Caster Angle w/ Small Lift

I have a specific question in regards to caster angle in regards to a small lift.

I bought a rust free 99 XJ about a year back that I have been slowly fixing up with the soul purpose of being a daily. I installed Rusty's 1.75" budget boost kit which was just spacers up front and shackles in the rear.

Since the lift I have been experiencing death wobble at highway speeds 70mph when hitting a bump on the highway. I can start feeling a small shimmy and instability when I hit 55-60mph.

Here is some background info first so you know what I tried:

Verified trackbar and everything I unbolted is torqued correctly. I had my wife turn the steering wheel back and forth while I watched the trackbar and tie rods for movement and didn't see anything.


Took the Jeep in for an alignment and they could only correct the toe.
Toe
0.13 left
0.14 right

Caster is locked at
+6.2 degrees left
+6.5 degrees right

The Rusty's directions recommend the caster to be set at +7.5 degrees. We were going to set the caster at the recommended +7.5 degrees but the passenger side control arm bolt was locked up to the bushing sleeve and we couldn't get this to pushout.

Factory caster specs are +5.25 degrees to +8.5 degrees and +7 degrees preferred.

My question is would adjusting the caster +1 degree going to make a difference especially since I'm within factory spec?

Basically Im trying to decide if I should spend time to try and get that control arm bolt free or if that would be a waste of time and moved on to the track bar and tie rod ends.

Side note: after the alignment it didn't correct the death wobble so I put my TJ wheels/tires on the XJ which also had no affect so I can rule out tires. The wheel bearings were replaced 3 months before the lift too. So if Caster isn't the issue, next steps will be new track bar and tie rods, followed by ball joints last.

Thanks!

1 degree could def make a difference. how are the control arm bushings? That was the main source of my DW.

It's not the caster! Start reading up on DW. Almost anything can cause it but a lot times it's several components together causing the problem.

DW is almost always caused by a combination of worn/loose/damaged suspension and/or steering components. Almost never is caster a single root cause item of DW, and 1* isn't going to change anything.

Thanks for the input.

szfofa - What did you do to check if your control arm bushings are good or bad? The rubber on mine shows some signs of regular aging like small cracks. I wiggled them by hand and I could see very slight movement from the rubber just barely flexing, but I noticed the same on my TJ control arms in comparison. For reference the XJ has 200k miles and the TJ has 85k miles.

I already get that multiple items and/or combination of things can cause DW (alignment, tires, wheel bearings, tie rods, ball joints, track bar, control arms). I was mainly after how big or little effect does 1 degree of caster has on DW. I kindof side with the idea if its in the factory spec range, its good, but I do find it interesting that Chrysler lists a preferred caster of +7 degrees. I wish I knew what the caster angle was before I put the lift on (probably 7 degrees lol)

A buddy of mine at work today whose on his 3rd XJ gave me a 2nd set of eyes and he mentioned he could feel the pitman tie rod with a faint amount of play in it.

This weekend Im going to see if I can force out the stuck control arm bolt with a ball joint press so I can see if I can get the control arm loose enough to put caster shims in.

I'm also going to go ahead and replace the 4 tie rod ends and get it realigned to see if that does it. If all that fails I guess I just start replacing the rest of the things one at a time that haven't been touched like track bar, ball joints, damper. controls arms.

if they are dried, soft and cracked... when I jacked the frame up and let the axle droop, I could almost see the bushing sleeve, it was so soft.

Even if 1º of caster wont do anything its easy to adjust, and you probably need to loosen that bolt eventually anyway, especially if your bushings are bad. I will say that if the manual says get 7.5º caster, might as well just do it as a matter of course.

it's also worth just retorquing everything that you didn't touch...my frame side track bar bracket was more or less loose and I never touched it before.

i also read that you want toe to be +.25

15yrs + on 2.9* caster!

^ I see, my control arms fortunately don't drop at full axle droop. I agree, I gotta just get the bolt out so I can mess with the caster or get the control arm off if ever needed. Maybe if I decide to replace the control arms Ill use that as an opportunity to upgrade to WJ control arms

Concentrate on the DW first, it can get ugly!