Toyota 8 Inch Differential Master Overhaul Kit ZK T8-A

This is the USA Standard Gear ZK T8-A master overhaul kit for the Toyota 8-inch rear differential, 1986 and up. It is the bearing and hardware side of a gear job: carrier bearings and races, pinion bearings and races, pinion seal, a complete pinion and carrier shim kit, ring gear bolts, pinion nut, crush sleeve, and the oil baffles and slingers where the housing uses them. Bearings are Koyo. You supply the ring and pinion; this kit supplies everything that wears out around it.

The Toyota 8-inch shows up under the 1986 and later Toyota pickup, the 4Runner, and Tacoma rear axles, and it is the axle most people are in when they regear for larger tires. Once the housing has run low on gear oil, or the pinion seal has been weeping onto the driveshaft yoke for a season, the pinion bearings get a rough spot and you hear it as a whine that changes with throttle instead of with speed. Replacing gears without replacing the bearings under them is how a fresh install comes back apart.

On the bench: pull the third member, mark and measure the existing pinion depth shim so you have a starting point, then press the old inner pinion bearing off and set the new one with the shim stack from this kit. Run the crush sleeve down to spec preload with the pinion nut, install the carrier with the side shims, then check backlash and paint the pattern before the housing goes back in the truck. The shim kit is deep enough to walk the pattern in without a second parts run.

One fitment note worth knowing before you order: the Toyota 8-inch was built in both two-pinion and four-pinion carrier form, and installers have reported the inner pinion bearing in this kit measuring differently than what came out of a two-pinion third member. Measure the bearing you pull before you press the new one on. This kit does not include axle shaft seals or a differential cover gasket, so order those separately if the axle is coming apart that far.