Flywheel lightening

Whilst I'm doing things, I intend to send off my flywheel to get it lightened (apparently it cant be properly balanced off the engine). Does anyone know if a standard flywheel has balancing weights on it?

Not a clue
Would be externally balanced though
It would seem nothing in life is simple and if your going to do it then it needs doing properly and impacts all down the line .Is it worth it

http://www.rpmmachine.com/engine-balancing.shtml

I love the web

They have drilled "dents" on the back face to balance them. They can only be oriented one way despite first appearance

Given the recent experience of another forum member who managed to crack his due to excessive heat, I'd be reluctant to try lightening it. Also unless you're working with a high revving not-particularly-torquey engine, the benefits are quite small.

http://www.pumaracing.co.uk/flywheel.htm

..but the benefits of lightening of the flywheel are the largest over anything else in the geartrain, including lighter wheels...

Alan Moore can help here, he's done a few of his own on the V6..

Alan..?..

I managed to aquire hot spots and heat cracks due to a slipping clutch and doing a hillclimb with it. I had to have the flywheel refaced. It was nothing to do with lightening on mine.

Mine had a few balancing dimples drilled in it too, and as David confirmed to me before I took it off, the 7 bolts can only hold it on in 1 position. Sure enough he was right too. It weighed about 10 KGs when I dropped it on the bathroom scales (not at all accurate) and it would be very nice to rip a bit over 3KGs off it. Just imagine, like loosing 120KGs from the cars weight in 1st gear (and only 40 KGs in 2nd).

Having said that, I only really use 1st off the line, and maybe out of a really tight corner. I'd guess that a lightened flywheel will put more stress on the gearbox as it will get would up faster as the power is transmitted faster to it.

I will be doing it! Its £50, should shed a few kilos and the engine should rev quicker, therefore the turbo will spool up quicker....a useful mod. I will have a spare one if it goes wrong (I'll just owe DG a couple of quid!!!)

I'd guess that a lightened flywheel will put more stress on the gearbox as it will get would up faster as the power is transmitted faster to it.

Quite the opposite really, as things are understress when they have high inertia/high mass, and are being asked to change states quickly, such as a heavy flywheel turning slowly in 4th, and you dropping it down into 2nd asking it to accellerate quickly and put strain on the crank, primary shaft etc...A lighter one will put less loads on this, much like lightweight pistons are easier to move and accellerate than heavy ones..

My flywheel for the Turbo ended up at 6.2 Kg, don't know what it started at. The centre boss section is left alone, with only a skim to make sue it was true and ended at around 11.5mm, the main clutch area thickness I brought to 13mm, by removing material from the back.

I also put concave grooves in this section approx 8mm wide by 2mm deep to perhaps give more surface area for cooling, but mostly to perhaps give a little more ridgidity to the area where the pressure plate is bolted. If the thickness of the flywheel at this point is reduced too much the face will flex when the pressure plate is operated.

The very outer area is 18mm thick to leave the ring gear in the correct offset, although this is where the most gains are made in regards the effect of losing flywheel weight. I thick I reduced the ring gear width by a couple of mm, and I removed the crank pickup teeth as a couple of the ones on the spare engine I bought had been broken off when the engine had been carelessly moved around, and I had been going to use a Motec that did not recognise this set up anyway.

Although David has got me convinced that the Adaptronic might be a better way to go and so I will now use the flywheel off my original engine and do the same work to it.

The balancing can be done separately, and was in my case, as the balancing machine pickups could not fit with the flywheel attached to the crank. This is done in the conventional way by drilling holes toward the outside of the flywheel. Sometimes pressure plates are balanced by welding weights onto them. The balancing person should also stamp the orientation of the pressure plate to the flywheel, to keep everything right.

I actually did the balancing of the crank myself on a friends machine as he had too much on. He set up the bob weights that had to be clamped to the crankpins to simulate pistons and rods. V engines are somewhat more involved in balancing, than straight 4s or 6s, that do not require this.

The A610 pistons were quite out of balance, and required the outer parts of the gudgeon pins to be machined to get the balance as there was not enough material inside the pistons to play with. So now each pin is allotted to a certain piston.

Sometime I will get around to putting it all together.

I was told to get the most benefit from balancing do the flywheel and clutch as an assembly. There are downsides too though, it makes the idle a bit lumpier sometimes and also can affect bottom end torque too - I have no idea why!

i have also heard it affects tourqe aswell but when i get the chance i will also get mine lightened when my bro had his 50% l+b flywheel put on his 5 it made a big difference the revs picked up that quick we thought the clutch was slipping at first

I was told to get the most benefit from balancing do the flywheel and clutch as an assembly. There are downsides too though, it makes the idle a bit lumpier sometimes and also can affect bottom end torque too - I have no idea why!

The idle can be lumpier as there is now not as much inertia in the flywheel to smooth out the power pulses.

The actual torque of the engine is not affected, only the flywheel effect that may be used as stored power to get you over a hill. Trials motorbikes generally have much heavier flywheels than enduro/motorcross bikes, to keep up inertia at low revs over obstacles.

Reducing the flywheel weight will not gain any Hp, but will show up an advantage in an acceleration run. Also gears are able to be picked faster as the speed of the engine on changes drops more quickly.

Peter ,Alan .Could you let me have some pictures, measures off the lightened wheels please Might as well get mine done .

It doesnt look noticably different so theres no point in sending pictures. I will weigh it and the other one I have to let you know the difference.

Using my not very accurate ceiling hanging weight ive got a smidgeon over 10kg for standard and a smidgeon under 8 kg for my lightened one!

Who did it & how much ?