If you have a leaf sprung Jeep and ever used degree shims to adjust your axles have probably used aluminum shims (or wedges). If you have used the aluminum ones you probably have seen what they look like over time and have listened to them squeak, creak, and clunk.
The jeepfan.com 78 CJ-5 has had several sets of aluminum shims over the years. The rear axle seems particularly good at destroying shims.
Recently we learned that Rubicon Express makes leaf spring degree shims that are made from steel and integrate into the leaf spring rather than just float around the spring center pin. Installation of the wedges is pretty straight forward, in this article we are installing the shims in the rear.
Raise the Jeep and remove the weight from the rear axle by properly supporting the Jeep by the frame allowing the axle to fully drop.
Since we were changing an axle this Jeep’s rear was completely removed but is not always necessary. Raise the axle enough to allow access to the spring center pin. Use a clamp to hold the spring pack together and remove the spring center pin.
Since the old center pin was very worn (below) and cut a new set was purchased. Jeeps can use two different size center pins so make sure you know the size before purchase. This Jeep used the 5/16 size.
old pin and old aluminum shim compared to new steel one
Use a drift pin to re-align the spring pack if needed and place the new shim on the spring. Install the center bolt through the shim and spring. Tighten the bolt and place the axle back on the shim. Repeat the procedure on bolt sides.
new shim and center pin installed
If the Jeep did not have shims it may be necessary to install new u-bolts. It’s a good idea to install new ones anyway if yours are aged. Since we replaced an old set of shims our u-bolts were the correct length and were re-used.
Complete the install by reinstalling the u-bolt plates, u-bolts, and reattach the shocks. Properly tighten the u-bolts and recheck tightness after 100 miles or less.
Rubicon Express Degree Shims come in 3 sizes. 4, 6, and 8 degrees.
For more information and pricing visit
