Yukon Gear Master Overhaul Kit For 09+ GM 8.6in Diff

A rear-end howl that rises with road speed, a wet pinion seal dripping onto the driveshaft yoke, or a clunk when you get on and off the throttle are the usual reasons a Silverado 1500, Sierra 1500, Tahoe, Yukon or Escalade owner ends up looking at the 10-bolt rear axle. In 2009 and later trucks that axle is the GM 8.6-inch, and this Yukon Gear and Axle YK GM8.6-B master overhaul kit carries the bearings, races, seal and setup hardware to rebuild it in one job, with or without new gears.

What the master overhaul kit does in a 2009-up GM 8.6

The 8.6 is a semi-float, 10-bolt cover rear axle with a 30-spline pinion. The pinion turns on two tapered roller bearings held under preload by a collapsible crush sleeve, and the carrier spins on two side bearings whose shims set both backlash and side bearing preload. Every one of those dimensions decides where the ring gear teeth contact the pinion. As the bearings wear, preload falls off, the pinion moves, and the contact pattern walks toward the toe or heel of the teeth. That is the whine you hear on acceleration or coast. A master overhaul kit replaces all four bearing sets and gives you the parts to reset the pattern, so the gears run quiet again.

Retail listings for this part number describe the contents as Timken carrier bearings and races, Timken pinion bearings and races, a pinion seal, a complete shim kit, ring gear bolts, a pinion nut, a crush sleeve, thread locker, marking compound with a brush, and a gasket. Axle seals are not listed in the box.

Symptoms that point to a rear axle rebuild

• Whine or howl from the rear that changes between throttle and coast at the same speed
• Growl or rumble that gets louder with speed, typical of a worn pinion or carrier bearing
• Gear oil weeping from the pinion seal and slinging onto the underside of the truck
• A clunk on takeoff or when lifting off the throttle once pinion preload is gone
• Fine metal paste on the drain plug magnet or in the oil when the cover comes off
• Noise that started right after a gear swap that was set up without checking the pattern

How to confirm it is the differential

Drive at a steady speed, then lift off the throttle and hold the same speed on coast. A noise that changes with load and not with steering is almost always the ring and pinion or its bearings; a noise that changes when you swerve left and right is usually a wheel bearing. With the truck in neutral and the wheels off the ground, grab the pinion yoke and try to rock it up and down. Any free play means the pinion bearings have lost preload. Before teardown, mount a dial indicator on the housing and read backlash at the ring gear so you know what the axle had and where to start.

Fitment

This kit is for the 2009-and-newer GM 8.6 rear. Retail fitment for YK GM8.6-B lists the 2009-2019 Silverado 1500 and Sierra 1500, 2009-2017 Tahoe, 2009-2013 Yukon, Avalanche and Escalade, 2009-2014 Suburban 1500, Yukon XL 1500, Express 1500 and Savana 1500, 2009-2012 Colorado and Canyon, 2009-2010 H3, and 2009 Trailblazer, Envoy and Saab 9-7x where they carry the 8.6. GM changed the pinion bearings for 2009, so a 1999-2008 axle needs the earlier 1999-2008 GM 8.6 master overhaul kit instead. Count the cover bolts (ten), check the axle RPO code on the glovebox label, and send us your year and VIN if you want us to check it before it ships. Every differential and transmission kit we stock is on the rebuild kits page.

Install notes

• Mark the ring gear with the included compound and photograph the old pattern before you pull anything apart.
• Pull the carrier bearings with a side bearing puller so the original shims come out intact and can be measured.
• Reuse the original pinion depth shim as your starting point if you keep the original gears.
• Always use the new crush sleeve. Tighten the pinion nut a little at a time and stop when turning torque reaches spec; backing the nut off after crushing too far ruins the sleeve.
• Clean the ring gear bolt threads, apply the thread locker, and torque the bolts in a criss-cross sequence.
• Check the new pattern, adjust carrier shims for backlash, then refill with the gear oil and friction modifier your owner's manual specifies, plus extra modifier if the axle has a locker. Gear oil is in our fluids section.

If the teeth are pitted or you are changing tire size, do the gears at the same time. The Yukon 4.88 gear set for GM 8.5 and 8.6 drops in with this kit, and the front axle on a 4x4 must be regeared to the same ratio.

Will this fit my 2007 or 2008 Silverado 1500?

No. The 2009-up 8.6 uses different pinion bearings from the 1999-2008 axle. For a 2008 or older truck use the 1999-2008 GM 8.6 master overhaul kit we list separately.

Do I need new gears to use this kit?

Not if the ring and pinion teeth are smooth with no pitting, chipping or heavy wear lines. Many noisy 8.6 axles are quieted with new bearings and a correctly set pattern on the original gears.

Are axle seals included?

Axle seals are not listed in the kit contents. If the axle shafts are coming out anyway, order a pair of rear axle seals and check the bearing surface on each shaft.

Can I reuse the old crush sleeve?

No. The crush sleeve is a one-time part that sets pinion bearing preload as it collapses. The kit includes a new one and a new pinion nut.

Does it work with the factory G80 locker?

The kit covers the bearings and setup parts around the carrier, so it can be used with an open or factory locking carrier. Inspect the locker itself while it is out, and use the fluid and additive your owner's manual lists for a locking axle.