ROPS Query - Your experience pls

[Erictharg]

I'm hoping to circuit race my Westfield Eleven in SR&GT. It already has a roll bar fitted for hill climbing. I expected that I might need something more substantial for circuit racing, but the Blue Book is vague when it comes to "unusual" cars. Everything in there for sports cars is aimed at steel monocoque vehicles.
I (perhaps foolishly) contacted the MSA technical folks who basically said "as per Blue Book or get it tested at MIRA".
So, if I follow their guidance, I need a full width symmetrical hoop, with diagonal and two backstays, all in 45mm tube. This is on a vehicle that weighs 500 kgs and has no spaceframe tube bigger that 25mm dia. In addition there is nothing substantial to mount the backstays onto. Having a "Seven" type live axle frame, all the strength is forward of the rear suspension mounts. Anything far anough back to mount backstays onto is purely to hang bodywork on!
I'm at the point where I will make a ROPS to that design, but I know it's not ideal. I also appreciate that there has been a lot of pressure from the MSA recently to standardise their regs with the FIA, and so less flexibility currently than in the past.
Also, I need some guidance on the mountings. The current arrangement was suggested by a local reputable roll cage manufacturer (who also supplied and bent the hoop for me). It consists of two sockets in CDS welded to the spaceframe, picking up a node of three tubes. the main hoop fits into the sockets and is crossbolted.
Any guidance for those more experianced than myself in what a scrutineer will accept?
The car is road registered and shows as 1970 registration date, but was never homologated. There are other Elevens out there racing, but the roll bar they use is less substantial than my current design.

[JohnD]

Eric,

This guy http://www.madabout-kitcars.com/pict...stfield+Eleven has made it a 'front-stay', but putting the longitudinal diagonal through the passenger compartment.

so has this guy http://www.flickr.com/photos/si558/3563134814/ thought there does eem to be a central, high-angle back stay.

This guy http://www.race-cars.com/carsold/oth...07548166ss.htm has built one inside the head 'fin' with the tubes poking out throught the skin.

Here's another, came in 15th http://simonwrightphotos.com/2009-05...ie_en_bleu.htm

And somewhere on this board http://boardroom.wscc.co.uk/cgi-bin/...Bf=3%3Bt=59115 there is a picture of a roll-hoop-and-back-stay equipped elevent with its skin off and all the tube son display.I leav eyou to find the pic.

All from a Google Image saerch for "Westfield Eleven".

John

[Erictharg]

Thanks. The green one with the assymetric red bar is similar to what I have at present, and what I'd like to race with. I'm going to pop over to Roll Centre who helped me with my current bar and get their advice. If I go with what the MSA tell me it won't be pretty, and whilst I know that's not the priority, if aesthetics were not at all important I'd be racing a Caterham! I hoping a compromise with the main hoop in 45mm tube, and one backstay may suffice...only one way to find out!