Replacing Wheel Bearings.
 

I have noted many posts reporting the failure of wheel bearings only a short time after replacement.

Many years ago a very knowledgeable and experienced mechanic showed me how to repack a bearing. The important point he made was that the bearing must be packed with grease from only ONE side, pressing the grease through until it comes out the reverse side. When packed from both sides an airlock forms in the centre so that the grease does not penetrate fully.

I doubt that many modern mechanics are taught the basics of proper practical workmanship. He told me that at the technical school he attended in his youth they had a bearing which could be disassembled after greasing to illustrate the point and he therefore learned the lesson well.

This tip may assist those doing their own work ( these I hold in high regard having been there myself ) but also may enable others to oversee work being paid for !

Note from the field...
 

I just replaced a rear bearing today and found the problem of short bearing life. The bearing's rollers are ridiculously undersized for the weight of the car and the offset of the wheel. I have replaced many hub bearings in the past and I can't recall ever seeing a wheel or hub bearing with such small rollers. The bearing housing (outer race) is normal to large, as hub bearings go, but the actual rollers are tiny, barely 3/8" long and maybe a 1/4" diameter (roughly half the length of a more common bearing.) This bearing would probably have worked reasonably well on the rear of a Loyale.

The outer race had one medium-sized pit and a few very small pits, barely perceptible. However, from 15-20 mph and up it sounded like I was dragging the rear bumper - to me that shows that there is a lot of pressure on each individual roller.

I think I've mentioned this before, but knowing how some mechanics do things, I'd bet that the under-spec'd bearings coupled with sloppy installation habits are the problem (Boy, watch that statement bite me in the butt... ;) ) In other words, what a lot of mechs get away with when installing bearings in most cars just isn't going to fly with these.

To be honest, there is one area of the installation that normally isn't a problem, but can be because of this particular bearing. Even if the complete bearing is installed into the knuckle correctly, the pressing of the hub into the bearing can be tricky. I have the correct press, it only pushes the hub and the inner races together, no pressure is exerted against the rollers. However, as it is an interference fit, the amount of pressure required to fully seat the hub into the bearings could overwhelm the spacer ever so slightly and create a wee bit too much pre-load on the bearings. This shouldn't be able to happen, the spacer exists solely to determine and maintain the pre-load, but I can't help think that maybe the bearing engineers were using specs for a bearing with much larger rollers that could tolerate the extra pre-load without disintegrating (small rollers = small lube film surface & higher loading/roller = higher operating temperature = higher rate of disaster.)

The notes from the factory that we've seen elswhere on this site are as stated "common sense" items for a mechanic. One would have to get pretty vigorous with an impact wrench to warp the knuckle/housing. The big nut in the center of the wheel should only be tightened by hand, with a torque wrench and while in the air, not on the ground. That should help to not exceed the pre-load setting on the bearing.

Sorry for the long post, I just wanted to be clear about what I saw today.

Re: Note from the field
 

Very astute Beav,
My only personal experience was 3 bearings 3K apart after i bought at 40K, until I demanded they replace the knuckle. The super tech at the dealer agreed after his special attention to the last 2 that this was the best shot. Then no prob for 30+K now. There are a lot of factors at work here. I seem to remember an upgraded bearing from SOA. As they say, this isn't brain surgery. Trannys are.... (for the owner, Hi Aredub..) B. :p :p :p

Interesting Site... see the current tips.

www.endwrench.com

Beav, Once again we have to thank you for spending considerable time in as always posting valuable, informative, information. I for one have printed it for future reference.

Trivor.

Synthetic grease?
 

We took our "new" (to us) '92 on its first road trip today, and I noticed rumble from the rear that increases and decreases directly with speed. After 250 miles, I'm fairly certain the noise is louder than when we first noticed it at the beginning of the run.

Assuming the notorious rear wheel bearings are the culprit, I have 3.5 questions:

(1) Are the Subaru bearings the only ones available, and if not, are they the best bet? (vs Fafnir et al)

(2) Any experiences packing them with synthetic grease?

(3) Is there a FAQ somewhere that explains all this in detail?

Thanks,
--jim

I bought my 92 with 90k and now it has 142k. So far no problems with any of the bearings failing.

No, there are bearings available aftermarket. I doubt that there's any advantage from one brand to another. Subaru doesn't make bearings so you can bet they buy them from the best price available.

I don't see the grease being a cause of failure, in my current experience of one. ;) The rollers are just way too small. I replace bearings in cars that weigh less than the SVX and the rollers in their bearings are substantially larger.
The difference is similar to this:
|__|
SVX - I'd say the diameter looks about right too.
|_____|
Normal, except the diameter portrayed is a bit small

There is a recent post that detailed the replacement precautions but I can't seem to put my fingers on it - perhaps someone that knows will point you in the right direction.

a thread and a little FAQ...
 

Here is a recent thread...
http://www.subaru-svx.net/forum/show...&threadid=3566

... and my favorite general FAQ.
http://my.voyager.net/~tmclane/

Re: Synthetic grease?
 

I am not sure what the aftermarket bearings cost but at $68 from the dealer, about 75ish with the seals. I think it's a resonal amount for a suby part.

Lwin

To the dealer, then..
 

Thanks for the replies, guys!

I was wondering about the bearing quality, which is why I asked about 3rd-party parts. Since the consensus is that the Subaru bearings (wherever they come from) as as good as anything else, I'll just point it toward the dealer and rumble my way over there.

--jim

How much does it usually cost, with labor, to replace a wheel bearing?

Although it's not the quantity but the quality you should probably bank on $250 depending on the rates where you are. Your milage will vary. B. :D :p (others add to this)

This is what I did with mine:

I went out and got another set of bearings for 4000.

Attached to the bearing:
3 extra bearings, white 1992 LS-L SVX.

Just giving you an option.

Lwin