JB, no the ground isn't required, the original Delco motor has 2 sets of windings in the field coils,one up and one down. These windings are connected to positive via the window switch and ground via the black wire, the switch chooses which winding to use. The later permanent magnet motor has no field coil it merely needs the motor polarity reversed for up and down. The window switch now has to be wired differently to reverse the current flow, which these switches are designed to do. IF electrical noise is a problem then indeed the motor may have to be grounded. And why did they use such a big motor? Well Lotus tried NEVER to make a part if it was available elsewhere, what other domestically made (UK that is) car had window lift motors? Rollers, Bentley, Alvis, Jaguar, of those what is the cheaper car? And even Jag out sourced to the US for some items that were cheap in the US but expensive for the limited UK luxury market, steering columns, Saginaw, AC compressors York and Harrison, PS pumps Delco, EVEN Rolls bought out hydraulic lifters from GM. And Rolls and Jag bought Gm or Borg Warner Auto boxes. So the size of the motors was probably dictated by price and the fact these motors were designed for large American car windows and GM made MILLIONS of these motors, yet I know blah, blah, blah, Cheers rp
