Driveshaft pinion angle

[kinghs95]

I have a 72 Plymouth satellite that has moser 8 3/4 rear end. The pinion angle in rear looks like 6 degrees up and front transmission angle is like .5 down. I’m wondering what angles I need? The rear is up little more bc I moved the front hanger up an inch from leaf spring. The front is low bc I adjusted it to go lower since I put 18” rims and there was gap plus hopskis torsion bars. The rear angle definitely needs to come down bc if it’s basically pointing toward the rear bench seat. I hear people say 3 degrees down and some say 2 degrees up. Help

 

[AR67GTX]

You’re right the front of the differential needs to come way down and probably the transmission needs to come down in the rear too. They basically need to be at the same angle with equal (as close as possible) but opposing angles to the driveshaft.

There is an alternative arrangement called the W arrangement. As an example the transmission slopes down to the rear and the differential slopes down to the front. The heights and angles need to be finagled such that the angle between the transmission and driveshaft and the angle between the differential and driveshaft, are as close to the same as possible and below 2-1/2 degrees (not sure that’s hard and fast).

But sounds like the differential nose needs to come way down. If you are competing the car on the strip then I believe it’s normal to leave the differential nose a little lower than normal as under hard acceleration the pinion tries to climb the ring gear and rotate the front up - thus the pinion snubber.

 

[threewood]

Shim the rear end down 4 degrees or so. The rear end will raise when you get on it and you want the trans and rear end angle parallel under power.

 

[beanhead]

Leaf springs? You want the pinion somewhere around 3-4 degrees down at rest, to get parallel or close to it under driving conditions
as Threwood said.
Unfortunately if it really is 6 up, I don't think you'll make it safely with shims. You'd need 9-10 degrees of change and the spring locating pins are "usually" only good for around 5-6 degrees of shimming, and even that's cutting it close. Sounds to me like Moser missed on the perch angle....but re-measure and be extra sure before moving the perches.