Would you reuse these rear hubs?

[kstylianos]

I took the trailing arms to a local shop to remove the hubs, bearings and races. The hubs were returned to me in this condition. The trailing arms and hubs were cleaned up and when I brought them to another shop for pressing, they said they would not feel safe reusing these hubs (the original shop was closed on sat. afternoons). So I took them back to the original shop on Monday and they said 'the hubs look fine', would press in no problem and they would 'help me out' if there ever was a problem down the road. Sounds like the original shop does not want to take responsibility for the damage and the other shop does not want to install suspect components. The damage looks to be right underneath where the race would sit. The shop said the race has plenty of meat to grab onto good parts of the hub.

BTW: I asked about their method of race removal and they said they cut a slit into the race and used some heat and an air chisel to spin it off. Looks like the air chisel made contact with more than just the race. 'We do this all the time'.

What should I do?

[masraum]

Yikes, nope, I'd be pissed.

[ChrisBennet]

This is exactly why a lot of us do everything we possibly can ourselves.
-Chris

[APKhaos]

Charlie,
I'm afraid they are toast. Butchered!

Here's part of an article on Porsche wheel bearing R&R that sheds a little light on the issue:


With SOME cars, you can just whack out your wheel bearings
with whatever is handy. Like your old Chivvy Caprice.
That is NOT the case with your precious Porsche.
The only proper way to remove the outer races from the hubs is to heat the hubs up first.
Then the only proper way to put new ones back in is to heat
the hubs up first (and, if needed, use a real bearing press with
real tools and which pushes straight).
If you do it any other way on these cars, you might as well
just FedEx your entire credit card collection to George B. and be
done with it.
Okay, you might get away with whacking them once, but that
method WILL take tens of thousands of miles off your hub life
(not bearing life, the hub thingie they're mounted in).
Here's why.
Your hubs were engineered and machined ONLY for the bearing
outer races to be removed and/or installed by first heating the
hub. The reasons for this are quite numerous, but mostly they boil
down to the types of materials used, the press fit needed, the
size "set" the outer race takes, and the "roundness" that has to
be maintained. It's all messy, so just believe me and we'll go
on from there.
Here's what happens when you don't heat the hubs and just the
outer races in and out with a nail punch or something similar. When
you whack the race out of the hub, you're actually moving material
in the hub...that's not designed to be moved. We're talking
thousandths of an inch here where the hub is completely ruined...
nothing you can see. Oh, and you'll make it egg-shaped by a couple
tenths of thousandths, to boot. Every time. You can't help it. Since even the worst POS bearings are made to hundred-thousandths tolerances, this is not a Good Thing.
If you whack a new bearing race in, you're doing the same
thing, except in reverse and maybe a bit straighter this time...
but don't count on it. You'd be surprised what's happening down at the thousandths-of-an-inch level when you're in the garage trying to eyeball it with a sledge and a piece of driftwood.
Okay, even if you only do it just once, the press fit is gone,
destroyed, gone forever, never again what it is designed and machined to be.
We're not talking the whack-in, whack-out liberties you
could take with your old Chevy Caprice...this is a genuine German
engineered thingamajig and machined to tolerances Chevy never
heard about until they started taking apart German cars.
What are the consequences, other than the bearings no longer
running true (also not running precisely parallel to each other, a
whole 'nother topic (called cranking) for another day)?
Sooner or later, and MUCH sooner if you log any track time,
the outer race (probably of the inner bearing first) will start to
turn in the hub.
At that point, there isn't anything you can do except call
George B. or one of the other guys, tell them you need new hubs and beg for mercy from Visa.
The reason those hubs are so expensive? Well, besides that
they're carrying Porsche part numbers...the extensive and exacting machining work, especially to...you guessed it...the areas where the bearings press in.

[kstylianos]

I am pissed, Damn pissed. The reason I took them to this 'reputable' shop is that they would know how to do this procedure correctly. I thought these hubs were hosed, now I know for sure.

So, how should I proceed with the shop that did the work? I just cannot demand that they replace the hubs.

[Superman]

Calm down. I'm not going to disagree with anything offered here, but I will point out that the above discussion of the importance of heating and pressing related to the fact that the bearing sits in an ALUMINUM trailing arm. The hub in the pictures above is steel. I'm not suggesting the hub is okay...indeed, it looks ugly. Just pointing out that the above passage seems to be talking about the importance of not scratching or wearing the aluminum hub retaining surface which is in the banana arm.

As ugly as the hub looks, that hub gets pressed against the bearing inner races with about 300 lb-ft of torque. If it's messed up, it can still wiggle even under that force. But it's just possible that the force of the castle nut can keep it still (steady) against the inner race.

I am a complete ignoramus in matters of rear suspension fittings, so please do not imagine that I am speaking from knowledge or experience. For the question you have asked, you need some real experience/expertise.

[kstylianos]

Superman,

That was my initial thought, the hub does get pressed into the inner bearing, then torqued to spec. I understand the hub itself does not spin within a bearing, its essentially attached to the inner races once its pressed home. My concern is if the hub does not slide into the bearing, as the damage may be too extensive, material may have to be removed causing a non-uniform (looser) fit all the way around. I don't know what the down the road consequences of this 'loose' fit may be either, and am hoping for some expert input. BTW: I'm still pissed they were butchered

[Superman]

If there are raised burrs on the hub, then they would probably need to be smoothed. Once pressed together with enough force, the parts may be stable. If not, then the hub (which is already toast) gets ruined along with the bearing and possibly the stub axle (or whatever you call that thing that bolts to the CV joint). The banana arm might also be at risk, but before it is ruined, it seems to me you would first be able to notice a bearing problem.

So, one option is to scold the perpetrator soundly, including in writing, and then let them put it all back together with their promise that either everything will be fine or, if the bearing starts making noise, you take it to the dealer where they replace everything and send the bill to the perpetrator. Option two would be for the perpetrator to replace the hub now.

But before you do something really silly like act on my advice, I'm hoping to hear from someone who has seen three hundred good hubs and a hundred bad ones, and has installed dozens of each.

[Green 912]

I don’t know about heating the hub as I dremmel the race off without cutting the hub and then COOL the hub and HEAT the race to fit new parts together. Hub gets smaller and race gets bigger. Plan and prep and things almost fall in place with little violence. You would have no problems with fit, as the bearing is a strong interference fit. The thing that is missing in this thread is the grinding has left not just visually unpleasant gouges but functionally unpleasant stress risers.

The right way to dremmel a race is to cut 3/4 way through the race parallel to the shaft and then pop it open with a well placed hit from a dead blow mallet and sharp cold chisel. The sucker pops open and slides right off and you never touch the race bed or ding up the shaft ends with a press or puller.