Bump steer

[Dmwstuff]

I have a 2021 JL Rubicon Unlimited. I just installed a 3.5” Metalcloak Gamechanger lift.
Upper and lower control arms, springs, shocks, front and rear track bars.
I also put 37” BFG KM3 mud tires on factory rims with 1.5” spacers.
I set caster at 6 degrees and toe in around 3/16”.
I verified torque settings.
I don’t have death wobble and don’t seem to wander.
I do have bump steer. When driving around 30-40 mph when I hit a small pot hole my steering wheel will shake back and forth 3 to 4 times then settle.
I owned a 2017 JKU that didn’t do this.
Note: i still have factory tie rod and drag link.
Any ideas would be great.
Thanks

 

[jeeeep]

with that much lift you'll need to flip the drag link and if you don't have a raised track bar bracket, install one to keep the track bar and drag link parallel

 

[docwilson]

I'm also on a 3.5" lift w/ 37" KM3s. I had an issue with being darty/wandering, which appears to have just been a sloppy alignment (way too much toe in). No bump steer even at high speeds (70+).

I have upgraded (bottom mount) drag link and tie rod from steer smarts, which may be helping, but I agree with the above about the raised track bar bracket. I do have this with my lift. Do you?

 

[Dmwstuff]

I'm also on a 3.5" lift w/ 37" KM3s. I had an issue with being darty/wandering, which appears to have just been a sloppy alignment (way too much toe in). No bump steer even at high speeds (70+).

I have upgraded (bottom mount) drag link and tie rod from steer smarts, which may be helping, but I agree with the above about the raised track bar bracket. I do have this with my lift. Do you?

I don’t have the drag link flip. I found out changing my tire air pressure helped. I did the chalk pattern to determine my Jeep’s proper air pressure. A good chalk pattern at 25 psi. I increased the pressure to 37psi and it didn’t go away but it got better.

 

[BlueRubicon]

Is your drag link parallel with your track bar? Tire pressure has nothing to do with it. Jeeep was trying to point out to you what I just asked.

 

[Dmwstuff]

Yes the drag link and track bar are parallel. I’ve heard that the steering box can flex from the frame.

 

[CalSgt]

I would try a little less toe in... Its a quick easy adjustment that can be done in the driveway.

I would also check track bar bushings and torque on the track bar bolts. Have someone yank the wheel back and forth while you feel for movement at the TB ends and steering linkage joints.

I was getting full on DW for a little while which was fixed when I flipped the DL & raised the trackbar mount... I think the root cause was a slightly worn trackbar mount hole but I am real pleased with the steering feel after the flip.

Before the wobble started I had your same symptoms.

I tried a steering box brace which did nothing for wobble or shimmy.

I tried a new trackbar that didn't fix it. I switched to Synergy because the EVO ones were going through bushings too quick for me which I thought was the cause of DW (which it is) but it was more of a symptom caused by it. Nothing wrong with the EVO trackbar but if something else causes wobble the bushings will go to shit quick. The bushing would probably hold up great if nothing else is wrong in your front end to add stress to them.

 

[Dmwstuff]

I would try a little less toe in... Its a quick easy adjustment that can be done in the driveway.

I would also check track bar bushings and torque on the track bar bolts. Have someone yank the wheel back and forth while you feel for movement at the TB ends and steering linkage joints.

I was getting full on DW for a little while which was fixed when I flipped the DL & raised the trackbar mount... I think the root cause was a slightly worn trackbar mount hole but I am real pleased with the steering feel after the flip.

Before the wobble started I had your same symptoms.

I tried a steering box brace which did nothing for wobble or shimmy.

I tried a new trackbar that didn't fix it. I switched to Synergy because the EVO ones were going through bushings too quick for me which I thought was the cause of DW (which it is) but it was more of a symptom caused by it. Nothing wrong with the EVO trackbar but if something else causes wobble the bushings will go to shit quick. The bushing would probably hold up great if nothing else is wrong in your front end to add stress to them.

My track bar is brand new (Metalcloak). I torqued them to spec and have since checked them. I did have someone move the steering back-and-forth while I got under the jeep to look for bushing movement. It seemed rocksolid. I do think I am going to do the drag link flip and track bar. Even it it improves it slightly I will take it.

 

[MericaMade]

My track bar is brand new (Metalcloak). I torqued them to spec and have since checked them. I did have someone move the steering back-and-forth while I got under the jeep to look for bushing movement. It seemed rocksolid. I do think I am going to do the drag link flip and track bar. Even it it improves it slightly I will take it.

We did the Synergy draglink flip on the TheMistress JL yesterday and he said it drives and feels better now.

 

[vxskaxv]

Firstly I’d say 100%, “get proper rims with proper backspacing”

secondly, “there’s no way that you put a 3.5 inch lift on and the drag link and track bar are still parallel to each other”

I wish you luck in you’re build sir.