Basic Do-it-Yourself Jeep JK Wrangler Front End Alignment

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wayoflife

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If you've just installed a brand new lift on your Jeep JK Wrangler and are wanting to get it aligned, there are a few things you should know before you take it to a shop and pay to have it done. First off, you should know that thanks to the new steering design on the Jeep JK Wrangler, very little is needed to have the front end aligned after the installation of a small to moderate suspension lift (2"-2.5" of lift). In fact, unless you've installed an adjustable front track bar and adjustable control arms, there really isn't a whole lot a shop can to other than recenter your steering wheel and take your money. Of course, if you did install a taller lift and added more adjustable components, you can still do your own front end alignment, in your driveway and with the use of just some basic tools. This write-up will show you how.

Alignment Topics
Steering Wheel Re-centering
Front Axle Re-centering
Setting Caster
Setting Toe-In


What You Will Need
• 15,18,21mm Socket & Wrench
• Ratchet
• Large Crescent Wrench
• Angle Finder
• Tape Measure
• Carpenters Level
• Floor Jack
• Jack Stands


Alignment Definitions
The following are wheel alignment definitions as defined by the Jeep JK Wrangler Factory Service Manual:

CASTER is the forward or rearward tilt of the steering knuckle from vertical. Tilting the top of the knuckle rearward provides positive caster. Tilting the top of the knuckle forward provides negative caster. Caster is a directional stability angle. This angle enables the front wheels to return to a straight ahead position after turns.

CAMBER is the inward or outward tilt of the wheel relative to the center of the vehicle. Tilting the top of the wheel inward provides negative camber. Tilting the top of the wheel outward provides positive camber. Incorrect camber will cause wear on the inside or outside edge of the tire. The angle is not adjustable, damaged component(s) must be replaced to correct the camber angle.

WHEEL TOE POSITION is the difference between the leading inside edges and trailing inside edges of the front tires. Incorrect wheel toe position is the most common cause of unstable steering and uneven tire wear. The wheel toe position is the final front wheel alignment adjustment.

STEERING AXIS INCLINATION ANGLE is measured in degrees and is the angle that the steering knuckles are tilted. The inclination angle has a fixed relationship with the camber angle. It will not change except when a spindle or ball stud is damaged or bent. The angle is not adjustable, damaged component(s) must be replaced to correct the steering axis inclination angle.

THRUST ANGLE is the angle of the rear axle relative to the centerline of the vehicle. Incorrect thrust angle can cause off-center steering and excessive tire wear. This angle is not adjustable, damaged component(s) must be replaced to correct the thrust angle.


Alignment Diagrams
Diagram from Jeep JK Wrangler Factory Service Manual.
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Disclaimer: Utmost care should be taken when modifying anything to your suspension. Injury to you, your Jeep, and/or others can result from improper suspension modifications or alterations. The author is not a certified mechanic and assumes no responsibility for damage or injury.
 
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Re-centering Your Steering Wheel

Re-centering Your Steering Wheel
Installing any amount of lift on your Jeep JK Wrangler will cause your steering wheel to be off. The higher you go, the more it'll be off and while an adjustable front track bar will help to minimize this, you will still need to re-center your steering wheel. Failure to do so will cause your ESP system to think that you're in a slide and will try to compensate for it by activating your BAS. Depending on where you are when this happens, it can be an annoying experience to down right dangerous. This write-up will show you what you need to do to re-center your steering wheel.

1. To re-center your steering wheel, use a 15mm socket or wrench to loosen the 2 nuts securing the the drag link turnbuckle.
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2. Once the nuts are loosened, firmly grab the turnbuckle and rotate it up or down as needed while a friend watches the steering wheel (or you periodically check on it yourself) go back to center. Rotating it up will turn the steering wheel to the left and rotating it down will turn it to the right.
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3. Once your steering wheel looks centered, use a 15mm wrench to secure the turnbuckle nuts in place and take it for a drive to verify you got it on. This may take a few tries to get it on 100% on but that’s all there really is to it.
 
Re-centering Your Front Axle

Re-centering Your Front Axle
Just like your steering wheel, any amount of lift will cause your axle to shift over toward the driver side of your Jeep. The taller you go, the more shift you will see. Up to about 3" of lift, all you really need to correct this is an adjustable front track bar and this write-up will help you to set it so that you can reposition your axle. Please note, if you have a 4" lift of taller, your steering geometry will be off enough that you will want to correct that as well as it will improve your handling. To do this, you'll need to install both a track bar relocation bracket and drag link flip kit. It is critical that BOTH are installed at the same time.

1. In order to set an adjustable front track bar, you will first need to determine how much your front axle is off by. To do this, firmly hold a carpenters level up against the sidewall of your driver side front tire making sure that it is aligned to the center of the wheel. Make sure that the bubble in the level is centered and then, using a tape measure, measure the distance between it and the edge of your fender flare (or other pre-determined point like the spring perch). If your level is making contact with a shoulder lug on your tire, be sure to make a note of it especially if the lugs are of different sizes or are located at different points along the edge of the tire and would influence your measurement. Repeat the process on the passenger side of your Jeep (again being aware of the shoulder lugs and how they might influence your measurements) and then calculate the difference between the two sides.
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2. Using a 21mm socket, remove the bolt securing your adjustable front track bar to the axle mount.
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3. Using a crescent wrench, loosen the jam nut securing the rod end to the track bar. Then, rotate the jam nut all the way to the head of the rod end and measure the gap between it and the track bar edge.
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4. With the help of a ruler for accuracy, rotate the rod end in or out until the gap between the jam nut and the track bar edge has effectively added or subtracted the length required to re-center your front axle.
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5. Use a crescent wrench to secure the rod end jam nut in place and make sure that you still have both misalignment spacers in place. With the engine OFF, put your key in the ignition, make sure that the steering wheel is unlocked and then have a friend turn it in one direction or the other until you can line up your adjustable front track bar rod end with the axle mount hole on your Jeep JK Wrangler. Secure the rod end in place using the factory hardware.
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6. Using a 21mm socket, tighten your adjustable front track bar to the axle mount of your Jeep JK Wrangler to 125 ft. lbs. of torque.
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7. Take your JK for a spin to work everything in and then repeat step #1 to verify that your axle is now re-centered. If not, calculate how much more or less you need to adjust your adjustable front track bar, and repeat the process until your axle is centered.
 
Setting Your Caster

Setting Your Caster
If you’ve just installed a 3" lift or taller on your Jeep JK Wrangler and are now running 35" tires or bigger, your caster will most likely have changed enough to cause a "flighty" or "wandering" sensation when driving at highway speeds. To address this, you will need to correct your caster angle and bring it back closer to a factory setting of +4.2°. More positive caster will help your Jeep to drive a lot straighter and reduce or eliminate these symptoms entirely but, you will run the risk of developing drive line vibrations.

The best way to set your caster is to install a set of adjustable front upper and lower control arms. The lowers should be used to reposition your axle under your Jeep and the uppers used to set your caster. If you're on a budget, you can get by with just a set of adjustable front upper arms but, you will need to make sure they can be set short enough to give you what you need. Adjustable front lower arms are more expensive but, they are much easier to install. While cam bolts can be used as a cheap solution to add a bit more positive caster, I would not recommend them.

For the purposes of this write-up, I will show you how to set your caster using adjustable front upper control arms. However, the principles are the same and can be applied to a set of adjustable lower arms as well. The only difference is that with upper arms, you will be shortening them up and with lower arms, you would be making them longer than stock.

1. Park your Jeep JK Wrangler on a level surface (or as level as possible). Place an angle finder on top of the ball joint or on the flat base of your front axle C as shown in the pic below to determine what your Jeep JK Wrangler’s caster angle is currently sitting at. You should also place your angle finder on the ground as well and make a note of it’s angle (if there is any) as it will need to be taken into account when setting your caster. When set correctly, you should have a reading of about 4° leaning toward the back of your Jeep here.
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You can also place an angle finder over the large hole located on the edge of your differential housing. When set correctly, your angle finder should be sitting close to vertical with a reading of 92° or 88° here.
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2. Using a large crescent wrench, loosen the jam nuts on your adjustable upper control arms.
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3. Using an 18mm socket, remove the bolt and nut securing the passenger side adjustable upper control arm to the front axle mount. Then, pull the upper control arm up off the axle mount and rotate it clockwise or counter clockwise to shorten (increase the amount of positive caster) or lengthen it (reduce the amount). Make a note of how many rotations you made.
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4. Because the physically length of your passenger side control arm is no longer the same as the driver side, you will not be able to bolt it back up to the axle without some help. Place the fork of the control arm over the axle mount and try to line up the mounting holes the best you can.

IF you determine that the axle mount needs to rotate up and fowards, place a floor jack under the pinion or base of the lower control arm mount at the axle and raise it up slowly until the holes line up.
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IF you determine that the axle mount needs to rotate down and back, place a floor jack under the tie-rod as close to the joint as possible and raise it up slowly until the holes line up.
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5. Once the holes line up, loosely secure everything in place with the factory nut and bolt and repeat step #3 and #4 on the driver side of your Jeep JK Wrangler making sure that you rotate the control arm in the same direction and the same amount of times.
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6. Check your caster angle again and repeat steps #3 - #5 until you achieve the positive caster angle you are looking for. Once your caster set to where you want it to be, use an 18mm socket and wrench to tighten down the axle mounting bolts to 75 ft. lbs. of torque.
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7. Using a large crescent wrench, tighten the jam nuts on your adjustable upper control arms and you’re done.
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Setting Your Toe-In

Setting Your Toe-In
Contrary to what you might think, your front wheels do not sit parallel to each other. In fact, if you were to look straight down on them, they would be sitting with the front of your tires pointing ever so slightly inward. This is called a "toe-in" and, on a rear wheel drive vehicle, it is set this way on purpose to help keep your Jeep driving straight and give your tires a more even wear.

Unlike the TJ before, the steering system on a JK does not have the tie-rod connected to the drag link and therefore, the toe-in setting will not be effected with the installation of a lift. Needless to say, an adjustment to your toe will be required. Having said that, if you've installed a new tie-rod or bent your factory one on a rock, this write-up will help you to set it back to where it needs to be.

1. Park on level ground and then with the help of a friend, measure the width between the fronts of your front tires and then compare it to the width of the back of your front tires. It is important to use the exact same measuring point front and back in order to get an accurate reading. If your tires still have a mold seam, this is a good point to measure from. Or, if you have a toe-in alignment tool (can be purchased at Harbor Freight for about $20), that will give you the most accurate measurements.
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2. Start up your engine, turn your wheels both ways fully and then straighten your steering wheel. Using a 15mm socket, loosen the nut securing the adjuster clamp on tie rod as shown in this pic.
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3. Firmly grab the tie-rod’s knurled adjuster and rotate it a little bit at a time taking measurements along the way. If you're Jeep sees a lot of water, mud or salt, you may find it necessary to spray down the threads with some penetrating oil and use a pair of vicegrips to help turn the adjuster. Ideally, you'll want to have approximately 1/16" of toe-in. You should not exceed 1/8" as anything more than that will be too much and that'll your tires to wear poorly.
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4. Once your toe-in has been set, use a 15mm socket to re-tighten the nut securing your Jeep JK Wrangler’s tie-rod clamp. Tighten this nut to 45 ft. lbs. of torque and make sure that the tie-rod does not move while doing this.
 
Thanks for this!

My tie rod is frowning at me a bit. 😔

Gonna check the toe in firs chance I get! 👍
 
Sweet, I was going to research this weekend how to check my castor angle, now I have it right here! :thumb::rock:
 
Chiromancer said:
Good stuff! I'll use this to help educate me on the stuff under my hood that makes it do the driving things!
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:cheesy: That totally sounds like me. I'm usually like "you lost me a track bar." :thinking::idontknow::crazyeyes:

It's been 6 months with the jeep and I'm still trying to learn basics. It's coming along though. This forum has really helped! :yup:
 
Thank you!

Oh my! Finally! When I first got my JK, I was looking exactly for something like the drawing you made, but couldn't find anything out there that was decent... Now you have the drawing *and* what to do with it all in one spot. Bravo!

My shop just did gears for me, and when I go back for the break-in diff oil change, they are going to do my alignment and install caster bolts to improve the 'flightiness', and compensate for all the Gobi/LoD weight I'm adding to the Jeep. But I have a very adjustable 4" Teraflex lift, so now you've got me wondering why the heck he had me buy the caster bolts??? Also, why don't you recommend them?
 
chamberlin said:
Oh my! Finally! When I first got my JK, I was looking exactly for something like the drawing you made, but couldn't find anything out there that was decent... Now you have the drawing *and* what to do with it all in one spot. Bravo!

My shop just did gears for me, and when I go back for the break-in diff oil change, they are going to do my alignment and install caster bolts to improve the 'flightiness', and compensate for all the Gobi/LoD weight I'm adding to the Jeep. But I have a very adjustable 4" Teraflex lift, so now you've got me wondering why the heck he had me buy the caster bolts??? Also, why don't you recommend them?
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Your shop is recommending them because they either don't know any better or, are just looking to sell you on something you don't need or want.

Cam bolts suck because in order to install them, you have to cut your factory axle mount holes and convert them from squares to rectangular slots. The bolts use washers that get fitted in between embossed tabs to help hold everything in place and, while these are cheap and will work fine on pavement, off road use will cause your bolts to loosen up and eventually allow everything to slop around. Not exactly something you want. Even worse, reversing the modification will require yo to have the holes welded up.
 
Thank you very much for your comments- at least I have some knowledge now before I question them on their cam bolt suggestions!
 
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Thanks for the write up Eddie!! It helps me better understand whats going on between me and the road. I really wanted to do most of this myself but since tweaking my back a couple of weeks ago I cant bend and twist like I should so I will be having Mel and his crew take a look when I have them do the drag link flip kit before Moab. I want it done right by people I trust to do a great job.

Thanks again,
Bob(BTKillerr)
 
Just note that when setting your caster, your also changing your pinion angle. Also, I noticed the write up goes from UCA's and skips to LCA's. Overall great write up, I wish all the forums write ups were converted over here. Much easier to read and see pictures when printed off!
 
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