Toyota 8 Inch IFS Solid Pinion Spacer and Shim Kit

This is the Yukon SK CST8S-CS solid spacer kit for the Toyota 8 inch independent front differential, the clamshell-style front diff used under Toyota IFS trucks and SUVs. It replaces the factory crush sleeve with a machined solid spacer and a stack of preload shims.

A crush sleeve sets pinion bearing preload by collapsing as the pinion nut is torqued. On a front diff that sees big tires, lockers or hard off-road use, the sleeve can keep yielding, preload drops, and the pinion starts to walk. That shows up as gear whine, a leaking pinion seal and eventually a chewed ring and pinion. A solid spacer does not crush, so once the shim stack is right the preload stays where you set it.

On the bench: set pinion depth first, then install the solid spacer in place of the crush sleeve and assemble the pinion with the outer bearing and yoke. Torque the pinion nut to spec and check rotating torque with an inch-pound torque wrench. Too tight, pull the yoke and add shim; too loose, remove shim. Repeat until the rotating torque is in range with the nut fully torqued.

Expect to take the pinion in and out a few times while dialing in the shim stack. Bearings, pinion seal and pinion nut are not included; most builders pair this with a new install kit when regearing.