JamesDowning wrote:I'm still not sure it's the CV angle. Why would that provide vibration only in 4WD? He's tried different CV shafts, taken out lift, and neither has helped.
I have the exact same issue here as everyone else. Here is my thought process behind my theory.
Before my lift I had no wheel vibrations in 2hi or 4hi.
I used marks 3" lift kit with z71 springs and rear blocks. Brand new Bilstein front struts and rear shocks all installed the same weekend.
Post lift w/ stock wheels- I had a rear end vibration now that is minimal which was not there the day before. Changed pinion angle / driveshaft angle or dried u joint cup is most likely the culprit as that issue is widely known with any lifted truck.
4wd w/ stock wheels- front end now has a vibration/ side to side wobble only under acceleration, coasting there is no vibration no wobble. Thus this is a driveline/ torque issue and is coming from the front end somewhere.
Parts/fixes thrown at truck:
4 different alignments ( only thing out of whack is caster, but amount is equal on both sides and shouldn't be an issue)
New wheel bearings
New wheels/ tires road force balanced. ( some of the rear vibrations were masked by weight of tires and wheels and have to really accelerate and vibration is still there)
Flipped upper control arms.
Problem still exists, only thing changed since lift is the angle of the cv shafts. The lift is putting the cv shafts out of optimal range, same syndrome that occurs to the rear drive shaft and pinion angles. Replacing cv shafts with same cv shafts is not doing anything because they are all the same lengths. I'm wondering if even lengthining the intermediate shaft 1/2" would help push it further back into the tripod closer to where is was stock. Being lifted its pulling out wards but how much? I don't know and would require boot sacrifice to see.