12a v 13b bearing sizes
12-22-16, 12:52 PM
#1
Full Member
Thread Starter
12a v 13b bearing sizes
Hey hate to clog up forums, but I did search and I'm a little confused now.
I decided to rebuild my spare 12a. But I can't find bearings anywhere local? The mazda dealer near me only has parts back to 86, which means 13b, right? My 12a hasa bearing with copper showing and I want to replace the whole set now. I mic'ed my crank and it's factory spec, on the high end even. So the question is, can I put 13b main and rotor bearings into my 12a engine?
I decided to rebuild my spare 12a. But I can't find bearings anywhere local? The mazda dealer near me only has parts back to 86, which means 13b, right? My 12a hasa bearing with copper showing and I want to replace the whole set now. I mic'ed my crank and it's factory spec, on the high end even. So the question is, can I put 13b main and rotor bearings into my 12a engine?
12-22-16, 05:39 PM
#4
Yes, both main and rotor bearings are all the same from first rotary up to 1992.
From 1992 they started offering sizes. You always want the biggest for a performance build.
Then there is Competition bearings. They are big, deeper recess and windowed. First rotary through 2012 on rotor bearings are all the same part, but main bearings first rotary to 2002 (2004-12 main bearings are competition bearing spec with more size offerings).
Then 2004-2012 they offer even more main bearing sizes for manual (and they are windowed, deep recess, set-screwed) and only one size for automatic (less performance/revs- not windowed, set-screwed) and only two sizes rotor bearings manual and one size automatic.
I sub in the biggest of the '93-2002 rotor bearings because they are cheaper than the comp rotor bearings and then use comp main bearings on my turbo 13B builds.
Mazda actually recommends using used bearings for rebuilds as long as they are not contaminated and there is some overlay on the copper still (it always wears off on the seam). This is because the #1 bearing failure is high spots from pressing bearings in. If you do put new bearings in Mazda recommends a much longer break in period to wear down any high spots.
For a 12A performance build you can just buy the '04-12 manual stat gears as they are hardened gears and come with the comp spec bearings (windowed, deep recess, set-screwed) and are already pressed in all for $120Front/$150Rear. You will have to seal the rear gear with oil resistant sealant as it does not have an o-ring/groove.
Buy the time you buy $30 regular main bearings and pay someone to press them in you are almost to the '04-12 stationary gear/bearing price without the performance. If you do your own work pressing in bearings you probably do your own homework and wouldn't have asked about where to get bearings.
When using the '04-12 parts make sure the oil passages line up- may have to be machined. Same with all the parts actually- often bearing isn't perfectly lined up with gear.
Mazdatrix has a great easy to use catalogue and you can call them to confirm what I have said because I am just some crazy guy online and they are pros from way back.
The owner Dave might be a little gruff over the phone, but just don't be coy- tell him what you are trying to do without wasting his time. He knows his stuff. Usually it is someone else answering now- if you are lucky you will get Kyle who really knows his stuff too but hasn't figured out how to get people off the phone as quickly as Dave yet.
From 1992 they started offering sizes. You always want the biggest for a performance build.
Then there is Competition bearings. They are big, deeper recess and windowed. First rotary through 2012 on rotor bearings are all the same part, but main bearings first rotary to 2002 (2004-12 main bearings are competition bearing spec with more size offerings).
Then 2004-2012 they offer even more main bearing sizes for manual (and they are windowed, deep recess, set-screwed) and only one size for automatic (less performance/revs- not windowed, set-screwed) and only two sizes rotor bearings manual and one size automatic.
I sub in the biggest of the '93-2002 rotor bearings because they are cheaper than the comp rotor bearings and then use comp main bearings on my turbo 13B builds.
Mazda actually recommends using used bearings for rebuilds as long as they are not contaminated and there is some overlay on the copper still (it always wears off on the seam). This is because the #1 bearing failure is high spots from pressing bearings in. If you do put new bearings in Mazda recommends a much longer break in period to wear down any high spots.
For a 12A performance build you can just buy the '04-12 manual stat gears as they are hardened gears and come with the comp spec bearings (windowed, deep recess, set-screwed) and are already pressed in all for $120Front/$150Rear. You will have to seal the rear gear with oil resistant sealant as it does not have an o-ring/groove.
Buy the time you buy $30 regular main bearings and pay someone to press them in you are almost to the '04-12 stationary gear/bearing price without the performance. If you do your own work pressing in bearings you probably do your own homework and wouldn't have asked about where to get bearings.
When using the '04-12 parts make sure the oil passages line up- may have to be machined. Same with all the parts actually- often bearing isn't perfectly lined up with gear.
Mazdatrix has a great easy to use catalogue and you can call them to confirm what I have said because I am just some crazy guy online and they are pros from way back.
The owner Dave might be a little gruff over the phone, but just don't be coy- tell him what you are trying to do without wasting his time. He knows his stuff. Usually it is someone else answering now- if you are lucky you will get Kyle who really knows his stuff too but hasn't figured out how to get people off the phone as quickly as Dave yet.