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9 inch pinion angle help

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Old 07-24-2011, 07:14 PM
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Default 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?
Old 07-24-2011, 07:19 PM
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put the angle finder on the pinion itself and adjust it to -2, lock it down and your done.
Old 07-24-2011, 07:35 PM
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Originally Posted by subhumanzz
put the angle finder on the pinion itself and adjust it to -2, lock it down and your done.
Would where I put it at not work? it was the bottom part where the 2 long bolts go through to hold the torque arm to the rearend.
Old 07-24-2011, 07:43 PM
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You need to set it with the suspension loaded
Old 07-24-2011, 07:50 PM
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Originally Posted by bigj2717
You need to set it with the suspension loaded
It was loaded. it was on a 4 post drive on lift.
Old 07-24-2011, 08:14 PM
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Oh ok I read it wrong. Yeah if you're measuring it on the bracket of the ta where it bolts to the rear end that's fine that's always where I measure mine
Old 07-24-2011, 08:47 PM
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awesome. thanks.
Old 07-24-2011, 08:58 PM
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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.
Old 07-24-2011, 09:04 PM
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He said it's a drive on lift
Old 07-25-2011, 07:25 PM
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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.



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