Drive Shaft Shim Kit
Skyjacker Suspension R14DSS Rear Driveshaft Spacer for 2013+ RAM 2500
What Is a Drive Shaft Shim Kit?
A drive shaft shim kit is a small but critically important component for any truck, Jeep, or 4WD vehicle that has received a suspension lift. When you raise a vehicle's ride height, the geometry of the entire driveline changes — the pinion angle on the rear axle shifts, the operating angle of the U-joints increases, and what was once a smooth, vibration-free driveshaft can become a source of annoying — and potentially damaging — vibrations at highway speeds.
Drive shaft shim kits (also known as pinion angle shims or driveline angle correction shims) are precision-machined wedge-shaped inserts that are placed between the leaf spring and the axle perch. By rotating the pinion yoke to better align with the driveshaft's operating angle, these shims restore proper driveline geometry after a lift is installed. Correcting this angle is one of the most overlooked steps in a lift kit installation, yet it can be the difference between a truck that drives smoothly and one that develops premature U-joint wear or a persistent vibration drone at cruising speeds.
Why Driveline Angle Correction Matters
When a suspension lift alters a vehicle's ride height, the transfer case output and the rear axle pinion are no longer operating at complementary angles. The further out of alignment these angles become, the harder U-joints and carrier bearings have to work — accelerating wear and inviting vibration. A quality shim kit addresses this by precisely adjusting the axle's rotational position so that the driveshaft can operate within its designed angular range. For two-piece driveshaft trucks, shims are also used in conjunction with carrier bearing drops to keep the center section of the shaft running as straight as possible.
What to Look for When Shopping
- Degree of correction: Shims are typically available in 2°, 4°, and 6° increments — measure your existing pinion and transfer case angles before purchasing to select the right shim.
- Material: Steel shims offer greater strength under heavy loads, while aluminum alloy shims provide a lighter alternative well-suited to most street and moderate off-road applications.
- Vehicle fitment: Always confirm the shim width and bolt pattern match your specific axle and leaf spring pack dimensions.
- Compatibility with lift kit: Many shim kits are designed to work in tandem with specific lift systems — buying from the same brand as your lift kit often ensures the best fit and performance.
Top Brands in Drive Shaft Shim Kits
Fabtech is a leading brand in this category for good reason. Fabtech has built its reputation since 1989 as a leading manufacturer of off-road suspension systems, and their drive shaft shim kits are engineered to complement their lift systems directly. Fabtech's driveline spacers are specifically designed to increase spline contact and restore proper driveline angle after lifting a vehicle, delivering smooth operation at all speeds.
Skyjacker Suspension is another trusted name in lift-related driveline correction. Skyjacker is widely recognized for comprehensive suspension lift packages, and their drive shaft shim kits are a natural complement to their lift systems — engineered to correct driveline angles and eliminate driveshaft vibrations that commonly follow a suspension lift installation.
Pro Comp rounds out the category with their aluminum alloy degree shims, designed to align driveline angles when lifted springs are used. Pro Comp backs their suspension products with a lifetime warranty, reflecting their commitment to quality in every component they manufacture.