Help needed with bump steer (I think)

Viclava

Viclava

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I have a 16 Rubicon with a 3” fabtech spring lift (I inherited) and just had steering inspected. All stock with exception of lower control arm bracket drop and RC adjustable track bars front and rear with rear trackbar relocation bracket.

I go over a bump with right tire and wheel shakes back and forth 2-3 times then stops. At highway speed steering tracks well and does not wobble. It does not do this when I go over a bump on left tire. I had offset ball joints installed (at recommendation of alignment guy) to give me lots of caster adjustment. It has been aligned and everything torqued and re-torqued. Still have the bump steer.

If anyone is able to see anything not at correct angles based on my pics, please speak up. This is driving me nuts. My alignment shop is the most recommended in town, as thst sll they do. Alignment tech says it is all tight and correct, but recommended a double steering dampener setup. That was a red flag to me he is not do great maybe.

Anyway, any help is appreciated.
IMG_0097.jpeg
IMG_0097.jpeg
 
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Looking at your pictures, your sway bar links are way too short. The tips of the sway bar should be above level, not below. Under full extension with the current ones, they can cause some serious damage. Aftermarket adjustable sway bar links now!

What I’m running on mine -

JKS
 
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Snowbird Tom said:
Looking at your pictures, your sway bar links are way too short. The tips of the sway bar should be above level, not below. Under full extension with the current ones, they can cause some serious damage. Aftermarket adjustable sway bar links now!

What I’m running on mine -

JKS
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The sway bar end links are what came with kit I believe, and is actually sitting level. I specifically asked alignment tech and he said they are where they are suppose to be. Hmm, he claims they don’t do much anyway. Thought that was an odd thing to say frankly.

Additionally, i have a Rubicon with the swsy bar disconnect feature. Not sure that that matters if they are actually too short or not.
 
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Viclava said:
Additionally, i have a Rubicon with the swsy bar disconnect feature. Not sure that that matters if they are actually too short or not.
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You can try disconnecting the sway bar and driving over something with the right tire to see if the problem remains.

Have you had the right front shock inspected/tested? Seems like that may create a similar issue.
 
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tJKrider said:
You can try disconnecting the sway bar and driving over something with the right tire to see if the problem remains.

Have you had the right front shock inspected/tested? Seems like that may create a similar issue.
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Thanks for the responses! No, I have not tried that, but I definitely will. The shocks are brand new Bilstein 5100’s.
 
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Steering dampeners do not fix anything, they just mask the symptoms. They are the equivalent of me shooting someone full of morphine for their broken arm arm and then sending them home without setting or immobilizing the fracture. And sway bars do a LOT. The statements from your alignment guy suggest you need a different shop. One that does 4x4 vehicles. "Most recommended" by 1,000 people with bone stock cars says nothing about their knowledge or ability when it comes to modified vehicles.

If you're getting even a minor amount of death wobble or bump steer, you've got something loose, worn, or misaligned. It could be in the front or rear.
 
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Viclava said:
The shocks are brand new Bilstein 5100’s.
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I always trace back to any recent changes when I have a problem. Sometimes it's coincidence, sometimes not. I would check the bolts and make sure all are tightened properly on that shock since they are new. A loose bolt could have similar symptoms. If anything, rule that out.
 
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Viclava said:
The sway bar end links are what came with kit I believe, and is actually sitting level. I specifically asked alignment tech and he said they are where they are suppose to be. Hmm, he claims they don’t do much anyway. Thought that was an odd thing to say frankly.

Additionally, i have a Rubicon with the swsy bar disconnect feature. Not sure that that matters if they are actually too short or not.
Click to expand...
You might try lifting the right front tire and checking for any wobble, shaking it vertically and horizontally. I would be inclined to check for vertical movement primarily, looking for a worn bearing, or something close to the wheel and axle.

Bump steering can be checked by standing on the front bumper and bounding up and down some while watching the top of the steering wheel through the windshield. If the steering wheel moves side to side, you do have some bump steer. That's generally caused by the drag link and track bar being out of parallel, which causes them to travel different lengths of arc as the wheels move vertically.
 
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Duster said:
You might try lifting the right front tire and checking for any wobble, shaking it vertically and horizontally. I would be inclined to check for vertical movement primarily, looking for a worn bearing, or something close to the wheel and axle.

Bump steering can be checked by standing on the front bumper and bounding up and down some while watching the top of the steering wheel through the windshield. If the steering wheel moves side to side, you do have some bump steer. That's generally caused by the drag link and track bar being out of parallel, which causes them to travel different lengths of arc as the wheels move vertically.
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Rotated tires front to back and back to front, checked for loose wheel bearings, new Bilstein does not appear to be bad, jumped up and down on RF fender and steering wheel had a slight back and forth movement, but slight. Torqued drag link, tie rod, and all was tight.

Went for test drive on road at low speed where i have been getting the bump steer ob a specific divot in the road, and still did it.

Went for highway drive where i would get a little but of shimmy in wheel back and forth At 50-60 mph. It still shimmied but now up to 65-67 mph. Only thing i can come up with is to have all tires rebalanced. My new RC trackbar and drag-link are pretty darn even. Im starting to pull out what little hair I have left😫.
 
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Viclava said:
Rotated tires front to back and back to front, checked for loose wheel bearings, new Bilstein does not appear to be bad, jumped up and down on RF fender and steering wheel had a slight back and forth movement, but slight. Torqued drag link, tie rod, and all was tight.

Went for test drive on road at low speed where i have been getting the bump steer ob a specific divot in the road, and still did it.

Went for highway drive where i would get a little but of shimmy in wheel back and forth At 50-60 mph. It still shimmied but now up to 65-67 mph. Only thing i can come up with is to have all tires rebalanced. My new RC trackbar and drag-link are pretty darn even. Im starting to pull out what little hair I have left😫.
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The "vertical" motion I mentioned is a loose feeling you might find by pulling alternatively on the top and bottom of the tire. If the bearing is the problem, the wheel assembly will feel slightly loose or sloppy. It shouldn't have anything to do with the shocks. Sorry if my remark was vague there.

The back and forth movement of the steering wheel when you jump up and down on the bumper now. That should not be there. It suggests the track bar and drag link are too far out of parallel. Quadratech has a couple of good illustrations about this:

https://www.quadratec.com/sites/default/files/knowledge_based_articles/tjsteering(1).jpg

https://www.quadratec.com/sites/default/files/knowledge_based_articles/bumpsteer1.jpg

The photo is of a tj set up, but the geometry issue is the same. The two try to swing different length arcs, pulling the wheel differently, as the diagram shows. The trouble would be that one of those units is too short, or is bent, which shortens one arm with respect to the other, or was not adjusted when your jk was lifted, then that could be your problem.
 
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