Yukon Gear Carrier installation Kit For GM 8.5in Diff w/ HD Bearings

Swapping a worn-out open carrier in a GM 8.5 inch 10-bolt for an Eaton Posi, TrueTrac, Detroit Locker or Auburn, and found the new unit will not take your old carrier bearings? Or chasing a growl from the carrier side of an 8.5 that already has one of those differentials in it? Yukon CK GM8.5-HD is the carrier installation kit for exactly that job. It is a carrier-side kit only: heavy-duty carrier bearings and races plus a carrier shim kit, so you can change the differential without paying for pinion parts you do not need.

What the carrier installation kit does in a GM 8.5

In the 8.5 the carrier and ring gear spin on two tapered roller bearings that sit in the housing under bolted caps. GM sets carrier position with shims or spacers on each side, and those shims control two things at once: side bearing preload and ring gear backlash. When you change carriers, the new case almost never lands the ring gear in the same spot as the old one, so the bearings have to be pressed onto the new journals and the side shims rebuilt from scratch. Yukon's carrier kits contain carrier bearings and races and what Yukon calls a super carrier shim kit, which is a selection of shim thicknesses so you can split the stack to get backlash and preload right without hunting for shims.

Why the HD version exists

Yukon's standard CK GM8.5 kit fits factory carriers in the GM 7.5, 7.625, 8.2 and 8.5. Many aftermarket carriers for the 8.5 are machined with larger bearing journals, and those need the HD bearings in this kit. Yukon's technical note lists the Dura Grip, Eaton Posi, ValueTrac, TrueTrac, Pro-Series Auburn and Detroit Locker, along with any standard carrier with large bearing journals. If your new differential is one of those, a standard kit will not press on.

Symptoms this kit addresses

• A constant hum or growl from the rear that is present on both throttle and coast, typical of a carrier bearing rather than gear contact
• Ring gear backlash that has grown since the last setup, felt as a clunk when shifting between drive and reverse
• Posi chatter or a locker that needs replacing, which forces a carrier change and new bearings
• Metal on the cover magnet after a bearing cage has broken up

Our carrier bearing noise guide explains how to separate carrier bearing noise from pinion bearing and gear noise.

How to confirm before you buy

Pull the cover and identify the carrier you are installing. Measure the bearing journal or check the carrier maker's bearing callout: large-journal aftermarket carrier, buy this kit; factory 8.5 carrier, buy the standard kit. Check the pinion too. If the pinion bearings are rough or the gears are worn, a carrier-only kit is the wrong purchase and you want a complete GM 8.5 HD master overhaul kit instead. The GM 8.5 10-bolt problems guide covers what usually fails in this axle.

Fitment

Fits the GM 8.5 inch 10-bolt rear axle with an aftermarket Positraction, limited slip or locker carrier that uses heavy-duty (large journal) carrier bearings. This axle was used under a long run of Chevrolet, GMC, Buick, Oldsmobile and Pontiac cars and trucks, so confirm you have an 8.5 and not a 7.5, 8.2 or 8.6 before ordering. The kit does not include pinion bearings, a pinion seal, crush sleeve or ring gear bolts. If you are not sure which bearing size your carrier takes, send us the carrier brand and model along with your year and VIN. More differential kits are in our rebuild kits section.

Install notes

• Remove the C-clip axles and carrier, mark the bearing caps left and right, and press the HD bearings squarely onto the new carrier journals.
• Install new races in the caps and housing, then build the shim stacks to get carrier preload and backlash to your service manual specification.
• Paint the ring gear with marking compound and read the pattern on the drive and coast sides before final torque.
• Ring gear bolts are not in this kit; use new ones if the old ones show any thread damage, and use thread locker.
• Fill with 75W-90 gear oil, adding friction modifier if the new unit is a clutch-type posi. If the pinion yoke is worn, a GM 8.5 1350 yoke can go in while the axle is open.

What is the difference between CK GM8.5-HD and CK GM8.5?

CK GM8.5 fits factory carriers in the GM 7.5, 7.625, 8.2 and 8.5. CK GM8.5-HD has heavy-duty carrier bearings for aftermarket 8.5 carriers with large bearing journals, such as the Eaton Posi, TrueTrac, Detroit Locker and Pro-Series Auburn.

What comes in the kit?

Carrier bearings and races plus a carrier shim kit. It does not include pinion bearings, a pinion seal, crush sleeve or ring gear bolts.

Can I use this kit when I change ring and pinion gears?

Not by itself. New gears need new pinion bearings, a pinion seal and crush sleeve as well, so a master overhaul kit is the better buy for a regear.

Will it fit a GM 8.6 rear?

It is listed for the GM 8.5 inch 10-bolt with aftermarket large-journal carriers. Confirm your axle size before ordering, and send us your year and VIN if you are unsure.

Which gear oil should I use after installing a posi?

75W-90 gear oil, with friction modifier added for clutch-type limited slip carriers unless the oil already contains it. Lockers and gear-type units such as the TrueTrac do not need the additive.