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[Kevin Wood]

Quite how you can lighten a complex dual mass fly wheel I dont know.....

Me too, and it's not pretty when a badly lightened flywheel bursts. Tread carefully.

Kevin

[RonaldMcBurger]

Sorry matt. Got to let you down. Turns out I only have one after all. Sorry about that.

[Andy B]

MMm .....  

I don't see how taking the odd few hundred grams off a flywheel will make a car of around 2000Kg "pick up" faster .. it might get to high revs faster in neutral .. but thats about it IMHO.

Laws of physics cannot be overcome by wishful thinking .. now if the car was 200Kg it might make a difference ........



Just my 2.7 p's worth (inc VAT)

It won't make a vast difference to the performance of the car. However, in addition to being accelerated down the road with the car, the flywheel mass is being accelerated to a high angular velocity, and it happens through each gear so it has a bigger impact than its' weight would imply. Probably still not that significant in a 1700 kilo car though.

The main impact of having a lightened flywheel is that the engine revs will drop quicker when you come off the gas at 6.5k+RPM to select the next gear. This means you can snatch the gearchange quicker than you would with a heavy flywheel. It also helps when changing down the box, as a quick blip of the throttle will match the revs more easily.

I replaced 16Kg of flywheel on my Westfield with 5.5Kg and it was a worthwhile modification (car weight 650Kg). The main difference is that you can change up as fast as you like now. Before, you could declutch and select the next gear with the engine revs still sky high. When you came off the clutch and back onto the gas there'd be so much energy stored in the flywheel it would either (in the high gears) cause the clutch to slip for a few seconds or (in the low gears) break traction at the rear end (and once it's gone, it's gone   )

The down side is that "normal" relaxed driving is not as easy, because while you're off the gas during a relaxed gear change the engine all but stops so you have to feed a little throttle in. Ditto during downchanges. Pulling away and driving at low speed needs more careful co-ordination of the controls too because it's easier to stall.

So, the benefits are felt when you're really driving like a hooligan. Whether it's worthwhile depends on how often that is, I guess.

Kevin

But that only works with a normal solid flywheel.

[JasonH]

Back to the original issue - are you certain the DMF has failed?

I thought mine had but it turned out to be the clutch pressure plate coming adrift.