pinion angle?

94GC

Active Member
Joined
Feb 1, 2011
Location
York S.C
Ok so im putting a 80 chevy one ton rearend under a 74 chevy frame and gotta cut a moove the perches. Does any body know where the pinion angle should be for a 6 inch lift on the 74 frame
 
Are you using the stock driveshaft or an aftermarket double cardon type?
 
With a single joint at both ends, use an angle finder and make sure the rear of the transmission or transfer case is within 2 degrees of the pinion yoke when measured vertically. That's all there is to it.

With a double cardan, point the pinion directly at the output of the transmission or transfer case and the double joint will take up all of the angle.
 
Single joint but the axle and rest of tye truck are at two different places got the rear axle at the shop doing the rear brakes and so i can moove the perches and truss it just not sure if there was a standard degrees to go by for a 6 inch lift
 
Croatan_Kid said:
With a single joint at both ends, use an angle finder and make sure the rear of the transmission or transfer case is within 2 degrees of the pinion yoke when measured vertically. That's all there is to it.

With a double cardan, point the pinion directly at the output of the transmission or transfer case and the double joint will take up all of the angle.
Click to expand...
here's your answer.
 
That makes sense too, they certainly do settle after a while. I just swapped the front springs out in my Silverado for some Alcans I had made a while back (money WELL spent, btw) and I noticed they settled after a week or two. Wasn't expected it that quickly, but they're broken in now and haven't settled any more. The ones on the front of my K30 DEFINITELY settled with the weight of the Cummins over top of them. I added a zero rate up front with the 4" springs and a 3" rear block and it sits level.

At most, I would add 2 degrees. If you buy shims, they're normally in 2 degree increments.
 
94GC said:
Single joint but the axle and rest of tye truck are at two different places got the rear axle at the shop doing the rear brakes and so i can moove the perches and truss it just not sure if there was a standard degrees to go by for a 6 inch lift
Click to expand...

I know it sucks but you really need the axle under the truck with the wieght of the vehicle to set the angle correctly.

Not to say you couldn't get it close, but why risk doing it twice?
 
The big problem with using angle finders, is that the angle is relative to the ground the vehicle is sitting on. You need to have the axle under the truck with the weight on the axle. Easiest way to do this is to roll the axle under the truck and set the perches on the axle tube unwelded. Set the weight down and use a jack under the pinion to get the angles right. Then tack the perches in place and remove the axle to weld them in good. Figure a couple degrees of spring sag as they break in. Figure a degree or 2 into axle wrap. Even going down the road unloaded, the pinion will want to push up just a little bit.
 
Definitely need to have the weight on the axle. Once it's mounted/mocked up under the truck, it won't matter if the ground is level or not. At that point it only matters the angles are close. He's spot on though. It's very easy to move it, even with the weight of the truck on the axle. I'd mark them with a paint marker personally, in case you need to move either perch in or out to make sure the axle is centered side to side. Just find a common point on something like the brake backing plate to measure from.
 
Sound like the vehicle really isnt ready for the pinion angle to be set.

Put the perches on the axle and clamp the axles to the springs with the u-bolts. Dont weld em til you get all the weight on the vehicle.then set the pinion angle and weld em up. As Croatan_kid said...a couple of degrees of included angle is about right.
 
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