Brothers Dw Is Back

[Knucklehead97]

I am very much so a procrastinator, sir! :D but I'm also an extremely busy, broke, 16 year-old haha. I also don't want to put any of my brothers money in the wrong place, which is why I drove it myself to see. But now balance seems to be the only thing. He said a week ago it tried to DW on him while he was slowing down to turn, but didnt.

[HOrnbrod]

Understand. I'm not saying the Hunter Road Force balancer will completely cure the vibes, but it will eliminate the most common cause - tires.  :thumbsup:

[Knucklehead97]

I understand that. I just wonder why it wouldn't wobble for a couple weeks and now it will hardly go 30 without it.

[Eagle]

I understand that. I just wonder why it wouldn't wobble for a couple weeks and now it will hardly go 30 without it.

 

You have to understand the difference between "shimmy" and "death wobble." Death wobble is when BOTH front tires start shaking so violently that you are ABSOLUTELY CERTAIN that you are going to die ... right NOW! If your life is not flashing before your eyes in full, glorious, Technicolor -- you don't have death wobble. If you can keep driving ... you don't have death wobble. With true death wobble, the ONLY way to stop the insane shaking is to stop -- almost to a full, dead stop. If you are driving and talking/thinking about it -- you don't have death wobble.

 

Tire shimmy isn't unusual, and it's almost always caused by improperly balanced tires. When only one tire is involved, it's "just" shimmy, and you can live with it. I've seen cars on the Interstate with one front wheel bouncing around like Meadowlark lemon doing his trick dribbling routine, and the driver keeps on going at 65 MPH and appears to be completely oblivious to the tire. That would NOT happen with death wobble.

 

Death wobble is a harmonic. One side starts wobbling. The wobble gets transmitted to the other side and, if everything is just right (or just wrong), the other side starts wobbling at the same frequency. Each side reinforces the other, so the amplitude of the wobble rapidly increases until it feels like the whole front is going to fall off the truck. But it's tough to pin down.

 

My first experience with true death wobble was in a new 1999 Grand Cherokee. The vehicle at the time was about 6 months old, totally stock, had maybe 7,000 miles on it and it had never been farther off-road than my gravel driveway. I was on a 2-lane state road heading into a very long downgrade. I just touched the brakes -- not to stop, just to keep my speed at the speed limit -- and BAM! Death wobble! It had never happened before, and it never happened again.

 

Remember -- it's a harmonic. The front tires, especially, travel different paths every time you go around a corner or a curve. Say two tires (on the front) each have a heavy spot that's not properly balanced. Say you start out with them both located at top dead center. As long as you only go straight, they'll stay that way, and both will want to go up or down at the same time.

 

But what happens after some turns? Now one heavy spot is at the top when the other side is at the bottom. So now when one is trying to throw that tire UP, the other side is trying to throw the tire down. When one side is trying to throw the tire forward, the other side is trying to throw it rearward. Hit a bump just when that's happening, and that may be all that's needed to set it off.

 

My second experience with true death wobble was in the '88 MJ. It only happened if I went into a gentle RIGHT turn (curve) at 50 MPH. Left turns/curves were no problem. Right curves were a BIG problem. I swapped a different set of tires onto it, and had no more problems.

 

Harmonic ... harmonic ... harmonic.

[Biotex]

Just want to add that you should check your toe-in. Zero toe-in can be a trigger for DX. Start at 1/8", and play around with it a little and see if that helps.

[carnuck]

I got rid of my death wobble by removing 2 shims each side on the lower control arm at the body to push the caster back slightly.

[Knucklehead97]

Just want to add that you should check your toe-in. Zero toe-in can be a trigger for DX. Start at 1/8", and play around with it a little and see if that helps.

thats basically just doing an alignment, right? Turning the tie-rd and all that? And its a little funny that the DW started not to long after he got a set of used tires. But it sometimes will just run right. And I was driving the truck myself, this was absolutely HECTIC on the front end until I got down to 5 mph. It was uncontrollable. I drove my truck for months with bad tire shimmy, so I decently know the difference :D