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There is way to much information on pinion angle out there, that I am confused. I bought an angle finder and took measurements. The confusion comes in when doing the math. If the pinion is facing down does that angle get a + or a -? So I drew a picture. Could someone please dumb down the whole pinion angle equation? Thanks



If I am interpreting correctly your diff is pointing 4.5 degrees downward toward the u-joint. You sum that angle and the driveshaft angle (assuming your drawing representation on the driveshaft sloping down to the rear).

Looks like you are 8 degrees nose down at the rear joint and 1.5 at the front. Since the slope of the driveshaft and transmission are the same direction you subtract.

Per the Mopar Chassis Manual, 9th Ed. Chapter 6.

Front U-joint should be 2.5 degrees or less, but not zero.

Rear U-joint
Standard Leaf: 5-10 degrees nose down, 5-7 preferred
Leaf Link: 3-5 degrees nose down
4-Bar (double pivot) link: 2 degrees nose down
Ladder (single pivot) link: 1 degree nose down
Oval Track Leaf Spring: 4-5 degrees nose down

So, in other words, if you have a leaf car you should be OK, but you could be better if you took 1-2 degrees out of the diff. If you do not have vibration cruising or under deceleration, then you are likely OK where you are.

-Michael

Michael 1968 Barracuda Notchback Coupe 440 EFI 6-pack, T56 Magnum 6-spd