Flywheel lightening
 

How much weight would be a safe amount to remove from a mt75 4x4 flywheel, enough to make a diffence as the standard one weighs a fookin ton but not too much to make it a risk of destroying itself and everything around it :sad:
I've seen a few aftermarket ones for sale but wondered how much can be taken from a standard one? Then I can have mine lightened and save some money for more fuel :top:

I'd just fit a 2 w/d fly wheel :grin:

Ok, why?

How much is safe is best left to the person doing the machining, as a example a std 2wd cossie is 8.9KG, I recently weighed mine before lightening and skimming/pegging.
Mine was taken down to 6.6KG, today we weighed Rossies one and it weighed 5.3KG, but was costly.
Mine cost me about £35.
Cossie flywheels are very heavy, for reasons of NVH no doubt, can make them a lot more responsive lower down with a lighter flywheel though.
tabetha

It won't cost me anything as luckily my dad owns an engineering firm :) Just wondered what people thought as there seems to be some very differing weights being used. Going to put it on my 24v so want it to pick up a bit quicker is all ;)

it's not so much to do with the weight of it, but the rotational mass, i.e. inertia.
you want to remove as much as possible from the outer edge as possible as this is where more energy is used in rotating the flywheel.
it does depend on how you want the engine to respond though.

HOW on earth is the weight not related to the MASS!!.
The rotating mass determines the INERTIA, inertia is simply stored energy, in this case by movement/rotation, this is 100% DIRECTLY proportional to the weight, as a whole.
The flywheels tend to be thinner nearer the edge, do NOT under any circumstances remove TOO much here, although it will have more effect than material nearer the centre, it can also lead to grenading, that is self destruction, and have seen flywheels go through bell housings and into the car compartment more than once, so if your leg happens to be there where it comes through you have no more leg.
tabetha

It will alter the engine all in positive ways APART from smoothness lower down, this is where heavy comes into it's own to dampen the vibrations caused by trying to rotate a device(crank) iregularly, it firing stroked every so many degrees apart, of course this can't be helped, but that's the primary reason they are so heavy.
It will accelerate quicker much more so than the weight you remove would have you believe, it will also allow for quicker gear changes(if the box is quick enough) by not maintaining the higher speed of the previous gear so easily due to less inertia.
Downsides are few but are all vibration related, and only at idle, very low rpm.
tabetha

Thats cool, thanks tabetha :) was looking at removing from around the centre as thats obviously where the greater mass is located, didn't want to touch the edges so thats a good thing :)

i was simply stating that mass removed from near the middle will have less of an effect than the same mass removed from the outer of the flywheel.
so mass removed isn't the point as such, where it's taken from is.

The biggest problem is without experience by the machinist doing the job, too much slotting around the outer edge can spell disaster.
On cossies there is a whacking massive great ring on the back inner edge of the outer, most of this can be taken off, ultimately depends how much power you wish to transfer through this also, as this could become limiting factor.
tabetha

Oh i'll only be hopefully pushing around 300 ponies when its all done :)