Recurring wheel bearing problems (Forrester)

[mmoerkens]

G'Day all,

A little question regarding wheel bearings on Subaru's.
A friend of mine has a Forrester and about three months ago the rear
wheel bearings had to be replaced.
When talking to the mechanic of the local Subaru dealer he told me that
it was a common problem and that Subaru had re-designed their wheel
bearings.


Three weeks ago again a(new,5000 km's)rear wheel bearing went to heaven,
and after making arrangements to get it fixed,and asking some questions
with the previous story in mind, the Subaru rep told me that it wasn't
our fold that the bearing didn't make it to it's expected life
expectancy. Prior the operation !!!!!!!

Are there any other Subaru drivers out there that had the misfortune of
replacing wheel bearings on (to) a regular basis.

Greetings, Michael

 

[Edward Hayes]

Be sure any bearing replaced is the roller bearing type. Special press type
tools are required to do the job and can not be preformed with a vice and
hammer home shop as often the bearing carrier will be distorted/damaged
causing repeated failures. eddie

 

[Greg]

And be advised that some Subaru dealers are not equipped to do the job.

 

[Rick Courtright]

Are there any other Subaru drivers out there that had the misfortune of
replacing wheel bearings on (to) a regular basis.

Hi,

It's a common problem with some cars. Do a search for "Subaru wheel
bearing failure." Lots of stuff pops up.

Two thoughts: first--Subaru has issued TSBs about the problem,
substituted roller bearings for balls, claimed ineffective grease seals
allow water into the bearing, and even come up with a "new" bearing.
Subaru's claim is that the bearing housing can become distorted thru
improper (including factory) installation and assembly. You should find
the TSBs in the search I mentioned above. I understand the failures are
primarily with ball bearings, and replacement with rollers has been
successful for many owners.

My second thought is a bit more controversial. Subaru claims the new
bearing is factory packed with the proper amount of grease, and NO
grease should be added at installation. We've discussed this before, and
I DON'T agree. In close to 40 years of packing/replacing wheel bearings,
I've NEVER seen one that was properly greased in shipment. Many even
come with warning tags to clean out the packing grease which is just an
anti-corrosive measure and grease properly at installation. I've had one
wheel bearing failure on my Subie (factory) and inspection of all the
bearings on the car prior to that failure indicated they were NOT
sufficiently greased. The one that failed was virtually dry (red rusty
dust evident) when I got the car at 209k miles. IME that's NOT normal.
I've also (so far, at least) never had a bearing I installed fail,
either from wear or entry of water, but they were all greased to the
hilt. I'm sure Edward Hayes will weigh in that too much grease is bad
for the bearing and seals. I usually agree with Eddie, but on this
point, I feel that's bunk. Too much grease may bleed out a bit and need
to be wiped off, but it won't harm the bearing (witness bearing lubing
systems for boat trailers where you pack the bearings FULL with a grease
gun!) If you read all the posts when you do the search, you'll find
several Subaru mechanics have weighed in on various fora concerning this
grease issue, and it seems they agree with me that the factory grease is
inadequate. But YMMV.

So, while there is a possibility of improper installation causing
problems, the installation of bearings at either the manufacturing or
repair level is NOT rocket science, and I'd suggest Subaru's insistence
on using ball bearings is a part of the problem, but the lack of proper
lubricant is THE biggest problem. Well greased, carefully installed,
rollers make sense to me.

Best of luck,

Rick

 

[Edward Hayes]

I will take one step back on this one Rick since I have not seen or opened a
new Subaru ball bearing. When one buys a bearing from a Subaru dealer that
has I warning the bearing has sufficient grease and NO additional grease
should be added I took that as gospel. Apparently some bearings
(out-of-the -box) don't have the proper amount of grease. I stand by my
opinion that bearings can be over greased to the detriment of the seals and
bearings. Boat trailers are pressure packed to keep from sucking in water
when the boat is launched and typically fail with only a year or two of use.
My experience with ball bearings on my old Porsches is that balls are good
IF the bearing carrier design correctly and the bearing is installed
correctly. I never had a rear wheel bearing fail me in I'm guessing 300,000
miles. My 2000 Forester with balls (I checked VIN number) is still going
strong at 62,000 miles. Thanks for the input Rick and as I said I take a
step back on the lube issue. eddie

 

[D L YOUNG]

A word of caution based on experience- overfilled grease lubricated
antifriction bearings can overheat, due to churning of the grease, and fail
at quite modest rpms unless excess grease is discharged automatically. I
doubt whether Subaru incorporate a grease discharge valve on their wheel
bearing housings- this would be clear from the service manual, which I don't
have.

Forester wheels at 70 mph rotate at between 920 and 950 rpm and I have a gut
feel that this may be getting into the danger zone for long trips at
interstate speeds

If there is no discharge valve, before running with an over filled bearing
housing I suggest discussing this with customer service people at a bearing
manufacturer- eg Torrington or SKF.

 

[Rick Courtright]

A word of caution based on experience- overfilled grease lubricated
antifriction bearings can overheat, due to churning of the grease, and fail

Hi,

This is in agreement with what Eddie's been trying to tell me!

Since my experience is different, and I may have to stand corrected,
please let me ask a question: when you say "overfilled," does that mean
the area in between the bearings was completely filled, too? IIRC, every
wheel bearing I've worked on was mounted in either a hub or a housing
that had "overflow" capacity between the bearings at either end. Only
enough grease is supposed to be put in that area to prevent corrosion.
That way, even if the bearing itself is WAY overgreased, the excess can
bleed or "discharge" into that area. The front hubs of my Subie (ball
bearings) have such an overflow area, and the rears (rollers in a
cartridge) also allow some expansion. I'm sure the designs are similar
on even the newest bearings. So if that's what you mean by a "discharge
valve," then, yes, there is one.

Thanks!

Rick

 

[T]

Re: bearings and failure and replace,net-

Has any one in Subbie Land had experience with Synthetic Bearing Grease?
I'm no shill but I've had success with VWs and Redline's stuff.


TBerk

 

[D L YOUNG]

Rick- regarding the effect of more or less grease in and around an
antifriction bearing- there is no general answer because so many factors are
involved.

The problem with overgreasing is that during operation, churning may heat
and soften the grease, which then flows to form a pool at the bottom of the
bearing housing. If the pool is deep enough for the rotating parts to
continue the churning action, then heat buildup may continue, and the
bearing temperature increases to an equilibrium level which depends on the
heat dissipating capacity of the housing and shaft. If the conditions are
bad enough, the grease may break down and early bearing failure can occur.

Thus, if the bearing only (not including the housing) is filled with grease
and the housing has a suitable shape and size, IMO the bearing life will not
be reduced. If the housing is filled with grease, all bets are off. If the
free space in the housing is negligible, even a relatively small amount of
excess grease may cause trouble.

Hope this helps... Doug.

 

[Rick Courtright]

Has any one in Subbie Land had experience with Synthetic Bearing Grease?

Hi,

I bought some Valvoline Synthetic a couple of years ago to do my CV
joints on the recommendation of someone here. (I'd used the "special"
grease that comes with the boots several times before.) Yawn. The joints
were NOT clicking before thorough cleaning, repacking and installing new
boots. Within a month, both sides WERE and the right side failed shortly
thereafter. Could be pure coincidence, since the joints were original
and the first failure occurred after 300k miles, but I wasn't impressed.

I used the rest of the can when I replaced my front wheel bearings, but
they've only got 20k miles or so, so can't comment on whether the
stuff's any better in that app than conventional hi-temp wheel bearing
grease.

Rick