Anybody know if these bearings are safe for use on a high output street car? Any durability issues?

Why? Unless youre spinning 10-11K on a daily basis, there is no need. If you live by the mantra that more is always better and the word overkill means you should have done more to it, then do it. FYI, FD rotor bearings have a deeper oil groove and a little extra clearance, just like the MFR race bearings.

So, if the FD rotor bearings are to similar spec, than the MFRs should be fine.



To me, overkill is overpowering stock internals.

Now, looking at the FD bearings Mazdatrix has their description as 93-95 -.005--.010. Does that mean the FDs have a much greater clearance than the MFRs ".0005" or am i reading it wrong?

I think youre reading it right. Keep in mind though, to take advantage of the extra clearance, you need a TII oil pump for its extra capacity. If you re going all out with the oil system, you might as well use FD stat gears and main bearings as well. The bearings are similar to the 3 window race bearings. But instead of 3 windows, theres a series of holes through the oil groove, and like the stat gears for 3 window bearings, they are grooved behind so oil can flow behind the bearing, and through the holes. The FD also uses a larger thrust bearing than the previous engines.

Did you mean the FD oil pump? Im building a TII engine. Ive got the RB hardened stats that has that done. You think the TII oil pump is enough to keep up?

The TII and FD oil pumps are the same. You should be fine then. If the pump isnt new, be sure to measure it and verify that its still in spec.

Cool, thanks for the input.

T2 and Fd pumps arnt the same as in they wont swap right in for each other, but they are fairly equivelent in function

Before Mazda came up with the FD engine the standard bearing clearance was .002-.005 of an inch. The normal clearance I have found across the board is .002 to .003 of and inch. on every engine I have checked, the Mazda Factory Racing deep groove bearings came with an additional .0005 of clearance. Basically half a thousand more clearance and the deep oil channel groove. After installing the MFR bearings I have measured and found the clearance at .0035 of an inch. The FD bearings come with more clearance then that from factory . FD rotor,front and rear main bearings are the way to go. Just make sure to measure after you press them in. you don't want to guess that your engine has the proper bearing to eccentric shaft clearances, you want to make sure.