Clutch size question
 

Not sure if this is a simple to answer question or not..

I have an SA with an FC transmission and the clutch is starting to slip.

So question is; Which clutch is "likely" in the car? Can it only be one or the other or can it be either, and I wont know till I take it apart?

the transmission doesn't matter, it'll take either clutch as the input shaft is the same.

a 79-82 engine should have the small clutch as the only stock flywheels are for the 215mm clutches, but you never know.... may not be a 79-82 engine!

So I likely will have to take it apart and measure before ordering then.
(Engine was replaced/rebuilt 2 previous owners ago so yeah, may well not be a 79-82...)


Thanks, for answering.

You may be able to see in through the inspection cover on top of the engine, and compare it to the flywheel information on the FAQ page at Mazdatrix's website. Specifically, you need to locate a casting number on the engine side of the flywheel.

All you need to know is if it's '79-80 (215mm), 81-82 (also 215mm), or '83-85 (225mm).

All 225mm interchange - you can use an FC clutch on an '83-up no problem. I've done it.

You can also use a 215mm disk on a 225mm system. Done that too. The only thing you can't do is put a 225mm disk on a 215 flywheel, and you can't cross-pollinate the pressure plates since the register depth is very different.

That will help greatly thanks for the tip!

Yeah, ultimately it's all down to the flywheel.

Where it gets interesting is that the lightest N/A flywheels are the '81-82 and the '89-92, and some engine builders get fancy and rebalance them to work with different rotor sets, so it's possible to have a 12A with the lightweight '83-85 rotors and a '81-82 flywheel. This was a common mod for some forms of racing that required an OEM flywheel, and these altered flywheels are still kicking around...

So yeah, all you need to know is what species of flywheel you have and that's it.

Yeah just went through a bit of this myself. Ended up using all 215mm stuff just for the sake of fitment on my fb. Should be all good. Good luck.

peejay, you can cross-pollinate one way; a 225mm disc on an 81-82 flywheel.

You can use a 225mm pressure plate too* if you get the long bolt set from Racing Beat.
https://www.rx7club.com/forum/attach...1&d=1187973326

The 225mm disc and pressure plate.
https://www.rx7club.com/forum/attach...1&d=1187973326

81-82 flywheel
https://www.rx7club.com/forum/attach...1&d=1187973326

*It is the older design 225mm but pretty sure the newer design also fits.
https://www.rx7club.com/forum/attach...1&d=1188022242

Aluminum spacers that come in the kit work just as well on a stock flywheel as on a Racing Beat flywheel.
https://www.rx7club.com/forum/attach...1&d=1188022242

The only thing you can't do is a 215mm pressure plate on an 83-85 flywheel. I think the three alignment dowels hold the pressure plate up high enough so the bolts won't even thread in. It should be your first clue. Not you peejay, but the OP. Then there's the register depth.

I concur with Jeff.

apparently my ebay clutch kit has a 215 mm PP and the alignment dowels are spread further out, so it wont even bolt up. back to the drawing board. might try to clean and reuse the PP i took out of it for the mean time. flywheel is freshly resurfaced. was a NOS BWD kit .