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-   -   Dangerous wheel shimmy after hitting a large bump (https://forums.off-road.com/jeep-short-wheelbase/173052-dangerous-wheel-shimmy-after-hitting-large-bump.html)

Alec78CJ 08-03-2003 11:04 AM

Dangerous wheel shimmy after hitting a large bump
 
Here's the story. I swapped a waggie d44 into the front of my CJ several months back. I have been driving it almost daily since then without any problems. However, yesterday I hit a very large bump and the front of my CJ started "jumping" up and down. It was like a tie rod end had broken and the tire folded in and being dragged sideways. This was not the case though. I looked out at the left front wheel and it was violently moving left to right. After I pulled over to the side of the road I gave everything a quick look (including my pants!) and it seemed alright. I went slowly up the street to a gas station to take a better look...nothing! Everything was tight. I had a friend turn the wheel so I could look for loose or broken parts...nothing! Could this be caused by to much caster...I ended up with 8 degrees after I narrowed it. For the past few months my CJ has driven better then it has for the past 10 years! Now, it kind of scares me. I checked both hi steer arms and they are tight. I also checked all tie rod ends and they are tight. Wheel bearings are tight too. The only thing I can come up with is the length of the shackles that I run. They are heavy duty shackled but they are slightly longer the stock. Now, when I turn the wheel the frame moves the opposite direction. Also, the steering box is tight and it does have a currie steering brace on it.
This has stumped me because it has been fine up until now, and it only happens when I hit a very large bump. Any ideas?

Alec

4x401CJ5 08-03-2003 12:00 PM

Re: Dangerous wheel shimmy after hitting a large bump
 
8 degrees of caster is a bit excessive, and the over length shackles will be compounding the problem. What
size tires you running? Are you running a shackle reverse? Do you have/ what kind of shape is your steering
stabilizer in? Sounds like a clear case of death wobble to me. You could try to shim out some of the caster,
but that may create pinion angle problems. I`m only running 4 degrees of caster with a S/R on my 44 and
haven`t expierenced any problems.

jamgood96 08-04-2003 02:22 AM

Re: Dangerous wheel shimmy after hitting a large bump
 
I'm running about 8 on mine(isn't that what we set it to?), and am not having any problems as of yet(knock on wood).

4x401CJ5 08-04-2003 09:55 AM

Re: Dangerous wheel shimmy after hitting a large bump
 
Really?! I don`t remember there being that much.

GeeAea 08-04-2003 11:27 AM

Re: Dangerous wheel shimmy after hitting a large b
 
Why should he have pinion angle problems? If he had too little caster I could see it ....you may be trying to point the pinion "down" and it would be on the wrong end of the fudge factor of the parallel planes of the yokes. It's a little easier tilting the pinion up 2 degrees. This thing has a CV front shaft doesn't it? Even if it doesn't no power is applied to it at any real speed. Now if the pinion is already pointing at the t-case yoke ..then I could see the issue since it would be sorta the same as pointing a pinion down to get more caster on a normal setup - except now your going the other way too far..

Educate me if I have something wrong here....

elusive 08-04-2003 11:45 AM

Re: Dangerous wheel shimmy after hitting a large b
 
do a search on death wobble.
you do have a steering stabilizer right?

babypoo 08-04-2003 11:57 AM

Re: Dangerous wheel shimmy after hitting a large bump
 
Did the violent shaking go away after you stopped and looked everything over if so that it's the same thing that happened to me a few weeks ago when my steering stabilizer to a poop I reaplaced problem gone.
John
[email protected]

MuddyCJ 08-04-2003 08:19 PM

Re: Dangerous wheel shimmy after hitting a large bump
 
I had basically the same problem with my 79 CJ's D30. I hit a bump doing about 55 with traffic all around me. The front end started shaking violently and I was all over the road. All front end parts were new and tight. The only thing that I hadn't changed was the steering box. I have power steering and the way that I was checking the play in the steering was by turning the steering wheel with the engine running. With the engine running I had no play. When I tried it with the engine off, I had about 5 inches of play in the steering wheel. I changed the steering box and have not had a problem since.


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