Alignment question.

Specs- 91, 4.5 RC long arm kit.

Ok so i've had this kit for about 4 mo. and had 2 local shops do a half a$$ alignments. I don't know what it is about this kit? Seems like these shops are intimidated by it and don't wanna do more than toe. I've noticed over the past month or more my front springs are getting a bow to them. Both bowing tward the front bumper. Yes i know caster is off. I've done the usual search and used the http://go.jeep-xj.info/HowtoAlignment.htm to figure out my caster is off and how bad. By the chart on go.jeep i only have 1* pos caster. No wonder my jeep rides and steers like crap! Now... With the RC long arm kit i would need to make the upper arms shorter to get more pos. caster. What else is going to change at that point? Wheel base? (meaning will i need to lengthen the lowers as well?) What is the magic # from center rear wheel to center front wheel? I'm pretty sure i'll need to set Toe again, correct?

CaliXJ said:

Ok so i've had this kit for about 4 mo. and had 2 local shops do a half a$$ alignments. I don't know what it is about this kit? Seems like these shops are intimidated by it and don't wanna do more than toe.

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Yep, anything except a 4wd shop is going to be like that, all they will do is set the toe and center the steering wheel, even on a stock XJ.

CaliXJ said:

With the RC long arm kit i would need to make the upper arms shorter to get more pos. caster. What else is going to change at that point? Wheel base? (meaning will i need to lengthen the lowers as well?)

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Other things that will change - wheelbase, toe, and pinion angle. Wheelbase is mostly up to you, just keep the tires out of the fenders and try to keep the springs from being horseshoe shaped like you said. You can lengthen the lowers or shorten the uppers to increase caster, or both to balance things out and keep your wheelbase the same like you said. Remember that you have to balance caster against pinion angle though, if you get perfect caster on a lifted rig with a stock axle housing you will probably get driveshaft vibes on the highway. You will have to set your toe again, do that second to last, last thing is centering the steering wheel.

The wheelbase won't change by adjusting the upper arms, only by adjusting the lower arms. You don't need much upper arm adjustment to correct caster. Assuming you have the stock style inverted Y steering the toe setting will change slightly as you rotate the housing for more caster. Stock caster spec is 7*, but with big tires 3-5* works just fine. You have to balance between having enough caster so the steering will center itself and you have decent "feel of center", and having too much pinion angle which can cause front driveline vibrations. While steering feel will be effected by caster, the ride quality will not be, if it rides bad it's from something else.

If the springs are bowing, it can be both an issue of not enough caster and because the wheelbase is a little too short after the lift. The spring pads aren't in line with the upper spring seat. You might have to adjust the lowers to move the axle forward slightly. A little bow in the spring isn't bad, as long as everything else is lined up properly.

Thanks for th great info and help here guys! I'm gonna have to do a little at a time and hope to get it close to 5* with no vibs. Thanks again!

Read the thread "pinion angle", I just posted how to do your own alignment, for future reference.

CaliXJ, if you want to come to Temecula we can setup your alignment in a couple of hours.

jeeperjohn said:

CaliXJ, if you want to come to Temecula we can setup your alignment in a couple of hours.

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Thanks for the offer man! I figured out the problem.. Or i should say most of it. So i pulled off both UCA and found that one of them was adjusted 1/2 longer than the other. So... WTF??? I'm pretty damn sure i set those to the recomended length. Which leads back to the last alignment shop i had it at. Beleave me, With all the info i've gathered here on my XJ won't be seeing and alignment shop any time soon. Jeeperjohn- ifi have any other problem with it i may just take you up on that offer. Thanks again!