Assistance with bump steer

Yellowdog

Yellowdog

Member
Joined
Sep 1, 2022
Messages
41
Location
SW Washington
Hello All,

I would be very thankful for some assistance with getting rid of bump steer (I think) on my 06 LJ.
When driving on certain paved roads my LJ rolls and dips and jumps left/right like I’m in a boat on rough waters.

Set up:
4” fabtech springs
falcons shocks and stabilizer
core 4x4 adjustable front L/U control arms
core 4x4 adjustable track bar
curry correctlinc drag link and tie rod
new ball joints
33” wildpeaks
stock pitman arm

Shocks are not bottoming out. Checked with zip ties and driving for about a week they only moved to middle of the shaft on all 4 corners.

Shop checked and torqued everything to spec (so they say). They didn’t notice any play that would affect drive ability.

They performed an alignment with the following results but the ride did not seem to improve.
I’m not sure the specs they set are correct.

Any advice on what I should look into next would be greatly appreciated.


FF324C98-2D4B-4D26-8A63-0C7CDEC08A3D.jpeg
 
1. Pictures of your steering from the front would help. You said your pitman arm is stock. Are your front track bar mount locations stock?
2. Toe should be inward about 1/8”. Read this: https://wranglertjforum.com/threads/how-to-align-your-jeep-wrangler-tj.85/ You can do it yourself easily.
3. Stock front caster is 7 degrees (on my 97, at least). Less will make your steering more twitchy but larger tires do increase trail and so tend to counter act less caster. But, I have 33” tires as well and 5 degrees doesn’t feel as stable as 7.
 
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There have been several times over the years where the alignment shop used the wrong vehicle alignment specs; which is why I always ask for the alignment print out.
IF the wrong vehicle specs were used; your steering could respond very oddly on the highway.
What vehicle is used for your alignment specs ?
 
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Just checked that report again and it lists 2007 Wrangler so I guess they used the wrong vehicle specs.

The Jeep went in for the alignment and suspension/steering shakedown to try to correct the bump steer but it doesn’t ride any different than it did before going in.

Trackbar locations stock.

84EE0FDE-3724-4F2E-915F-CCF166D907CC.jpeg


7EF4B3C0-EB44-480E-88BD-16C3F6CF3B5F.jpeg


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Jerry Bransford said:
Exactly what symptom(s) are you experiencing that you're describing as bump steer? Does it happen on smooth highways? Only when driving over bumps/dips in the road?
Click to expand...

This. Also, how long have you had the Jeep? Did this start after mods? If so, which mod? Has it ever been better since you’ve owned it?
I’d confirm the toe is correct and do a dry steering test to check for anything loose (https://wranglertjforum.com/threads/can-anyone-explain-a-dry-steering-test.14163/). If that’s all good, perhaps increasing the caster to 6 or 7 degrees would help.
 
Jerry Bransford said:
Exactly what symptom(s) are you experiencing that you're describing as bump steer? Does it happen on smooth highways? Only when driving over bumps/dips in the road?
Click to expand...

Its drives pretty good on smooth highway. On roads with bumps and dips the Jeep kind of jumps around, getting pushed side to side. A dip on the right will push it to the left, vice versa. Like a boat that is getting pushed around by other boats wakes.
 
Woodrow said:
This. Also, how long have you had the Jeep? Did this start after mods? If so, which mod? Has it ever been better since you’ve owned it?
I’d confirm the toe is correct and do a dry steering test to check for anything loose (https://wranglertjforum.com/threads/can-anyone-explain-a-dry-steering-test.14163/). If that’s all good, perhaps increasing the caster to 6 or 7 degrees would help.
Click to expand...

I bought the jeep in June and all parts were already installed except for the JKS antisway bar links up front and the ball joints.

Ive completed a dry steering test and didnt see anything out of the ordinary. Both through visual inspection and feeling.
 
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Yellowdog said:
Its drives pretty good on smooth highway. On roads with bumps and dips the Jeep kind of jumps around, getting pushed side to side. A dip on the right will push it to the left, vice versa. Like a boat that is getting pushed around by other boats wakes.
Click to expand...
Ok that sounds like classic bump steer. The photos are pretty good but the driver's side track bar mount is stock right? No aftermarket that drops the mount any? And the passenger-side track bar is mounted into the stock mount that is not dropped either?

Is that big steering stabilizer gas charged? If you have had it off does it expand outward on its own with a lot of force? The steering stabilizer should be hydraulic that does not expand outward on its own.
 
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Yellowdog said:
Its drives pretty good on smooth highway. On roads with bumps and dips the Jeep kind of jumps around, getting pushed side to side. A dip on the right will push it to the left, vice versa. Like a boat that is getting pushed around by other boats wakes.
Click to expand...

Are you getting feedback through the steering wheel when this happens?
 
Jerry Bransford said:
Ok that sounds like classic bump steer. The photos are pretty good but the driver's side track bar mount is stock right? No aftermarket that drops the mount any? And the passenger-side track bar is mounted into the stock mount that is not dropped either?

Is that big steering stabilizer gas charged? If you have had it off does it expand outward on its own with a lot of force? The steering stabilizer should be hydraulic that does not expand outward on its own.
Click to expand...

I loosened the stabilizer and it didnt move at all so I assume hydraulic.

Pics of the frame side and axle side track bar mounts.

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We be twins. Well, except for that steering stablizer. I would take the stablizer off and go for a test drive.

Bump steer, as I understand it, comes from different angles and/or lenghts when comparing the track bar and the drag link. You do not have a good head on photo, but I'd guess your setup is OK.

IMG_8724-X3.jpg


I've had some really strange handling when one end of a swaybar link got loose. Your fronts look new. have you checked the back?

We should ask about your shocks too. What shocks are you running?
 
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Hey there twinsie!

Sway way bar end links are tight. Backs are tight. I have JKS adjustable rear swaybar end links that I haven’t installed because at their fully extended length they are the same size as the ones already installed.

Shocks are Falcon piggybacks.
Here is a better pic of the front end.

Im going to try to set the toe in again tomorrow.

C4DC6B2C-8971-4F25-964C-F0D4D871BDF4.jpeg
 
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Yellowdog said:
Hey there twinsie!

Sway way bar end links are tight. Backs are tight. I have JKS adjustable rear swaybar end links that I haven’t installed because at their fully extended length they are the same size as the ones already installed.

Shocks are Falcon piggybacks.
Here is a better pic of the front end.

Im going to try to set the toe in again tomorrow.

View attachment 363731
Click to expand...

I think your front end geometry is good. You can play with the toe in, but I don’t think that will matter. I’m guessing those shocks are adjustable. If so, and if it were mine, I would check the settings on the shocks.

You have an LJ with all the good mods. I am jealous. I love my TJ but wish I had more room. Sometimes I think about selling the TJ and buying a 4 door Jeep. I have resisted the change so far.

i-fhbGVTs-X3.jpg
 
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Yellowdog said:
I loosened the stabilizer and it didnt move at all so I assume hydraulic.

Pics of the frame side and axle side track bar mounts.

View attachment 363583

View attachment 363584
Click to expand...

That axle end track bar hole has been redrilled inboard to run an oem bar at some point and the aftermarket bar is in it. While technically it's not the original track bar location I have a really hard time thinking that could be off enough to cause noticeable bump steer. Sorry it's not much but we're down to where there's nothing obvious, might be grasping at straws.

As has been mentioned the stock alignment specs used aren't right for a Tj but I don't see anything wrong enough to cause problems, and if they did it wouldnt be bump steer.
 
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I have given my self a day off from my manly duties. That means I am playing on the internet. I thought of something else you should check. Your tire pressures. They should all be the same. I run mine at 24 psi.

I've watched your movie a couple of times. Your Jeep didn't look that bad to me (at first). I went out to drive mine and make a comparison movie (see link below). It helped me see what you are complaining about. When I bought my Jeep, it had a cheapo lift kit on it and was hard to drive. In fact, if I had known what I know now, I would not have bought the Jeep, at least not for what I paid for it. As it turned out, the struggle to improve the drivability of my Jeep advanced my Jeep education a LOT. It wasn't my brian power that made the difference. The members here made great guides. Generally, problems like yours are not fixed by any one thing, but by a series of small changes. Jeeps are so good when they are good, and so BAD when they are bad.

https://andy29847.smugmug.com/Jeeping/Jeep-rubicon/i-nrTVrpk/A
 
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Thanks all. I appreciate the effort and knowledge.

@andy29847 the shocks dont have any adjustability.
Tires are at 26psi. Easy enough to lower a couple psi and try again. I may play around with different pressures front and rear.
Thanks for taking the video. Maybe everything is the way it is and Im just overly sensitive to the motion of the ocean. ;)

@freedom_in_4low you mentioned the axle side track bar end not being in the original location. I wonder if there could be a chance that the hole is wallowed out? I guess I should disconnect it and take a look. Although dry steering test doesnt show any movement.
 
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