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Violent front end shakes over 50mph

G

GusDaDog

NAXJA Forum User
Location
Merrillville, IN
I am just at a loss right now. Any time I try to drive over 50mph this last month I've been getting a violent shaking. Oddly, it seems to be temperature related. It never happens below 50 degrees outside so matter how much I TRY to make it happen but over 50 degrees it happens 100% of the time. Only front end mods is 2" coil spacers and the swaybar is removed. I've had an alignment, tires balanced and rotated, checked the trackbar bushing and checked it was tight, and installed new front shocks yet it still continues....

...please help!
 
Sounds like death wobble DW. What you describe sounds like it is related to the fact that rubber bushings are stiffer at cold temps. I would check out the bushings on the control arms. This is fairly common. A search of DW or death wobble will give you a nice Sunday afternoon's reading.
 
What were the alignment numbers? If you lifted it, you reduced caster angle. The shop should have added shims behind the lower control arms to bring the caster back to stock specs, but I'll bet they only checked toe-in.

Tom has a point about cold bushings, but tire balance is what sets off shimmy at around 50 to 55 MPH. You may have paid to have your tires balanced, but I'll bet they aren't balanced correctly.
 
Eagle said:
What were the alignment numbers? If you lifted it, you reduced caster angle. The shop should have added shims behind the lower control arms to bring the caster back to stock specs, but I'll bet they only checked toe-in.

Tom has a point about cold bushings, but tire balance is what sets off shimmy at around 50 to 55 MPH. You may have paid to have your tires balanced, but I'll bet they aren't balanced correctly.
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correct on both accounts probably. most shops use cheap labor, lst time I went in the kid was sweepin floors one day then aligment rack the next
 
xjnation said:
correct on both accounts probably. most shops use cheap labor, lst time I went in the kid was sweepin floors one day then aligment rack the next
Click to expand...

It never fails to surprise me when the tire guys put the wheel on that sophisticated zillion dollar precision machine and balance it to the nth significant digit without having scraped the inch-thick cake of mud off the inside of the rim.
 
I will jump in on the tire balance issue. A big problem with CHEAP oversize "aggressive tread" tires is, aside from them being hard to balance, they tend to be OUT OF ROUND.

An out of round tire will NEVER balance correctly. To fix out of round tires, they usually need to be shaved first, then rebalanced.

If there ever was a good reason for spending LOTS of money, it's to avoid getting crappy out of round tires.
 
I have 50% worn BFG Radial Long Trails in 265's I think...nothing too aggressive.... The manager at Tire Barn did it himself, took about 35 minutes from the time it went into the garage.... seemed like a good job
 
GusDaDog said:
I have 50% worn BFG Radial Long Trails in 265's I think...nothing too aggressive.... The manager at Tire Barn did it himself, took about 35 minutes from the time it went into the garage.... seemed like a good job
Click to expand...
You got death wobble. If it just starts by itself when you get to 50 MPH, without your hitting a bump or something, it's tire balance as the root cause, and the manager didn't do a good job.
 
Eagle said:
You got death wobble. If it just starts by itself when you get to 50 MPH, without your hitting a bump or something, it's tire balance as the root cause, and the manager didn't do a good job.
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Not so- DW can be started by a zillion things, and you shouldn't really point to one potential problem and say it HAS to be that.

As mentioned several times a week, ad infinitum, DW/ shimmies can be caused by literally any part in the front end. One loose tie rod end, or shock bolt, or even a sway bar disconnect can set it off, so a thorough inspection is in order. Every XJ is different as to what loose parts will be tolerated before getting into oscillations, so there is NO pat answer that will fix this condition.
 
JJacobs said:
Not so- DW can be started by a zillion things, and you shouldn't really point to one potential problem and say it HAS to be that.

As mentioned several times a week, ad infinitum, DW/ shimmies can be caused by literally any part in the front end. One loose tie rod end, or shock bolt, or even a sway bar disconnect can set it off, so a thorough inspection is in order. Every XJ is different as to what loose parts will be tolerated before getting into oscillations, so there is NO pat answer that will fix this condition.
Click to expand...

actually he can say that because if it starts without hitting a bump or turning then the other worn parts dont come into play until they have a cause to force the issue.

If he is driving straight on a smooth road and it starts then its either tire balance, bent rim, or out of round tire starting it.

The tires are the catalyst to start the problem, but not the problem them selves. They just start the DW the cause is another problem
 
xjnation said:
actually he can say that because if it starts without hitting a bump or turning then the other worn parts dont come into play until they have a cause to force the issue.

If he is driving straight on a smooth road and it starts then its either tire balance, bent rim, or out of round tire starting it.

The tires are the catalyst to start the problem, but not the problem them selves. They just start the DW the cause is another problem
Click to expand...

Hey xjnation, how about you quit following me around throwing bad rep, I don't need it, and do know what I'm talking about. If you don't agree I couldn't really give a rip, I'm tired of catching your errors.. so go away.
 
JJacobs said:
Hey xjnation, how about you quit following me around throwing bad rep, I don't need it, and do know what I'm talking about. If you don't agree I couldn't really give a rip, I'm tired of catching your errors.. so go away.
Click to expand...

was not me this time...Ive only givenyou neg rep once...Im not the only one must feel you are full of crap too.

matter of fact I got good rep a ton of ti from this thread.
 
JJacobs said:
Not so- DW can be started by a zillion things, and you shouldn't really point to one potential problem and say it HAS to be that.

As mentioned several times a week, ad infinitum, DW/ shimmies can be caused by literally any part in the front end. One loose tie rod end, or shock bolt, or even a sway bar disconnect can set it off, so a thorough inspection is in order. Every XJ is different as to what loose parts will be tolerated before getting into oscillations, so there is NO pat answer that will fix this condition.
Click to expand...

X2.

Check the bushings. Over 50* it's the bushings. I have mine doing the same thing, under 50* no prob, over 50* shake. Temp isn't going to matter when it comes to a tire that was balanced, BEFORE he started his lift and it was cold, to all of a sudden go out of balance. IIRC, I was told that DW couldn't possibly be from a trackbar that was too short, either. Lengthened my trackbar and DW went away...
 
Urban Redneck said:
X2.

Check the bushings. Over 50* it's the bushings. I have mine doing the same thing, under 50* no prob, over 50* shake. Temp isn't going to matter when it comes to a tire that was balanced, BEFORE he started his lift and it was cold, to all of a sudden go out of balance. IIRC, I was told that DW couldn't possibly be from a trackbar that was too short, either. Lengthened my trackbar and DW went away...
Click to expand...

Im with you on the trackbar and eagle would agree too but I have experienced DW on an older xj several times unlifted and wheel weight was knocked off when I hit a pothole and viola shakes.

A marginally out of balance tire unlifted is magnified 10 fold when lifted because the inverted y geometry the higher you go the less stable. Even a weight placed on the wrong side of the wheel can set it off if you have problems.

Both Eagle and I agree that the tires are not the problem but what is causing the problem to show up. Your bushings where the problem and the lift and probably too wide offset rims and the factors set into play your DW

1/4 oz on the wrong side of a rim is enough to set it off if you have other underlying problems
 
Just for you guy's info. JJacobs has been wheeling a long time, but more important, he is one of the best mechanics and fabricators you will ever find and specializes in alignment for a local dealer. He has forgotten more about DW than most people will ever learn.

DW and balance are two different things. Balance can help start DW but balance can't cause DW unless there are other problems in the system such as loose joints or worn bushings. You can have the worst out of balance tires and have them bounce all over the place, but DW is a whole different level. If there aren't pucker marks on your seat, it isn't DW.
 
xjnation said:
Your bushings where the problem and the lift and probably too wide offset rims and the factors set into play your DW
Click to expand...


interesting- I had a DW fixed once by taking off 15x7 4.75 backspace wheels and putting on 15x8 4"backspace. That is, they stuck out more- completely cured the xj, drove better at all times than it had since stock

This stuff is really weird, my main point is there's no one fix all but lots of little oddities that can stack up into a dangerous problem.
 
old_man said:
DW and balance are two different things. Balance can help start DW but balance can't cause DW unless there are other problems in the system such as loose joints or worn bushings. You can have the worst out of balance tires and have them bounce all over the place, but DW is a whole different level. If there aren't pucker marks on your seat, it isn't DW.
Click to expand...
Sorry, Tom, but you're wrong. As I have commented previously, the only time I experienced true death wobble was in a new 1999 Grand Cherokee that had never been off-road and had been meticulously maintained for the 6 or 8 months I had it prior to the incident. There were no worn bushings or anything else out of spec in the front suspension.

The actual trigger was a warped brake rotor, probably coupled with a tire that may have been marginal on balance. But it took a particular set of circumstances to set it off, because it happened in New Hampshire after I had just driven 150 miles on the interstate and another 50 or so miles on NH state roads with no incident. And once I slowed down to 12 MPH to quiet the DW, I continued the trip and never had a recurrence.

You can have worn busings at every connection point in the front suspension. If the tires are properly balanced, you won't experience death wobble. Worn busings do not and CANNOT "cause" death wobble. They can only allow it to happen. Something else has to cause it.

Tire balance.
 
old_man said:
Just for you guy's info. JJacobs has been wheeling a long time, but more important, he is one of the best mechanics and fabricators you will ever find and specializes in alignment for a local dealer. He has forgotten more about DW than most people will ever learn.

DW and balance are two different things. Balance can help start DW but balance can't cause DW unless there are other problems in the system such as loose joints or worn bushings. You can have the worst out of balance tires and have them bounce all over the place, but DW is a whole different level. If there aren't pucker marks on your seat, it isn't DW.
Click to expand...


Im gonna have to agree with you here OLD MAN that is what Ive been saying but maybe not as elequantly. It can start th wobble but ther as to be underlying problem for it to continue

I actually bought a late model fan at the dealership in loveland a few years back while visiting a friend.

I really dont think we are arguing that far apart either, I think JJ just did not understand what I meant.
 
well my butt of the truck is also low which is something I've been told to fix ASAP and see if it helps. My rear is 3" lower than my front because I installed 2.5" lift spacers in front and extended shackles in back but the rear lift total was minimal to the front. I have a set of 3" blocks I still need to install to level it off but I am having trouble finding U bolts for a Dana 35.

Also ordered a kit to reinstall my swaybar with new bushings.

Then what?

Oh, and i CAN get over 55mph on a smooth as glass road, it is bumps, even minor ones that trigger the DW....
 
Gus...check for loose stuff up front, its there.....trust me. Lie on the ground under the front and have a helper crank the wheel back and forth, you will see movment somewhere that should not move, listen also, for creaking, and snapping as that could also point to your issue. As far as u-bolts...any spring shop will be able to bend them for you, just give them the diameter of the axle and how long you want them.

HTH

Rev
 
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