Shim Kit GM 8.875in 12 Bolt Car

The Allstar Performance Shim Kit for GM 8.875-inch 12-bolt differentials is a precision bearing preload and pinion setup component designed for rear axle assembly, tuning, and repair. This complete kit addresses the critical task of establishing proper pinion depth and crush sleeve preload—specifications that directly affect differential noise, bearing life, and driveline efficiency. Built by a manufacturer with deep roots in performance automotive engineering, this shim kit provides the individual shims and hardware necessary to dial in factory-spec preload without guesswork.

The kit includes pinion retainer shims, preload shims, bolts, a crush sleeve, and a pinion nut—all components required for correct assembly of the 8.875-inch GM 12-bolt carrier. Proper pinion depth and crush sleeve preload are non-negotiable for this differential platform; incorrect settings introduce backlash, gear whine, premature bearing wear, and potential catastrophic failure under load. Each component in this kit is sized and specified for the 8.875-inch 12-bolt, ensuring compatibility with factory and performance rear axle assemblies in compatible GM vehicles. The included hardware meets OEM standards for this application.

This shim kit is essential for shop technicians, restoration specialists, and performance builders working on rear axle assembly, rebuild, or differential service on GM 8.875-inch 12-bolt platforms. Whether addressing worn components, upgrading to performance gearing, or executing a complete carrier rebuild, having a complete set of factory-spec shims eliminates the need to source individual components separately. At 2.23 lbs, the kit is compact and suitable for bench storage in any service environment.