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Jeep TJ Coilover System - Comfort And Capability

Posted in How To on December 26, 2006
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The Poly Performance front and rear coilover shock systems are designed for use on '97-'06 Jeep Wranglers and Wrangler Unlimiteds.

The Poly Performance front and rear TJ coilover bracket kits are designed to facilitate installation of either 12-inch- or 14-inch-travel, 2-inch-diameter, remote-reservoir shocks. A separate kit is available to accommodate hydraulic bumpstops, but the stock bumpstops may also be retained if so desired. The front kit is very multifunctional in that it will allow fitment of a variety of shock and coil spring arrangements. Once the brackets are installed, a set of coilover shocks can be used, but you also have the option of retaining use of your existing stock or aftermarket coil springs and mating them with much longer travel shocks than the factory shock brackets permit. This makes the Poly kit a great option for those not immediately prepared for the expense of coilover shocks, and it will also appeal to those simply seeking a means of mounting longer shocks. The kit also permits use of air shocks. To achieve maximum articulation, the Poly Performance coilover kits must be used along with a long-arm suspension system, and they allow for fitment of 33-inch tires and larger. Many of the available aftermarket long-arm systems are compatible with the Poly Performance coilover kits, but the company also has a system of its own in the works.

Increased flex is one benefit of the Poly Performance system. The coilover shocks also set ride height, which is an awesome feature that allows fine-tuning for each application.

All of the necessary brackets and hardware are included in the kits but that doesn't mean that the system should necessarily be installed by the home mechanic. Installation requires fabrication and welding skills and involves cutting factory suspension brackets off the frame up front and notching into and welding a section of frame in the rear. The Poly Performance kits can be installed on any-year Jeep Wrangler or Wrangler Unlimited, and an extended rear bracket kit is also available for those who may have moved the rear axle back to lengthen the wheelbase. Another version of the front kit uses hoops instead of brackets for upper shock mounting and accepts 2-inch-diameter, 14-inch-travel reservoir shocks along with 4-inch-stroke hydraulic bumpstops.

Use of coilover shocks can improve vehicle handling characteristics and increase suspension articulation by allowing fine-tuning capability to each application. This means that each shock is tailor-tuned to your vehicle's specifications, including weight (soft top, hardtop), lift size, and tire size, as well as to deal with other factors such as engine and/or axle conversions. Using this information, Poly Performance can recommend the proper coil spring rates and shock valving for the vehicle on which the kit will be installed.

The coilover system was installed up front along with a 2-inch, 14-inch-travel SAW RaceRunner coilover shock and a 4-inch SAW air bump.

Why would you need or want coilover shocks on your Wrangler rather than the traditional coil-spring and gas-charged-shock factory arrangement? Coilover shocks offer enhanced control in cornering and improved ride quality on the road or on the trail. Also, ride height is adjustable by altering the position of the spring on the shock body using threaded spring collars.

Shock mounting plays a crucial role in the design of the kit and is as important as obtaining the proper shock valving and spring rate. This is where the quality in design and engineering is so apparent in the Poly Performance system. Even with 37-inch tires and 6 inches of lift, the system permits a smooth and fluid factory-quality ride while maintaining aggressive off-road capabilities. Coilover shocks allow the flexibility needed for scaling extreme obstacles, but will also let you scream down a washboard road at speed without bouncing out of control.

The rear coilover kit is installed by notching the framerail and welding the mount in place.

To complement the Poly Performance kit, we contacted Sway-A-Way to acquire a set of its RaceRunner 2.0-inch, remote-reservoir coilover shocks. The RaceRunner shocks offer an electro-less nickel-plated shock cylinder and high-strength, 7/8-inch, nitro steel shafts. The shocks are also completely rebuildable and revalvable. The shock body/cylinder is threaded for both single- and dual-rate applications and use 2.5-inch-ID coil springs. Teflon-lined steel spherical bearings are used at each end for mounting. The extended length on the 12-inch-travel shock is 31.50 inches; the compressed length is 19.50 inches. The 14-inch-travel shock has an extended length of 35.50 inches and a compressed length of 21.50 inches. We'll also install limiting straps so we don't overflex and create driveline bind.

Poly Performance carried out the installation of the front and rear coilover conversion on our '01 Project TJ. It was a detailed yet seamless installation that took about two days to complete. It wasn't easy watching the stock suspension brackets coming off the frame, but with our factory warranty long gone and the TJ being replaced by the all-new '07 Wrangler JK, we figured it was about time we got down to business.

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The front upper bracket was then welded in place for a factory-like fit and appearance.

Loving It
Have you ever wanted to go really, really fast on a bumpy road? Have you ever gone really, really fast on a bumpy road and almost lost control of your rig after being violently tossed around because your suspension couldn't handle it? I have. I even rolled it over one time as a result. While many of the available aftermarket suspension systems are up to the task of tackling extreme terrain at low speeds, only a handful of them offer such capability at a higher rate of speed. Those that do incorporate a coilover suspension configuration in the front of the vehicle, but for the most part the rears retain the factory design and simply use taller springs and shocks. With the Poly Performance system replacing the rear setup, as well as the front, with a coilover shock, the resulting off-road driving capability is very impressive.

High-speed off-road driving ability isn't the only benefit. Low-speed crawling also gets a boost. In fact, with the increased flex provided by the Poly Performance kit, we were able to climb many obstacles while still in 2WD.

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