Originally Posted By: pjc360
I have a 1991 dodge power ram 150 4x4 truck. I wanted to use 1 grease for everything on this truck and I ended up choosing valvoline synpower grease. Now over the last couple years I have trashed u-joints on my rear driveshaft left and right. Person at the driveline shop dpsaid it could be from my 4 inch suspension lift kit.
So I had a friend check out the angle of my driveshaft and he said it looks fine to me, he said I don't see any steep angles that would cause a u-joint to fail early.
So now I have been wondering, is it the grease I have been using? Valvoline synpower grease says its moly fortified and I have heard a lot of ppl say no moly in u-joints. Could this be what's going on?
All u joints are not created equal. In my world, it is Spicer or nothing. Precision are junk, neapco are not much better. That being said, if you are eating u joints, you need to examine some other parts. First, take a new quality spicer u joint and put it in the yoke on the rear axle and tighten the straps or u bolts, see if the u joint moves freely. If it binds, replace the yoke! Repeat on the transfer case yoke. Now to address your u joint angles. Most lift kits use tapered rear lift blocks to lessen u joint angles. This causes a problem in that it creates unequal angles on the u joints. To operate properly the u joint angle needs to be within around 2 degrees from front to back. To check this angle, find a flat surface on the back of the transfer case, place the angle finder on this flat area and record the reading. Next go to the rear of the axle housing, usually placing the angle finder over the head of two bolts will work. These two readings need to be within about 2 degrees of each other. Machining the taper out of the blocks is one way to make the angles closer. A better way is to keep the tapered rear blocks and have a constant velocity drive shaft made.