Did I Trash My Rear Wheel Bearing?

Rasta Monsta · Rasta Monsta's Garage

I was just working on my aluminum armed 924, and think I screwed it up! I had the bearing replaced by a machine shop, as the arm was out of the car. I installed the arm, and began buttoning up the brakes. I thought replacement of the handbrake shoes would be easier without the hub in the way, so I popped out the stub axle and began tapping on the hub with a hammer. Bear in mind, this is a ZERO mile assembly, and the axle nut has never been tightened. The hub started moving, but when I turned it to tap in a different place, I felt the crunchy crunches of an unhappy bearing. I stopped tapping immediately, turned the hub a bit to assess the damage, and bolted the stub axle back up. With the stub replaced and axle nut tightened, the bearing feels fine, and is as smooth as the other one. Do you think I damaged the bearing? Should I trust it at all, or just replace it immediately?

YAR!

mikepellegrini · mikepellegrini's Garage

I don't understand what you're talking about. You're saying the (unlubricated?) bearing ground on something as you tapped on the hub?

Bearings are really hard so I'd really doubt you could make a gouge in one. I'd think the bearing might shatter first - although that's also unlikely. And the bearings in there are big ones - not some lightweight stuff.

If you put it together and it spins okay, I wouldn't worry about it. If you're still paranoid, then make periodic inspections for play. But if nothing turns up in the first month or so, I'd relax.

Rasta Monsta · Rasta Monsta's Garage

Not really ground, but it felt clunky, and UNsmooth. I agree those things are beefy, and I only whacked the hub 2-3 times with The Persuader. . .

924RACR · 05-17-2010, 03:45 AM

What Mike said - if it turns smoothly and without play, then I'd feel safe driving it... wouldn't hurt to go back and recheck later, but probably not a problem.

944 Ecology · 05-17-2010, 04:05 AM

If you damaged the bearing, you will know it soon enough. Just button it up and take it for a few test drives before you flog it in earnest. And, oh, you probably should order a spare just in case.

Porch · 05-17-2010, 06:50 AM

Even though it's zero-mile, the inner race is a tight fit on the axle stub. When you were tapping it out, you pressed the inner race out of the outer race and probably unsealed the seal on the side. Then you put it back together and it all went back to normal...except, probably, for the seal.

Your call on whether you put it back together like that. You'll probably be fine, but you may lose all the grease in a short amount of time too.

matthewb · 05-17-2010, 08:38 AM

I agree. Its very unlikely that you hurt the actual bearing itself unless the cage cracked. The part I would be concerned about is the grease seal. If you did pop it out it will probably not go back in and seal properly. If you think you popped it out I would consider replacing it.

bazar01 · bazar01's Garage

Quote:

Originally Posted by Rasta Monsta

I was just working on my aluminum armed 924, and think I screwed it up! I had the bearing replaced by a machine shop, as the arm was out of the car. I installed the arm, and began buttoning up the brakes. I thought replacement of the handbrake shoes would be easier without the hub in the way, so I popped out the stub axle and began tapping on the hub with a hammer. The stub axle sits on a very small section of the inner race and will not stress or damage the ball bearings when you tapped it out.
It was when you tapped on the hub that probably did some indentation on the ball and race because the hub sits on the full width of the half of the split inner race, if you know what I am talking about. The split inner race is a press fit on the hub journal that is why most of the time the inner race separates from the outer race and is left on the hub journal when it is tapped out.

Bear in mind, this is a ZERO mile assembly, and the axle nut has never been tightened. The hub started moving, but when I turned it to tap in a different place, I felt the crunchy crunches of an unhappy bearing. I stopped tapping immediately, turned the hub a bit to assess the damage, and bolted the stub axle back up. With the stub replaced and axle nut tightened, the bearing feels fine, and is as smooth as the other one. Do you think I damaged the bearing? Should I trust it at all, or just replace it immediately?

YAR!

Normally when the hub is out of the aluminum arm, the bearing is considered trashed. So when you tapped on the hub and it already started to come out, damage could aready have been done on the balls and races.
But it's your call, you can pu everything back together and test drive it. If it hums or makes a wub-wub-wub noise, it is damaged.