Forget about the transmission angle, that applies to chassis set up.
You are not going to change the angle at the transmission/xfer case with relative ease. The pinion angle needs to be addressed. You need to find the difference between the driveshaft angle and the pinion yoke.
To check pinion angle..... I use the Craftsman digital protactor. All the measurements should be at ride height. It doesn't matter if the truck is on a slope or not.
- Stick a angle finder on the driveshaft. Record that number. Say it slopes down, -7*
- Get the angle of the pinion. Either pull the driveshaft and put the protractor on the face of the yoke or put a socket on the end of the bearing cap and put the angle finder on the socket. Say the pinion angle points up 5* (nose up).
Now the difference between the two angles is 2* at rest. Which is no good under load. As power is applied, the leafs deflect and rubber bushings distort around 3*-5*. So under power, the pinion rotates above the driveshaft. What you're looking for, is to set the pinion angle lower so when power is applied, it is inline with the driveshaft.
Now with leaf springs and rubber bushings, you need atleast around -3* to -4.5* but more closer to 5* IMHO. You wanna be within 1*-2* difference under load. The u-joints can tolerate the 1*-2* difference. You don't wanna be a 0* because the needles in the yoke won't spin.
So going back to the above example, 2* is not enough. You need to buy 4* shims to place under the leafs which rotate the pinion down if you installed the shims the correct way. If you measure the pinion at rest, it should read around 1* (nose up). That makes it a difference of 6*. So under load, the pinion is going to rotate 3*-5*. This brings you within spec.
You really shouldn't play with the carrier bearing. The shaft between the carrier and the transmission/xfer case is really an extension of the transmission/xfer case.
Now throw in traction bars which "lock" the pinion angle. You can reduce that 5* difference alittle. The leaf bushings/traction bar bushings (if any) still distort.
Some don't like using shims and prefer angled blocks. Ring a bell now....why some blocks have tapers to them.
For more reading:
Pinion Angle - Wolfe Race Craft
Here is a pic of my driveshaft angle with protractor. I have my notes at my shop.
Hope this cleared some of the confusion.
Billy T.
gnxtc2@aol.com