98 TJ bump steer diagnosis

Jerry is bang on here, the only other thing I noticed is that picture you posted first off (second picture you talked about is missing) looks like it's got a WJ or JK steering setup. Is that I need what you have or is yours the standard TJ y link setup?


There must have been a time
when we could have said no.
i have the standard y link setup. i just a beefed up moog kit. i posted a pic on begining of thread that had the dual steering stabilizers and a rough country adj trac bar with a drop down bracket. today i posted the photo with the metal cloak trac bar and removed the second steering stabilizer
 
Take it to a shop with an alignment rack and ask them to tell you what your caster angle is. They should give you a printout once they're done which you can post here. It should be at least least 5 to 5.5 degrees, as close to 6 degrees as possible. Much below that will cause steering wander. They'll verify your toe-in too. I'd call your various 4x4 shops first to see if they have an alignment rack. A common alignment shop is seldom competent with a 4x4 Wrangler.
that was about my only other thought was to have an alignment shop take a look at it. havent had much luck with firestone tho so may have to bite the bullet on 4wheel parts shop 300$ alignment which is super steep but its the only shop close that understands 4x4s.
 
that was about my only other thought was to have an alignment shop take a look at it. havent had much luck with firestone tho so may have to bite the bullet on 4wheel parts shop 300$ alignment which is super steep but its the only shop close that understands 4x4s.
Only pay them that if your control arms are adjustable for length which would allow them to set/adjust the caster angle. Otherwise only the toe-in could be adjusted which wouldn't be even close to worth paying $300 for.
 
Only pay them that if your control arms are adjustable for length which would allow them to set/adjust the caster angle. Otherwise only the toe-in could be adjusted which wouldn't be even close to worth paying $300 for.
absolutely. i have the stock control arms on right now because im rebuilding the currie johhny joints before reinstalling. once i get it all back together i will take it in for an alignment.
 
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update. metal cloak bar on and toe is set properly but still having bump steer. sad to admit i may have to drop it off at 4wheel parts to get a diagnosis. hate to do it but im out of ideas and options
 
I'm late to the thread, but have you checked your toe-in and made sure you have a stock Pitman arm?
 
Exactly what symptom are you describing as bump steer? Exactly what happens and exactly when does it happen? Is it repeatable?

And just to be sure, the OE inverted-Y steering system is an outstanding design, it really doesn't cause problems unless something gets installed that screws up its OE geometry design.
 
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Exactly what symptom are you describing as bump steer? Exactly what happens and exactly when does it happen? Is it repeatable?

And just to be sure, the OE inverted-Y steering system is an outstanding design, it really doesn't cause problems unless something gets installed that screws up its OE geometry design.
slow speed is no issue until i reach 20mph. then once i hit a groove in the road the jeep wanders and will over correct. i cant find center, its constantly back and forth at higher speeds.
 
my drag link and trac bar are completely even at driver side. however the trac bar sits higher than drag link at pass side. 3'' difference to be approximate. stock pitman arm and all mounted in factory locations w no modifications to mounts.
 
slow speed is no issue until i reach 20mph. then once i hit a groove in the road the jeep wanders and will over correct. i cant find center, its constantly back and forth at higher speeds.
I should have asked you that question before, that is not bump steer. That sounds like your caster angle is insufficient which will definitely cause steering wander on the highway. Sufficient caster angle gives stable steering on the highway and insures good return-to-center after completing a turn.

Adjustable length control arms up front are required to adjust/correct the caster angle.

It's hard to accurately measure the caster angle, I'd take it to a 4x4 shop with an alignment rack and have them measure it for you. 7 degrees is the factory caster angle for factory size tires. The larger the tire diameter, the less caster angle that is needed but I'd want nothing less than 5.5 to 6 degrees.

Incidentally, bump steer is a geometry issue that manifests itself by 'bumping' the steering left/right as the front axle is bumped up/down by bumps/dips on the road surface.
 
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copy that. will send it in for an alignment at 4wheel parts

1.jpg
 
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I had an inexcusable brain fart above which I just corrected. I meant to say you need adjustable length control arms up front to adjust your caster angle.
will i need both upper and lover adj control arms for the front or will adj lowers be sufficient enough? thanks
 
will i need both upper and lover adj control arms for the front or will adj lowers be sufficient enough? thanks
Let's see how far off your caster angle is first before deciding if/how many control arms are needed. Get it measured and let us know what it is.

If it's not off by much, you can save big $$$ by installing cam bolts where the lower-front control arm bolts to the axle. That allows about 1.5 degrees of caster angle adjustment. All TJs came with a pair of those cam bolts until around mid-1999.

Cam bolt kit.JPG
Cam bolt.JPG
 
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perfect. i actually just removed these from the factory arms and put them on the curries arms that i installed.
 
Let's see how far off your caster angle is first before deciding if/how many control arms are needed. Get it measured and let us know what it is.

If it's not off by much, you can save big $$$ by installing cam bolts where the lower-front control arm bolts to the axle. That allows about 1.5 degrees of caster angle adjustment. All TJs came with a pair of those cam bolts until around mid-1999.

View attachment 50516 View attachment 50517
so i removed these from the factory control arms and installed my currie short arm kit all around. even swapped over the adjustment bolts from the stock lower control arms. took the jeep up to 4wheel parts yesterday so we will see what they are able to accomplish with all the adjust ability. im hopeful they can get the tj road worthy again. will post print out of alignment once i speak to them
 
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