Yep, at SCCA Practice event Saturday the trans 2nd gear went again. Typically about 12 runs on practice day, I got 5. Real shame, with each run I was setting and resetting Top Time of Day and it held all day if we don't count GoKarts. So, the car is working really well otherwise. Time for version 4, will start looking around the local yards and EBAY as time permits this week (also closing escrow on our new site for Good-Win Racing so that's about a million times more important at this moment).
I have lost two transmissions, same pattern both times. At the moment of failure full throttle and over 6500 rpms in 2nd gear, full load transition at the moment of failure AND steering input change from left to right on high grip tires (putting a lot of twist through everything).
I hear that ND2 trans internals not changed from ND1 version 4, but I also understand the case may be ribbed for less flex and those ribs continue into the lower part of the engine casting so entire unit of engine/trans will suffer less twist, which sounds like the right answer. This pic posted by FM's Keith at miata.net to point to some of the updates (like ND2 gets stronger engine case, upgraded connections to trans, and oil heat dump to coolant). My guess from pics is ND2 trans needs the ND2 engine, so upgrade to that ND2 trans will mean you put in the ND2 motor too. So, as soon as somebody has a line on first one to get crashed after release later this month, let me know!