During the mid 80's M & S ran into a lot of difficulties which made M & S fall to the bottom of most races and car engineering in which the M & S Downfall.
In 1985 (after the 72 and 82 Le Mans wins)rules changed to keep M & S and Chaparral which made from winning races which made Chaparral go to F1 and us (M & S) go to Group C racing. During the 1985 24 Hours of Le Mans one of the two car M & S entered crashed which kill the 2 drivers and was caused by a Toyota going out of control and crashing into M & S during the rain on the corner 18 and ended M & S racing for 3 years and forced M & S to make normal cars(like a Honda Civic) for 14 years.