I did spend hours of my time and read tens of pages of forum threads about the FASST overheating issue. Its a fact, that FASST receiver turns itself off at 60-70 degrees Celsius. Just go and read about the buggy Euros, guys had problems, Savoya made holes into his radio box before final etc.
walste's information about that he has had no problems ... well nice to hear you haven't had any problems
But it really doesn't help other guys who have had! Also you didn't specify if you have run 60-minute main final on a very hot summer day. I also haven't had any problems with FASST, because I have the module but haven't got the receivers because of the problem. Now its fall/winter and maybe I will order FASST receivers finally
I measured about +50 degrees Celsius inside XT8 rado box after running some practice. It was ONLY about 25 Celsius outside. So the problem is easy to come!
It's a fact that you have problems with FASST if the rx gets hot. It's a fact that Xray radio box gets hot (hot day + heat from the engine). It's a bad mix of two... 60-70Celsius inside a radio box is too much, but the rx should work (non-FASST do work).
I think using foil+foam and mounting the rx as far as possible from the engine helps. I did a modification and didn't use the radio box at all, but it gave too much chassis flex on the truggy. I think it would be problem on the 808 also! I had to go back to using the radio box to get less chassis flex. IMHO too much chassis flex stresses the diff bevel gears, bearings etc.