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-   -   Main Bearing Question (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/main-bearing-question-48726/)

banzaitoyota 05-17-2005 09:03 PM

Somewhat confused here



Mazdacomp has "standard" main bearings in selected sizes to allow you to fine tune the bearing clearance. However the "3 window" bearing is only available in a standard size.



So I am assuming that the clearance for the race bearing must be fined tuned by hand to fit, vs selective sizing with the color coded bearings.

mazdaspeed7 05-17-2005 09:12 PM

3 window bearings have more clearance than standard bearings. The engines that use those bearings typically run looser clearances on the bearings to sustain high rpm better, so possibly the clearance is enough that both the minimum and maximum ecc shaft journal dimensions still fall within a suitable range for the bearing?

scottystraub 05-19-2005 07:52 AM

to my knowledge there are stock bearings and race bearings, the race have a slightly bigger id and a deeper oil groove for high rpm use. the e shaft does not get re ground like a crankshaft? am i correct on the e shaft guys?

mazdaspeed7 05-19-2005 11:31 AM

[quote name='scottystraub' date='May 19 2005, 08:52 AM']to my knowledge there are stock bearings and race bearings, the race have a slightly bigger id and a deeper oil groove for high rpm use. the e shaft does not get re ground like a crankshaft? am i correct on the e shaft guys?

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Correct, for the most part. The ecc shaft can be reground, there is an oversize main bearing for that. But the question was whyare the stock bearings available in more than one clearance spec, while the race bearings only have one clearance spec.

banzaitoyota 05-19-2005 11:38 AM

I had an interesting conversation with Stan @ SDJ last night about this. He has had more bearing related issues with the 3 Window Competition bearing than the stock. So that is whats going in the P-Port.



BTW: MAZDACOMP ROCKS!

Cheers! 05-19-2005 11:41 AM

[quote name='banzaitoyota' date='May 19 2005, 11:38 AM']I had an interesting conversation with Stan @ SDJ last night about this. He has had more bearing related issues with the 3 Window Competition bearing than the stock. So that is whats going in the P-Port.



BTW: MAZDACOMP ROCKS!

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so u using stock? U haven't even stacked the motor yet? isn't autox season already started?



From a manufacturing standpoint. The market for stock bearings is bigger, hence you can justify the cost of producing several different variants of it. The market for 3 window aftermarket bearing is low. the cost to make several different runs for diff sizes is $$$$.Hence that is probably why there is only 1 size for race bearings


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