I've noticed lately on a few of the forums im on, that alot of guys don't know how to properly set up fully adjustable arms. Everyone asks "how long...", or "they didn't give a measurement." That's because the measurement is Jeep specific. Every one is different. Also don't focus on how long the arms are. I see Imped always saying, "arm length is a byproduct", and guys get mad at his vague answer, because he never told them the magic measurement. Well, there isn't one. Any of you more experienced guys (Imped, Jerry, Unlimited04), feel free to add anything that I missed. Im not covering axle centering, or how to set bump stops, im covering control arm setup.
Before I start, im going to state that I am in no way responsible for stupidity, lack of judgment, or you not following directions. Use your fawking head when doing this. Don't go remove all but one arm with the rig on its own weight, you will break your shit and die. Don't try to do all of this with a Hi-Lift, or some other bs jack. Use a good floor jack or decent bottle jack(or both). Now that we have that out of the way lets talk about tools. You need whatever tools it takes to remove your springs and arms, jack(s), and at least 2 jack stands. Possibly a coil compressor.
Besides tools to remove the coils and arms you need:
Front Control Arms
Jack your rig up, and put the jackstands whever you usually like to put them, and then remove the tires/wheels. Pull the springs, and set them aside. I don't know what lift you have or anything, but it doesn't matter. Also you will think some of these steps aren't necessary, and can be skipped. Don't be lazy. Now take your front lowers and adjust them to a starting measurement. 16" eye to eye is a good staring point. You can just snug the jam nuts, don't fully tighten them. Now set the new uppers to a good starting point. Anywhere between stock length and 1/4" longer. Ok now go put your tape measure away so you don't screw up.
Now your jack should be under your axle, since you just removed your springs. Jack both sides of the axle up until you are at full bump. If you are using factory jounce bumpers, pull them out, they fully compress into the cup anyways. At full bump, you want your bumpstop to be centered on the lower bumpstop pad. If you need to adjust your bumps, now would be the time to do it before you start. There's alot of ways to adjust your arms, I like to remove the uppers and let the jack keep the axle from rotating. Whatever works best for you. If you opted to keep the uppers on, that's fine. Adjust the control arm(s) on both sides to get the bump centered at full bump. If you left your uppers on, extend/shorten them by the same amount that you did to the lower on that side. You don't need to measure. If you did the lower 6 turns to make it longer, turn the upper 6 turns. When you have both sides adjusted, and your bumps are centered, put your coils back in, and reinstall everything you removed to do so. Leave the arms somewhat loose. You want them snug enough so they don't move around. Now put your tires back on, and set the rig on its own weight. This is not your final arm length, so dont go adjusting them to the same length. We will come back to that.
Now we rougly set our uppers. Put your floor jack under the front diff, and take some tension off of the uppers. I like to place my jackstands under the frame as a backup plan. They don't have to be touching the frame, just in place incase your jack fails/slips, and your springs happen to come out. Remove both front uppers. If you placed the jack in the right spot under the pinion, it will keep the axle from rotating. Now we need to set our caster angle.
I had my alignment done, and got a printout, which included caster. I did this before I even messed with adjustable arms. Now you have an error proof guideline. Find a spot on the axle to put your angle finder for caster. I use the flat part on the bottom of the axle "C". I recorded the number my angle finder read, and compared it to the printout. The difference between the numbers was my equalizer. Example: alignment shop spec sheet said my caster was 3*. My angle finder, placed at the bottom of the "C" showed 4.5*. Say I want my caster at 5.5*. My angle finder needs to read 7.75* for me to get an alignment shop worthy 5.5* of caster. I recorded that my angle was 1.5* more than the actual caster angle. Now I know how to compensate.
Ok, you have both uppers removed, and your jack under the pinion. Measure for caster and raise/lower the jack until you get the caster you want. Keep in mind the pinion angle is related, so make sure that won't cause your problems. Its a trade off between caster/pinion angle. If you have an hp front axle, you don't have to worry. If you can't get your desires caster without vibes, back off the caster some. That's really only a problem if you are 4"+, or at least 3" with a tt. Take one upper and adjust it so the bolts easily slide in. You don't want any force on the bolts at this time. Now snug the bolts. The next step is a debate, some say to leave the jack under the pinion to relieve pressure, others say lower it. At this point, I just lower it. Now adjust your other upper so the bolts easily slide in. YOUR ARMS SHOULD NOT BE SET TO THE SAME LENGTH. If it happens that way, then it's fine. If you just install the first upper, then set the other the same length and force it in, you are wasting your time reading this.
Now we want to square the axle. There is alot of debate about measuring point differences, and the placement differences from the factory. I tried to make up for that by taking 2 measurements per side. I usually measure from the axle tube, right beside the "C", to the front of the body mount
I'll also measure from the axle tube in the same spot as the 1st measurement, back to the front of the skid. I do this on both sides and compare the numbers. It's best to write them down. I'll look at my first measurements I took. Say the drivers side is 1/2" farther forward. But the 2nd measurement says it's 1/8" too far forward. I'll call it a difference in the assembly line, and adjust 1/4". The likeliness of that big of a difference isn't very big. That was just an example.
So now that I have my measurements to square the front axle, I'll have to decide weather I want to lengthen the short side, shorten the long side, or a little bit of both. It really just depends how how drunk you were by the time you started centering the bumps in the lower pad. If there's a big enough difference I'll split the two. For example, I ended up with 1/2" difference, but Im really unsure of the axles being square with fixes arms, I'll lengthen one by 1/4", and shorten the other the same amount. If you took your time while at full bump, you should be pretty damn close. Remove one lower at a time and adjust the amount each needs. Its a good idea to count the number of turns it takes, so you can duplicate the upper the same amount. You might have to force the axle forwards or backwards to get the lowers back in. This is the only time that should happen. The reason is, your axle wasn't square, but you adjusted so it would be, so no you have to get it to line up. I usually set a chock in front of or behind the tire, and start the jeep and drive forwards or backwards. The chock will let the jeep push or pull that side of the axle. It can also be done with a come-a-long or heavy duty ratchet strap. Another way, is to use your jack. If you lengthened one side, place the jack under the axle side track bar bracket and jack up. It will rotate the axle enough to slip your bolts in. If you also shortened the other side raise the pinion with the jack. Now your squared up. Tighten the lowers, and tighten the jam nut. You can record each arm length and position to have as a record.
This next part is also debatable. Some like counting turns and adjusting the uppers the same way. This way is alot easier and its foolproof. Place your jack under the pinion, and remove both uppers. Check your caster and see if it changed. If it did(which wouldn't be much unless your lowers were originally way off) re set it. Take your first upper and adjust it so the bolts slide in easily. Tighten the bolts and jam nut. Do the same with the other side. This time, leave the jack under the pinion. Easily slide your bolts in, tighten, then lower your jack. Now measure one last time to make sure the axle is square to the frame. If everything looks good, go back and torque everything to proper specs.
To do the back is the same process. Start with lowers 16-16.25" eye to eye, uppers 1/4" longer then stock. Remove the tires/wheels and pull the coils. If you have the factory jounce bumper, remove it and jack to full bump. Depending on your rear coils, you may have had to loosen the rear track bar for enough droop. If so, loosely reinstall. Now adjust your lowers to center the bumpstop at full bump. Also pay attention to diff clearance, and track bar to gas tank skid clearance. Put the springs back in, and put the wheels/tires back on. Now put the jack under the pinion, and remove the uppers. Set you pinion angle with the jack, then adjust the uppers so the bolts slide in. Tighten until they are snug, lower the jack. Now measure your rear axle squareness. I like to measure just to the inside(diff side) of the axle tube beside the lca mounts. Find a place that is the exact same on both sides. I usually go from the back of the skid, to the axle tube. As a 2nd measurement, ill measure from the front axle tube, to the rear axle tube(now that your front axle is square). Then you can lengthen one lower, and shorten the other to square the axle. Once you do that, put your jack under the pinion, and remove the uppers. Re-check your pinion angle and adjust if necessary. Now adjust both rear uppers so the bolts easily slide in. Once both are in, remove the jack. Check rear axle squareness one last time. If everything is good go through and torque all your bolts, and tighten the jam nuts.
I will mention, before you square the rear axle, step back and check to seen if the tire is centered in the rear wheel well. It should be, since you centered at full bump. Remember, there isn't much adjustment back there, so if you decide to move it back more, watch for track bar to gas tank skid clearance at full bump.
Congrats, this was a long read, but now you have a step by step to setting up fully adjustable arms properly. Everything is square, and you don't even know how long each arm is. Why? Because it don't matter, your shit is square.
If anyone has anything to add, or knows any shortcuts, feel free to add.
Maybe this will keep guys from being butt hurt when someone tells them, "control arm length is a byproduct", or when they are pissed because they spent $2800, and Savvy can't even give them the measurements.
Before I start, im going to state that I am in no way responsible for stupidity, lack of judgment, or you not following directions. Use your fawking head when doing this. Don't go remove all but one arm with the rig on its own weight, you will break your shit and die. Don't try to do all of this with a Hi-Lift, or some other bs jack. Use a good floor jack or decent bottle jack(or both). Now that we have that out of the way lets talk about tools. You need whatever tools it takes to remove your springs and arms, jack(s), and at least 2 jack stands. Possibly a coil compressor.
Besides tools to remove the coils and arms you need:
- Angle finder (this is the one I recommend: https://www.amazon.com/dp/B00WQLHG2G/?tag=wranglerorg-20)
- Measuring tape. I'll let you know when to put it away, so you don't get confused
- A good heavy duty ratchet strap, or come-a-long.
Front Control Arms
Jack your rig up, and put the jackstands whever you usually like to put them, and then remove the tires/wheels. Pull the springs, and set them aside. I don't know what lift you have or anything, but it doesn't matter. Also you will think some of these steps aren't necessary, and can be skipped. Don't be lazy. Now take your front lowers and adjust them to a starting measurement. 16" eye to eye is a good staring point. You can just snug the jam nuts, don't fully tighten them. Now set the new uppers to a good starting point. Anywhere between stock length and 1/4" longer. Ok now go put your tape measure away so you don't screw up.
Now your jack should be under your axle, since you just removed your springs. Jack both sides of the axle up until you are at full bump. If you are using factory jounce bumpers, pull them out, they fully compress into the cup anyways. At full bump, you want your bumpstop to be centered on the lower bumpstop pad. If you need to adjust your bumps, now would be the time to do it before you start. There's alot of ways to adjust your arms, I like to remove the uppers and let the jack keep the axle from rotating. Whatever works best for you. If you opted to keep the uppers on, that's fine. Adjust the control arm(s) on both sides to get the bump centered at full bump. If you left your uppers on, extend/shorten them by the same amount that you did to the lower on that side. You don't need to measure. If you did the lower 6 turns to make it longer, turn the upper 6 turns. When you have both sides adjusted, and your bumps are centered, put your coils back in, and reinstall everything you removed to do so. Leave the arms somewhat loose. You want them snug enough so they don't move around. Now put your tires back on, and set the rig on its own weight. This is not your final arm length, so dont go adjusting them to the same length. We will come back to that.
Now we rougly set our uppers. Put your floor jack under the front diff, and take some tension off of the uppers. I like to place my jackstands under the frame as a backup plan. They don't have to be touching the frame, just in place incase your jack fails/slips, and your springs happen to come out. Remove both front uppers. If you placed the jack in the right spot under the pinion, it will keep the axle from rotating. Now we need to set our caster angle.
I had my alignment done, and got a printout, which included caster. I did this before I even messed with adjustable arms. Now you have an error proof guideline. Find a spot on the axle to put your angle finder for caster. I use the flat part on the bottom of the axle "C". I recorded the number my angle finder read, and compared it to the printout. The difference between the numbers was my equalizer. Example: alignment shop spec sheet said my caster was 3*. My angle finder, placed at the bottom of the "C" showed 4.5*. Say I want my caster at 5.5*. My angle finder needs to read 7.75* for me to get an alignment shop worthy 5.5* of caster. I recorded that my angle was 1.5* more than the actual caster angle. Now I know how to compensate.
Ok, you have both uppers removed, and your jack under the pinion. Measure for caster and raise/lower the jack until you get the caster you want. Keep in mind the pinion angle is related, so make sure that won't cause your problems. Its a trade off between caster/pinion angle. If you have an hp front axle, you don't have to worry. If you can't get your desires caster without vibes, back off the caster some. That's really only a problem if you are 4"+, or at least 3" with a tt. Take one upper and adjust it so the bolts easily slide in. You don't want any force on the bolts at this time. Now snug the bolts. The next step is a debate, some say to leave the jack under the pinion to relieve pressure, others say lower it. At this point, I just lower it. Now adjust your other upper so the bolts easily slide in. YOUR ARMS SHOULD NOT BE SET TO THE SAME LENGTH. If it happens that way, then it's fine. If you just install the first upper, then set the other the same length and force it in, you are wasting your time reading this.
Now we want to square the axle. There is alot of debate about measuring point differences, and the placement differences from the factory. I tried to make up for that by taking 2 measurements per side. I usually measure from the axle tube, right beside the "C", to the front of the body mount
I'll also measure from the axle tube in the same spot as the 1st measurement, back to the front of the skid. I do this on both sides and compare the numbers. It's best to write them down. I'll look at my first measurements I took. Say the drivers side is 1/2" farther forward. But the 2nd measurement says it's 1/8" too far forward. I'll call it a difference in the assembly line, and adjust 1/4". The likeliness of that big of a difference isn't very big. That was just an example.
So now that I have my measurements to square the front axle, I'll have to decide weather I want to lengthen the short side, shorten the long side, or a little bit of both. It really just depends how how drunk you were by the time you started centering the bumps in the lower pad. If there's a big enough difference I'll split the two. For example, I ended up with 1/2" difference, but Im really unsure of the axles being square with fixes arms, I'll lengthen one by 1/4", and shorten the other the same amount. If you took your time while at full bump, you should be pretty damn close. Remove one lower at a time and adjust the amount each needs. Its a good idea to count the number of turns it takes, so you can duplicate the upper the same amount. You might have to force the axle forwards or backwards to get the lowers back in. This is the only time that should happen. The reason is, your axle wasn't square, but you adjusted so it would be, so no you have to get it to line up. I usually set a chock in front of or behind the tire, and start the jeep and drive forwards or backwards. The chock will let the jeep push or pull that side of the axle. It can also be done with a come-a-long or heavy duty ratchet strap. Another way, is to use your jack. If you lengthened one side, place the jack under the axle side track bar bracket and jack up. It will rotate the axle enough to slip your bolts in. If you also shortened the other side raise the pinion with the jack. Now your squared up. Tighten the lowers, and tighten the jam nut. You can record each arm length and position to have as a record.
This next part is also debatable. Some like counting turns and adjusting the uppers the same way. This way is alot easier and its foolproof. Place your jack under the pinion, and remove both uppers. Check your caster and see if it changed. If it did(which wouldn't be much unless your lowers were originally way off) re set it. Take your first upper and adjust it so the bolts slide in easily. Tighten the bolts and jam nut. Do the same with the other side. This time, leave the jack under the pinion. Easily slide your bolts in, tighten, then lower your jack. Now measure one last time to make sure the axle is square to the frame. If everything looks good, go back and torque everything to proper specs.
To do the back is the same process. Start with lowers 16-16.25" eye to eye, uppers 1/4" longer then stock. Remove the tires/wheels and pull the coils. If you have the factory jounce bumper, remove it and jack to full bump. Depending on your rear coils, you may have had to loosen the rear track bar for enough droop. If so, loosely reinstall. Now adjust your lowers to center the bumpstop at full bump. Also pay attention to diff clearance, and track bar to gas tank skid clearance. Put the springs back in, and put the wheels/tires back on. Now put the jack under the pinion, and remove the uppers. Set you pinion angle with the jack, then adjust the uppers so the bolts slide in. Tighten until they are snug, lower the jack. Now measure your rear axle squareness. I like to measure just to the inside(diff side) of the axle tube beside the lca mounts. Find a place that is the exact same on both sides. I usually go from the back of the skid, to the axle tube. As a 2nd measurement, ill measure from the front axle tube, to the rear axle tube(now that your front axle is square). Then you can lengthen one lower, and shorten the other to square the axle. Once you do that, put your jack under the pinion, and remove the uppers. Re-check your pinion angle and adjust if necessary. Now adjust both rear uppers so the bolts easily slide in. Once both are in, remove the jack. Check rear axle squareness one last time. If everything is good go through and torque all your bolts, and tighten the jam nuts.
I will mention, before you square the rear axle, step back and check to seen if the tire is centered in the rear wheel well. It should be, since you centered at full bump. Remember, there isn't much adjustment back there, so if you decide to move it back more, watch for track bar to gas tank skid clearance at full bump.
Congrats, this was a long read, but now you have a step by step to setting up fully adjustable arms properly. Everything is square, and you don't even know how long each arm is. Why? Because it don't matter, your shit is square.
If anyone has anything to add, or knows any shortcuts, feel free to add.
Maybe this will keep guys from being butt hurt when someone tells them, "control arm length is a byproduct", or when they are pissed because they spent $2800, and Savvy can't even give them the measurements.
