clutch disc hitting flywheel bolts

Dash · Post by **Dash** » Sat Dec 03, 2011 9:35 am

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?

dirtygalant · Post by **dirtygalant** » Sat Dec 03, 2011 3:19 pm

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.

FST4RD · Post by **FST4RD** » Sat Dec 03, 2011 5:54 pm

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...

Komeuppance · Post by **Komeuppance** » Sat Dec 03, 2011 6:57 pm

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

-Robert

Dash · Post by **Dash** » Sun Dec 04, 2011 10:01 am

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.

Superscan · Post by **Superscan** » Sun Dec 04, 2011 12:22 pm

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..

Dash · Post by **Dash** » Tue Dec 06, 2011 5:32 am

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

enthuzed · Post by **enthuzed** » Tue Dec 06, 2011 6:04 pm

I think they're about 25mm.

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

Please don't, it may kill you.

dirtygalant · Post by **dirtygalant** » Tue Dec 06, 2011 9:18 pm

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

fugazi · Post by **fugazi** » Tue Dec 06, 2011 9:25 pm

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

Superscan - Dash, reread dirtygalant... :D

I suggest you get another flyweel...

Dash · Post by **Dash** » Wed Dec 07, 2011 10:32 am

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?

Lummy · Post by **Lummy** » Wed Dec 07, 2011 11:17 am

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.

Dash · Post by **Dash** » Wed Dec 07, 2011 1:33 pm

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?

OLD FART · Post by **OLD FART** » Wed Dec 07, 2011 4:54 pm

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

Lummy · Post by **Lummy** » Wed Dec 07, 2011 6:18 pm

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.

Austarion

clutch disc hitting flywheel bolts

clutch disc hitting flywheel bolts

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