Rock Krawler Aluminum PRO Long-Arm Jeep JK Suspension

Aug. 25, 2011 By Pete Bach
Our previous JK project tipped the scales at well over 6,000 pounds.

Aluminum components have been making their way into the aftermarket Jeep industry for years now, but they’ve never been more in demand until recently. Much of this demand is due to the weight of the Jeep Wrangler JK. We’ve seen many portly JK’s that tip the scales at well over 6000 pounds (our previous project is one example), but now with the help of manufacturers like Rock Krawler Suspension, we can fight Jeep obesity with lightweight aluminum.

Our current JK ran the Rock Krawler mid-arm kit first. We’d get the chance to see the difference on the same JK between the long-arm and mid-arm kit. 

Like many JK owners, we started with a 3.5-inch suspension kit, complete with adjustable control arms, track bars and lift springs. Our Rock Krawler kit was the PRO version that uses aluminum control arms and track bars, creating some nice weight savings for our overweight Jeep. The Mid-Arm PRO kit impressed us with unsurpassed road handling characteristics and off-road performance that never let us down. 

After running the Mid-Arm PRO kit for 12 months, we decided that it was time to take our JK to the next level, as many Jeep owners do. Rock Krawler Suspension informed us that a new PRO Long-Arm upgrade was available so we decided to try out the natural progression and move up to the long-arm kit.

Very Important Note:  When upgrading to the XFactor or Triple Threat Long Arm system, you are undertaking a major installation process. An expert welder needs to tackle much of the job and an alignment shop that is familiar with lifted four-links suspensions is required once complete. Cutting of the factory suspension mounting locations is also a must with this kit, so turning back is not an option. Lastly, modifications to the exhaust system are also required, so a highly qualified exhaust shop should be sought out after the suspension install is complete. 

Here is the exhaust modification completed.

Our upgrade came complete with the X-Factor front three-link long arms and rear three-link conversion, which are all made from 7075 aluminum. We also chose to use a Rock Krawler raised front track bar bracket, aluminum tie rod and steel drag link with flip kit in conjunction with our 3.5-inch RK Springs. We couldn’t find a more complete suspension on the market. 

The complete Rock Krawler PRO Long-Arm Kit.

Shortly after installation, we headed to Moab and caught up with the guys at Rock Krawler Suspension at the Easter Jeep Safari and asked them what makes their aluminum kit so special. They gave us some high tech information and also broke it down for us simpletons so we could understand why 7075 aluminum was used throughout.

“[The] 7075-T6 is a heat-treated aluminum in itself. The diameter of the lower links is 2 inches and the uppers are all 1 5/8 inch, all solid,” Rock Krawler’s Jeremy Purich explained. “The diameter for the Mid-Arm kit is 1 5/8 inch solid for the lowers and 1 1/2 inch for the uppers. The 7075-T6 aluminum has a yield strength of 73,000 psi. By comparison, 4130 annealed Chromoly steel has a yield of 66,700 psi. The 7075-T6 Aluminum is a third the weight of its steel counter part and costs typically twice as much.”

So, as Purich explained, 7075 aluminum is tough stuff and is extremely lightweight. In fact, it’s so strong, the decision was made to tap each end of the control arms for threads, rather than welding on a bushing end due to the difficulty associated with welding 7075 material. This decision was also made after some serious trail abuse during prototype testing. Rock Krawler now makes each arm double adjustable, which is something we really like during installation and for fine tuning our suspension. 

Double adjustable links are better and stronger.

So, we got what we wanted from our upgrade: lightweight components and the strength to not worry about breakage on the trail. What about ride quality and performance?  Running the RK long-arm suspension, with the three-link conversion, is something that you simply have to experience to appreciate. We combined our PRO kit with Bilstein 5160 remote reservoir shocks. The ride quality on the road is better than any other Jeep we’ve driven. Handling is crisp and precise thanks to less unsprung weight. The lightweight aluminum long arms also help in smoothing the Jeep’s ride due to their length, creating better operating angles that so many TJ and JK owners are after. 

Additionally, by utilizing adjustable track bars mounted to raised brackets welded on the axles, roll centers are corrected with our 3.5-inch lift height. This reduces unwanted body roll during hard cornering on the pavement, which increases comfort and safety. We highly recommend upgrading to use a front raised track bar mount on any JK lifted three inches or more. While our JK’s on-road characteristics impressed us, we were obviously more curious to see how it would perform off-road with the new PRO suspension. 

Rock Krawlers exclusive three-link rear suspension design.

The secret to designing a modern Jeep suspension that works well off road is to eliminate suspension bind. All traditional four-link suspensions, with a track bar, naturally bind at a certain point during articulation. Even with high-degree flex joints, binding will occur and suspension movement stops. This creates more stress on mounting points and causes less predictability while in the more extreme trail situations.  For these simple reasons, the Rock Krawler Long Arm PRO kit is a great choice for any JK owner looking for superior performance on- and off-road. Whether you keep your Jeep on the street, crawl it over boulders or run it through desert terrain at 80 mph, the lightweight long arms react quickly and did not bind.

Moab was almost too easy with our Rock Krawler-clad Jeep.

In Moab, we hit the hardest trails with no issues. In fact, our Unlimited Rubicon with Rock Krawler suspension components took some of the challenge out of many trails that we once thought extremely difficult. Back in the boulder-strewn trails of Colorado, we find the high articulating attributes of the RK suspension to be beneficial; however, we do tend to beat on the rear lower link mounts at the frame. We doubt that these mounts can be mounted in a location higher on the frame, which is typical of long-arm suspensions, but we’d love to get them out of the rocks! Maybe we are just bad drivers? 

These weld on RK mounts take a beating but can handle it.

After hitting the slick rock in Moab and the boulders of Area BFE, we worried that aluminum vs. rock would have gotten the best of our long and vulnerable control arms.  We can safely say that 7075 aluminum holds up great to the banging and dragging over the tough stuff. We now have the typical scratches and light gouging that you’d see with steel counterparts and feel that these arms are as bullet proof as they get.

Rock Krawler really did their homework when designing their three-link JK Long-Arm suspension. It works very well, and now that the kit is available in aluminum, you can finally start shedding the pounds on your JK. With the PRO kit, Rock Krawler still offers its hard parts warranty and ships each kit complete with their excellent, rebuildable flex joints.

Our JK is lighter than ever on the trail. 

We have now combined our Rock Krawler PRO Suspension with an aluminum RK front bumper and rear frame cover/bumper, eliminating a bulky rear tire carrier and spare tire.  By running Bestop tube doors and skins when wheeling, these few modifications have eliminated a lot of weight. Our porky JK is becoming more friendly in the rocks, dirt, and the street. Aluminum is becoming our new favorite friend!

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