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high End Shock Performance - urethane Eyelet - Photo 31488429

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For stock-style Jeeps and other trail rigs, the urethane eyelet works well because it's quiet and long-lasting. Two sleeves, with either 14mm or 1/2-inch bores, can fit into the same urethane bushing which streamlines production and speeds customer service.

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These are the components that make up a King coilover shock. It's pretty obvious there's a lot happening in between the blue-anodized end cap and rod end. While most of the shock is filled with oil, the reservoir is partially filled with oil and partially with nitrogen. There's a dividing piston floating in the reservoir, separating the oil and nitrogen. As oil heats up, it expands against the dividing piston and the nitrogen which in turn compress into a smaller area. As oil cools down, it contracts and the nitrogen then expands to take up the "slack." In short, the reservoir's purpose is to keep shock action smooth and consistent.

Inside a shock you'll find oil, an actuating rod, a piston, and two sets of flexible shims that determine how fast the piston can pass through the oil. On the left, the piston is traveling upwards in compression. Holes (ports) in the piston head allow the piston to move through the oil. When the oil encounters the flexible shims on the underside of the piston, those shims flex the shims away from the face of the piston. If the shims flex more, the piston can travel through the oil more quickly. If the shims flex less, the piston travels through the oil more slowly. On the right, the piston is traveling downwards during the rebound stroke. This time, the compression shims are forced closed against the face of the piston and the oil travels though a set of rebound holes (ports) in the piston head. A set of rebound shims on the top of the piston head now flexes open. The degree of flex determines how fast or slow the rebound stroke will be.

Shock valving shims come in different diameters, and varying thicknesses. The widest shims are usually assembled directly against the piston, and smaller shims get stacked progressively on top. Shock valving shims also come in different thicknesses. The thicker the shim, the more energy it takes to deflect it. Most changes in shock valving are done by changing the number, arrangement, and thickness of the shims.

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Here's a view of the business end of a monster-sized 4.0 King Kong shock. On the top of the piston, you can see the intake ports for the compression stroke around the perimeter. The rebound shim stack is bolted to the top of the piston, and the progressive diameters are easy to see. Brett King informed us that "Shocks are like engines. They need to run at around 200 degrees to work properly. At that temperature, you can't touch the shock or it will burn you, but that doesn't mean it's overheated. At the same time, 300-degree shock oil is too hot. At that temperature the oil will break down."

Here are the most common coilover configurations. Left to right: remote reservoir, piggyback reservoir, and non-reservoir/emulsion. With an emulsion shock, the oil and the nitrogen occupy the same space and there is no dividing piston. The piggyback and the remote reservoir configurations offer the best performance, but tight mounting spaces sometimes mean no room for a reservoir.

King offers its air shocks in 2- and 2.5-inch diameters. Air bypass shocks, not shown, are also on the King menu. Air shocks are compact, easy to adjust, and offer a streamlined installation with a single set of upper and lower shock tabs. Even though today's air shocks are better than older versions, King recommends that its air shocks be used on lightweight vehicles only, and only for off-road-specific applications. This means air shocks are a perfect choice for a lightweight rock buggy, but not for a street-driven Jeep. Walker Evans Racing and Sway-A-Way share this opinion.

King's optional compression adjuster, shown on a TJ shock here, can be added to any remote reservoir or piggyback reservoir shock. There are 20 positions, offering a wide range of compression damping that's tunable with the twist of a knob.

King eliminates the stock cross pin on Wrangler applications, replacing it with a custom King bracket that's much stronger.

King bump stops come into play when the suspension hits the last few inches of compression travel. They are available in stroke lengths from two to four inches to accommodate a variety of vehicles and suspension configurations. The mounting cans are honed inside to ensure a precise fit.

King has a growing line of OEM performance kits. These kits bolt up to stock vehicles with no other modifications required. Brackets and hardware are included. Like the TJ and JK Wrangler shocks, custom valving was developed for each application. This photo shows King's OEM kit for the FJ Cruiser.

Look closely. Inside the coil spring there's a Light Racing Jounce Shock.

Whats' a Jouce Shock? It's a hydraulic bump stop with tuning capabilities beyond those offered by any other manufacturer. Jounce Shocks are filled with oil and pressurized with nitrogen. They have externally adjustable compression and rebound circuits for on-the-spot tuning with a simple hex key. Jounce Shocks, produced by Light Racing, can be installed on a vehicle with otherwise stock suspension, and upon installation the vehicle will be imbued with a new level of suspension control. This is because a Jounce Shock comes into play during the last part of the suspension stroke, eliminating harsh bottoming and the abrupt rebound that usually comes afterward. Towing, crawlin' or haulin,' a Jounce Shock is unlike any other hydraulic bump stop available.

The top of the Jounce Shock is machined with external threads which can then be installed into pre-made upper mounts offered by Light Racing. These pre-fabbed upper mounts simplify and streamline installation.

Just as the top of the Jounce Shock can be mounted in different manners, Light Racing offers different strike pad configurations for the business end of the Jounce Shock. This domed target pad at left fits perfectly with the cupped end mount on the right. The cupped end mount threads onto the Jounce Shock's shaft.

Walker Evans Racing isn't a warehouse. It's a machine shop. Custom shock lengths, custom rod ends, and custom valving are all possible.

Walker Evans transitioned smoothly between the high-speed world of desert racing and the high-angle world of rock crawling.

Along the way he developed a line of two-inch-diameter adjustable reservoir shocks that have become favorites in the Jeep world. These shocks come with direct-fit mounts in models developed for Jeep TJ's and JK's.

For stock-style Jeeps and other trail rigs, the urethane eyelet works well because it's quiet and long-lasting. Two sleeves, with either 14mm or 1/2-inch bores, can fit into the same urethane bushing which streamlines production and speeds customer service.

Even though urethane bushings work well for stock-style mounts, spherical bearings are needed in coilover applications. Urethane isn't strong enough to withstand the forces that coilovers put them through. The spherical bearings are easily replaceable using a pair of snap ring pliers.

Adjustable compression damping has been a Walker Evans staple from the shock's introduction. The compression adjuster controls the flow between the shock and the shock's reservoir. Oil enters the compression adjuster cap through a port on the side (not shown) and from there makes its way through a set of ports and valving shims. Walker Evans Racing's Rich Brown explained, "The 2.0 shock with the adjuster will handle just about everybody out there, whether they're creeping through tight woods in the east, or blasting dunes in the west. Our adjuster has mechanical stops in both directions, so you can't accidentally turn it too far. Go clockwise for firm, and counterclockwise for soft."

Curious as to how a shock's end cap takes shape? Here are four main stages. In between the raw extrusion and the finished end cap are lots of tooling, a big investment in CNC machinery, and many hours of computer design.

Walker Evans Racing was one of the first to offer air shocks, and they're still part of the product lineup. For best results, use these on lightweight, off-road-only buggies. They're not the way to go for street-driven trail rigs.

Here's what's coming soon at Walker Evans Racing: bigger shocks. With so many years and milestone victories in the desert, it's a natural progression for Walker Evans to bring out a line of long-travel 2.5-inch coilovers. Bypass shocks are also in the works.

Even though custom shock valving is no problem for the crew at Walker Evans, they've still got several formulas figured out. John Searle of Walker Evans Racing showed us a drawer-full of pre-packaged pistons and valve stacks. John also explained the service department's modus operandi: "We don't nickle and dime people who send in their shocks. If someone is already paying for a rebuild and they want their valving changed, there's no charge for doing that because we've already got their shock apart. We encourage people to send their shocks in to us, rather than working on them themselves. Our phone number, (888) WEE-RACE, is right on our sticker, and we really do want people to call us when they've got a question."

If you see red anodized hardware and an external-style top end cap, there's a good chance it's a Sway-A-Way shock. The photo on the left shows a 2.0- coilover next to a 2.5-inch-diameter bypass shock. Sway-A-Way uses Nitro Steel shock shafts, which have excellent resistance to pitting and rock chipping. Sway-A-Way's Brian Bell explained "Nitro Steel is a nitriding process that produces a hard finish up to fifteen thousandths (0.015 inches) thick. By comparison, chrome is usually only five thousandths (0.005 inches) thick."

Sway-A-Way's lineup includes hydraulic bump stops which are adjustable for oil volume and nitrogen pressure. If you're running a bypass shock, you can often use the last stage of compression as a bump stop zone, using a rubber or urethane puck to prevent metal-to-metal suspension-to-frame contact. If you use a coilover without a bypass shock, hydraulic bump stops can add a level of bottom-out resistance that's beyond the reach of the coilover alone.

Here are two views of a Sway-A-Way 2.5-inch-diameter air shock with a 16-inch stroke. A close-up of the piston head reveals a big spring next to it. Brian Bell commented, "An air shock has a lot of extension force, so the internal spring is a return spring to control that force when the shock reaches full extension. We've also noticed that a lot of the rock-crawlers who use air shocks don't want to run external limit straps, so the internal spring helps to dissipate the extension force and the loads introduced by the big tires used in rock-crawling."

We mentioned the external-style top cap that Sway-A-Way is known for. To understand the benefit, take a look at the inside of the shock cylinder.

The smooth bore continues right up to the end, which means that the piston can travel all the way to the top of the cylinder. The top cap's attachment threads run on the outside of the cylinder. This means you can build a shorter shock with a longer stroke compared to a shock with an internal-style top cap. The external-style top cap helps create more travel when shock mounting locations are in tight quarters.

Here's another slice of Sway-A-Way trickery. Bypass tubes can sometimes hit other components. This problem is often solved with custom bypass tube placement on the shock body. Sway-A-Way offers bypass shocks with a swiveling top cap, so that the shocks can be rotated as needed to clear other mechanical parts. If you still need custom bypass tube placement, Sway-A-Way can take care of you.

Brian Bell shows another Sway-A-Way exclusive: an O-ring-preloaded wear band. "The O-ring puts pressure on the wear band and makes a better seal. It also makes up for tolerances between the main bore and the piston. With the preloaded wear band, the valving is more effective because fluid isn't blowing by the piston." Sway-A-Way also uses 7075 aluminum exclusively for its pistons. "We tried 6061 and 2024, but they just don't hold up under hard use," Bell revealed.

Most shock tuning can be done using standard-issue hand tools, but a few special items are needed. One of these items is a set of aluminum vise jaws to hold the shock shaft in place while the rod end or the piston is being manipulated. Sway-A-Way has aluminum vise jaws for all the shaft diameters that come with its shocks.