rxseven

I cannot decide if i should use new bearings. The rotor bearing surface is in great shape but the front main bearing shows a scratch or 2 and there is a patch where the grey coating (whatever it is) has worn off and a bronze area is exposed. About 1/4" x 1/2" area. I have been reading the mazdamotorsports.com tech section in which it says "if the flaking is less than 1/2 the total bearing surface, reuse the bearing as an old one is prefered to a new one"

WTF?? That seems like a lot of wear to me!



Gurus, please confirm this for me so that I may get some peace of mind when I slap everything together. :unsure: :unsure: :unsure:

13BAce

If you replace the bearings make sure to extend the break-in period.

isamu

I noticed similar wear on the bearing of my front rotor. Is this common? I was debating on replacing them also.

13BAce

I can check some spare stationary gear bearings tomorrow, but I don't think I've ever noticed it.

isamu

That would be cool man but if you haven't seen it, it must not be common (Isamu bows to the infinite wisdom of 13Bace).

If I can get a good pic tomorrow I will post one of the wear on the bearing.

13BAce

Yeah, a picture would be a good idea.

isamu

Here are a couple of pics I just took.

isamu

This one is better

13BAce

That looks pretty bad to me. It doesn't look like normal wear to me. How do the stationary gear bearings look?

rxseven

Ok, i did some research into this, looked up some sleeve/journal bearing books. The sleeve would be an alloy of bronze, tin and is "highly leaded". I am assuming the top coat would be the leaded part being an excellent anti-friction material (so don't lick the bearing surface!). Theoretically, there should be no wear because the oil prevents metal to metal contact but since them funky mazda guys put an oil bypass, I am sure that's the main reason for the wear you see. I have similar wear but not to that extent. The only reason i see as to why mazdaspeed recommends using old one even if only half the surface is intact is because this outer layer is thin enough so that the worn bearing is still within tolerance. The std clearance is 0.002". If this made it 0.0025", it may be preferred. Really for race applications don't they have additional clearanced bearings anyway? Damn it, I wish I had an inside micrometer.

I am surprised 13BACE has not seen this before! He seemed to know it all