Confused about bump steer

Porch951

Porch951

NAXJA Forum User
Location
Albuquerque, NM
I recently went to a ~5" lift and added a bit of bumpsteer with it. I went to Serious long arms at the same time. It is definitely tolerable bump steer but i'd like it more if it were gone!

I drew out the lines between the steering and the track bar and everything looks good.
P8193358.jpg


In searching around on this site it sounds like the next thing to check would be whether the axle was centered. I couldn't find a really easy way to do this when i did the LA conversion, so i did what i could. The shocks seem to sit at the same (but opposite) angles and it really "looks" centered.

Someone in another thread mentioned that having different length steering and track bar would cause the bump steer, so i measured and ended up with 37" on the drag link and 33" on the track bar. Obviously i can't shift the axle over 2" to get these values equal.

Is it just time for me to go to a different type of steering, or is there more i can do with what i've got?
 
the only way to change what you have is to make the panhard (trackbar) longer.

you can either go further on the frame end or further on the axle end.

the only way to get 0 bumpsteer in the range of motion you have is to get the panhard and drag link parallel and the same length.
 
Alright, thanks. I don't see any easy way to make the trackbar longer (it doesn't really have room to grow on either end), so it looks like i'm due for a new steering setup. I checked out a few of them and it looks like they'd shave 3-4 inches off the steering length. Time to start saving for that now... [sigh]
 
On the kits I do, the track bar is moved to the steering stab location on the diff and the stab moved. That location shares the same pivot area as the steering. Get them both in the same area and the bumpsteer will mostly go away. Your current track bar on the diff is in the stock location while the steering pivot is well above it.

I've done many of these kits and there is zero bumpsteer.
 
jbsjunk said:
On the kits I do, the track bar is moved to the steering stab location on the diff and the stab moved. That location shares the same pivot area as the steering. Get them both in the same area and the bumpsteer will mostly go away. Your current track bar on the diff is in the stock location while the steering pivot is well above it.

I've done many of these kits and there is zero bumpsteer.
Click to expand...

no.
 
This morning i measured the pinion angle, which was right at 5*. I have the pinion pointed straight into the driveshaft. According to this site, that makes my caster 4.0?
http://jeep-xj.info/HowtoAlignment.htm

Toe is right at 1/8", where i always keep it :)
 
Hmm, in thinking about it i'm pretty sure last time i measured the pinion angle it was about 6.5* or so. I measured this morning in my driveway and there was some slope to the driveway, so i tried to factor that in...might have screwed up. What caster/pinion angle should i be shooting for?
 
I dont go by pinion angle. But as for caster i shoot for 5 to 7 degrees positive. The more you have, the least suspectible to deathwobble you will be.
 
Okay that's good to know, i'll double-check it on mine and see if that helps.

I'm not really having much trouble with death wobble, though.
 
Porch951 said:
Okay that's good to know, i'll double-check it on mine and see if that helps.

I'm not really having much trouble with death wobble, though.
Click to expand...

Ah shoot. Meant bumpsteer. But it holds true for both.
 
Im having the exact same issue. If an axle is slightly crooked will that cause it? Like if the passenger side is say an inch or two pushed father foward that the driver side?
 
Similar question here, although I have a much simpler lift.
I have 3 inch spacers with a drop pitman arm and a track bar relocating bracket (moves the axle mounting point about 1 inch towards the center of the axle) and even though I've had everything aligned to within factory specs, the truck wants to jump all over the place when I hit a bump on the highway (I can feel the steering wheel pulling with each bump. I even dropped in new rancho shocks and a rancho steering stabilizer, but that didn't help much... At this point, I'm thinking I need to do one of the following:
Install longer lower control arms
Install a longer track bar (while removing the relocating bracket) or relocate where it bolts to the body
Install a pitman arm with an even lower drop

Any recommendations? Are all lifted Cherokees this bad/unsafe to drive?
 
peterchase said:
Similar question here, although I have a much simpler lift.
I have 3 inch spacers with a drop pitman arm and a track bar relocating bracket (moves the axle mounting point about 1 inch towards the center of the axle) and even though I've had everything aligned to within factory specs, the truck wants to jump all over the place when I hit a bump on the highway (I can feel the steering wheel pulling with each bump. I even dropped in new rancho shocks and a rancho steering stabilizer, but that didn't help much... At this point, I'm thinking I need to do one of the following:
Install longer lower control arms
Install a longer track bar (while removing the relocating bracket) or relocate where it bolts to the body
Install a pitman arm with an even lower drop

Any recommendations? Are all lifted Cherokees this bad/unsafe to drive?
Click to expand...

pics of your setup will help....

but with only 3" of lift, I would ditch the DPA and Drop TB.
 
OK, here are 2 pics. Now that I look at it, I'm wondering why they even included the DPA, since it's definitely messing things up. I'm guessing if should probably do the following in order to get back to a somewhat normal ride: 1. Re-install factory pitman arm 2. Then if necessary, pick up an adjustable trac bar. 3. Then install some longer sway bar links. Also, will I be needing longer brake lines all around as well, if I intend to do some basic 4 wheeling?
Misc016.jpg
Misc017.jpg
 
almost looks like you should take out the drop bracket for the track bar on the axle end instead. that should give you decent angles.
 
What he said:wstupid:...you'll need to drill a new hole in the TB mount to center the axle (that's what that gay bracket is doing...but it helps create bump steer).

At 3", no DPA, and just redrill for the trackbar:greensmok
 
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