Austarion

I recently had my flywheel machined from 22lbs down to 15lbs. Unfortunately now the springs in the clutch disc are hitting the flywheel bolts. Would anyone recommend machining down the bolt heads and the flywheel bolt surface?

why was so much meat taken off the flywheel surface? you're meant to take it off the backside of the flywheel. To me that's a throw-away flywheel - find another one and start fresh or buy an actual proper lightweight flywheel. Taking off excessive meat on a cast flywheel is asking for strength troubles.

You could always find a clutch disc with smaller profile/diameter springs I suppose.

Almost a 1/3rd of the weight of a factory flywheel? (assuming it's factory) Good effort but sounds like they either took the wrong bits off or far to much...

You sure you put the disc in the correct way...??

-Robert

dirtygalant wrote:why was so much meat taken off the flywheel surface? you're meant to take it off the backside of the flywheel. To me that's a throw-away flywheel - find another one and start fresh or buy an actual proper lightweight flywheel. Taking off excessive meat on a cast flywheel is asking for strength troubles.

You could always find a clutch disc with smaller profile/diameter springs I suppose.

The flywheel was machined at Suvic in Napier.
First I asked them to take it down to 17lbs, not 15, and then like you've pointed out, I thought they would have removed more weight from the back, but instead they've taken the front right down. Thought they would've known better.

Some pics of my lightened flywheel







The flywheel started at 10.1kg's (22.2lbs) had 2.1kg's (4.6lbs) removed and ended up weighing 8kg's (17.6lbs) with weight only taken off the outer area of the flywheel, where it does the most good...

I've seen billet 4340 flywheels come in under 5.5kg's (12.1lbs) but I would NEVER use cast iron flywheel that has had more than 25% weight removed. Rev it too high and it MAY shatter.
If it does, just think what body parts are in-line with the flywheel when it comes through the bellhousing and floor..

Thanks for that. It's obvious that my flywheel has been done all wrong.
What is the standard thickness of the flywheel?

I think they're about 25mm.

Just machine the flywheel bolts down...I dare you!

Please don't, it may kill you.

doesn't look like much has been taken off - as above, are you sure you have the clutch disc fitted the right way around?

dirtygalant wrote:doesn't look like much has been taken off ....

Superscan - Dash, reread dirtygalant... :D

I suggest you get another flyweel...

The flywheel pictured above is Superscan's flywheel, mine is much thinner than that. I've decided to go billet steel! don't know how light I'll go yet though. Has anyone gone down this path?

I run the Fidanza aluminium flywheel on mine, works well, although I did have to machine the replaceable friction surface as it wasn't true from the factory.

I run the Fidanza aluminium flywheel on mine, works well, although I did have to machine the replaceable friction surface as it wasn't true from the factory.

What is the weight?

Dash wrote:The flywheel pictured above is Superscan's flywheel, mine is much thinner than that. I've decided to go billet steel! don't know how light I'll go yet though. Has anyone gone down this path?

I have one but it is not much lighter as I was advised that to make it too light would lessen the torque and it would break traction more

10.5 lbs

They're very nicely made, I'm happy with it.

Yes, light flywheels change the way the car "feels"....it's easier to stall and it revs out quicker, but mine is a dedicated track car, so stalling is rare and low-speed driveability isn't a concern.