Don't believe it's DW

[99NAZXJ]

I have a 99 XJ with front end bounce not DW, the steering wheel feels like the tires are bouncing like a basketball. It steers during this and will go straight unlike DW. We have a 4” lift with aftermarket trac bar and pitman to match the lift. I’m running 265-75-17 with spider adaptors from 5x4.5 to 5x5 for “09” Wrangler Rubicon wheels. The caster has been move both positive and negative with no help (now at 6). The control arms are also aftermarket (Rusty’s for all the front end parts changed). We have braced the front core support and redone the welds. The tie rods are braced with angle iron to stiffen them. The springs are about a year old for a V8 Grand Cherokee with 2” spacers, shocks are Rancho 9000 and they are on adaptors for loops both ends.
Last change was a gearbox that showed a little play no help. The shop helping is good and builds sprinters. They work on lifted trucks all the time but this XJ has beat us. This just started about two months ago after I put my summer tires on with less aggressive treads, same tires I ran last summer with no problem. The dance starts with the 60+ hit a bump just like the DW and we have to brake down to about 15-20 mph for it to stop.
I know the feel of the DW and everyone who has not driven the XJ says that’s what it is, but after driving the XJ (watching their eyes get big was great) the tune changes. Side note running 8.8 in the rear. Trans is dropped to match angles. We are open to any and all help.

 

[mako my day]

Swap front to back tires.

If still bouncing, get some good shocks.

And Welcome to naxja.

 

[offroadordnance]

Do you have the rubber spring isolators installed?

 

[99NAZXJ]

Had NAPA gas grande very stiff and yes to the sprng isolators,
Now "rancho 9000 and have tried all settings.
Put back winter tires so we have taken the tires out of the the problem

 

[philagony94xj]

What is the sway bar situation? Also what about the steering stabilizer?

Just throwing suggestions out there.

 

[98stocker]

There are plenty of great DW threads on here. Go through them and you will find your problem. You have play where there should not be play, and your caster, camber, offset, toe may be exacerbating the harmonic.

What you described is most certainly DW. It will feel different on different setups. I had a Toyota with a d44 front that would get DW in reverse at 15-20mph. So bad that I could see the top of the tire when it bounced up(full width).

 

[99NAZXJ]

Watched the passenger side tire and saw the tires shake. The tie rod has an angle iron welded to length to reforce it and there is no noticable flex. We found the mount for the steering box busted after new box was installed last week and fixed it yesterday. Than tonight there was the popping noise again so the weld may not have held with the shaking. I have been through most the threads and we have done them I think. May have to pull everything take it apart and reinstall the whole front end, inspecting each piece and frame.

 

[rockclimber]

Try toeing the tires out a bit. If that greatly reduces or stops it, it will tell you to look at the panhard/drag link.

 

[zachandandy]

A picture of the front end would help greatly in looking for obvious problems.

 

[99NAZXJ]

I don't know if they have worked with the toe I'll ask. Will try to post a picture soon. We are also think replacement of springs to stornger.

 

[Jolly_Red_Panda]

Track bar: check bracket and bolts. Make sure jam nut is on there and tight. What brand track bar? Does it have an aftermarket double shear bracket or does it retain the factory bracket and tre? If it uses a heim joint make sure its not sloppy
tie rod
drag link
wheel bearings
Ball joints
control arm bushings & bolts
check the tre at the pitman arm
steering box & bolts : was it new or a chinese reman?
Are the tires balanced correctly?
sway bars?
To prevent bump steer the drag link and track bar should be parallel
personally i prefer to run a steering stabilizer, some guys dont use them
im sure this has been mentioned before, get under there while someone is turning the wheel and look for worn parts. Pics will help.