Ewan, I being very serious here for a moment..If your hardox disc is anywhere near the size /weight of the disc I saw at Magna then you will need a good bit more that a 2:1 reduction on your Astroflight 40!..Trust me on this one Ewan, I know that motor inside out and I guarantee that at 2:1 you WILL cook it very quickly!
Ill talk to you about it at Denbigh at the weekend.
Geoff.