So changed the clutch today and found what appears to be little crack on the flywheel

Is it time to change the flywheel or is it nothing to worry about..... Hopefully..

 

It needs changing!

 

I'm no expert but i would say it needs replacing. Be interesting to read what others say.

 

Ok, this is just my opinion, and I'm not a mechanic or anything, but I would *definitely* change that if it was my car.

When you rotate a heavy lump up to 7.5-8k RPM, it stores up a *lot* of rotational energy, which causes stress in the flywheel itself. If it does self-destruct, then it's possibly good bye gearbox bell housing, and/or the section of the bell housing that is part of the engine.

Also, as the flywheel is in line with your leg / passengers leg, you could also severely injure yourself.

There are lots of videos on youtube if you look for broken flywheels.. Here's a small selection:
flywheel through bonnet: making an rx7 jump:

 

Seems strange its just in the middle, it's not on the inside or outside

 

The position is strange, but definitely change it. Given the amount of energy going through it and the rpm they spin at the potential for massive destruction is huge.

 

this is my favorite flywheel video.................V-TEC YO

 

It needs changing. If you look closely at the 2nd picture there are multiple hair line cracks.
It's not worth taking the chance imo

 

Definetly change!

 

Like a bomb going off in your engine bay.

 

Multiple heat related surface cracks (although that particular one looks pretty bad)
Can usually be removed by machining but in this case would think replacement.

 

looks like ill be after a new FW

 

Ok, talking from experience I have seen fissures like this on solid flywheels during clutch changes. Did not replace flywheel (due to low value of car, dealer requests on sales pitch cars, or warranty company refusals etc ), and nothing came of it.

This, I must add was on everyday cars, like Fiestas, Astras etc. So the only abuse they see is clutch riding at lights and junctions. One car was driven by an oldish guy who constantly slipped the clutch and we had to change it every 6 to 8 months; The flywheel had severe heat damage, all colours of the rainbow and lots of fissures.

Anyway, if it were MY car, I'd change it, because whilst I don't ride clutches I do do 4K+ rpm hard standing starts, flat shift, and regularly run to to the red line. As noted from the vids, it's when doing stunts like this is when they fail. (Along with gearboxes and driveshafts ), don't forget clutch covers (pressure plate) can also explode in the same way too as thats a hefty chunk of metal, so bear that in mind when sourcing parts from dubious sources (eBay, Bedroom seller, China etc.).

I will add one crack in the last picture appears to extend beyond the friction area towards the ring gear, that does look like a biggy, and its this one that bothers me, the others are mostly just surface fissures IMO.

So yeah, unless you drive like Miss Daisy, change it! And the same goes if it's been lightened or is a aftermarket item.

 

How many peeps would even be looking / inspecting their flywheel

 

its only done when clutch is changed...

at least get it skimmed, or ideally id replace it. running/bedding in a new clutch without doing either will end up not bedding in too nicely and may even vibrate/feel lumpy (going on previous experience )

had 2 done on imprezas - one on my old hawk using my existing flywheel but skimmed and it was perfect, another using a previous skimmed flywheel and it can vibrate a bit. next one ill just be replacing the flywheel.