Replacing 1st Generation Trooper Front Wheel Bearings and Grease Seals

Now to be honest, I don’t think I needed to replace my wheel bearings.  They could probably have just been cleaned and regreased, but the cost was around $70 for both front bearings and the grease seals, and since I was already doing a brake job and replacing the auto locking hubs, it wasn’t much more work.  Also, my Trooper is from 1991 and I think the bearings were never repacked since the factory.  The service manual says they need it every 30,000 miles, and I was about 180,000 miles overdue!

It’s always important to be comfortable when working on your car!

Sources

The factory manual section on the hubs:

The Internet Archive of the Planet Isuzu article on repacking the bearings

Red Beans 2/Maint + Upgrades from Planet Isuzu

Removing the Wheel

Block the rear wheel to keep from rolling over a neighbor

Break the lug nuts free

Jack the Trooper up

Use a jack stand too, just in case

Remove the lug nuts and the wheel

Removing the Brakes

Remove the caliper mounting bracket’s two bolts and hang the whole brake assembly out of the way without twisting the brake line or dislodging the brake pads.  They are torqued to 103-126 ft-lbs so bring your A-game

Disassembly

Using some blocks to keep the wheel from turning, break free the hub to rotor bolts (only if you are replacing the brake rotor as well)

Break free the hub housing assembly bolts

Remove all the bolts

And pull the housing assembly off to reveal the auto hub (the manual calls it the “Drive clutch assembly”)

Inside you will see a snap ring that is holding the hub on. Here you can see that I already pried it out of it’s groove

Remove the auto locking hub

Pull off the inner cam (sometimes it comes off with the hub assembly)

Remove the three small screws holding the retaining ring (or lock washer in the service manual).  I replaced mine with stainless steel allen screws but the OEMs are Phillips head.  Look for “Machine screw flat – Phillips 4mm x 8mm”

Pull out the retaining ring

Remove the hub nut by unscrewing it. A screwdriver works if you tap it a few times, or use the tool described below

Finish unscrewing the hub nut

Then pull out the outer bearing that should just be sitting there

And pull off the hub assembly

If you are replacing the rotors, separate the hub from the rotor, otherwise you can leave them assembled

The hub and rotor pulled apart

With a seal puller, remove the rear grease seal

Once it’s out, pull out the inner bearing

Replacing the Races

With a small punch, drive the races out. Each has two small cutouts to place the punch into.  Try not to muck up the wall and keep the punch only on the race edge

Seat the new race as squarely as possible

For the inner race, I don’t have a large enough driver and used a block of wood to get it seated

So I used a punch and carefully worked my way around the edges. Very painstaking but no sign of marring anything up

The outer race is smaller and my driver can install it.  Much easier to use the right tool!

Check to see that it’s installed all the way down and even

Both races installed

After driving in the new races, add a few ounces of grease (the manual says 1.24 ounces.  If you know a good way to measure that, let me know!)  to the space between them and then coat the rest of the inside

Packing the Bearings

There are several tools that do this for you.  I am cheap though and just take a bunch of grease in the palm of my hand and work it into the open edge of the bearing until it squeezes through to the other side and then I make sure it’s coating the whole thing.

Work the grease into the bearing with your hands or go buy a special tool for it

Here’s a short video demonstration how you can do it and keep the bearing clean until you are ready to install it:

Installing the Bearings

Place the inner bearing (the larger one) in first

Place the new seal squarely over the top and drive it in. I like to use a small section of 4×4 and place a thick paper towel over it so nothing falls into the hub

Reattach the hub to the rotor if you removed it earlier

Slide the assembly back on

After packing the smaller outer bearing with grease, slide that into the hub as well

Adjusting the Preload

The procedure for setting the preload requires a way to tighten the hub nut and although you can do it by feel (I think many people do), the manual says to use a torque wrench.  The cheapest way is buy a Ford 4-prong socket and grind off two of the prongs and grind down the other two to fit in the hub nut holes.  It cost about $15 for the tool.

Pages from the manual for the amount of grease in the hub and the bearing preload

New Ford socket about to get cut up

A Ford 4WD nut with two of the prongs ground off

And the other two prongs ground down

Tighten the hub nut to 22 ft-lbs, spin the wheel a few times, back it of, hand tighten the hub nut again

Tighten it until the preload with a spring scale reads 4.4-5.5 ft-lbs with new bearings and seal or 2.6-4.0 ft-lbs with old parts

Line up the retaining ring with the screw holes on the hub nut.  The holes are aligned slightly differently if you spin it 180 degrees to line up the holes.  Otherwise, adjust the hub nut as little as possible to get it lined up

Reinstall the three small screws to hold the hub nut in place

Now just reinstall the inner cam, the hub, reinstall the snap ring, reinstall the housing assembly, tighten the hub to rotor bolts, reinstall the brakes, put the wheel back on, lower the vehicle, and tighten the lug nuts.

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  1. […] replaced the front brakes at the same time as replacing the wheel bearings so the directions are included in that […]

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