Anyone car to take a stab at it or give me ideas? This is what I have and what I have checked.

Prior to doing the rear and suspension, there was no vibration. Since I last drove the car, have a new rear and the Pete Z bar suspension. I did recently break the TQ arm mount and smashed a driveline and think I could have a problem with the 1350 yoke itself since the u-joint snapped.

My only thoughts are Pinion angle again, 1350 yoke issue, U-bolts (one was slightly bent from the mentioned breakage. Any other thoughts on this would be great.

Setup
Ford 8.8 (Moser 1350 yoke, moser axles, Ford 31 spline torque lock, Motive 4.10 gears, Moser Bearings)

Pete Z bar suspension w/ no TQ arm (See link under suspension)

Custom built 3.5" steel driveshaft using stock yoke in front for now (Calling them tomorrow to ensure balance and may drop off to them to have rebalanced)

Pinion angle is at -4 (Car is an M6)


Symptoms
Get a vibration at 55mph+

5th gear at acel/decel/steady pace has more vibration than 6th

Keeping a constant speed, I loose the vibration if I catch it right but then get what sounds like driveline slop/slap.

 

Check the driveshaft for balance and set pinion angle to 0 to -1.. I assume you are setting pinion angle correctly with the car absolutely level and zero out the angles before adjustments.

 

I'll try the lesser pinion angle tonight.

The shop has confirmed it was balanced. They are a very reputable shop in the area with cars running deep in the 8's on their d-shafts.

 

Slowhawk, Thanks again for your help. No more vibration