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© 2001 Brian F. Schreurs
Even we have a disclaimer.

We started by trying to adjust the wheel bearings into spec, but that didn't work, so we went for the full replacement. It's not that hard on the front -- the rear is a different story -- so there's no good reason to avoid doing this project. The wheel bearings are Timken Sets 16 and 17, common enough, but you'll also need a hub seal. Ours was #052-1617, but we don't know who made it. As far as tools, best be stocked up on metric stuff -- plus, go get a bearing/seal driving kit. This is the only way to get the new bearing races seated properly.

Start off by checking whether the wheel bearing just needs an adjustment -- bearing failure is actually pretty uncommon for the 928. To adjust, take off the wheel and the dust cover. The dust cover comes off easily enough by using a small prybar on the groove, leveraged against a wheel stud.

Here's the hub with the locking collar. Try adjusting this first.

Directly under the dust cap, you'll find the locking collar. It's a funny-looking bugger, but it's easy enough to figure out. It clamps shut with a cap screw that takes a 6mm hex key. Loosen it up enough so that it'll move. Can't get a hex key on it? That's what the slot in the hub is for! Line up the slot with the cap screw and it'll fit fine. Now you're ready for the adjustment.

According to Wally Plumley, a 928 guru, this is the most reliable method for setting the proper preload on a 928 wheel bearing. Take a pair of channel locks or other large pliers and tighten the locking collar as far as you can while spinning the hub. Then loosen it up, and retighten with just your hand. Tighten the locking collar to 11 ft-lb -- in other words, just enough to keep it from moving -- and test.

Spin the hub. There should be no resistance from the bearings. Try to wobble the hub side to side. It should not move. If it passes both of these tests, then you're done, without spending any money!

Ours failed the wobble test, so now we can show you how to replace a wheel bearing.

Remove the caliper and housing. It is held on by two 19mm bolts. They are extremely difficult to remove (that's a hint: stock up on super threadlocker for reassembly). Pull the rotor off -- which also could take some serious effort (hint: anti-seize for reassembly).

Remove the locking collar and the washer underneath it.

When you pull the hub off, the outer bearing will likely fall right out. The inner bearing is held in place by an evil seal. Think you can get it out without damaging it? Fuggheddaboutit. You'll be lucky to get it out at all. We did it by trapping the hub inside our shop vice, in such a way that pulling on the seal with a seal puller put the pressure on the underside of the vise jaws.

The inner wheel bearing, with the Evil Seal in place.

By this point, you've no doubt already removed the outer bearing. Now you'll be able to remove the inner bearing. Both races have to be punched out. The inner comes out with great difficulty. The outer comes out relatively easily. In both cases, use a small punch on the backside of the race; there's a slight lip you can punch. Be very careful to not score the bore where the races go, or you won't be able to get the new ones in.

On our car, there seemed to be two types of grease on the inner bearing, and several rollers had collapsed. The outer bearing is intact but the grease is all caked. We later learned that the previous owner had the same wheelbearing replaced three months ago, just before we bought the car! Hmmm... problem area? As us again in three months.

Clean, clean, clean. Make everything spotless.

We had put the new races in the freezer overnight beforehand, but frankly we're not convinced it did much good. Punching in the new inner race was still no fun, and the outer race was loose enough that we rather doubt we would have had any trouble at room temperature either. Regardless of whether you try freezing your races, assemble the entire inner bearing unit before doing anything with the outer bearing.

The spindle all greased up and ready for action.

Grease up the inner wheel bearing with black moly grease and drop it in. Follow that up with the grease seal, which will require some gentle persuasion from the punch to go into place.

Now flip the hub over, go get the outer race, and install it. It goes in much easier than the inner. Grease up the outer wheel bearing and drop it in.

Go to the spindle and clean off all the old grease. Then smear it with new grease. Slide the hub over the spindle, followed by the thrust washer, topped by the locking collar. Go through the adjustment scheme we described previously. Once you've got the right preload, reinstall the dust cap, the rotor (with anti-seize!), the caliper (with threadlocker!), and the wheel (with lugnuts!). Drop the car and go!

Wheel bearings are a pretty non-glamorous part of the car, with many gearheads probably never touching theirs, ever. But considering just how dangerous a bearing failure can be, this is no place to dawdle -- when there's a sign of failure, fix it! It's an easy afternoon project. By the way, check that rotor -- if it's damaged much, you might want to think about replacing it.

Secondary note: To anybody else whose car takes Sets 16 and 17, now you can tell all your friends that your car uses high performance Porsche wheel bearings! Yeah baby!