mikerosa

Funny !!

I have a 2000 Grand Cherokee Limited, V-8 AWD/4WD.

I bought a 4 inch Rough Country lift.

The lift had 2 "accessories" that I didn't take, steering stabilizer and heavy duty track bar.

Mine road great but from bumps off roading in the swamps, I developed death wobble.

Upon looking at the Rough Country site I stumbled upon the 2 options, bought them both and installed them both.

Problem solved ! A very faint wobble that you can feel the steering stabilizer quell.

I'm happy

apac020

Another update

Took it to get the rear tires balanced yesterday, drove home and still had the rear tire shimmy. Decided to swap the rear with a spare to see if that improved things.

On my way to work today I decided to stop by discount tire and get my front tires and the spare rebalanced, cause it was still shaking. It death wobbled on me at about 35-40 mph a 1/2 mile from the tire shop. I think I hit a bump. That was with the 'good' tires on the front. Sigh.

I've noticed a very slight amount of play in my iron rock double shear track bar bushing, at the track bar bracket. Maybe a millimeter or two. From my research, this seems like it's due to the track bar bushing flexing and not an issue, but I thought I'd mention it.

I took another look at my control arm bushings and they don't look as great as I'd thought - I can see some cracks/dry rot in a couple. I've also heard that the rough country bushings just don't hold up. Can anyone confirm that bad control arm bushings would definitely be a root cause of death wobble? I've seen people report that it fixed theirs. I've also seen people with bushings that look terrible and never had any issues.

Is there a verifiable "test" for the bushings to see if they're any good, before I pull them off the vehicle? Getting these things off doesn't look easy, there's not a great place to get leverage under there.

I'm now looking at my other options. Either buying adjustable upper/lower control arms, or getting a full blown long arm upgrade. Is 3.5" to 4" of lift too small for long arms? If my death wobble is NOT due to control arm bushings, would the long arms hurt, help, or be indifferent to the problem? It would seem like the long arms would be less stable, with less connection points to the frame.

If not long arms, can anyone recommend an affordable set of adjustable upper/lower short arms?

apac020

Lug centric. They are pretty standard D-windows.

XXXJR

I had the RC 4.5 for my XJ. They failed to mention any of those items that would have even have been helpful for installation. Had to complain to them on Amazon. But they are a big company and dont listen.

apac020

OK I finally bit the bullet and ordered a steering stabilizer. At this point I don't care that it's a band-aid, it just needs to be drivable. It's not usually a daily driver, but right now it is, and I hate the white-knuckled commute.

Still interested in thoughts about control arm upgrades for the future.

SteveMongr

To test for very worn or damaged control arm bushings, watch the front tire, put jeep in drive and let roll two or three feet then hit brakes, look for movement at the hub of the wheel. Do the same in reverse. The axle will visibly shift if the bushings are worn 'enough'.

The bushings are not hard to replace but there is a right way and a hard way.

For 4" longarm look at Clayton Offroad, Full Traction, Rock Krawler. Some of these are 4-link.

I suggest Rock Krawler control arms, however many are happy with Iron Rock.

apac020

Thanks Steve.

I think I confirmed my own suspicions driving home from work today. While at highway speeds I turned both my mirrors down to look at the rear tires. When I felt the shimmy in the shift linkage I tried to watch for the rear tires shimmying. Didn't see any movement. I then stuck my head out the window and did notice the front tires shimmying very slightly back and forth. However, I don't really feel it in the steering wheel.

At low speeds I definitely notice it happening too, a slight left-right-left-right movement on the back of the front tires. Maybe 1/8" of an inch.

I'm thinking it's definitely the control arm bushings. Here's my theory. The steering is solid, but the axle itself is moving back and forth. The track bar is tight, so it's not moving laterally side to side, but I think the axle is pivoting/wobbling. That would make the front wheels shimmy, but not the steering. If I hit a bump with one tire, it would push that side of the axle back, and the opposite side of the axle forward. If that happens just right, I think it starts the death wobble oscillation.

So, hopefully I can limp it along until I get some new control arms. I'm thinking a long arm upgrade is the way to go, since new adjustable control arms are almost as much.

The TNT long arm setup is the one I'm looking at.

884x4

I'll be watching this thread...it really hope your new arms fix your wobble...
I'm getting a wobble exactly like yours. I'm at 4.5" on brand new 35s
I just did:
new spicer ball joints
New 760x u joints with full circle clips
New lca's
Brand new BFG km2s
Balancing bbs in the tires
All new steering and ends(stock exept for zj tie rod)
Durango steering box
Iro rock double shear
New hubs
Caster at 7 degrees
Got it aligned
9/16ths grade 8 bolts in the lca's (tighter than stock 14mm)
Good luck to you man
I haven't gotten a new steering stabilizer cause that's a bandaid but a band aid might be what I need until I can figure this out
Maybe it's cause I got stock ucas?

Rockfrog

884x4 - Did you get the 35s balanced or just use bb's ?

If just bb's time to buck up for a balance.

884x4

They were balanced by 4wheel parts, the second the rear tires went to the front after I rotated them (at like 400 miles cause they were all off anyways while I did some work to it) then the shake I had at 40 turned to full death wobble.
I wheel my jeep hard and air down to about 13psi. The wheel can and will slip inside the tire at that pressure when wheeling.(throwing wheel balance off)
Thought that that might have been the problem so I got rid of the wheel weights and put in 8&1/2 oz of .25 gram air soft bbs(in each tire)
It now will not vibe at all then all of a sudden, boom, full blown death wobble that won't stop till I completely stop the jeep.

Tsaani97xj

Copied from here:


http://www.jeepforum.com/forum/f9/en...g-read-663777/

I know its the TJ forum but the suspensions are so close it makes sense.


*I believe* this causes instability/death wobble because big tires(33”+) have a lot of sidewall play as there is a lot more of it, so basically the entire rim is trying to wobble left and right inside the tire. German cars have a ton of caster without problems, but they have 17-19in wheels, skinny and stiff tires, and less play in the steering systems (rack and pinion vs. steering box and linkages).

That is my theory on caster angles vs. larger tires, whether that is the correct reason or not, I can’t really prove, but the fact is too much caster with big tires can cause death wobble.
It should also be noted that as you lift a TJ, because of the front control arm lengths and angles, caster decreases so it actually works out in our favor alignment-wise. I predict the problem could be more pronounced in low COG builds (example: 35” tires on 1.5” lift). In this case adjustable front upper control arms should be installed for optimum caster angles.

I’ve seen it posted around that 5 to 5.5 degrees of caster is ideal for 35” tires.

884x4

Hmmm intresting...
I may have fixed mine though, so when I adjust the caster to 7 degrees from 10 degrees it toed my tires in more.
I diddnt really bother adjusting toe but after I turned them back about 1 degree.(tried to get to stock toe @ 1/8th in) the death wobble and vibes went away!!!(so far)
The balancing beads really made a big difference with the vibes but the actual wobble was cause by the excessive toe in(maybe) I've only driven it up to 50 mph but so far so good. Will post back up wit updates

SteveMongr

I have to agree about excessive caster. 7.8 degrees may be within spec but it is excessive.
Stock upper arms should be replaced along with axle bushings for uppers, because their condition is unknown/questionable.
I run 5.5 degrees caster at 4.5" lift on 31" tires, short arms with drop brackets. No wobble, no bump-steer, steering returns to center.

884x4

I may be wrong but I have a theory about the stock inverted y steering.
Because the Knuckles are connected together by the drag link and the tie rod there is a tre in the middle that will allow movement with suspension travel.
In my opinion hitting a large bump or anything that would cause the suspension to travel will change the toe in toe out.
If things are not in perfect harmony with each other( hard to do with a lift and stock steering) maybe that cycling steering toe will cause or initiate a wobble...
Just food for thought

SteveMongr

Good point, you are on the right track. When the suspension (both wheels) travels upward, the steering turns right. On the rebound, steering turns left.
The toe is not changed much unless the angles in your steering are ridiculous.

In this picture look at the curve to the right upon landing, even though I am holding the wheel straight. I went over a hump and the jeep catches air. Upon compression the steering turns right along with the jeep. Makes for a wild ride in the whoops at 30 mph. Currie steering.