Jeep Xj Control arms affect alignment?

Hello, Im awaiting getting my jeep Xj aligned after I did my lift, all tie rods, track bar, ETC. I just ordered up some upper and lower control arms from two diff vendors, only to recieve two sets of lower control arms, I was supposed to get my jeep aligned later this week and was waiting til i got the control arms on, now that this happened then this will set me back a week.

I was wondering if the control arms affect the alignment at all, so that I could go ahead and get it aligned and then put the new control arms once I get them in the mail again?

I think the lowers are the only ones that should affect alignment, unless your uppers bushings are really shot.

The control arm length determines the caster angle. Caster is the angle of the steering knuckle relative to the ground. Think of the wheels on a shopping cart and their optimal angle for being able to turn smoothly under load. We have the same thing on our front axles with regard to how the vehicle feels when we turn the steering wheel. The length of the lower and upper control arms determine the rotation of the axle, and as a result they affect the caster angle and the handling.

Unfortunately when you change the height of a 4WD vehicle you have to rotate the axle to keep the pinion pointing at the transfer case, so changes to caster are pretty much unavoidable for a full-time vehicle. Alternatively you can keep the caster in the factory range and pull the front driveshaft for DD usage. Mine is a foul-weather beater with all-wheel-drive so I need the front driveshaft.

One other thing, the knuckles are setup with a specific camber (top-to-bottom angle of the wheel axis) that is appropriate for the factory caster angle, so when you rotate the axle you will rotate the camber plane. This can give your jeep a little bit of an exaggerated / \ look. Setting the toe-in (front-to-back angle of the wheel axis) will correct it a little bit

Unless you are willing to remove and rotate the knuckles there is nothing you can do about the caster-vs-pinion dilemma and the resulting camber issues.

Toe-in can be adjusted with the tie rod easily. That is pretty much the only thing you can modify without cutting and welding

that doesnt answer my question tho. Can i go ahead and get it aligned and then put in my control arms afterwards without messing up the alignment?

It will depend on what you and the shop do. If the new control arms are set to the same length as the old ones then No they will not change the alignment.

If the jeep is lifted and the shop is all about "we have to put caster at the factory range" then they will screw up your driveshaft angles.

If you start trying to change the pinion angle or extend the wheel base, then you'll change the caster.

The camber will change too but cannot be modified at all (not the question you asked but it will be something the alignment people think about)

If you change the steering parts, or if you even just put different sized tires on the jeep, you'll change the toe-in (not the question you asked)

You're not really asking the question in a way that can be answered easily. Honestly, taking a lifted jeep to an alignment shop that does not specialize in lifted jeeps is a waste of time. The only thing you want them to do is change the toe-in, which you can do yourself in 5 min. If they try to do anything else they will just make trouble for you

200SportXj said:

that doesnt answer my question tho. Can i go ahead and get it aligned and then put in my control arms afterwards without messing up the alignment?

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if the new control arms are not the same length as stock, center to center, then the alignment measurements will change.

simple enough?

Ok so my control arms are 3" extended length control arms that are fixed, my jeep has a 3" lift and so I figured they wuld be good enuf. I have 18" rims with 32" tires. All the suspension has been upgrade and I replaced everything underneath

I have played with the toe in but figured there was more to an alignment.

your control arms are 3" extended? i find that hard to beleive, unless you aimed for a stretch. my fixed RE superflex arms arent even 1" over stock, and im at 4.5" of lift. do you mean that they are meant for a 3" lift?

do a driveway alignment, get your new arms installed, get it professionally installed. save yourself and us the headache.

I'm pretty sure he meant extended length for a 3" lift.

If it were me and I was going to pay someone to do an alignment, I would wait until I had all the new parts on.

Otherwise, I would just do it myself... which is what I do now. I use this guide:
http://jeep-xj.info/HowtoAlignment.htm

ocean_jet said:

If it were me and I was going to pay someone to do an alignment, I would wait until I had all the new parts on.

Otherwise, I would just do it myself... which is what I do now. I use this guide:
http://jeep-xj.info/HowtoAlignment.htm

Click to expand...

Yea you may as well wait to do the alignment once all the work has been done.

200SportXj said:

that doesnt answer my question tho. Can i go ahead and get it aligned and then put in my control arms afterwards without messing up the alignment?

Click to expand...

You never know what you will run into when replacing suspension parts that may require the use of a BFH (Big F---ing Hamer), That can cause parts to shift around.
Wait until your new control arms are installed before getting it aligned.

Yes they affect the castor