The M3W clutch is not a MX5/Miata clutch but is made by a company called TTV Racing, if you contact them and mention M3W they will not bother replying even. If you contact www.clutch-specialists.co.uk they will help you with standard M3W clutch parts.

An illustration of the M3W clutch is below, as you can probably see it doesn't use any MX5 parts, even the release bearing is a Volvo /Land Rover part, not Mazda. The "flywheel" is more of a starter ring gear.

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