Cracked stock flywheel, common?
 

The stock OEM flywheel on my 93 R1 has/was cracked, discovered it while having a new clutch installed. The car has 58,000 on it, and the drivetrain, engine, turbos are all completely stock, no mods at all. In the 9 years and 17K miles I've owned it I haven't abused the car with drag starts or popping the clutch or anything ( I am 57 after all) other than autocrossing, so I was wondering if this is a fairly common problem with OEM FD flywheels, or was this one just too much old beer can and not enough steel?

Turns out what I thought was a slipping clutch was actually the flywheel flexing, so the Excedy clutch I bought wasn't needed, but it's going in anyway.

I have never heard of an oem flywheel cracking. You may want to consider a lighter flywheel when replacing it. Light flywheels are very street-able. I recommend keeping the stock clutch for your use. Many times, aftermarket clutches don't fit exactly right ............. low pedal engagement. You don't need a heavier clutch.


Adam

The Excedy Stage One is very close to a stock clutch replacement, clamp load wise. I've had one in my Miata for some time and really like it.

I'm thinking of going with a Racing Beat Light Weight Steel flywheel - at 17 lbs plus counterweight - instead of another OEM unit, as the cracking has soured me on those. A couple of pounds won't make a difference, I know, but I've had good luck with Racing Beat stuff on my Miata.

like cracked on the mating surface or cracked like in half?

cracking on the face is common due to high heat from stuff like clutch slipping, slow clutch releasing, city driving, etc.

normally you can get the flywheel machined like a rotor for that situation, unless the crack is too severe, at 58k miles i dont think it should be too bad, but ive seen weirder things.

kevin

It's cracked through the mating surface, to deep to be resurfaced.

You should weigh your flywheel. I'm thinking that they are about 20 lbs (as my poor memory serves me). If the RB flywheel is17 (plus the counterweight) that won't make much of a difference. I bought the SR Motorsports flywheel. I think it is about 12 lbs (including the counterweight). Definitely not too light for street driving, and will give you a little better acceleration.

The surface of the pressure plate and gets cracks in it all the time. At an autocross you are probably doing your best drag launch you can w/o all the sticky surface of an actual drag strip.

I'm thinking your cracks are in the surface, not all the way through the flywheel. Any pics?

Don't use it if the cracks appear to be deep or substantial. Have you ever seen a flywheel that let go? I have, and it's not pretty--it can pretty much destroy the car (and you) unless you have a safety bellhousing.

+1 for replacement with a lighter unit.