drive line help on lowered 68 lwb

[tallic68]

First off. Thank you to everyone for your help and all the discussions on this page. When I have issues one of the first places I turn is here. Almost all of my problems have been solved with a search and through showering of results and l find someone with the same problem or at least a close problem and the solution to the problem.


I haven't really found a close enough problem and solution so I'm doing a thread to get some help and for it to be found by the next guy that does have this or close to this problem and help them.

Little history. 68 long bed 5.3 4l60e 12 blot rear. Conversion done in 2012 ish. lowered 2 front with springs and 4 rear springs and blocks. Daily driver for almost 15 years. No issues aside from carrier bearing went out 3 time in the time frame. Due to my commute since 2020 she has been a garage queen and I have started putting good money into her making her more "Showie"

In comes the issue. Keeping in mind the carrier bearing. I did a QA1 suspension swap. I don't know the exact amount of drop from stock. But the upper most curve of the wheel wells are now in the 28" area. Im guessing she is lowered 4-5 front and 6 or so rear. Have not perfectly equalized the four corners yet as waiting to drive a bit and for it to settle in before I get exact.

I am fighting a massive drive line vibration. 55-60 mph with two piece shaft and 50-55 mph with one piece shaft along with a quick wobble of column shifter off the line. I have replaced the carrier bearing with a cpp poly polished bearing. Added a cpp slip shaft to the rear. Confirmed balance of the two piece shaft. Had a one piece shaft made. Double confirmed balance on one piece shaft. The QA1 system has an adjustable pinion system. I have tried to match pinion to the trans angle. Tried to match pinion angle to the angle of the first shaft. I have it set up now to match pinion angle to engine angle with a one piece shaft. I've come the the conclusion that the engine angle is to much.

2002 5.3 4L60E early version dirty Dino slider mounts. 73-85 bbc perches and rubber clamshell mounts. Dirty dingo adjustable trans cross member (fully adjusted up) to the highest is can be. I could flip the rubber mount platform and get quite a bit more higher but I will be hitting the trans tunnel.