Speedy Auto > Car Tech > 4x4 > Suspension Brakes

Jeep Suspension Control Arm Options - Jp Magazine

Verne Simons Senior Editor, Jp

Many Jeeps since the mid-’80s came from the factory with coil suspensions and control arms. Most of these control arms are more than adequate for a little off-roading, but things wear and not all control arms are the same. If you own a TJ, XJ, ZJ, WJ, MJ, JK, or others, your Jeep has control arms and they may need some attention. Over the past couple of years we’ve been beating on a set of stock control arms in hopes of finding the weak links, wear points, and points of failure. A good case of death wobble and looks to match the beatings finally encouraged us to swap these stock arms for some well-designed and functional aftermarket arms from JKS Manufacturing. Follow along as we swap out the stock beat arms for some shiny and trick new parts. We’ll also give you some cheap alternatives that should work for you while you save up for some real control arms. These tips and tricks should work for TJs, XJs, ZJs, MJs, WJs, and JKs. The last two, WJs and JKs, come from the factory with pretty decent tubular control arms.

PhotosView Slideshow

Our ’97 TJ is a pretty budget-minded wheeler and still uses stock control arms and suspension geometry. Now having said that, the Jeep is not stock, and does have lockers, 35s, and a swapped-in Toyota rear axle. Plus we wheel it hard. We also run a slip-yoke eliminator on the TJ and that necessitated an upgrade to adjustable lower control arms so we could rotate the rear pinion up a touch. Still all four front control arms are stock as are the upper rear control arms. They work, but are weak compared to aftermarket components. Ours were showing wear, with the bushings looking sad. The stamped steel was scratched, bent, and even stretched out in a few spots. Time to upgrade.

A quick call to our friends at JKS Manufacturing yielded two lower control arms that we would use in the front of our TJ (PN 6100, $405), two front upper control arms (PN 7100, $330), and two rear upper control arms (PN 7101, $310). Our TJ already had rear adjustable lower control arms, but if you want a set they are the same as the front lower control arms. These arms also fit on several other Jeeps with coil suspensions, and other applications are available (for JKs or WJs).

Installation is pretty easy, but does involve jacking up the Jeep, securely placing the frame on jackstands, removing the tires, removing the coils, and cycling the suspension with a floor jack. We started up front with the lower control arms. One key is to only remove one arm at a time and be ready to push or pull on the axle so holes will line up. A ratchet strap can be used to move the axle around if necessary. Here is the first arm we pulled. Use a tape measure and the stock arm to set the length of your control arm unless you are going for a budget stretch or adjusting pinion angles or caster.

Clevite or rubber control arm bushings wear out; with 120,000 miles, it’s not surprising that our bushings were in pretty bad shape. You can just replace the old bushings if your stock arms are in good shape using a press of sorts and some different pieces of tubing. Our new JKS arms came with new rubber bushings already installed.

When we pulled the other front lower control arm, one of the bushings just fell out. The hole the bushing was pressed into is made from pretty thin stamped steel, and our regular beatings had stretched out the hole. If it would have stretched to the point of tearing, the control arm could have fallen out of the Jeep. That would have caused some major problems, especially if we had been driving down the highway.

We also noticed that at full droop with our budget-boost shocks the stock control arms were hitting the lower coil mounts/spring perches. The new JKS arms are mounted with the gold anodized end aiming towards the axle, so the recessed area of these arms allow more droop without hitting the coil mount/spring perch. Other aftermarket control arms have the front bushing slightly offset to better clear this mount.

Our upper front control arms were in much better shape than the lowers mainly because they had not come in contact with the ground, but the bushings were still in pretty bad shape. In the past, we have bent stock upper front control arms. This time our upper arms were pretty straight, but the bushing in the frame end was working its way loose and the rubber was degraded.

The control-arm bushing on the axle end of the upper front control arms is pressed into the brackets on the axlehousing. If your Jeep suffers from death wobble or if these bushings are looking worn, this is probably the time to do it. Here we used a ball joint press to remove and install a bushing in a WJ’s front axle. Just be careful not to bend the stamped-steel control arm bracket if the bushing tries to go in crooked.

The upper rear control arms went in seamlessly using the same methods mentioned above for the front axle. Also, the old arms were in surprisingly good shape despite the stresses of being attached to a rear axle where the pinion wants to climb under acceleration and dive with engine braking. Having the JKS adjustable rear upper control arms will allow us to fine-tune our pinion angle if we need to. When combined with adjustable lower control arms, this will allow us to do a mini stretch to the Jeep (see the sidebar “The Budget Mini-Stretch”).

The Budget Mini-Stretch

PhotosView Slideshow

Adjustable control arms are necessary when you need to adjust caster of a front axle or the pinion angle of a front or rear axle, but if they are built like our JKS arms, they also can be used to add a little more wheelbase. We wanted to try to push the front axle of our TJ forward a little. The first step was to have a look under the Jeep to see if there was space for the front axle to come forward. Usually the steering is the limiting factor. On a front axle, you don’t want your tie rod hitting your pitman arm on suspension compression, or your sway bar hitting the springs. On a rear axle, you don’t want the diff cover hitting the fuel tank or tank skidplate. The best way to check this is by pulling the springs and putting the axle at full bump or where it has both bumpstops compressed.

We figured we could push the front axle in our TJ forward about an inch. The JKS control arms can be set a little shorter than stock or a couple inches longer than stock. To stretch our front axle forward a little, we simply set the JKS lower and upper control arms one inch longer than the stock arms we were removing. Will this make a huge difference in performance? Probably not, but it can’t really hurt either, and it will allow for more tire clearance at the rear of the front fenders. Bonus! In the end we had to remove about 1⁄2-inch from our stretch as the track bar was hitting the front diff cover on compression. Our Jeep does not have a front sway bar to hit, nor a stock track bar or track bar bracket.

Upgrades on the Cheap

PhotosView Slideshow

If you are too cheap to pony up for new control arms, don’t give up on your Jeep. There are other options, but heck, none of them are gonna last as long or offer the same benefits as our JKS parts. First, we have heard of guys with welders beefing up their stock control arms by welding flat bar stock to the bottom of their stock arms. Just make sure to use some bar stock that is near the same thickness (like under 1⁄8-inch) as the stock arms. Otherwise, when the arms flex the plates need to flex with them or the welds may start failing or stamped sheetmetal may start tearing.

Another cheap alternative involves spending some time at the junkyard. You can look for tubular WJ lower-control arms (bottom), or occasionally you may run across some aftermarket control arms like we did (top). Sure, neither of these sets of arms are adjustable, but they are both way stronger than the stock stamped parts. You may have to invest in new rubber or polyurethane bushings for these used arms, cause chances are that the soft parts in them will be bad.

Jeep Suspension Control Arm Options - Jp Magazine

You Might Also Like

DON'T MISS