I have a 99 XJ with stock suspension and I have a front passenger side tire bounce at around 70mph. The mechanic said the driver side front tire is about 1/2 inch back further than the passenger side. I have replaced rims and tires, front end alignment, lower control arms, steer damper, upper and lower ball joints, tie rods, track bar, axle u joints, wheel bearings, sway links, and everything else related. Can that 1/2 inch make the tire bounce? I'm running out of ideas. Thanks in advance.

 

Tire imbalance. So pull that side apart. Ensure the brake rotor is seated. Once seated check the rotor for runout.

 

That right front tire ever get fix a flat in it?
Might be worth dismounting it.

 

put offending wheel in rear, rear in front then test drive, see if vibration from bounce changes. If it changes, then you likely have an out of balance wheel/tire.

 

Front shock on that side might be blown out as well.

NOGGIN POKIN TIME

 

The tires and rims are new. I replaced the shocks last summer but it didn't change the issue.

 

I have no idea but neither does anyone else. So
Try swapping the brake rotors side to side.
the only other thing I can think of is a bent front axle shaft, don't know why that would be speed sensitive but who knows

 

Did you swap tires and rims front to rear? if not do so and see if problem moves to rear or not.


An out of balance axle usually wont cause a lot of vibration as its diameter is so small. the same wieght imbalance on a outer rim or tire will cause much more vibration as the diameter is larger.

Is the tire round? check by raising truck till tire has clearance under it, note amount of clearance then spin tire fully around and watch to see if clearance changes with rotation.

shocks can fail, so do the old corner of vehicle bouncing test, rock her up and down and note how quick the movement stops, good shocks will stop the up and down movement quickly, bad shocks will allow the vehicle to keep bouncing a while.


good lucks

 

re the rotors I was thinking of the "Chinese Replacement Auto Parts" problem.(out of round /out of balance etc
On a bent axle shaft I was thinking of it setting up some sort of wobble.
I do wonder how certain the OP is that the vibration is that wheel/tire considering all of that has been replaced with no change. These things have a way telegraph around
He did mention he replaced the LCA'S, are the UCA'S ok?

 

If the passenger side tire is really 1/2 inch back, that can be adjusted
with shims in the LCA bracket on that side.

The UCA mounts on the axle end are flimsy and it doesn't take much for
them to be weakened by rust or wear. Worth it to have a look at them.