Replace the bearing but not the race?

toddu · 08-01-2007, 08:10 AM

I'm in the process of some front end work. Figured while I had things apart I would repack the bearings (which from a receipt from the PO were new about 3 yrs ago). Races are in great shape, and so are the bearings, except one outer bearing has a bit of a ding on the outside of the tapered end. Perhaps harmless, but figure for $10 might as well replace it.

Is it a sin to not replace the race as well? Not a scratch, blemish or anything on the race.

Todd

IROC · IROC's Garage

You need to replace the race and the bearing together. They are a matched set.

Cory M · 08-01-2007, 08:15 AM

Yes, it is a sin. The bearings and their races are matched. The old race will have different wear patterns than the new bearing. Bearings look simple but are actually highly engineered and their tolerances are extremelly tight. So don't take the easy way out, replace the complete set or don't do it at all. You can call some bearing manufacturers and ask them if you need more verification.

toddu · 08-01-2007, 08:20 AM

Ok.

I've read the heat and freeze method. Do I need a special tool to get the race out/in with this method? Or will just a punch work, being very careful?

Rot 911 · 08-01-2007, 08:24 AM

I just use a long punch. I am sure I will go to hell for using such a crude method.

Cory M · 08-01-2007, 08:34 AM

Punch is simple and effective. Just don't scratch the bores! I freeze the races and use a press to install them. I don't know how much the freezing actually helps but I have a fridge in the garage so it's easy to do. If you don't have access to a press you should consider taking them to a shop that does.

Eagledriver · 08-01-2007, 08:20 PM

I'd keep using the old bearing. Save the new one for when you need it. When a bearing goes bad you'll know it. It will growl when you go around corners. To replace the races I put together a tool out of a big bolt and washers that were just the right size to push out the old races and drive in the new. Heat the hub to expand the aluminum. I put them in my oven at 240 degrees.

-Andy

barney911rs · barney911rs's Garage

I was in this same boat not long ago. I was not sure about doing the bearings, so I took everything to a local Porsche guy, and he did the work while teaching the process as we went. He used a punch and carefully drove out the both the inner and outer races in the hub. I'd suggest using a brass drift if you have one.

To install the new ones, he used the old race flipped over so the two edges were lined up perfectly. He said you have to be careful, but it works fine. After getting it most of the way in, he flipped the old race back over to finish the job. The reason for this is to provide a small edge you can use to knock it back out again. Only took a light tap to do this. He did not use any heat or freezing at all on the fronts.

Depending if the ding is on the roller bearing or on the cage will determine if the bearing should be reused. If the ding is in the cage, like Andy said, you can continue to use that bearing.