Lightened M20 flywheel in M50 - Help

[Sooty]

Finally got round to machining the M20 flywheel (to lighten it & get clearance), ready to go into the M50, but now I can't find anyone that's prepared to balance it without bending me over.

Local cowboys down the road want over £70 to balance the crank & flywheel saying that they HAVE to be done together (I say that's bol****s).

Can anyone who has done this mod let me know what they did?

Many Thanks

Iain S

[Jhonno]

my local place said £80 for flywheel and crank lightening and balancing or £40 for just the flywheel when i asked a while back..

[Sooty]

Thanks for the info Jhonno.
Knew it was bull about having to do them together & I don't want to have to rip the crank out unless it's absolutely necessary.

I know that a couple of guys have done this mod, and I really need to know if they went to the trouble of getting the flywheel balanced after lightening or did they not bother?

[Jhonno]

has to be balanced really..

ideally with the crank as they rotate together, however you can get away with just doin the flywheel as the crank will already be balanced from the factory

[DanThe]

Didnt get mine ballanced.
In all honesty they shouldnt need it due to the quality of the machining to begin with.
As long as the flywheel is mounted on the lathe square you shouldnt have any problems with out of ballance.
I thought you had to have the crank and flywheel as one to ballance anyway?

[Sooty]

Just been talking with my son about this, as he's just had his Vauxhall flywheel lightened & balanced (seperate from the crank !!) by a well established Race Engine builder.

He made the point that, for road use, as the mounting holes are dowelled so that the flywheel will only fit in one position, it should'nt really matter whether the crank is with it or not.
When you think about it, do BMW balance each crank & flywheel assembly together for all the production cars?

Who am I to argue with someone that's been doing it for years and knows what he's talking about?

As long as the flywheel is mounted on the lathe square you shouldnt have any problems with out of ballance.

When I did mine, I managed to get to within 0.02mm runout on the lathe.
Do you reckon that should be close enough for road use?

[Jhonno]

for road revs its not necessary to do em together, rushed my reply earlier.. when i said ideally i meant its the proper way to do it but only necessary for higher revving race engines..

not sure on the run out personally..

[stevetigger]

Im thinking I need to do this, How much was it Dan?

[DanThe]

You will need:-
M20 flywheel £?
M20 starter motor £?
M20 clutch £100

I got mine shaved by an engineering firm I know for £20

[stevetigger]

Bit to much for me, can I lighten the M50 flywheel>?