We have had the Dixon Bros. Racing long-travel suspension kit on our project Ranger for more than a year now and we have to tell you how much we are still enjoying it. Since installing the kit, we have taken the Ranger all over the California desert, to places like Death Valley, Joshua Tree, and Glamis, in addition to the Nevada backcountry, Baja California to follow the Baja 1000 race, and Moab for Easter Jeep Safari. In the many miles of off-roading that the truck has been through, it has taken a pounding and the kit just keeps working-one of the strong points being the Bilstein 9100 reservoir shocks. One thing we have found is that we are driving the truck more aggressively these days, so we decided it was time for a shock valving adjustment and we called our friends at Bilstein in Poway, California, to have RangeRunner's shocks revalved, which is something we hadn't had time to do previously. Follow along as we take apart our 2.65-inch Bilstein 9100 reservoir shocks and tune them for our Ranger.
 1. After taking the truck...  1. After taking the truck out to a desert test track, where numerous notes were taken on the trucks suspension dynamics, we returned to Bilstein's west coast headquarters where the shocks were removed from RangeRunner. |  2. Once the shocks were removed,...  2. Once the shocks were removed, R&D Manager Lou Laurenzana places them on the shock dyno, so he could get a baseline for the valving that was already installed. |  3. Next, Lou carefully disassembled...  3. Next, Lou carefully disassembled the shocks and pulled out the piston rod assembly. |
 4. Here you can see the internals...  4. Here you can see the internals of a Bilstein 9100 shock. Visible is the 22mm hard-chromed and super-polished shaft. On the left side of the shaft is the piston carrier and valve stack, to the right is the rod guide and wiper cap. |  5. The rod guide centers the...  5. The rod guide centers the shaft inside the shock body and houses the main shock seal, wiper, and bearing, which are visible in this photo. On the lower left is the wiper cap, which is visible on the outside of the body. |  6. With a dyno baseline in...  6. With a dyno baseline in hand, Lou then lays out the entire valve stack and measures each valve and shim to determine what set of valving we started with. Our shocks have the old-style 46mm linear pistons, visible in the center of the stack, which ride in 60mm piston carriers, visible on the bottom of the stack. |
 7. After careful calculations,...  7. After careful calculations, the new valving stack is determined and a new combination of valves and shims (from a seemingly endless number of sizes) is reinstalled onto the shaft. The valves determine the overall shock performance by controlling the amount of oil flowing through the piston ports from both the compression and rebound side. |  8. Once the shocks are recharged...  8. Once the shocks are recharged with nitrogen, they are placed back on the shock dyno to determine if our changes brought us to where we needed to be. Once satisfied with the new valve stack performance, the shocks are reinstalled on the truck before a final test back on the road and trail. |  9. In addition to valving...  9. In addition to valving adjustments in all four shocks, our front shocks were in need of a rebuild, so Bilstein technician Joel Ward pulled apart our coilovers and installed new oil and seals, along with new hoses in about the same amount of time as it took you to read this caption. Thanks Joel! |
Unlike our shocks, which use a 46mm piston in a 60mm piston carrier, Bilstein's new linear piston for 9100 series shocks is a full 60 mm. The beefy new piston is made from high-strength 7075 aluminum alloy, which is then hard-anodized. It also features a full 1-inch Teflon wear band that provides a replaceable wear surface that cuts down on friction from the piston to the inner cylinder walls, offering better support and longer life in all conditions. All 9100-series shocks now come standard with this new piston.