Posted by Roger in La on Thursday, February 22, 2007 at 22:39:29 :
In Reply to: Clint and Paul, repost from last forum posted by Tim Holloway on Thursday, February 22, 2007 at 22:08:15 :
Tim, if I'm thinking of this correctly, old, saggin springs would not change the angle of the differentials, but weak springs would lower the frame and the t-case. The angles at the u-joints would change as the springs weaken and the frame becomes lower, but the yokes would not become anymore or less parallel. If you put a heavy load in the rear, the t-case would slope down to the back, making the rear yoke more parallel with the rear diff, but it would make the front yokes less parallel.
My 57 shop manual indicates that yokes should be within 1 degree maximum of being parallel. They don't have to be aligned but parallel. EXCEPT, it states that auxillary transmissions, with a short drive shaft should be not only parallel but perfectly aligned horizontally and vertically. The shorter a shaft, the more critical the parallelism and alignment.
Also, the shop manual states that you can use tapered shims between the springs and seats on the axle housings to change the angle of the differential.
I believe my diffs point slightly upward too and my t-case is more or less 90 degrees, but I haven't measured them.
Roger