I'm looking at the Parts diagrams for a 89 rx7. Page 1H3 for anyone that is curious.



I see two listings for main bearings.



0820-10-502B (STD)

N350-10E02 (OS)



What is the dimensional difference between the two? I see that mazdatrix only sells the STD. Also if you order a new stat gear (they come with bearings preinstalled) You will get the std size right?



Also I'm reading the FSM here Page C-41. And I'm trying to find the dimension for the OD at the main journal bearings. The manual only gives you clearance required between the bearings and the journals. But not the actual sizes themselves. Anyone happen to know from experience what are the expected dimensions for jounral OD, and bearing IDs for stat gears and rotors?

The OS bearings are for ecc shafts that have been machined to remove damage to the journals. The OD should be the same, but with a smaller ID. J9 might be able to give you a number, my curiousity stopped with it requiring machining to the ecc shaft.

yeah mine just says std and os. thats the dumb part of mazda's books, they list the fd bearings by +/- from standard, but nowhere do they mention what standard is.