JK installation and alignment of most lift kits with new arms & track-bars continued
6) Set your toe-in: The JK is on all fours, on level ground. Center the front tires by eye; so that they look like they're parallel to the rear tires; when viewed from the rear of the JK. On one front wheel, measure the height of the hub center from the ground; write down the measurement. Using a piece of chalk, draw a cross on the front of each front tire at the center of the tire tread (or as close as you can), at a perpendicular/vertical distance from the ground equal to the height of the hub center. Have a friend help you measure the distance from the center of one cross to the center of the other. Write it down. Jack one tire off the ground and rotate it 180 degrees; such that the cross will be at the hub height upon lowering the tire to the ground. Do the same for the other front tire. Measure the distance from the center of one cross to the center of the other (now at the rear of the front tires). Write it down. The distance between crosses measured at the front should be 1/8" to 1/4" shorter than the distance between crosses measured at the rear. Adjust your tie rod until you get the desired measurement differential.
7) Center your front axle housing: Length-measure from the front lower control arm frame mount to the center of the corresponding lower ball joint (right and left). Cross-measure from the lower ball joints to the opposite front lower control arm frame mount (right and left). Write the measurements down. The length-measures should be the same, or very close; but the cross-measures will be noticeably unequal if the axle isn't centered. Center the axle housing to the frame/body in a similar fashion used for the rear by removing the adjusting-end of the track-bar (usually the axle housing end) and using a small come-along or ratchet-strap to pull the frame/body to the right or left of the axle housing; until the cross measurements are the same. Adjust the front track-bar length; so that it will install in the bracket. Lightly tighten the track-bar bolts/nuts.
8) Measure the wheelbase: First, center the front tires as best as you can by eye. Then, using jack-stands, or something similar, run a string-line from behind the center of each rear tire across the outer sidewalls at the height of the hub center; and forward, across the front tire sidewalls at the height of the hub center to a point in front of the center of each front tire; terminating at another jack-stand, or something similar; such that the string line is tight across all edges of the tires. Keeping the string lines taught, move the front jack-stands outward to the sides until the string line on each side, barely comes off the front tire's sidewall; either at the front or rear of the front tire. Turn your steering wheel right or left so that you even-up the distance that the string lines are from the sidewalls at the front of the tires (right and left). You are trying to get the string lines to be touching both edges of a rear tire; and the rear edge of the front tire, with the same gap (right to left) between the string and the front sidewall of the front tires. You can't achieve perfect parallel alignment because the front tires are "toed-in". Once you have the gaps the same, right to left; they should be about 1/16th to 1/8th inch wide.
Now, have a friend help you to verify that the wheelbase measurement is the same right to left. Measure from the rear wheel hub center to front wheel hub center, on the right; and compare to the same measurement on the left. If you were careful in all your measurements previously; then the wheelbase should be the same. If not; then you have to go back and do all the length and cross measurements again, to try to find your error. Once your wheelbase is the same; then go back and tighten all suspension bolts/nuts to the correct torque values. Tighten the control arm's and track-bar's jamb-nuts to the correct torque values. Lube all the suspension bearings and articulation pivots.
9) Center your steering wheel: Once the wheelbase is the same; then check to see if your steering wheel is centered, IE the "Jeep" logo is horizontally level. If it isn't; then block the front wheels so they can't turn right or left; and adjust your drag link, in or out, until your friend tells you the steering wheel is centered. Conversely, you can have your friend turn the steering wheel until it's centered, and hold it still in that position. This will miss-align the gaps of the strings to the tires. While your friend holds the wheel centered; you adjust the drag link until the string gaps even out, right to left; as they were when you set the strings up to measure the wheelbase. The adjustment of the drag link is easier if you take some weight of the tires by lifting the center of the front axle slightly. After adjusting, drop the axle back down and cycle the steering full-right to full-left and then back to center. Check the string gaps again for sameness. If they are the same; then tighten the drag link components you had to,loosen to adjust the steering. Lube the steering components.
Take your time and do it right; and you won't need to spend the bucks to pay for an alignment; because you've already done all the adjustments that are possible. If you do take it in to check the alignment and you don't get a good result; then ask the technician to explain where the problem is, and what he would do to correct it, before he actually performs any correction/s. Because... You can align the suspension without centering the axles; and your rig will drive/track perfectly straight. The wheels just won't be centered under the rig; which could cause clearance issues between the body/frame and the wheels/tires at extreme flexing. Additionally, if you squared and centered the axle housings; then you can use this procedure to do an alignment at any time in the future.
10) Some notes: I've never taken my JK in for a suspension alignment. I have no steering pull, and am experiencing no uneven tire wear. If you experience frame damage; then you'll have to re-check the length and cross measures. Otherwise you wont have to ever do that again; unless you change out your control arms.
I run two different sets of wheels and tires; and one set doesn't have the correct setback; so I use wheel spacers, front and rear. I need a larger spacer in the rear; so I can run rear tire chains, if necessary. I don't like to run a large wheel spacer on my front wheels; to minimize stress on the unit bearings; consequently, I run uneven spacers. Obviously, miss-matched tires front to rear will yield the same issue. However, even with uneven spacers; I can still use the string method to get my wheels aligned. It just takes a little more time to get the strings set up properly; so I can measure the "gaps" correctly.
I hope this article is helpful to any and all JK owners out there. If anyone would like some illustrations to accompany this post; then respond to me via private message (bear with me, as I'll have to draw them up). If anyone can find any errors in the logic or writing of this piece; then, please inform me of such, so that we all can be properly informed. Thanks for your interest.
6" FTLA w/HD TB & SS,
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Sup'r CrMo xls, 5.13 R&P, Reel 1310 DS,
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sPOD; Aeroforce, FlashPac, Airaid CAI, Magnaflow relo,
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