Wobble after bump?

Getting servere death wobble after hitting a bump but not at any other time. I'm running rusty's 4.5 kit with ACOS (3 inches needed for arb bumper) up front with adjustable upper and lower arms with jamnuts. Rusty's stabilizer. Rusty's HD tracbar and HD bracket. Rear I have 4.5 springs with 2 inch shackles. 33 inch swamper SSR's. Does anybody have an idea for ideal alignment specs?

Point the toe angle outwards just a little bit. That should help some, if not cure it completely.

I'd definately get a really good tire balance. I had the exact symptoms you're having and it was ALL tires. I thought it had to be something else since it happened only when hitting bumps but when I got new tires it totally stopped. I had it alligned twice before getting them and just wasted my money. Go someplace good for an balance (not wal-mart as they made my tires worse before).

y2kxj said:

I'd definately get a really good tire balance. I had the exact symptoms you're having and it was ALL tires. I thought it had to be something else since it happened only when hitting bumps but when I got new tires it totally stopped. I had it alligned twice before getting them and just wasted my money. Go someplace good for an balance (not wal-mart as they made my tires worse before).

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XJCRAWLER's statement that the problem only happens when he hits a bump throws any consideration of balance problems out the window. A set of RE drop brackets will reduce your control arm angles which will soften the effective spring rate of your front suspension. This will change the natural frequency of the front end, decreasing the tendancy towards uncontrolled oscillations.

In the near term, If it were my Jeep I'd run 0 to 1/8" toe-in and set castor to 5 or 6 degrees if your pinion angle will allow it. Running too much toe-in or toe-out will only trade tire wear for a potential reduction in wheel shimmy. Experiment with lower air pressure (~25psi), make sure you have a good steering stabilizer and check all steering and suspension joints for wear.

y2kxj didn't just get a good balance, he changed his tires. What size and type tire did he have? What size and type tire did he change to? When you do more than one thing at a time to troubleshoot a problem, in this case balance and new tires, it's impossible to say which change made the improvement.

good luck

Maybe this can help you out. The same thing just started happening to me. After I got a new steering stabilizer and added 2" coil spacers. It didn't do it before this either. But i did have a situation on the way back from wheelin where my trac bar bracket came loose and i got a death wobble at 45mph. Could it be that the trac bar is getting loose again? Let me know I would like to fix mine as well.
Thanks James

MaXJohnson said:

y2kxj didn't just get a good balance, he changed his tires. What size and type tire did he have? What size and type tire did he change to? When you do more than one thing at a time to troubleshoot a problem, in this case balance and new tires, it's impossible to say which change made the improvement.

good luck

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So why would that mean that his problem isn't tires? I'm confused. I switched from 235's to 31's (TRXUS). I only had wobble when hitting bumps and new tires fixed it so I don't know how you can say that his problem which is the same as mine is definately not tires?

There are only four things that cause DW. They are the track bar, need new tie rod ends, stearing stabilzer, and the drag link ends. I would agree that the tires are not the issue. When you go to bigger tire or wider rims it creates more force and pressure on this areas/

Sandman XJ said:

There are only four things that cause DW. They are the track bar, need new tie rod ends, stearing stabilzer, and the drag link ends. I would agree that the tires are not the issue. When you go to bigger tire or wider rims it creates more force and pressure on this areas/

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so I guess I was imagining the whole thing? DW is hard to miss.

When I experienced "Death Wobble" it was just that, I couldn't control the jeep. Some people think a really bad wobble is death wobble, but I'm here to tell you there is a difference. If your heart was beating much faster or you had to change your pants, chances are that was death wobble.

Mine was track bar related.

Good luck finding the source.

Gary

Sandman XJ said:

There are only four things that cause DW./

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I'm sure you are a DW expert then but I think you're way off in not listing tire balance. I'm sure there's many others also. Just four? Nope

y2kxj said:

so I guess I was imagining the whole thing? DW is hard to miss.

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Maybe, have you been smoking anything?

I am just pointed out the main culprits so not reason for you to get all upset over it.

Sandman XJ said:

Maybe, have you been smoking anything?

I am just pointed out the main culprits so not reason for you to get all upset over it.

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who's upset?

Monday the jeep is going for a tire rebalance by a friend at a jeep dealer that has a high tech balancer that does a road force test for a bad tire and also tells you where the tire needs to be on the wheel for the least amount of weights. Next I will have the alignment rechecked to better caster and toe specs. This did seem to get worse when I added the 1 1/2 inch to adjust for the heavy bumper, giving it more angle on the control arms. Do you think going to a long arm kit would eliminate this problem all together?

y2kxj said:

So why would that mean that his problem isn't tires? I'm confused. I switched from 235's to 31's (TRXUS). I only had wobble when hitting bumps and new tires fixed it so I don't know how you can say that his problem which is the same as mine is definately not tires?

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His problem is tires, among other things.

His problem is not tire balance.

If the tires have a balance problem, you will feel a shake in the steering wheel at the critical speed (usually around 50 - 55 MPH). The shake or shimmy will be proportional to the amount of inbalance. This imbalance can trigger Death Wobble. A single wheel bump and several other things can also trigger it. The conditions favorable for Death Wobble already exist waiting for the trigger to set it off.

Tires can NEVER be the reason for DW. NEEEEEVEEEEERRRRRRR. In no way. Not a chance. Will never ever be the reason. Banish the thought.

The ONLY causes for DW can ONLY come from improper or worn/broken/bent suspension setups. The only way. No other way. No chance in hell that it's anything else.

A properly set up suspension, be it stock or modified, will not have DW no matter what tires are on it. Bring those same tires of death and mount them on my TRAIL RIG and I promise you'll never get so much as a death shimmy.

An imbalanced tire can set off a case of DW just like a bump in the road or road debris, but Jeep never designed DW into the equation when making the XJ. To say that tires caused the problem is to say that the suspension is designed improperly from the factory.

The wrong geometry comes from worn parts, broken or bent parts, and stupid-asses that lift thier Jeeps.

You can have the tires balanced or replaced, but you're only masking the problem that's still there until it's fixed.

Forget the tires being the problem.

Did I mention that the tires aren't the problem?

Check out your ball joints, thats how mine was acting when i hit a bump. The first time it happened was coming through downtown louisville on I-64 in heavy traffic. That scared the S*#t out of me. Jack up the front end, grab the bottom of the tire and push/pull it to see if there is any play, if there is you may consider ball joints.

Okie Terry said:

Tires can NEVER be the reason for DW. NEEEEEVEEEEERRRRRRR. In no way. Not a chance. Will never ever be the reason. Banish the thought.

The ONLY causes for DW can ONLY come from improper or worn/broken/bent suspension setups. The only way. No other way. No chance in hell that it's anything else.

A properly set up suspension, be it stock or modified, will not have DW no matter what tires are on it. Bring those same tires of death and mount them on my TRAIL RIG and I promise you'll never get so much as a death shimmy.

An imbalanced tire can set off a case of DW just like a bump in the road or road debris, but Jeep never designed DW into the equation when making the XJ. To say that tires caused the problem is to say that the suspension is designed improperly from the factory.

The wrong geometry comes from worn parts, broken or bent parts, and stupid-asses that lift thier Jeeps.

You can have the tires balanced or replaced, but you're only masking the problem that's still there until it's fixed.

Forget the tires being the problem.

Did I mention that the tires aren't the problem?

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I have to concede defeat here. Never thought about it like that. Jeep couldn't make a suspension that would freak out if a tire lost a weight. Hmmm so my DW is gone but I must have something worn. Well I'm sure it'll be back to haunt me some day then. Strange though how it never tries to do it over bumps anymore. Strange indeed.

I have to disagree. I can't tell you how many Jeeps I worked on that had severe frt. end shake. Where I worked we put aftermaket wheels and tires on 75% of the TJ's we sold, and some XJ's. I had several discussions(arguments) w/ the owner and the "tire" guy over the fact that I could take this problem vehicle w/ no bad parts in the strg./susp., proper alignment, and no mods other than the tires and swap the tires/wheels for a OEM set and eliminate the problem. The customer could take the vehicle for a week, say that the problem was fixed, and then I'd swap the tires back to what they had, and the problem would return. Yes, there are many contributing factors to this problem, and tires/wheels are one of them. Most aftermarket wheels are not hub-centric (pilots on the center of the hub). This can cause runout problems even if careful when tightening the wheels. In addition, I've seen plenty of stock Jeeps w/ worn loose strg. components, that drove just fine w/ no shimmy problems noted by the customer. My TJ with just coil spacers added developed a severe strg. shake. During the short time I drove it before getting new tires, the problem was constant. On the way to friends shop, I had to come to almost a complete stop from 75mph before the frt. end quit shaking. I then put on the new 32" TSL Radials and the shake never happened again. This w/ a heavier and obviously more aggresive tire.

Okie Terry said:

Tires can NEVER be the reason for DW. NEEEEEVEEEEERRRRRRR. In no way. Not a chance. Will never ever be the reason. Banish the thought.

The ONLY causes for DW can ONLY come from improper or worn/broken/bent suspension setups. The only way. No other way. No chance in hell that it's anything else.

A properly set up suspension, be it stock or modified, will not have DW no matter what tires are on it. Bring those same tires of death and mount them on my TRAIL RIG and I promise you'll never get so much as a death shimmy.

An imbalanced tire can set off a case of DW just like a bump in the road or road debris, but Jeep never designed DW into the equation when making the XJ. To say that tires caused the problem is to say that the suspension is designed improperly from the factory.

The wrong geometry comes from worn parts, broken or bent parts, and stupid-asses that lift thier Jeeps.

You can have the tires balanced or replaced, but you're only masking the problem that's still there until it's fixed.

Forget the tires being the problem.

Did I mention that the tires aren't the problem?

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this is why we keep Terry around here

he's really, really, really funny :jester: