I’ve been chasing down a mysterious thumping ever since I installed my lift kit. It happens when I take off from a complete stop while letting off the clutch, but only if I’m giving it extra gas (1500 rpms or more). If I keep the rpms lower it doesn’t happen. The sound is a quick *thump thump thump* that seems like it’s coming from directly under the shifter

To eliminate some possibilities, I’ve replaced: transmission mount, sway bar bushings and end links, lower control arms, coil springs, shocks, upgraded tie rod ends, steering stabilizer

The only things I can think of that may be causing it are: ball joints, axle u-joints or upper control arm bushings

Anyone ever have this issue?

 

How about the exhaust system?

 

Bad drive shaft u-joints or need to grease the splines on the xfer case output? How much lift? Enough that the rear diff pinion angle is way off or the rear shaft is too short now?

 

 

I changed out the driveshaft u-joints about 2 months ago so they should be good. I’ll greased the splines when I put it all back together as well. It’s a 3.5” lift with a tcase drop

 

How close is your exhaust to the crossmember?

 

noone mentioned motor mounts.

 

Good point.