I am just getting around to making my roll bar and have a question. The car is a 2 seater open sportscar LMP style not 7. I want to know whether the compulsory diagonal and stays need to be the same size as the main hoop (50mm). I have read the MSA regs and....don't understand! I would like to use the minimum size possible. Does anybody have a radical or similar they could measure??

Whilst I am asking questions.....The feet of the main hoop sit on Aluminium Honeycomb (car is a monocoque). I have my own ideas about load spreading etc but has anybody any idea of what is acceptable? Photos much appreciated.

Ta

A Radical may possess a ROPS approval which would not be applicable to a bar you build & design yourself.

You would be best to contact the MSA technical department to get a clarification on the dimensions of tubes for the bar, diagonal and stays.

Depending on the use of your vehicle and its "category" there are differing requirements - See MSA 'Blue Book"

[Edited on 27/10/12 by minitici]

Hi, please take a look at slackmotorsport.com
porsche 962 monocoque/ chassis they have an alloy monocoque with
steel rollbar/cage, there you can see how they spread loads,

wilfried.

Oh, and for the mainhoop 40x2mm DOM diagonals 40x1.5mm DOM
and 40x1.5 in crmo 40x1.5 crmo

acording to FIA/ACO

wilfried

MSA blue book is clear enough:

a) Mandatory tubular members
45 x 2.5 or 50 x 2.0

A roll bar is mandatory, so therefore needs to be as above. Whilst the FIA regs are slgihtly different, motorsport in the UK is governed by the MSA, and it will be MSA scrute's that approve the car/sign the log book.