Bill, Faili and all,
Roy wrote a piece for the club magazine a while back I believe on the rear sub-assy of his 40. I'm over there this weekend so I'll see if he has a copy to post here.
In the meantime, the new rear frame looks like this:
The old one fitted looked like this:
The side angles were originally longer and a sharper angle making more of a tunnel effect but were a pain when loading on the trailer.
Did they work? don't know for sure, but after running 170+mph, they had 'scraped the ground' so possibly. I suspect that they would have little or no effect below 100.
Now Roy and Ray have done windtunnel tests on a model... but that's another story. (a somewhat funny one too as I recall!)
best regards
paul.thompson@gtd40club.co.uk [img]images/icons/grin.gif[/img]