Bad rotor bearings? (pics)
 

I tore down my first rotary yesterday and was a little suprised at what the rotor bearings looked like. Do these look reuseable?

im guessing no, i could be wrong, can you catch the grooves with your fingernail?

im no engine builder, yet, tho.

kevin.

It looks like "water stains" after you washed it with some chemicals?
If it's not grooves, the bearing is fine.


-Ted

Mic the bearing and see if its within specs. If not, I would have a new one pressed in. I have the tools to press them in. $20 each rotor plus parts and shipping.
Thanks Robert

Here's the other bearing. The seam is show more brass for some reason, but less scratches.

God I wish I knew what I was looking for/at :(

I really need to watch a video of someone rebuilding an engine, hahah.

have they had any problem moving? I meen I don't know too much about the rotor bearing but they don't look too bad. It really does look like marks from cleaning it with something (like windex lol), if you have the time and money while thier out might as well put new bearings on though.

id replace em man why not? there no overly spendy and if you have it apart you might as well do it right

Copper showing at the seams is not a big problem.
That's normal and not a problem to reuse.


-Ted

Actually, not correct.

Used bearings are more desirable versus new ones.
New bearings take longer to break in properly, and almost any Mazda reference will recommend you use used bearings if they are within spec.


-Ted

Ted I think you stated once that new bearings were more likely to spin than original bearings as well. Hence the recommendation to always reuse bearings unless out of spec.

I would reuse those bearings unless those are deep scratches...but they are not, else copper would be showing through. The general consensus is that less than 20-25% copper showing on a bearing is reuseable.

And I am in the school that used bearings are superior to new ones.

1) used bearings have been heat cycled thousands of times, and are therefore stronger than new ones.

2) used, oem installed bearings NEVER spin unless someone runs the engine dry of oil. IN contrast, I see many more spun bearings, for no apparent reason, on rebuilds where they were previously replaced. This leads me to believe that replacing bearings makes them more likely to spin in the future. unless I have to, I prefer to leave the originals in place.

3) the originals are already perfectly clearanced for your shaft. The new ones will need to be clearanced to fit, this is just one less thing to ponder on when reusing bearings.

4) your breakin is less of a concern with used bearings...no worries about bearing babbit contaminating your oil supply and requiring a swift oilchange.

5) less cost and time during the build. That's $100 for FC engines and $150 for FD engines that you've saved. You can put that money toward something far more important such as new coolant hoses, cleaned injectors, a fuel pump, etc.

I agree, those bearings are fine.. If those aren't scratches on the first pic, I'd say go for it... and if they are.. .it would depend on how deep it is, if its deep you might be able to rub it out with some 600+ grit paper... Copper showing isn't bad as long as the diameter is within spec and not out-of-round. Rotor bearings shouldn't really ever touch your eccentric shaft while running.

Shitty OEM bearings are WAY better than pressed in new bearings in my opinion.

Next engine I do, I'm buying a mazda reman. Always new rotors(with new bearings pre-pressed in and new housings(most of the time). Great source of new parts.