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Jeep Wrangler JK Resources
JK How-to Guides
How to align the front end of your Jeep Wrangler JK
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<blockquote data-quote="Chris" data-source="post: 422898" data-attributes="member: 1"><p><strong>Setting Your Caster</strong></p><p>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. </p><p></p><p>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.</p><p></p><p>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.</p><p></p><p>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.</p><p></p><p>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.</p><p></p><p>2. Using a large crescent wrench, loosen the jam nuts on your adjustable upper control arms.</p><p> </p><p>[ATTACH=full]114370[/ATTACH]</p><p></p><p>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.</p><p></p><p>[ATTACH=full]114371[/ATTACH]</p><p></p><p>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.</p><p></p><p>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.</p><p></p><p>[ATTACH=full]114372[/ATTACH] </p><p></p><p>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. </p><p></p><p>[ATTACH=full]114373[/ATTACH]</p><p></p><p>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.</p><p></p><p>[ATTACH=full]114374[/ATTACH] </p><p></p><p>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. </p><p></p><p>[ATTACH=full]114375[/ATTACH]</p><p></p><p>7. Using a large crescent wrench, tighten the jam nuts on your adjustable upper control arms and you’re done.</p><p></p><p>[ATTACH=full]114376[/ATTACH]</p></blockquote><p></p>
[QUOTE="Chris, post: 422898, member: 1"] [B]Setting Your Caster[/B] 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. 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. 2. Using a large crescent wrench, loosen the jam nuts on your adjustable upper control arms. [ATTACH=full]114370[/ATTACH] 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. [ATTACH=full]114371[/ATTACH] 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. [ATTACH=full]114372[/ATTACH] 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. [ATTACH=full]114373[/ATTACH] 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. [ATTACH=full]114374[/ATTACH] 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. [ATTACH=full]114375[/ATTACH] 7. Using a large crescent wrench, tighten the jam nuts on your adjustable upper control arms and you’re done. [ATTACH=full]114376[/ATTACH] [/QUOTE]
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Jeep Wrangler JK Resources
JK How-to Guides
How to align the front end of your Jeep Wrangler JK
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