so im putting my engine back together soon, luckily a friend said he would give me his running s5 n/a engine thats been rebuilt. So obviously i wanna use his rotors, e-shaft, front conter weight, and flywheel. But would there be a point of swapping stat gears?

See i have new e shaft bearings already pressed into my s4 stat gears but would s5 stat gears be better? Cuz im not sure if using the unknown condition and life remaining on the s5 e-shaft bearings out weighs the advantage of using s5 stat gears.

Well if there are any....

The question is, is there a difference between s4 and s5 n/a stat gears?

Also would it matter if im not even going over 7800rpm????!!?!? Even though i do have an aggressive streetport that makes power well up till the limiter hits, i dont want my legs severed by an explosion going over 8000rpm

thanks

 

Does not matter, niether gear set is hardened, not until 93+, proper oil hole mods and bearing clearances are the keys...if you are going to be paniced about anything exploding, worry more about the 25+ lb. inertia type stock cast iron flywheel with the heat induced stress cracks from almost 20 years of clutch scorching and unkown maintenance...

 

s5 were supposed to be hardened, but the chances of a rebuilt s5 motor from a big rebuilder having s5 gears in it, is small

 

Have not found anything to suggest the S-5 gears (N/A or turbo application), as anything special and Mazda states only the 93+ 13B stationaries as being a hardened gear set simular to thier competition gear set and states they may be used as a alternate replacement for any 13B...