M20 Flywheel skim - How much?

[frantic]

Hi all,

This one is abit vague and I can't find a definitive answer as everyone just seems to go down the lightned flywheel route,

How much of the back side of the M20 flywheel must come off to clear the sump/block of an m52?

"light skim" are we talking 0.5mm, or 1-2mm minimum?



By the way - I would check but motor is sitting in storage for another month and abit so just sorting things out while I wait to get started.

[rix313]

Where are you located? I had a local machine shop turn one down for £20 then sent it away to be balanced which was about £60.

[maggspower]

The back side in your picture can be taken down to flush with the ring gear.

The back can then be scalloped out.

So loads really.

A skim would really be talking about the friction side, but this really needs a ground finish rather than machined.

[johnmaccow]

Just put mine in to bloke near metrocentre, he's taking 5mm off mine as he felt uncomfortable with anything more.
Pick it up in morning so will see.
Not as light as I wanted but still lot better than dual mass crap.

[frantic]

What weight before and after? Same back thickness as mine?

It's at 8.4KG my one above, Front face has already been stone ground so surface is fresh. Just need back side shaved down on lathe. I am in New Zealand however, Just wanted to know how much needs to be lathed off as a minimum.

[Motorhole]

Got mine from DanThe. I think he takes them down to 6kg.

[maggspower]

The part of the flywheel that is under the most stress is the center, around the bolts that hold it in place. Taking material from arount the outer edge will actually decrease the overall stress on this area as there is less mass having the centrifugal force pulling on it.

Taking material off until it is 1mm proud of the ring gear will allow it to be fitted to an m5x, but there is more that can safely be removed.

[frantic]

Alright, That must be about 7-8mm worth then?

I didn't think it was that much. I may have it flattened to just behind the ring gear and not too much scalloped out. Trying to keep it at about 6.5-7kg since it will be in a daily I don't want to have a rough idle.