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MG MGB GT V8 Factory Originals Technical - Benefits of lightened flywheel

Hi there,
I have just pulled my 3.5 Vitesse engine out of the car, due to early signs of bearing failure in the LT 77 gearbox. I had lots of transmission oil on the clutch and flywheel aswell, so I took them off. The clutch is shot and the flywheel has minute cracks extending radially from the center towards the ring gear. I presume, it means that the flywheel is gone too.
So the next obvious question is, should I go for a lightened flywheel, billetsteel or cast? In what way does a lightened flywheel transform the caractersitics of the car?

Oppinions please

Cheers Erik

Lightening the fly wheel has some plusses and some minuses.
The main alterations will be dependent on how much you lighten it.

Less engine weight overall (usually a small gain if any) , less rotating mass so quicker pick up / rev up , smoother running if the flywheel is balanced at the same time (and it should be).

Less rotating mass so the idle speed may need to be increased to keep the momentum up and prevent stalling.

If the old one is showing radial cracking it is scrap and for safety reasons needs to be replaced before it fails.

It is worthwhile getting the new one face ground. This is where the clutch contacts the flywheel and will help provide a smoother action.

Cast or billet depends on what you want to do. High revs for racing I would go billet and a scatter shield.
Both are fine for a road car.

Cheers , Pete.

Peter Thomas


Thank you, seems like a lightened cast flywheel is the one to go for. Say hello to Melbourne from me the next time you´re there. Had loads of fun in St:Kilda in the seventies.


This article might be interesting:
Dan Masters

Light flywheels are needed speically in a vehicle that is equiped with a force induction shuch as turbo's, centrifugal superchargers. It helps to rev the engine quicker to get the rubo spool faster and minimaze turbo lag.
Bill Guzman

Spot on article, thanks.


This thread was discussed between 06/02/2008 and 10/02/2008

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