Jeep Wrangler JK on 37-inch Tires … on Stock Springs

May. 31, 2016 By Pete Bach, Photos by Jeff Lampman

We get this question nearly every day: “How’d you do that?” Even the most seasoned Jeepers ask, with puzzled expressions, “How is that possible?” It’s not every day that you see a Jeep with factory springs and 37” tires.  Our two-door Wrangler build has been carefully planned to run large tires with very little suspension lift, long arms, tons of articulation and stability. While strategy went into planning, the formula is simple: Lighter weight equals positive results. And while we will go beyond the very minimum budget, this Jeep started off as an incredibly cheap project that can run some of the toughest trails in the country and that nearly anyone can afford.
The Jeep JK Unlimited is pretty much the hottest 4x4 on the planet… and we love them! However, with the success of the four-door Unlimited Wrangler, it seems that our little two-door, 94-inch-wheel-based best friend has gone by the wayside. When out on the trails, we watch the endless lines of monstrous four-door Wranglers lumbering through tight, twisting roads; most of them clad with thousands of dollars worth of body armor, 40”+ tires, big lift kits and 1-ton axles.

Big four-door JKs (JK Unlimitieds, or JKUs) are cool, but they can be expensive and sometimes cumbersome on the trail.

While we are fans of these Jeeps that are built for buggin’ out of the next zombie apocalypse, we are bigger fans of the old concept of “less is more.”  No, we are not going back to the leaf-sprung, carbureted simplicity of a Jeep CJ, but we have started to build a simple Jeep JK that leaves the extra weight, height and expense at home.

We realize that not everyone has, or wants, a Jeep that is mostly purpose built for the trail, however this Jeep can still run down the road smoothly, as most JKs do. Eliminating weight from any JK is easy. It’s already very heavy from the factory so we started removing pounds that anyone can eliminate from their Jeep, which included our rarely used back seat, doors, hardtop and almost all plastic attached to the body. Just by ditching these few items, our Caravan 3.8L engine came alive! We are always surprised at how much a two-door JK benefits in the performance department when losing this weight. We also realized that our Jeep gained at least 1.5 inches of height – it’s kind of like a free lift kit. Capitalizing on this free “thing,” we grabbed some used front JK Unlimited Rubicon front and rear springs out of our Bach Crawler shop parts bin and threw them on to see what we could work with for a final lift height.  Overall, we got a solid 2” of lift!  Less weight, with no money spent and we got more lift and better engine performance…nice! 

There are many factory JK springs to chose from. We chose Orange and Green labels for our two-door project.

We like 40” tires on a JKU, but 37” tires work great on a two-door, cost less and are a little easier on the minivan motor and 3.73 gears. Factory 17” Rubicon wheels are being sold or given away everywhere on the Internet so we picked up a cheap set that we paired with a set of SpyderTrax wheel spacers we found, giving us a factory look that keeps unsprung weight down. With tires this size and very little lift, there are a few things that are necessary in order for everything to work nicely together. Rather than cutting the front side of the rear wheel wells, we spent a few bucks on Rock Krawler rear upper and lower control arms and moved our rear axle back by about 2” inches.  We then trimmed our rear wheel wells on the rear side so there is no interference. In the front, we didn’t bother with bump stops and trimmed the fenders to match the grill line. The only plastic left on the body (except the grill) are the highly trimmed factory flares, which are not really needed but we think they clean the look up a bit. 

The tweaks to our project vehicle extend the wheelbase to provide larger wheel well openings that can fit 37” tires.

With these few modifications alone, other Jeep owners are astounded by the Jeep’s looks and transformation, not to mention the performance improvements.  “How’d you do that?” has become a common question when anyone peers underneath the Jeep. While our Jeep is nearly perfect with 37” tires under it, we want to be able to effectively run 40” tires, if and when we want to. More trimming to eliminate weight and make room for larger tires will be next. 

Taking the Jeep to another level as already begun, with a hand built, high clearance long arm suspension up front and custom bumpers that necessitated the elimination of 7 inches of frame in the rear, as well as the front.

You can see the heavy trimming from the frame that create unmatched approach and departure angles.

Catch up with us next time to see our cheap custom long arm suspension, custom bumpers, more trimming, lockers and more.  If you see this Jeep in person… it will leaving you saying, “How’d you do that?”

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