Bump steer and death wobble

[jharfst]

Got a friend with a 98 TJ he just bought from someone. It has a 4" lift w/33x12.5's and he is having bump steer and death wobble problems. From what I can tell, it has a drop pitman arm and a homemade? trac bar relocation bracket such that it and the drag link are parallel. It's got a crappy homemade bracket setup for a dual steering stabilizer setup also which is practically useless. I did notice a half-busted/bent driver side lower link arm axle mount that has made the drivers side of the axle skew rearward about two inches more than the pass. side. Is this enough to cause said problems and is there anything else to look for? Is 4" too much to still have the stock link arms? Can lack of an effective stabilizer "cause" this?

I advised him to get the link mount fixed asap as that is a definite safety issue. Which brings up another question. Who in the GTR area can/will weld on another link bracket on the axle and verify alignment? Being a safety issue and all, I will weld on my own stuff, but am not comfortable welding on someone else's.

-jim

[jeepchipjones]

Death wobble is difficult to pin down, it just takes a while to go through everything. The link mount definitely needs to be fixed, but this will not guarantee to fix the DW. We can fix it at WRF down here in Gluckstadt, but thats quite a drive just for that. From my experience, the steering stabilizers are not worth having unless youre running a 37" tire or larger, definitely no need for a dual setup. Check for looseness in the ball joints in the steering, loose bolts/nuts on the track bar, worn out hub assemblies (raise front tire off the ground, and push in on top and bottom to detect any play), uneven wear on tires, excessive play in the steering box, etc.

[rsmith]

Caster angle and wheels with little backspacing could be an issue. Sounds like it has been "rigged" on a bit.

[biggreen]

Jack up and support this vehicle by the frame! Use a pair of floor jacks to raise and lower front suspension while steering wheel is locked in the straight ahead position via the column lock and note just what is / is not moving with the suspension thru out its travel limits . This is where and how to find bump steer problems. Death Wobble is most likely due to looseness in gearbox or tierod ends....remove both stabilizers keeping steering wheel locked and have extra pair of hand "wiggle" tyres left then right and note where looseness is and REPLACE worn parts !!! Have competent frontend shop check caster and camber ONLY AFTER these repairs have been accomplished....otherwise they willcharge you dearly to tell you to replace "THESE WORN PARTS" before they can determine anything!!!!!! I worked breifly in a front end shop and this was "OUR" procedure........ hope it helps....4 free.

[jharfst]

Thanks for all the info.

Yeah, I can imagine the castor angle is messed up a bit from the bent lower link arm mount pulling back on the axle and the upper arm remaining firm. I figure once he get that fixed a lot of the problems will be solved. I did notice a torn tie rod boot but didn't check for looseness.

Anyone know where in Starkville or GTR area that would fix it? I told him to check with City Alignment here in Starkville, but I don't know if they would do it or not.

[deltawjgrand]

Bent control arm is more than likely the culprit. Worn bushings is usually the leading cause if the drag link and track bar travel in the same sweep path. The best way to diagnose the problem I've found is to crawl underneath the jeep and have a friend work the steering back and forth. This will usually tell the tale. Good luck, You may end up fixing one issue to just find another, it sounds like the lift was thrown together and that can be a pain in the ass to find the root cause. I always try to keep away from buying turn key wheeler (that have been modded) unless you know the standard of quality it has been built at, cause you never know whats been short cutted to get it rollin'. Short cutted, I'm pretty sure that's not a word. Haha.

[jharfst]

Thanks for the suggestions. We have finally gotten rid of most of it. He never took it in to get it fixed; he only drives it between work and home so he hardly ever gets above 40 mph. The lower link bracket on the axle finally broke off, so we trailered it to my house and tore into it. He bought and we installed some new HD lower link brackets and a lower drivers side link arm. That in itself pulled the axle back forward about 3" on the drivers side. We also have replaced the passenger side axle ujoint (unit bearing setups are nice in that respect), and fixed a loose TRE. We also found that the rear panhard bracket on the frame had been "modified" for the lift and had loosened up its mounting bolts so it allowed about 3" of axle travel side to side. Fixed that and he got the front end aligned and most of the problems are gone. He did say that he still had a little wobble right at 40 mph so we looked again and it appears the passenger side ball joints may be loose/worn. He was gonna look at that himself, but everything else appears to be all nice and tight now. We'll see how it comes out.