Differential Carrier Shim Kit

What Is a Differential Carrier Shim Kit?

When rebuilding or upgrading a rear or front axle differential, precision is everything. A differential carrier shim kit provides the thin, precisely machined spacers that are placed alongside the carrier bearings to set the correct preload and side-to-side positioning of the ring gear carrier inside the differential housing. These small but critical components directly affect how the ring and pinion gears mesh, which in turn influences gear noise, wear life, and overall driveline reliability.

Carrier shims are typically made from hardened steel and come in assorted thicknesses so the builder can dial in the exact preload specification called for by the axle manufacturer. Getting this setting right is non-negotiable: insufficient carrier bearing preload can result in premature bearing failure and ring and pinion failure in all differentials. Too much preload creates excess heat and drag. The shim kit gives builders the range of thicknesses needed to land precisely in the sweet spot.

When Do You Need a Differential Carrier Shim Kit?

Carrier shim kits are essential any time the differential carrier is disturbed — whether you're installing a new ring and pinion set for a gear ratio change, swapping in a locking differential, rebuilding worn internals, or correcting noise and vibration issues. Most common Salisbury-style axle assemblies require preload shims to be tapped into place in order to achieve the required preload during setup. Rebuilding without the correct shim assortment on hand can bring your project to a halt or, worse, lead to a costly come-back repair.

• Ring & Pinion Gear Changes — New gear sets require a fresh shim setup to achieve correct backlash and bearing preload.
• Locker or Limited-Slip Installations — Replacing an open carrier with a locker changes the carrier dimensions, requiring new shims.
• Bearing Replacement — Worn carrier bearings alter preload; new bearings need fresh shimming to spec.
• Noise Diagnosis & Correction — Whine or clunk traced to the carrier can often be remedied by re-shimming to the proper preload.

Top Brands in Differential Carrier Shim Kits

Richmond Gear is one of the most recognized names in driveline components, with decades of experience producing ring and pinion sets, rebuild kits, and associated hardware. Their carrier shim kits are engineered to pair seamlessly with their gear sets, making them a go-to choice for both professional builders and serious enthusiasts tackling a gear swap.

ARB brings its off-road expertise to the differential shim category with precision-made shim kits and installation tooling designed to support their Air Locker differential systems. ARB has been manufacturing 4x4 parts for over 40 years, and their shim products reflect the same attention to quality that defines their locker lineup — right down to zinc-plated finishes for corrosion resistance.

Yukon Gear & Axle is a specialist in axle shafts, ring and pinion sets, and rebuild components, offering one of the broadest shim kit selections available. Their super carrier shim kits are available for popular axle platforms including Ford 8.8, Ford 9.75, GM 12-bolt, and many more, making Yukon a reliable source when you need the right thickness for a specific axle build.

What to Look for When Shopping Carrier Shim Kits

Always verify axle compatibility before ordering — carrier shim dimensions vary by housing design and bearing size. Look for kits that include multiple thicknesses so you have flexibility during setup. Steel construction is standard for durability under load, and quality kits will spec out thicknesses in small increments for fine-tuning accuracy. Pairing your shim kit with the correct installation tools ensures the shims seat evenly without cracking or distortion during assembly.