So I'm a bit stumped here. My '01 XJ (with a brand new engine from a cracked 0331 head...bah!) has developed an odd behavior. When I'm stopped at a light and give light/moderate gas to accelerate I get a shimmy with an audible clunky type sound just for a few seconds, then it stops. Higher speed travel has a slight vibration but not all that bad.

I've completely replaced my sway bar bushings, ends, tie rod ends on drag link, track bar, bushings on track bar, steering stabilizer, and tie rod ends on tie rod, all to no avail. Just jacked it up and checked for wobble in the wheel hub/ball joints but I get no movement at 12/6 and only slight movement at 9/3 (which is my tie rod moving around a little).

Any other ideas on what I should be looking at? U-Joints on the driveshafts feel fine and I can't get the u-joints on the axles to budge.

 

Check your tranny mount and engine mounts. Probably a bad tranny mount.
Stick a big ol screwdriver or prybar between the tranny case and frame/crossmember and see if there's play - there shouldn't be any without you really prying it.

 

I'll check the transmission mount here in a minute. I just picked it up from the mechanic 3 days ago and he said the engine mounts were fine.

I wouldn't even think of the tranny mount, thanks!

 

The clunk is probably the exhaust hitting the cross-member.
If/when you replace it, get a Mopar or Napa mount - do NOT use Anchor, they're not tall enough and just junk.

 

Okay, checked transmission mount and it visually looks fine, and there's no movement in the transmission when I took a 2 foot breaker bar and pried against the transmission/crossmember.

Hmmmmmmm

 

I swear it FEELS like the front passenger wheel is loose. It's a very weird wobble and sounds like a very dull thud, but in relatively rapid succession until it calms down after 2-3 seconds.

 

Maybe double check the torque on the mount nuts.
Shock mounts also if you haven't checked those.

 

It might be worth checking the motor
mount (both but drivers side if that's where it feels like it's coming from) is tight. Everything can look ok, but maybe loose.

 

I really can't imagine it's the motor mount considering it just got a brand new reman engine put in 3 days ago. Mechanic said the mounts were great and I trust them to have torqued the mounts down correctly. The problem existed before the engine swap as well.

 

Yeah, if it's been there prior to the swap.

Definitely a head scratcher. Maybe check the pinion bearings at the axles for play.
I might check the shock mounting is tight, control arm bushings and also that the three axle hub bolts are tight.
Transfer case output shaft, not sure what else could be causing that behavior.

 

Threw the gopro underneath to see if I could catch anything and everything looks tight as can be. Super odd. I'm definitely at a loss here.

I'll run through and torque down all the suspension bits and bobs tomorrow and see if anything is out of spec.