Front wheel hub exfoliation corrosion

[PNW Targa]

It's always a joy to unearth bigger problems when completing a simple job, isn't it? In the midst of a brake overhaul, I noticed some pretty significant corrosion on the front right wheel hub of my 1971 911T (pictured below). I believe this is referred to as "exfoliation corrosion". With the way that it's bubbling up and revealing all of those flaky layers, I'd have to guess that this hub is toast.

So, I have a few questions for the group. First, what are my options for replacement? A new Porsche hub runs ~$600-800. Ouch! Second, the left side doesn't look nearly as bad. Should I go ahead and replace it as well, assuming it's likely to be as weakened internally?

Finally, is this a common occurrence with these older aluminum hubs? Or might it be a result of past damage? It looks pretty ugly. But I guess it's better to discover now than while out on the road.

[mepstein]

I've seen this a lot. Mostly cars on the east coast and midwest. It's just heavy corrosion. If it's just bad on one side, just replace the one hub with a similar side.

I have some hubs from my 67 that are just falling apart. The rest of the car wasn't much better and needed a lot of metalwork.

[Locker537]

I haven't dealt with that, but it doesn't look good.

You can go new or get a used one from somewhere like dc auto (https://www.dcauto.com/). dc is very good to deal with in my experience.

[wrxnofx]

The Porsche tax is stupid for a new one. Just grab a good used one unless you’re interested in concours. Then buy a used one, media blast it, and clear coat it or cerakote it.

[PNW Targa]

Hah! Definitely not a concours vehicle. Just a good driver with surprisingly little rust overall. That's why I'm surprised at the condition of the wheel hub.

Thanks, Locker537, for the dC Automotive suggestion. Nothing currently in stock, but I'll keep checking. I'm fine with a used hub. Just want to be sure I don't end up with something that's also suffering from heavy corrosion. The condition isn't always entirely apparent when shopping online. Going with a reputable used part vendor can help in that regard.

[wrxnofx]

Sounds like an AWESOME ride. Color me jealous for sure.

Maybe put out a WTB ad here? I don’t know if a front wheel hub on a ‘71 is the same as for a G body car. Someone on here has to have a good one they’re willing to part with.

Actually, just checked. Looks like an F body wheel hub is different from a G body hub. So that narrows the options down. Looks like you are looking for PN 901 341 065 04.

[wrxnofx]

Here is a pair in the Bay for $450.
https://www.ebay.com/itm/224139975572

[Arctic Rat]

Brand new $250.


https://www.ebay.com/itm/324426954364?fits=Year%3A1971%7CModel%3A911&hash=item4b895a767c:g:WFUAAOSwlyBeOvO1&amdata=enc%3AAQAHAAAAoKw3FTdsSKXtXhDBMYs1vy53qotOv djFJVl5m8UUOdMMFmC1kL0sFsEjk1kYPVTUKK3rSljBlG7TbRN BfC6Kfk2K2YHxA10QM%2Fzvxt%2FfXPwdOqPrAUfvG9DLkNa%2 FnbfwjhxvXICE%2F%2BQZqUNWHFz65olbYZ4cbANQdKXaLWxhz 3V3q23a%2BQlv16o8qQ2s2nZ0ZOo5v09pHDSJtLmRswuwkhA%3 D%7Ctkp%3ABk9SR7aJ5-66YQ

[PNW Targa]

Well the left side hub doesn't show any signs to corrosion. Strange how bad the one on the right is. I'm going to go with a used hub to replace the corroded one. If I were buying new, I would replace both. But I won't really know if a used hub is any better or worse than the good one that's currently on the left. So I'll likely just replace the bad one on right for now.

So here's my follow up question... When I receive the replacement hub, is it likely to come with an inner bearing? If so, should I trust it, or replace it with new? I don't have a bearing press, which may limit me. The outer wheel bearing disassembly/assembly is pretty easy. I'm less clear on what's involved with that inner bearing in terms of pressed-in seals/races.

[mepstein]

It won’t come with bearing or seals.

[Walt Fricke]

It is likely to come with both the pressed in races, but not either bearing. You don't need a press to remove either race, and new bearings with both races are cheap. You can use drifts (a brass one would be nice, but I've not had issues with steel ones) to drive both out. To drive the new outer races back in, it makes sense to go to your local NAPA or similar parts store, and pick up a set of aluminum bearing race drivers - disks with tapered sides and a ridge, and a steel handle you can pound on. Not at all expensive for a basic set with several sizes. I used to drive them back in with the drift until I got smart.

I bet if you search for how to replace front wheel bearings on a Porsche 911 you will find some nice how to's, step by step.

That flowering (flouring?) is wierd. Electrolysis? I'm not sure it has damaged the hub - I'd be inclined to grind it off and see where the good aluminum begins again, and go from there. Concerning, no doubt about that.

[PNW Targa]

I had a feeling that I was in for race removal and bearing replacement. There are a good number of YouTube videos out there on front wheel bearing replacement. I've really enjoyed the series put together by Greasy Fingers (a G body, yes, but still relevant), however his shop is pretty well decked out. His use of a hydraulic bearing press shook my confidence.

I'll take your advice, Walt, and look for an aluminum bearing race driver set. It will be good to know that everything is going back together with new parts. I was happy to see the wheel bearings well packed with grease during disassembly. It looked like this car hasn't seen too many miles since the last wheel bearing maintenance.

The corrosion on this hub gives the appearance of bubbling up from below with many flaky layers expanding outward. The first picture shows the worst spot, but similar bubbling/expansion is present elsewhere between the wings of the hub. Perhaps it could be ground away, but with the forces experienced by a front hub I'm reluctant to keep using it.

Once I've located a replacement, I'll get to work on the bearings. Thanks, everyone, for the helpful input.

[mepstein]

Most of the flaps - autozone, advance auto, etc will lend the race setting tool for free.

[wrxnofx]

Nah, you don't need any kind of press like the YouTube guy. You're fine. A press is ridiculously overkill, and he's mixing up his own paint and using an airbrush to touch up seat rails. I didn't even use a press to install the rear wheel bearings/hubs.

Walt is right that this hub will probably come with the old bearing races still in it because everyone is lazy.

All you need is a brass drift/punch which you can get from Amazon for under $30 - brass is very soft so it won't damage the hub as you pound it out.

To insert the new bearing races, you'll want to rent an aluminum bearing race installation kit. You don't need to even buy one - go to your local autozone and rent one. I literally just rented this one 2 weeks ago for my bus.

Again, the aluminum on the bearing race installers is softer than the steel races so you won't damage them on install.

[PNW Targa]

Excellent suggestions, mepstein and wrxnofx. I hadn't considered the loaner tool program. I've also now got a set of drift punches coming my way. With those and a borrowed race driver, I should be all set. Just need to get the replacement bearings ordered.

[bkreigsr]

FWIW, all hubs are not created equal - here's a little primer:

Can anyone confirm: front wheel hub depth '67 vs later

[mepstein]

I leave the races in until I bead blast them clean.

[wrxnofx]

Awesome, great to hear. You'll also want to get a new seal in addition to the bearings.

Just reach out if you run into problems.

Another option is to reuse the bearings from your existing hub if you didn't have any problems with them before. If you go that route you'll still need a new seal, and then you'd probably want to get a seal puller. You'd then want to repack the existing bearings just as if it were a new bearing.

Remember - it's a Porsche, not a puppy.

[mepstein]

You don’t want to use bearings from one hub and races from another.

[wrxnofx]

Originally Posted by mepstein

You don’t want to use bearings from one hub and races from another.

Fair point, but I didn't say that. I said he could reuse his bearings from his OLD hub. That means he'd drive the races out of his old hub and drive them into the new-to-him hub (after he drove out the ones that came with the hub).