tweetybirdy

Ok a little back story, i bought a moser 9". After i installed it i put the stock torque arm back on along with an aluminum driveshaft from capriomotorsports. I had some drivetrain vibration because i couldn't set the pinion angle, but i got around on it for the time i needed to, then the stock TA broke, when it did the DS hit the rearend and split the yokes open (hard to explain) but the DS still works, but it can't be trusted with any kind of power. I installed a new UMI adj TA with a front DS loop and i went to put the broken DS back on for my motor break in (just dropped it in last week)

NOW HERE IS THE PROBLEM:

When i pull the DS back fat enough to engage the rear yoke the front yoke hits the DS loop about a 1/4"-1/2" before the back u-joint engages. This is with the rear end under full load, not to mention that to get the rear u-joint engaged i have to pull the front yoke 3/4 of the way out of the tranny. Now i have already ordered another DS from the same company and it should be here this week. However when i inquired about the length to the owner of the company he said that the stock length DS is what i need. After laying under the car for awhile i realized i could shim the TA crossmember down about a 1/2" and that would center the loop around the front yoke, but i am afraid that would ruin what is left of my ground clearance, and in my mind i shouldn't have to do that with a "custom" driveshaft. I am not sure if anyone else has had this problem, but i would apprecaite some feedback.

thanks in advance - Carl

Injuneer

One of the problems with using the 9-inch is the fact that it drops the centerline of the pinion shaft about 3/4" and offsets it to one side of the centerline of the car. This causes more extreme u-joint angles, and changes the alignment of the DS, possibly explaining the issue you are having with the DS loop not being centered on the DS. 3/4" drop at the pinion shaft should produce a much smaller offset at the location of the loop, so there may be another problem as well.

You can check the engagement of the DS slip tube by bottoming it out in the tranny tailshaft housing. Then slide it back until it seats firmly in the pinion yoke. The DS should have moved back at least 1/2" for "stockish" HP levels, and no more than 3/4" - 1" for higher HP applications. If it moved back more than 1", its very possible you don't have adequate spline engagement, and can twist the splines.

tweetybirdy

well i got everything installed and moving yesterday, i check the length that the DS pulled out of the tranny and it is definately more than 1" it is more like 2"s. I am having some obvious rear suspension clearance issues, but i am sure i can work through them. Currently i have the tranny shimmed up about 1/4" and the TA mount shimmed down about 1/8". With that combination it centered the DS very well in the DS loop, but i am still getting some DS to exhuast rubbing as well as some "thumping" in the rear end, but it is hard to desiminate the "thumping" from the locker noise. I am not certian the TA is set properly for the pinion angle but it is at least close. Tomorrow i am going to try to take one shim out of the tranny and add some pinion angle to see if that opens up some clearance. As for the DS i am still waiting on the brand new one i ordered, but i am going to contact the guy i am buying it from and make him aware that the last one he sold me is not the right right length, in hopes he can correct the problem(even though he should have shipped the DS last week) thanks- carl

Injuneer

"Shimming" the tranny is moving things in the wrong direction. The 9-inch lowers the pinion shaft. Now you've raised the tranny. Each of these steps forces the U-joints to make steeper angles, and that's not what you want to do.

tweetybirdy

thanks for the input, i know shimming the tranny up wasn't the final solution, but it got the DS up far enough to clear the loop so i can at least start putting a few miles on the engine. I am not getting into the gas at all and the DS is already junk so i figured, why not. My hopes are that if i get the new DS about 1" longer it will get the front yoke farther forward, making it so only the DS tube is in the DS loop, not the entire front yoke (like it is now). Once i get that in place i can take the shims out of the tranny and reset the pinion angle back to -2. The hardest part now is getting the DS guy to some through for me. That should work though right? - Carl