Attention: TDR Forum Junkies Worked on one this week with a rather harsh, seat of the pants vibration from about 65-72 mph. The vibration analyzer showed it as a first order drive line vibration. First thing checked was run out of the rear shaft, OK. It had already been replaced once. Next checked the drive line Angles. The cancellation angle was high at 2 degrees, so we added washers to raise the transfer case. That made no difference, so we picked up some shims and raised the pinion angle 2 degrees. That moved the cancellation angle to the desired 1 degree, but it still had the vibration. The slip yoke seemed a little loose, so not having an extension housing available, took the one from my truck and swapped it. The customers truck was 90% better, and mine was still perfect. Didn't make any sense, so we pulled the shims out, and on the rack it felt just as good. Driving, it was still not good. Added the shims back like we had them.
So the bottom line was the extension housing, and getting the prop shaft angles in spec.
Can't explain why mine does not vibrate, but the customer truck no longer vibrates, so all is well. I ordered a new extension housing today for mine, and when I change it I will pay attention as to the centering of it on the transfer case. Will send the old one back to DC for analysis.
So the bottom line was the extension housing, and getting the prop shaft angles in spec.
Can't explain why mine does not vibrate, but the customer truck no longer vibrates, so all is well. I ordered a new extension housing today for mine, and when I change it I will pay attention as to the centering of it on the transfer case. Will send the old one back to DC for analysis.
