Fair point. The clutch slave on my Suzuki car failed at a mere 50k (which is disappointing) but was accompanied by a nearly worn out plate. I reckon the car belonged to somebody with poor driving abilities when new, from a few things I have found. Saying that, proper CSCs tend to last very very well. I have had a few cars well over 100k on original clutch kits. Repro items not worth the savings. As to flywheel, I forgot the MX5 is a tad smaller than the Triumph item. The "slightly serious" investigation I have done were for Zetec stuff where he simply used a MX5 plate. (hilariously the chap initially cut a larger diameter plate down using a dummy input shaft, a drill and a grinder, before somebody sent him a message about teh correct size plate being an off the shelf item) Another thought, can you not get the backplate scanned? I am pretty clueless on most of this stuff, but a mates son has a scanner that appears to be very accurate. He suppliments his income by scanning bits of car and 3d printing them. Latest bit is cosworth wheel centres as originals are so valuable now people won't leave them on their car when out at shows, so are buying his and keeping the originals at home. But his are very accurate reproductions. Should be good enough for an adaptor plate?

Sounds good!  like a high revving 2litre.

@JohnD My thinking is I'd rather like to have it as a CAD drawing that I can use to properly find the centrepoint rather than making up a centring spigot to the MX5 box (not too difficult, but I don't have a working lathe at the moment, so if I'm going to pay for a machinist's time it'll be to cut the final part). I've got a saloon backplate and a Spitfire backplate that I was going to use to take some dimensions from, but to get it sufficiently accurate I'll need some gauge pins which are around £160 for a set (or the time of someone who is experienced at accurate measuring, which will probably be fairly similar). The monkey CAD work if lining up twi drawings I can confidently do myself  @zetecspit The main issue with using a Triumph flywheel is I'd like a lightweight steel one, and the options for fitting a big 6 flywheel into an MX5 bellhousing mostly include machining down the OD to fit the MX5 ring gear. At that point, it sort of makes sense to just order a custom dimensioned flywheel to use the MX5 clutch in its entirety and just use the single clutch kit whenever it needs replacing. Oh, and I cannot stand the idea of concentric clutch slaves. I have a very low tolerance for stuff that makes regular maintenance more difficult, and putting a clutch slave in a place that means you have to remove the gearbox to get at it is madness as far as I'm concerned 

This car was at the Spa Six Hours earlier this year; See, at about two minutes in: As can be seen, black, red stripe down the side, no reg.no. It wasn't in the actual Six Hours as that's for supercars, but there were three days of racing at the meeting, too many to search for and find where it raced. Anyone know whose it is? John

Why faff with a flywheel? The 2 litre Triumph engine uses a 215mm plate, as does an early 1.8 MX5 so easy to swap. Then a CSC. I think Nick may have used the MX5 plate (but CBA to go back through his most excellent thread)

Just stumbled across this modified gt6, assume it’s Triumph powered.  

So it would appear - that TW was from 2013

That jacket was mighty impressive. So will all gas canisters, in srorage, have to wear one ........I bet not.   Roger

BiTurbo, I'm puzzled!   If you have an physical Triumph plate, you could mark out an adaptor by drilling though that onto the blank. I have some six-cylinder plates you could have, but don't know if they are the same as on a Spitfire. John

This one?   See from 3:30 in. Sad to say, I've never seen those covers in use!   John