GM 8.25 IFS Front Differential Master Overhaul Kit

Master overhaul kit for the GM 8.25 inch IFS front differential, USA Standard Gear part number ZK GM8.25IFS-B. This is the independent front suspension carrier found under 4WD GM half-ton trucks and SUVs from 1999 through 2013 (Silverado 1500, Sierra 1500, Tahoe, Yukon, Suburban 1500, Avalanche) and under the 2002-2009 TrailBlazer and Envoy. It is a full setup kit, not a bearing-only pack.

Contents are Koyo carrier bearings and races, Koyo pinion bearings and races, pinion seal, a complete shim kit, ring gear bolts, pinion nut, plus crush sleeve, oil baffles and slingers where the application uses them. Having the shim pack in the box is what lets you set pinion depth and carrier preload properly instead of guessing with the old shims, which is where most front diff whines come back from.

On the bench: pull the carrier, record the shim stack, press the old pinion bearing off and the new one on, install the pinion with the crush sleeve and set preload with the new nut, then run gear marking compound and read the pattern before you set backlash to spec. Take your time on the pinion depth. The front diff sees load only part time on these trucks, so a marginal pattern often survives a while before it gets loud on acceleration.

This kit covers the 8.25 IFS front unit only. It is not for the GM 8.6 or 9.5 rear axles, and not for the 7.25 IFS front used in smaller GM 4WD applications. Verify your ring gear size before ordering.