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Thread: WRITE-UP : Basic DIY Jeep JL Wrangler FRONT END ALIGNMENT

  1. #1
    Administrator wayoflife's Avatar
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    WRITE-UP : Basic DIY Jeep JL Wrangler FRONT END ALIGNMENT



    If you've just installed a brand new lift on your Jeep JL Wrangler and are wanting to get it aligned, there are a couple of things you should know before you take it to a shop and pay to have it done. First, unless you've installed new aftermarket components such as an adjustable track bar and/or adjustable control arms, there really isn't a whole lot a shop can to other than recenter your steering wheel and take your money. Due to the design of the JL steering system, your toe-in will not change at all and being that it comes with a solid front axle, its camber will not change either. Depending on how much lift you install, your caster may be off enough to feel it but again, nothing can be done unless you've installed aftermarket components that will allow you to make adjustments. Second, even if you have installed a 2" lift or taller and added adjustable components, doing a basic front end alignment is easy, something you can do in your own driveway, with the use of some basic tools and 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
    • 15,18,21,24mm Socket & Wrench
    • Ratchet
    • Large Crescent Wrench
    • Angle Finder
    • Tape Measure
    • Carpenters Level
    • Floor Jack
    • Jack Stands


    Alignment Definitions
    The following are common wheel alignment definitions as defined by Jeep and that you will need to be familiar with:

    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 JL Wrangler Factory Service Manual.



    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.

  2. #2
    Administrator wayoflife's Avatar
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    Re-centering Your JL Wrangler Steering Wheel
    When you install a lift on your Jeep JL Wrangler, the position of your steering wheel will be off a bit. This is a result of your axle being pulled to the side of your Jeep that your track bar is mounted to. Even if you install a drag link flip/track bar relocation bracket or an adjustable track bar, some adjustment will still be needed to recenter your steering wheel. Failure to do so will cause your ESP system to think that you're in a slide and it will try to compensate for it by activating your BAS. This write-up will show you how you can re-center your steering wheel and with the help of a 15mm wrench.

    1. To re-center your JL's steering wheel, use a 15mm socket or wrench to loosen the nut securing the drag link adjuster clamp.


    2. Once the nut is loosened, firmly grab the knurled adjuster 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.


    3. Once your steering wheel looks centered, use a 15mm wrench to tighten the adjuster clamp nut and then take your JL for a drive to verify steering wheel is in fact centered. This may take a few tries to get it on 100% on but that’s all there really is to it.

  3. #3
    Administrator wayoflife's Avatar
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    Re-centering Your Front Axle
    Being that the Jeep JL Wrangler has a front track bar that's mounted on the passenger side of the front axle and on the driver side frame rail on the other, any amount of lift you install will cause your axle to shift and toward the driver side of your Jeep. At up to about 2.5" of lift, the amount of shift will be negligible but once you get up to the 3" range or more, you may find yourself wanting to make some kind of correction and an adjustable track bar will help you to do just that. Because aftermarket adjustable track bars vary in design, the following write-up is intended to be just a guide to help give you a better idea of what you'll need to do.

    NOTE: If you've installed a 4" lift or more, your steering geometry will be off enough to effect the handling of your JL. To address this, you will need to install a drag link flip with a front track bar relocation bracket kit.

    1. In order to set an adjustable front track bar, you will first need to determine how much your front axle has shifted over. To do this, 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.


    2. Using a 21mm socket, remove the bolt securing your adjustable front track bar to the axle mount.


    3. As mentioned, aftermarket adjustable track bars come in a variety of designs and for the purposes of this write-up, I used one with an adjustable rod end at the axle mount. That being said, the process should be similar with other track bars. That being said, use 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. (photo is of a JK and intended for reference)


    4. Rotate the rod end in or out until the gap between the jam nut and the track bar edge has effectively added or subtracted to the total length required to re-center your front axle. Use a ruler to help verify this measurement. (photo is of a JK and intended for reference)


    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. Then, have a friend turn your steering wheel one way or the other as needed to help get your front track bar joint aligned with the mounting hole on the axle and then secure it in place with the factory bolt and flag nut.


    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.


    7. Take your JL 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.

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    Administrator wayoflife's Avatar
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    Setting Your Caster
    If you’ve just installed a 2" lift or taller on your Jeep JL Wrangler, your caster will have changed enough to cause some people to feel a "flighty" or "wandering" sensation when driving at highway speeds. To address this problem, you will need to add more positive caster on your front axle and so that it sits closer to stock again. The caster settings from the factory are as follows:

    Rubicon = +4.8°
    Sahara = +5.5°
    Sport = +6°


    Of course, being that the JL utilizes an FAD (front axle disconnect) system, even more positive caster can be added and without ill effect. Bringing your caster to about +6° or so will help make your JL's steering feel even tighter.

    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 lower arms but, you will need to make sure they can be set long enough to give you what you need. Both methods are covered in this write-up. While cam bolts can be used as a cheap solution to add a bit more positive caster, I would not recommend them.

    Checking Your Caster Angle
    Park your Jeep JL 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 JL 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.


    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.


    NOTE: While it is easier to set your caster angle with your front axle on jack stands and with the wheels removed, it can definitely be done with the wheels on and with the full weight of your JL on the ground.

    Setting Caster Using Upper Control Arms
    1. Using an appropriate size wrench or large crescent wrench, loosen the jam nuts on your adjustable upper control arms.


    2. Using an 18mm socket and wrench, remove the bolt and nut securing the driver side adjustable upper control arm to the front axle mount. Pull the fork up and off the mount and then rotate in a full turn or two to shorten its length. When all is said and done, this will cause your pinion to drop and thereby increase the amount of positive caster your axle will have.


    3. Because your driver side upper control arm will now be shorter than the passenger side, it will be difficult to reinstall it onto the axle mount without some help. With the control arm fork back onto the axle mount, place a floor jack under the tie-rod as close to the tie-rod end as possible and then carefully raise it just a bit until the mounting holes line up.


    4. Once the holes line up, loosely secure everything in place with the factory nut and bolt and repeat step #2 on the passenger side of your JL making sure that you rotate the control arm in the same direction and the same amount of times.


    5. Being that the passenger side upper control arm is now the same length as the driver side, it should be easier to slip the bolt through the mounting holes. If needed, place a floor jack under the pinion or base of the lower control arm mount and raise it up just a bit until the holes line up.




    6. Check your caster angle again and repeat Steps #2-5 as needed until you achieve the positive caster angle you are looking for. Once your caster is 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.


    7. Using an appropriate size wrench or large crescent wrench, tighten the jam nuts on your adjustable upper control arms and you’re done.


    Setting Caster Using Lower Control Arms Only
    1. Using an appropriate size wrench or large crescent wrench, loosen the jam nuts on your adjustable lower control arms.


    2. Using an 21mm socket and 24mm wrench or large crescent wrench, remove the bolt and nut securing the driver side adjustable lower control arm to the front axle mount. Then, lower the control arm from its mount and rotate the joint out a full turn or two to make it longer. This will cause your pinion to drop and thereby increase the amount of positive caster your axle will have.


    3. Because your driver side lower control arm will now be longer than the passenger side, it will be difficult to reinstall it onto the axle mount without some help. With the control arm slipped back into the axle mount, place a floor jack under the tie-rod as close to the tie-rod end as possible and then carefully raise it just a bit until the mounting holes line up.


    4. Once the holes line up, loosely secure everything in place with the factory nut and bolt and repeat step #2 on the passenger side of your JL making sure that you rotate the control arm in the same direction and the same amount of times.


    5. Being that the passenger side lower control arm is now the same length as the driver side, it should be easier to slip the bolt through the mounting holes. If needed, place a floor jack under the pinion or base of the lower control arm mount and raise it up just a bit until the holes line up.




    6. Check your caster angle again and repeat Steps #2-5 until you achieve the positive caster angle you are looking for. Once your caster is set to where you want it to be, use an 21mm socket and 24mm wrench or crescent wrench to tighten down the axle mounting bolts to 130 ft. lbs. of torque.


    7. Using an appropriate size wrench or large crescent wrench, tighten the jam nuts on your adjustable lower control arms and you’re done.

  5. #5
    Administrator wayoflife's Avatar
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    Setting Your Toe-In
    Contrary to what some may think, the front wheels on any vehicle will NOT be sitting parallel to each other. On a rear wheel drive vehicle like the Jeep JL Wrangler, the front of your front wheels will sit slightly closer together than the rear and this is called, "toe-in". This is purposefully done to help your front wheels to become parallel as they pull apart from each other during forward movement. In addition to it helping your JL to drive straighter, it will also help your tires to wear more evenly.

    Unlike the TJ Wrangler from years ago, the steering system on a JL Wrangler does not have a tie-rod connected to the drag link and therefore, the toe-in setting will not be change with the installation of a lift. Having said that, if you've installed a new tie-rod or bent your factory one, this write-up will help you to set it back to where it needs to be.

    1. To determine what the toe-in setting is on your Jeep JL Wrangler, you will need to take 2 measurements - one from the front of your front tires and one from the back of them. With your Jeep parked on level ground and with your wheels pointing straight ahead, have a friend help you take these two measurements using the mold seam (if your tires still have them) or a specific lug in the center of the tire tread as shown below. Be sure to write these measurements down.


    2. Using a 15mm socket, loosen the nut securing the adjuster clamp on the tie-rod as shown.


    3. With the clamp loosened, firmly grab the knurled adjuster and rotate as needed to increase its length to add more toe-out or decrease it to toe-in. As you make this adjustment, re-check the measurement on the front of your front tires until it's approximately 1/16" closer together than the rear. You should not exceed 1/8" as anything more will cause your tires to wear poorly.


    NOTE: If you're Jeep sees a lot of water, mud and/or salt, you may find it necessary to spray down the threads of the adjuster with some penetrating oil prior to adjusting your toe-in. A pair of vicegrips may be needed to help turn the adjuster as well.

    4. Once your toe-in has been set, use a 15mm socket to re-tighten the nut on the adjuster clamp. Tighten this nut to 45 ft. lbs. of torque and make sure that the tie-rod does not move while doing this.

  6. #6
    Meme King WJCO's Avatar
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    Awesome write-up. Thank you. I totally overlooked that you can add more caster with the FAD and not have to worry about driveline vibrations. Good tip

  7. #7
    Knows a Thing or Two GrayBeard's Avatar
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    Another excellent How-To article. As always, informative, well written and eady to understand. Thanks

    Sent from my [device_name] using JL Wrangler Jeep Forum mobile app
    2018 Jeep JLUR, Granite Crystal Metallic, Automatic, 2" Mopar Suspension Lift, 37x12x17 Toyo Open Country R/T Tires.

  8. #8
    Extremely well done and thorough, not to mention very helpful. Thanks so much Eddie.


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  9. #9
    Caught the Bug cliff538's Avatar
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    Eddie's making it so I can just about do everything to my Jeep myself!


    Thank you sir, great write up.
    2018 JLU Punk'n ordered Jan 23, 2018. Picked it up May 10, 2018.

  10. #10
    Knows a Thing or Two RMC2's Avatar
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    Good write up. Thanks
    Matt

    Do the speed bumps at the mall count as crawlin?

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