Help me diagnose my bump steer - JeepForum.com
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post #1 of 48 Old 07-14-2021, 01:26 PM Thread Starter
KiloWatts
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Help me diagnose my bump steer

I'm at a loss. By "bump steer" I mean the steering wheel itself wants to jump to the right when I let go of it. The Jeep has been aligned twice and it still pulls. The jump really happens when I hit a bump or when weight is taken off the axle. The wheel jumps a couple inches to the right and I start turning.

What's different? I'm on OME coils which puts me at 1.5" higher. 30" tires. I replaced my trackbar with JKS adjustable and centered the axle perfectly. Stock control arms, aligned to spec.

I don't think I have a dragging brake, but I'm going to check. There's no abnormal noise. I have rotated all tires. My thoughts are maybe a bent drag link, or something involving the steering stabilizer? Or the steering gear itself? I'm at my wits end here. I don't want to keep replacing needless parts. Thanks all.

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post #2 of 48 Old 07-14-2021, 01:35 PM
nam3l3ss
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Try to look if the steering stabilezer (amortization) is working in both direction.... mine was on one side soft so was entering in vibration ... and also try to look if the silent blocks are good...

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post #3 of 48 Old 07-14-2021, 01:49 PM Thread Starter
KiloWatts
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Silent blocks = bushings? Good idea, I'll inspect the stabilizer and see if it moves both directions.

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post #4 of 48 Old 07-14-2021, 02:26 PM
nam3l3ss
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You should take out the stabilizer from one side, and it should move hard in both directions... silent blocks - rubber bushings

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post #5 of 48 Old 07-14-2021, 02:29 PM
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Quote:
Originally Posted by nam3l3ss View Post
You should take out the stabilizer from one side, and it should move hard in both directions... silent blocks - rubber bushings

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Ya .. I forgot. If you changed the springs more higher you should install some more spacers... is not enough only the springs.
..

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post #6 of 48 Old 07-14-2021, 02:49 PM Thread Starter
KiloWatts
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Spacers? Where? I replaced the isolators... I should not need to add coil spacers

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post #7 of 48 Old 07-14-2021, 03:18 PM
nam3l3ss
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You should install spacers on rear side between the puffer and the car body and in front inside of the coil spring. only and only if the spring coils are higher than the one before... the spacers should be on the same distance as you get higher.. in case you get higher more than 50mm you should put 4 more spacers between the gearbox between the support and the body the spacers should be around 25mm. Attachment 399776920210714_231624.jpg20210714_231204.jpg

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post #8 of 48 Old 07-14-2021, 03:31 PM Thread Starter
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Oh you mean the bump stops. Yes I know, I still need to lengthen mine, but that shouldn't cause my steering issue.

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post #9 of 48 Old 07-14-2021, 05:04 PM
nam3l3ss
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If you already are higher than the factory one with the spring coils and you don't have the "bump stops" be sure you will fill that the car is not stable... at least the back side....

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post #10 of 48 Old 07-14-2021, 05:11 PM Thread Starter
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I do have the bumpstops on all four corners, but they're factory length. Again, this should not affect the steering...

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post #11 of 48 Old 07-14-2021, 08:37 PM
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Help me diagnose my bump steer

Ok. So…bumpsteer is cause by a lot of things but you want to look at your caster first. Low caster will make the car darty and the steering wheel may not return to center easily which can be perceived as bump steer. At your lift though I don’t see Caster being horrible. Also make sure your track bar and drag links are at the same angle, if they are not this will cause bump steer. Steering stabilizers do sometimes cause a pull as well so remove it completely to see if it changes to rule it out as the cause of the issue.


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post #12 of 48 Old 07-15-2021, 12:58 AM
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Quote:
Originally Posted by nam3l3ss View Post
You should install spacers on rear side between the puffer and the car body and in front inside of the coil spring. only and only if the spring coils are higher than the one before... the spacers should be on the same distance as you get higher.. in case you get higher more than 50mm you should put 4 more spacers between the gearbox between the support and the body the spacers should be around 25mm. Attachment 3997769Attachment 3997771Attachment 3997773

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There is absolutely ZERO need for a transfer case drop on ZJs, and it is actually a pretty damn stupid idea on XJs and TJs as well.

As for bumpstops, they have nothing to do with with the issues OP is having.

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post #13 of 48 Old 07-15-2021, 04:21 AM
yjsaabman
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LittleFoot has some good input.

Have you measured the wheelbase side to side just to make sure something isn't out of whack? Something worn or misaligned causing the geometry to be a little off? Also do you have print out from the alignment you could share?

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post #14 of 48 Old 07-15-2021, 07:03 AM Thread Starter
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Well, I've been to a couple different shops chasing this issue. My local shop welded a new lower control arm bracket on after it bent in a minor fender bender. They said they aligned it, but it was doing this, so I brought it to a different shop while I was away out of town just to check. Printout attached. They said my caster is out of whack but they can't align it because the cam bolts are maxed out. So I figured that was the issue and planned for adjustable control arms.

But I decided to bring it back to my local shop, (I guess out of loyalty), and see if they would be willing to correct their work (that I paid quite a bit for) or at the very least weld on an additional matching bracket just in case it's a tiny bit different than stock. They said they had the alignment re-checked and corrected (didn't give me a printout), and told me I needed a new track bar. They were right, my axle was 1/2" off to the side, so I bought an adjustable and did the job myself. It's more stable now, but the pulling problem remains.

So I'm pretty much back at thinking about adjustable control arms so I can lengthen them and get more wiggle room for alignment. But I've made a number of bad calls here and really just want to get it right this time...

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post #15 of 48 Old 07-15-2021, 07:31 AM
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