Engine Bearings
06-19-2002, 01:02 PM
#11
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Join Date: Nov 2001
Location: Bay Area, CA
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Originally Posted by rxseven' date='Jun 19 2002, 02:19 PM
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
I am surprised 13BACE has not seen this before! He seemed to know it all
06-19-2002, 05:51 PM
#12
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Join Date: Apr 2002
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Interesting point is mazdaspeed tolerances on bearing clearance is more lax than the factory manual. It also says to allow an additional 0.013mm clearance at the rear portion of the rear gear for eshaft flex. It also says for over 8500 rpm operation your clearance should be atleast 0.001" higher. Point is the only way to be sure is actually get a darn inside micrometer. But it does seem that the flaking you see will not put the bearing out of tolerance.
06-19-2002, 06:04 PM
#13
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Originally Posted by rxseven' date='Jun 19 2002, 07:51 PM
Interesting point is mazdaspeed tolerances on bearing clearance is more lax than the factory manual. It also says to allow an additional 0.013mm clearance at the rear portion of the rear gear for eshaft flex. It also says for over 8500 rpm operation your clearance should be atleast 0.001" higher. Point is the only way to be sure is actually get a darn inside micrometer. But it does seem that the flaking you see will not put the bearing out of tolerance.
06-19-2002, 07:18 PM
#15
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Originally Posted by 86gxl' date='Jun 19 2002, 09:17 PM
thats not too good just redo it .it will be worth it when your turning 10,000 RPMS
06-20-2002, 01:32 AM
#16
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Join Date: Feb 2002
Posts: 78
Personally, i'm thinking u would be better off replacing the bearing, and wearing the extended breakin period. Far better option than finding out in a few months that u need to pull the engine down again, or having some high rpm failure.
06-20-2002, 11:38 AM
#17
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Join Date: Apr 2002
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besides the flaking, there is nothing wrong with it. I think i will stick with conventional wisdom and just get another used gear or a new bearing. By the way, is the mazda tool necessary to press the new sleeves in or can any machine shop do it?
06-23-2002, 03:21 AM
#18
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Join Date: Jan 2002
Posts: 27
Totally replace anything when your engine is in pieces I say. I mean, if you know it's dodgy, or even possibly dodgy, replace it. Saves another rebuild before it's due. And as for replacing rotor bearings, if you get a shop to do it for you, stay and watch the whole time. Took ours in to be done, vise marks all over the surface, corners all bent in, no gap for an apex seal. Major setback.
06-23-2002, 11:17 PM
#20
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Join Date: Jan 2002
Posts: 27
Originally Posted by rxseven' date='Jun 24 2002, 01:53 AM
damn bro, what a waste of a rotor. I am planning on sending it to a rotory shop like mazdatrix and have them install the new bearings. I would gladly pay shipping and get it done right.