Hi Everyone,

This is another variation of recent thread which discusses the setting of the caster angle. I'll be focusing on the installation of the OME LT kit from Northridge on my '08 JK 2-door.

First let me say that because of the variation I was seeing in the reading between right and left using an angle finder on the front knuckles, I thought it would be best to pay to have it put on an alignment rack and measured.

As Rob (RedneckJeep) pointed out in the other thread, the caster changes with just the lift itself, given that the control arm lengths stay the same.

I thought that the best approach for setting up the adjustable upper control arms before having the alignment checked was to shorten the control arms from the stock length of 18-3/4" to 18-1/2". I based the 1/4 distance upon a crude geometry model that reflected that shortening the control arms by 1/4" should increase the caster by about 1-1/2 degrees. (Without being able to measure original angles of all the fixed and pivot points exactly, I know the geometry would be off by a little, at least.)

Goodyear put the JK on their alignment rack and printed out the results.

The left caster was 4.1 and the right caster was 4.2. It was dead-on for OEM specs. This proves (to me, at least) that what Rob said is true. By shortening the upper control arms 1/4" I basically brought the caster back to spec.

Now I need to readjust the upper control arms even shorter. If the original calculations were any good, shortening the uppers by another 1/4" should put the caster at something close to 5.8 or 5.9, which appears to close to what almost everyone is suggesting. (If the caster is close at that point, the length will also be close to where David with Northridge suggested I start out. I was just concerned it would be too much.)

I'll report back when the change is made and Goodyear checks the alignment. (They were quite willing to re-check it if I would make the changes myself.)

I have a couple of questions for anyone else who has worked with adjustable upper front control arms.

1. When I readjust the control arms should I loosen the fasteners at the frame and at the axle for both upper arms, or is it acceptable (and will it allow me to remove the CAs from the axle mounts) if I leave the frame bolts torgued?

2. Should I loosen the track bar fasteners at the axle and frame? (In order to get a better shot at the angle mounts for the CAs I may have to do this anyway.)

3. A bigger problem may be with the adjustment on one of the CAs. I had a tough time shortening one of the arms to get it where it is now. Has anyone else experienced this problem and been able to work through it? (I'm hoping that the threads on the female surface are chased far enough back into the CA.)

Thanks for any advice.

I'll also measure the angles across the knuckles and post how they compare to the actual alignment measurements.

Jeff

 

I dont think you'll like the caster that high on your 2dr. I know I sure didn't. It steered good but got a lot of vibes.

You should only need to loosen the track bar at the axle. You can leave the frame bolts torqued on the arms as well, but it makes it harder to work with them. I usually loosen both ends on the arms when working with them.

 

Hi JackMac,

Thanks for your advice.

How much caster do you have in your 2-door? At 4.1/4.2 I didn't have any wobble or eratic steering; but, I haven't had it over 50 yet, either.

And speaking of "over 50", that's about the only problem with breaking the torqued bolts loose... well, actually, it's the retorque while lying on my back on the cold concrete that makes me feel like a bit of an old man. Makes me envy guys with 2-post lifts. I agree with you, breaking both ends of the CAs will make it much easier to readjust them.