Yukon Gear Axle Bearing & Seal Kit For AMC Model 20 Rear / 1-Piece Axle Design

Gear oil on the inside of a CJ rear wheel, a grinding or rumble from one corner, or axle end play you can feel by pulling on the drum all point to the outer axle bearing in an AMC Model 20 rear. This Yukon AK M20-1PIECE kit is the bearing and seal set for AMC 20 rears in 1976-1986 Jeep CJ5, CJ7 and Scrambler that run one-piece axle shafts, the common upgrade from the factory two-piece shaft and pressed-on hub.

What this kit does in an AMC Model 20

The factory AMC 20 in the CJ used a two-piece axle: a tapered shaft with a separate hub keyed and pressed onto it. The hub is harder than the shaft, and under big tires or a V8 the splines can shear or the hub can spin on the taper, which is why so many owners convert to one-piece shafts with an integral flange. Either way, each shaft rides in a tapered roller bearing at the outer end of the housing, with an inner seal to keep gear oil in and an outer seal to keep dirt and water out. The shafts are located by the bearing and a retainer plate at the housing end, not by C-clips, and some setups use shims there to set end play.

According to Yukon, the AK M20-1PIECE includes a Timken-type axle bearing, the inner and outer axle seals, and shims, and it services one side of the axle. Order two kits to do both sides.

Symptoms of a worn AMC 20 axle bearing or seal

• Gear oil on the backing plate, brake shoes or inside of the tire on one side
• A rumble or grind that changes in turns as weight shifts onto that side
• In-and-out end play at the axle flange when you push and pull on the drum
• Brakes that grab or fade on one rear wheel after oil reaches the linings
• Rust-colored grease or water in the bearing on a Jeep that sees creek crossings

How to confirm before you buy

Jack up the rear, release the parking brake and spin each wheel by hand while listening at the backing plate. Grab the tire at the top and bottom and check for play, then push and pull it in and out to feel end play. Oil on the brake parts is the clearest sign of a leaking inner seal. Before you order, pull the cap or look behind the drum: a castle nut on the end of a tapered shaft means you still have the factory two-piece axle, while a flange that is part of the shaft means a one-piece conversion is installed. This kit is for the one-piece design. Noise that changes with throttle rather than with turning usually comes from the ring and pinion, and the AMC 20 master bearing kit covers the carrier and pinion bearings.

Fitment

Yukon lists the AK M20-1PIECE for the AMC Model 20 rear in the 1976-1983 Jeep CJ5, 1976-1986 CJ7 and 1982-1986 Scrambler (CJ8), all 4WD. One-piece conversion kits differ by track width and by Quadra-Trac versus part-time 4WD, and different kit brands use different bearing and retainer combinations, so match this kit to the bearing in your conversion. If you know the brand of shafts you installed, tell us, or send the year and VIN and we will confirm. For a Dana 44 rear, the Yukon AK SET10 is the matching bearing kit, and more axle parts are in our rebuild kits category.

Install notes

• Pull the shaft and cut the old bearing retaining ring off carefully; a slide hammer and seal puller set makes the inner seal and bearing cup removal much easier.
• The new bearing is pressed onto the shaft and held by a press-fit retainer. Have a shop press it if you do not own a press, and follow the orientation in your conversion kit instructions.
• Install the new inner seal straight and flush so the shaft does not ride on the old wear groove.
• Check axle end play and use the supplied shims if your conversion kit sheet calls for them, then torque the retainer and backing plate nuts.
• Clean any oil off the brake shoes or replace them, top off the differential with the gear oil grade in your manual, and recheck for leaks after the first drive.

For the bigger picture on this axle, read our AMC 20 rear axle problems and rebuild cost guide.

Does this kit do both rear wheels?

No. Yukon states it services one side: one axle bearing, the inner and outer axle seals, and shims. Order two kits for a full rear axle job.

Will it fit the factory two-piece AMC 20 axle?

This kit is listed for the one-piece axle design used in AMC 20 conversions. The factory two-piece axle with the pressed-on hub uses a different setup. Check for a castle nut behind the hub before you order, or send us the year and VIN.

Which Jeeps does it fit?

Yukon lists the 1976-1983 CJ5, 1976-1986 CJ7 and 1982-1986 Scrambler with the AMC Model 20 rear, 4WD. Match it to the bearing used by your one-piece conversion kit.

Why are shims included?

Yukon includes shims so axle end play can be brought back into spec if your shaft and housing setup calls for them. Follow the end play figure and shim instructions that came with your one-piece axle kit or your service manual.

What should I replace at the same time?

Replace any brake shoes soaked with gear oil, inspect the wheel studs and drum, and change the differential oil. If the carrier or pinion is noisy, do the AMC 20 master bearing kit while the axle is apart.