Wheel Bearing Question

[metrod]

I went to replace my front wheel bearings and after pulling them apart the inner race has a second seal joined to the bearing whereas the new ones do not!

The Bearings came as inner bearing/ outer bearing and grease seal I purchased them locally as I am in Tasmania and they are for 74/89 911 and fit fine other than this seal, in the tech info and Bentley manual it does not appear?

Photo depicts one removed and new one.

Thanks

Nigel

[testa-rossa]

Yes I believe there is a seal that goes there. You should be able to find it on PET. I just did mine recently too.

[metrod]

Sorry to sound like a dummy nut what is PET?

Thanks

Nigel

[metrod]

That was meant to be Dummy BUT not NUT!!

[Flat6pac]

PET is the exposed drawings of system showing all parts in assembly.
If you go up on "tech info" it should be there.
Bruce

[The cap'n]

The seal just happens to be stuck to the bearing. It comes right off. It's a disposable part, replaced every time it's removed. You, like many others asking for help, have neglected to give us any information about your car, so it's not possible to offer you the part number in our replies. Here's a link for the Porsche online catalog. If your car is newer than what is covered by this catalog, you can Google a bit and find the catalog you need.

Genuine Parts Catalogue - Classic Genuine Parts & Technical Literature - Porsche Classic - Dr. Ing. h.c. F. Porsche AG

BTW, you can order a CD copy of the catalog from Porsche, and it's very reasonably priced.

The Cap'n

[Jesse16]

As others have said, that seal is simply the inner grease seal that gets pushed, tapped in right before you put the front hub back on. Its a separate part, is not included with the bearing. Our host sells and you can get at a local part store over here. $5 or $6 bucks as I remember. Your photo makes it look like the seal "fits" the bearing but in fact it only barely touches the outer race if at all after install.
I believe you tap it in flush with the hub or maybe there is a space in the hub to receive it, can't remember. It gets replaced usually anytime you replace the bearings, good to keep a few on the parts shelf.

[Mark at Pelican Parts]

Hi metrod,

Check out our technical article on this very topic. We cover the entire process and detail the bearings and seals.

Let us know if you have any questions. Here's a link to the article:

Front Wheel Bearing Replacement ('65-'89 911)

Mark/Pelican Parts

[testa-rossa]

Question for all of those bearing experts... I recently went to an Autocross event and the tech inspector grabbed the top of my front wheels and gave it a good shake. He said that the wheel bearings were not tight enough. I had thought I followed the proper procedure to tighten but not over tighten. So last night I removed the wheel and tightened it up a bit more. It looks like they are now solid when you shake the front wheel.

Does that make sense?

bottom line.. i had to tighten the wheel bearings more than i assumed you did.

[L8apex32]

The tightening process for the front spindle nut can take some practice. Basically, tighten the nut with a wrench until tight and the hub won't spin easily by hand. Then, back off and re-tighten by hand. The torque spec is just past hand tight.

After a drive, if you can feel looseness by wiggling top/bottom on the wheel with it off the ground, then repeat the process and go a little tighter.

I've only had one Porsche and it seems spindle nuts take a little more torque than on other cars I've worked on to prevent any top/bottom play. For example, on my early 90's Mustang, the spec was literally achievable with your fingers and that was enough.

[Jesse16]

I've had the same at DE's, told they could feel shake and had an inspector tell me that its hard to tighten too much. I had to go much snugger than I expected to eliminate all looseness. Also, maybe a long drive to the track could warm things up and reveal looseness. I go really snug now at assembly, no idea that you could measure it as torque though (maybe).

[Walt Fricke]

Well, Jesse, the tech inspectors don't know what they are talking about, which is a shame as none of this is complicated.

The 911s through the 3.2 Carreras should have the front bearing loose enough that you can just elicit a small movement when the wheel is up in the air and you grab it at 12 and 6 (top and bottom) to shake it. This bearing is not designed to be so tight that there is zero play in the bearing. I believe the difference is between an angled roller (the front) and a roller (the rear). That ought to give an inspector pause if you lay that on him, even if not quite correct.

There actually is a torque spec for the thing which works like a nut on this spindle, but it is in inch ounces or the like, and you'd have to fabricate something to act like a socket, and about nobody has or uses either of those.

The standard instructions you will find in every manual written for these cars say to tighten it up hard. Then, as mentioned you back off (or tighten from a somewhat loose position) until you can just nudge the keyed thick washer from side to side with a screwdriver tip. Ideally, you are supposed to be able to do this with no prying action at all (the stamped metal cage for the rollers is easily bent) but just barely. I afford myself a little careful prying at times. This means there is a little play in the bearings when you get the wheel back on and try to move the top in and the bottom our, or vice versa, which is what is specified. Often you will find that you go back and forth trying it a little tighter, a little looser, but that is easy and not time consuming. When satisfied, you use the Allen wrench to tighten the pinch bolt, smack the cap back on the hub, and you are done with that side.

If I have had the hub off to replace or service the bearings, replace a brake rotor, or for some other reason, I tend to do this a couple of times - tighten, back off, tighten. You are trying to make sure the bearings are set, and you have squeezed out from contact points all the grease you can, so that your final adjustment will be accurate. There will still be plenty of grease around to do its job.

The rear wheel bearings, on the other hand, and the front bearings on the 964s and newer cars, are designed to have the nut and so on keeping things together very tight, to a torque specification which is pretty high. It is a different design of bearing, made for being tight that way, and requiring it. In 911s of any vintage, any wiggle to the rear bearing (via shaking the tire) is an indication that the bearing needs to be tightened, but more often that it is worn out and needs to be replaced. Same with the fronts on the later cars.

I've tended to run my angled fronts a bit on the loose side. This has had no ill effect, and I don't think I have ever replaced one of these bearings on my cars which was so worn it needed replacement. None have run out of grease (even when the grease seal on the inside has failed), or been all blue when inspected, or pitted. But running them to spec is the way to go.

Just not really tight, so there is zero play.

[Jesse16]

Thanks for the feedback Walt and the adjustment detail. I'm definitely more of your mind when it comes to the tightness. This is "old school" stuff. I've just gone tighter as I assumed others were looking out for me at a performance DE event, not just going straight down the highway. Maybe guys with shops are more sensitive about customers coming back being told their bearings are loose. It can all get a bit subjective maybe. I was able to adjust at the track without issue the one time I was called out on it. Who knows, maybe I was a tad loose.

[Walt Fricke]

I knew I had my terminology wrong, so I looked it up.

The front bearings are "single row tapered roller bearings," and they need only a very little preload (almost none, in fact).

The rears are double direction angular contact thrust ball bearing. The way these are set up they are basically two ball bearing sets side by side. The axle parts (drive flange with the brake rotor and wheel studs in it surrounds and engages with splines the stub axle, which comes in from the inside and the CVs and so on) are drawn together by the big nut on the outside, which is on the stub axle. This compresses the inner races of both bearings together, so all these parts are clamped together. Any preload needed by the bearings themselves is already designed into them, and I don't think the clamping force affects that much, if at all. The clamping is needed to keep all this stuff together delivering the torque to the rear wheels. Which is why there can be no looseness there (or with that kind of bearing, which is now at the front starting with the 964s).

And if you could remember those terms, you could stump a tech inspector. Maybe you wouldn't have to explain that you adjusted according to the factory manual, and that, in fact, you have it right. You know you are too tight when you can't move that washer, even if you twist a big screwdriver's end a bit against the bearing cage. You've got to try moving from various positions, as some part of the washer will generally be as far as it can go one way, so you are pushing it back to center, or over it.

[E Sully]

My friend is a Master Mehanic for Ford. He told me that they are taught that the front bearings are better a little loose than tight. I would think that as the bearings warm up, they expand.

[Walt Fricke]

That's been my approach with this kind of bearing, too.

[Raulg]

Will a worn or loose front wheel bearing cause vibration?
My 88 Carrera starts vibrating at 45 mph. I have looked for play at the wheel at 6 & 12 oclock positions and the wheels appear tight.
I have had the car for over 15 years and the bearings haven't been touched.
Should I tried tightening the assembly at the pinch bolt/nut?
Thank you in advance for any advice you can provide.

[tharbert]

These bearings very seldom wear out but are an easy DIY replacement job for someone getting to know their car. Do as some of the above posts suggest. Jack up the front. Grab the tire at 12 and 6 o'clock and try to rock the tire back and forth on the vertical plain. The feeling is subtle but, if they need adjustment, you'll feel just a little play. At that age, I'd pull the bearings, clean and repack. Make sure to replace the seal. Pelican Tech page.

[The cap'n]

Not the first thing I'd look at. Ball joint, tire balance, or internal damage to the tire would be where I'd start. Is it a vibration or maybe more like a wobble? A wobble can be due to alignment, and (again) tire damage.

The Cap'n

[E Sully]

Out of ballance tires caused my front end vibration.