car has Dual Mass Flywheel - does it matter?

[magpies]

We are building a Jag engined car AJ30 and it's standard Getrag 221 gearbox. There is no 'simple' single mass flywheel available - unless you know of one? The engine will be rated at about 270bhp and car will be about 950kg.

So question is - does tracking/racing starts destroy the DMF? and mean less aggressive starts will be the way forward.

[nickfrog]

I would have thought it would be OK as it's a light car. You don't need to do any aggressive starting in 1st on a track day. On a race weekend that will be a bit different but you won't actually do a lot of them either.

[Steve H]

Some VW Cup cars have gone back to DMFs and suffer less gearbox problems as a result. I’d say try the DM and see how it works.

[bigothunter]

Is this any good?

http://ttvracing.com/product/jaguar-3-0-v6-duratec...

[bigothunter]

Significant reduction of flywheel inertia makes a big difference to acceleration in lower gears. Same as extra power but for free.

Flywheel inertia works in proportion to the gear ratio squared. So if your first gear is 3:1, effect of flywheel inertia is 9 times greater in 1st than direct 4th. It has a surprisingly large effect in 1st gear, often more than 30% extra vehicle mass.

Reduced inertia puts torsional resonance well beyond working speed range of even highly tuned engines. Also the flywheel isn't prone to falling apart unlike a DMF. Downshifting into bends is easier because you are accelerating less engine inertia so heel-and-toe accuracy becomes less critical.

Downside of very light flywheels is absence of separate ring gear so mangling the teeth demands replacement of the whole flywheel £££.

We always use ultra-light flywheels on competition car builds.

[magpies]

cheers

been in touch but £1000 is too much so will stick with standard

[bigothunter]

magpies said:

cheers

been in touch but £1000 is too much so will stick with standard

Ultra light flywheels have always been expensive but under £400. How on earth do they justify £1000?

Suggest searching the internet. American sourced parts are often much cheaper. They like aluminium/aluminum flywheels too, but I'm not convinced they are a sound alternative.

[magpies]

bigothunter said:

Ultra light flywheels have always been expensive but under £400. How on earth do they justify £1000?

Suggest searching the internet. American sourced parts are often much cheaper. They like aluminium/aluminum flywheels too, but I'm not convinced they are a sound alternative.

That is with the clutch and vat. actually quoted £940