9 inch pinion angle help
#1
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9 inch pinion angle help
I have a Moser 9 inch and just installed a UMI full length adjustable torque arm and UMI torque arm relocation mount all in my 6 speed camaro. I searched through tons of threads on how to set pinion angle and got highly confused. I had the car on a 4 post lift and put the pinion angle finder on the mount where the 2 bolts go through the housing to connect the 2 and i adjusted it to -2 degrees and went with it. Is this ok or totally wrong?
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#8
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Setting the angle on a 4 post lift won't work. The suspension needs to be loaded so you'll need a drive on lift or just do it on the ground.
Then you measure from the torque arm mount where the 2 bolts go through. Then measure your drive shaft angle. Add the two and that is your pinion angle.
From there just adjust the torque arm until the total of the TA and the driveshaft equals between -1 and -3.
Then you measure from the torque arm mount where the 2 bolts go through. Then measure your drive shaft angle. Add the two and that is your pinion angle.
From there just adjust the torque arm until the total of the TA and the driveshaft equals between -1 and -3.
#10
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The idea here is to have the centerline of the crank parallel with the centerline of the pinion when you're under full load. While on the lift with the suspension loaded, use the angle finder on the front face of the harmonic balancer to find the crank angle. Move the angle finder to the yoke of the differential and adjust the torque arm till you're facing down 2 degrees from the angle of the crank centerline. That way when you get on it, the centerlines of both the crank and the pinion are parallel because the rear yoke on a 6 speed rotates upwards about 2 degrees out of the hole. For example, my car measured a downward angle of 2 degrees, toward the rear of the car when my suspension was loaded. I adjusted my torque arm till the angle finder measured about zero.
The problem with the generic number thrown around that you adjust it to 2 degrees down is that while it may be right for a car at stock ride height and suspension, on level ground, all the relative measurements change with a 9", tire heights, and even a little bit from changing motor mount setups. With the method of adjusting as I described, (assuming you could still load the suspension to ride height) you could mount your car horizontal or upside down (again, hypothetical) and still get the correct pinion angle set. Its all about the relationship to the crank centerline and how much the yoke moves upward under load.
The problem with the generic number thrown around that you adjust it to 2 degrees down is that while it may be right for a car at stock ride height and suspension, on level ground, all the relative measurements change with a 9", tire heights, and even a little bit from changing motor mount setups. With the method of adjusting as I described, (assuming you could still load the suspension to ride height) you could mount your car horizontal or upside down (again, hypothetical) and still get the correct pinion angle set. Its all about the relationship to the crank centerline and how much the yoke moves upward under load.