after installing a NEW Diff Mount on my XT6's thinking my problem would be over.

 

here is a video of the rear thump, new mount installed.

 

Huh.... That sounds like one of two things I have encountered before. 1) The insulator in your carrier bearing on the driveline is toast. You won't get a thump in first gear since you are easing off the clutch to get going. There is more shock to the driveline in second, third and fourth since you are de-clutching faster. You won't get it downshifting because the driveline is being loaded is a different direction. It sounds more like 2) The trans mounts are shot or the pitch stopper is. Since I assume your XT6 is AWD LCD, torque should be equalized between the front and rear diffs when locked and more load to the front diff when not. I have ran into situations where a noise actually originates elsewhere and transfers through to body, frame or drivetrain and sounds like it is somewhere else. I would check the things I mentioned first, and if you don't find anything, I would jack the rear end up and place ramps under the rear tires and set it on the ramps to gain some clearance to access the suspension/drivetrain while keeping it 'loaded' as if it were sitting normally. Then take a prybar to every mounting point for the diff, mustache bar, trailing arms, torsion bar tube and upper and lower strut mounts leveraging in different directions to see if anything is moving more than it should if at all.

My XT6 is AWD 5 Speed and no it doesnt have LCD (not sure what hat is) or at least i thin kit doesnt.

 

now when you say " carrier bearing on the driveline is toast " whats the carrier bearing ? got pic ?

 

the trans is solid, theirs no movement at all, the sound orignates from the Rear.

Could this be axle splines going bad or CV joints going bad?

 

John

LCD is a locking center differential in the tranny. There would be a button in the middle of the stick you would push to engage it. The carrier bearing is the center support bearing in a 2 piece driveline. Sounds like it's time to jack it up and start prying.... lol

oh then yes, he has LCD.

 

oh the the bearing between the 2 drive shaft halfs.

 

my father said something about a Plate inside the Rear gone bad, if this is the case i have a another 3.90 Rearend out of a Auto Loyale ithat i could try.

is the top of diff hitting floor or exhaust hitting floor ?