By the time the sidecars came out to play, the light was terrible. I'm not too sure on settings for nikons. I think we have to find you some brighter locations, are you signed on ?
If you dont mind getting locked in, go up the mountain into some open area's, or maybe Ballaugh. as the sun can reach the course. If you wanted to stay closer to Douglas, maybe signpost corner or the the creg.
The difference in a bright road and shade is vast, for example, mine are shot at iso400 on a 300mm F4. I'm Photo 151 if you see me about.
Regards
Kris