two is your actual pinion angle. I personally set mine to -2 degrees. GM sets the pinion angle waaay positive for comfort and to save U joints but saves little to be desired for traction and parasitic divetrain loss. You see, when you launch the car, the pinion angle goes positive about 2-3 degrees. With the -2 degree offset, the pinion angle would be 0 at launch providing you with 0 pinion bind/friction so all the power goes to the wheels and not lost to the friction.