rear vibration after uca and lca's

[Mikestang01]

Hey guys ,

Just had a set of new solid upper and lowers put in along with some new moser axles. and Battle box reinforcements, Now i have picked up a vibration when i let off the gas around 85 or so. anything below that and its not bad at all, nor is it bad under acceleration. it only seems to be above 85mph and letting off the gas. also there seems to be some slack somewhere, Example if i move a few feet in reverse then go to 1st and kinda goose it ( just easy like ) there seems to be a wheel hop type motion go on,

i have tried rotatating my driveshaft but taking it loose at the rear diff and rotating it 180*. same problem. is it possible my u jonts have been wore and since my stock uca and lca we're so wore out they maybe we're absorbing some of this vibration? and since i got solid ones now it just amplifies my issue?

i really don't think going to solid uca and lca's would cause this vibration, i really think it's driveshaft related but not sure. what do you guys think?

 

[blackfang]

My guess is LCA's/UCA's and torque boxes being you just installed those mods and now have that issue. Plus those mods do increase NVH.

 

[MaxedGT]

Two things to check. First the u-joints. Pull the drive shaft. Check that the u-jounts don't bind, when you make them flex back and forth. Also check for looseness. If you see any rust coming from the u-joint seals that joint is gone. The second thing is the drive angle at the rear end could be out now. The pinion shaft must sit parallel to the transmission output shaft when the car is sitting on the ground. That needs to checked by a shop that has a drive angle meter and knows how to adjust the rear end drive angle. If the angle is wrong the u-joints will cause a vibration and eventually fail.