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Racing Tips to Make Your Unitbody Survive

Posted in Features on April 28, 2015
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“Uh…do you see that gully?!” I ask nervously from the passenger seat of the Grand Cherokee “Got it,” is all that Skyler Gambrell replies, driving with laser-sharp focus. I brace for impact, but it never arrives. We cross the ravine at 40 mph without missing a beat. This is Jeepspeed racing, where I had the opportunity to navigate for Gambrell as he won the Henderson 250, beating the next closest competitor by 15 minutes.

Dust can be a killer in the desert, so many racers route an engine’s intake into the cowl or interior. Interior mounting can be loud for a street-driven vehicle, but Spectre makes a kit to mount the intake on an XJ in the cowl.

Jeep Cherokees have been used for everything from mail delivery to hardcore rockcrawling over the years. Their low price, solid axles, excellent suspension, and strong drivetrains make them well suited for these varied endeavors. But desert racing? Isn’t that the territory of half-a-million-dollar tube-framed trucks with 3 feet of suspension travel? Not exclusively, as the JeepSpeed series has proven over the past 12 years. We took a behind-the-scenes look at JeepSpeed vehicles to share the secrets of how they survive such punishment.

Did we mention how important cooling is when running at wide-open throttle for hours on end? Some JeepSpeed racers use manual transmissions, but AW4 automatics are the norm. This Jeep runs dual coolers to keep the trans fluid temperatures in check.

Top 10 Tips for a Fast Jeep
-Frame stiffeners The Unitbody structure can twist and fatigue when subjected to abuse, but frame stiffeners tie together the suspension and add bracing to the Unitbody.

-Custom tuned bypass shocks Good shocks are not cheap, but they will allow your vehicle to increase speed more than any other modification.

-Hydraulic bumpstops “Air bumps” smooth out the last couple of inches of suspension compression to provide more control and less harshness than traditional rubber or polyurethane bumps.

-Limit straps Too much down-travel can be a bad thing if it allows the driveshaft to separate or the shocks to top out. Limit straps will keep other components from being damaged.

-Reinforced steering box Hydro assist is not allowed in Jeepspeed 1700 class, so bracing the steering box and track bar mount are critical to their survival.

-Full ’cage This ties in to the frame stiffeners to create an even more rigid and durable platform and allows the rear hatch to be removed.

-Braced suspension mounts The front control arm mounts take a lot of abuse when racing, and if they are not reinforced, they can get ripped right out of the Unitbody.

-Gutted interior (less weight) Everything else we have recommended adds steel to the vehicle, so removing glass, seats, and carpeting will offset some of that weight gain.

-Paint pen This one is cheap and easy. After torqueing suspension and steering fasteners mark them with a paint pen to easily tell if they have loosened after wheeling.

This truss might not be the hot setup for rockcrawling, but it keeps the front axle straight after going airborne. Also visible is the Currie Currectlync steering, a bolt-on upgrade that offers significantly more strength than the stock steering components. This truss might not be the hot setup for rockcrawling, but it keeps the front axle straight after going airborne. Also visible is the Currie Currectlync steering, a bolt-on upgrade that offers significantly more strength than the stock steering components.
Tired of breaking off mirrors on the trail? These tubular mounts are a stronger option, and we have even seen some dune buggy models that are similar but use a spring to allow them to fold if they hit an obstacle. Tired of breaking off mirrors on the trail? These tubular mounts are a stronger option, and we have even seen some dune buggy models that are similar but use a spring to allow them to fold if they hit an obstacle.
Hood louvers are an easy upgrade to help remedy some of the cooling issues that Cherokees are known for. These can range from re-appropriated junkyard louvers to fancy aluminum parts like Race Ace and GenRight offer. Hood louvers are an easy upgrade to help remedy some of the cooling issues that Cherokees are known for. These can range from re-appropriated junkyard louvers to fancy aluminum parts like Race Ace and GenRight offer.
The factory control arm mounts are just sheetmetal and can fatigue over time. Adding more material helps but often just moves the stress to where the plate ends. Tubes like this spread the load over a larger area. The factory control arm mounts are just sheetmetal and can fatigue over time. Adding more material helps but often just moves the stress to where the plate ends. Tubes like this spread the load over a larger area.
The front suspension uses a separate coil and shock with a single shock per corner, but note that there is a bumpstop nestled in the coil similar to the JKS ACOS system. Also, that Bilstein shock uses bypass tubes that change the volume of the cylinder as the shock moves through its range of motion for more control. The front suspension uses a separate coil and shock with a single shock per corner, but note that there is a bumpstop nestled in the coil similar to the JKS ACOS system. Also, that Bilstein shock uses bypass tubes that change the volume of the cylinder as the shock moves through its range of motion for more control.
Adding steel to the Unitbody not only makes it stronger but also makes the chassis stiffer, which translates into improved durability. T&J Performance makes frame plates and stiffeners for XJs, ZJs, and WJs. Adding steel to the Unitbody not only makes it stronger but also makes the chassis stiffer, which translates into improved durability. T&J Performance makes frame plates and stiffeners for XJs, ZJs, and WJs.
Most teams ditch the windows to save weight and keep them from breaking on the course. Brandon Berge replaced the rear glass in his ZJ with diamond plate and added hinges to provide easy access to the rear cargo area. Most teams ditch the windows to save weight and keep them from breaking on the course. Brandon Berge replaced the rear glass in his ZJ with diamond plate and added hinges to provide easy access to the rear cargo area.
Axle assemblies can be swapped out in Jeepspeed, but they must retain the semi-float design and 5-on-4.5 bolt pattern. Currie Enterprises 9-inch axles are popular with its wide selection of gear ratios and the lightweight of the housing. Axle assemblies can be swapped out in Jeepspeed, but they must retain the semi-float design and 5-on-4.5 bolt pattern. Currie Enterprises 9-inch axles are popular with its wide selection of gear ratios and the lightweight of the housing.
Note the big fuel cell slung low under the back of this Jeep. Not the best ground clearance for the trail, but fuel is heavy and this keeps the weight down low. The big tank also offers plenty of capacity to extend time between pit stops. Note the big fuel cell slung low under the back of this Jeep. Not the best ground clearance for the trail, but fuel is heavy and this keeps the weight down low. The big tank also offers plenty of capacity to extend time between pit stops.
Want less restrictive rules? Wanna run a V-8? Class 3700 has fewer rules than 1700. Grand Cherokees are the most popular vehicle in the class but nearly any Jeep can enter. Want less restrictive rules? Wanna run a V-8? Class 3700 has fewer rules than 1700. Grand Cherokees are the most popular vehicle in the class but nearly any Jeep can enter.

Sources

Jeep Speed
909-289-5731
www.jeepspeed.com

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