Can anyone explain the exact process of dialing in the pinion angle? I bought the adj. TA from UMI and will be installing it next week. Thanks!

 

Setting Pinion Angle

There are two angles to deal with:

1) Driveshaft angle
2) Pinion angle

You subtract pinion angle from driveshaft angle to get TRUE pinion angle

Here's how you do it:

First, had you measured your stock drive shaft angle and pinion angle before you removed your stock torque arm, you would have calculated a 0 deg. TRUE pinion angle. This is how all cars come from the factory, no suspension bind.

Using an angle finder place it on the driveshaft (a flat smooth spot) and record the angle indicated.

Next, place the angle finder on the flat surface where the torque arm mounts to the rear end (this surface is parallel with the pinion shaft) and record the angle indicated.

Subtract the pinion angle from the driveshaft angle. The result is "TRUE Pinion Angle".
In order to apply preload you need negative TRUE pinion angle. Adjust the torque arm so that the front of the pinion goes down; continue to check each angle until the pinion angle is more degrees down than the driveshaft angle.

We recommend –1 degrees on a mildly modified daily driven car. For high horsepower applications we have gotten the best results with –2 to –3 degrees. There is no reason to run more negative then that, it will actually hurt your performance because it will induce driveline bind.

You don't want to drive around with your suspension preloaded all the time, it's a lot of unnecessary binding on the u-joints and suspension. It should only be used when racing.

Here's a tip. When adjusting for your TRUE pinion angle, count the number of flats (or the 1/6 of a turn) as you turn the adjusting nut, to know how many it takes to adjust 1 degree of negative TRUE pinion angle and in what direction (clockwise, or counter-clockwise). Once you know that, then adjusting the arm at the track or before a race will take almost no time, and no angle finder will be needed.

Adjusting your Spohn Torque Arm: You adjust the pinion angle by turning the pinion angle adjuster, (located at the rear of the lower torque arm tube) either clockwise or counter-clockwise. As you turn the adjuster you will see the pinion nose of the rear housing moving up/down. Moving the rear housing's pinion nose down will give you more of a negative pinion angle degree, and up will give you more of a positive pinion angle degree.

You will quickly learn that it does not take many turns to adjust the angle by several degrees, so go slowly and check your angles often.

This is directly off the Spohn TA instructions.

 

There's a bunch of how-tos which only succeeded in
confusing and pissing me off. Add, subtract, blah blah
blah.

The only way I was able to get it right, was first to get
it set to dead even (trans pan to torque arm flat) by the
angle finder; pointed same direction, get the same angle
reading in both places. All simple. I put the car up on
four Rhino ramps to get it evenly loaded and level, mine
is too low to swing a wrench otherwise.

Then, just at the back, you crank on it until the pinion
nose goes down by a degree (all hard / poly links) or
two (rubber) from there. That would be backing out the
lower threaded adjuster.

What tells you you're done, is a minimum of driveline
vibe under full throttle acceleration. You may never
have felt driveline vibration in a stock setup but with
a misadjusted TA you will. Try -1, -2, -3 and keep
track of what felt the best on hard pulls, so you can
step back to it. Counting flats is a good way to go.

Do not expect any of this to affect traction, that is a
different story (torque arm and LCA angles). Just go
for a minimum of beating on the driveline.

 

Thanks guys for the info!!