8 lug wheel bearing/hub GMT 800

merlin5577

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You will need:

Floor jack
2 Jack stands
15mm socket
**21mm socket**
36mm socket
½ inch drive ratchet
The biggest breaker bar you can get your hands on.
Sharp flat blade screwdriver.
Hammer
Rubber Mallet
Grease
A coat hanger or wire tie.
3 foot or longer piece of steel pipe.
Tire Iron.
Protective glasses or goggles.


You will probably need;

Small block of wood.
Beer.


**Have at least 3 of these around. I broke 2 during this project.


BEFORE DOING ANYTHING, PUT THE TRUCK IN 4WD HIGH, AND SET THE PARKING BRAKE!!!

Jack the side of truck up, and put the jack-stands under it. Use 1 under the frame rail and position the other under the lowest cross section of the A-Arm. Remove Wheel.

Unplug the wheel speed sensor wire near the top of the shock. Remove the 4 plastic clips that hold the wire to the A-arm.

There are two 21mm bolts that hold the brake caliper frame to the axle support. Use the breaker bar and the pipe to break these loose, than use the ratchet to get them out. Be prepared to grunt, strain, and break sockets. Remove the bottom, than loosen the top one so you can remove it with your fingers. Do not allow the caliper to hang from the brake hose or you will most likely have to replace the hose. Use the coat hanger to tie the caliper to the top of the shock mount.

Remove the rotor. If it does not easily come off, use the rubber mallet to tap it from behind. If that doesn’t work, get a block of wood, the real hammer and start swinging. Be careful not to hit the rotor with the hammer directly. Rust will fly, you have your eye protection on right?!?!

Pry the center dust cover off with a sharp flat blade screwdriver. Be fairly gentle as you will reuse this.

That nut in the center keeps the axle from wandering too deep into the differential. It is also a locking nut, so it will be tight most the way off. Again, the breaker bar is your best friend. Use the 36mm socket and remove the nut. There is also a thick steel washer that you will need to slide off.

Gently tap the axle with the rubber mallet into the hub until it stops. It will move approximately 1 inch.

There are four 15mm bolts that hold the hub on. You can get to them with the breaker bar if you turn the steering wheel, if not, more grunt and strain.

The hub should slip right out. But it doesn’t. Gently tap around the perimeter of the hub with the hammer until the hub actually moves, then it will slide right off.

Clean all mating surfaces, grease the o-ring in the base, and apply grease to the axle shaft before installing the new hub.




Installation is just the opposite of removal. But a few notes are to be made.

Make sure the wheel speed sensor is at TDC on installation, and the dust shield is put back on the way it came off. The wire goes UNDER the tab on the dust shield. Snap the 4 wire holders into the same holes the old one came out of, and reconnect the connector near the shock.
Put wheel back on, lower truck. Start the truck up and pump the brakes for a minute to allow the calipers to adjust.

Now before anyone asks, no, I don’t know the official torque specs. But trust me, you cannot over tighten these bolts. I did some searching online and found these;

TORQUE SPECS
Hub and Bearing Assembly to Steering Knuckle Bolts - 133 lb ft
Axle Shaft Nut - 155 lb ft
Caliper Mounting Bracket to Knuckle - 221 lb ft

:thumbs:

:cheers:
 
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merlin5577

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One more note, this procedure will work on any GM 8-lug vehicle. From the Express van to the Avalanche. It can also be used as a guide for you 6-lug guys, but the exact steps will be different.
 
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daddy

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Nice WRITE-up. Get a new camera. :D
 

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