Interesting roll cage addition?

[NJH]

Found some pictures on the net of real Porsche 944 turbo cup car from the 80's. Spotted something I don't recall seeing in the blue book or any of the off the shelf roll cage designs for this car.

http://picasaweb.google.com/RONFWISER/Porsche951Cu...

Its the bar running down the transmission tunnel that connects onto the dash bar in what would have been the glove box in a road car. Is this something historic or would it still be allowed today?

[Scuffers]

would make getting out the passenger door somewhat hard (used to be a rule about this somewhere?)

[NJH]

Oh I see the driver getting out the other door when the drivers side is in the barriers. It would make that escape route more difficult but looking at all the pictures not impossible. ISTR FIA rules for GT cars have a time for escape, where getting out the passenger side can only take at most 2 seconds more then the drivers door (ISTR 7 and 9 seconds respectively?).

http://picasaweb.google.com/RONFWISER/Porsche951Cu...

Looks like it actually sits a little lower then the upper door bar as can be seen in the above picture when one looks at how high it is in relation to the seat back. Still though it must make that escape route more difficult.

I just found it interesting to see what Porsche themselves came up with back in the 80's when this was would have been a factory race car. This is assuming of course that the car still has the original cage.

[stifler]

Might be the same situation as the 'petty bar'. A bar from the centre odf the roof to the passenger footwell. Legal in american racing, illegal in british racing.

[NJH]

Have to admit that I did think straight away that, that bar fitted in a new cage wouldn't pass MSA scrutineering because it doesn't appear in the blue book.

[Nick_F]

This bar runs from just off-centre on the main cage hoop to the chassis outrigger at the forward end of the passenger footwell; never had so much as a question from an MSA scrutineer, albeit only at sprints & hillclimbs.

[MartG]

stifler said:

Might be the same situation as the 'petty bar'. A bar from the centre odf the roof to the passenger footwell. Legal in american racing, illegal in british racing.

Some MR2 Championship & Challenge cars have them, racing in the UK

[/URL]

Edited by MartG on Tuesday 10th February 21:45

[anonymous-user]

The first picture is a really nasty cage which breaks one of the general rules of a good cage, which is don't have a bar passing it's load into the middle of another unsupported member. The door bar design and the way the centre bar attaches to the cross bar under the dash are hopeless.

[MHM]

MSA roll cage rules are you either do it to the drawings in the 'Blue book' or pretty much do as you like (within reason) as long as you get a certifcate for it proving that it is strong enough.

[NJH]

Thanks guys, think I found it in the FIA regulations. Have a look at diagram 253-26, the text for it says "For members shown on Drawings 253-26 and 253-27, the angle between the central leg and the vertical must be at least 30°".

The document:

Article 253
Equipements de Sécurité / Safety Equipment
(Groupes N, A, B, SP / Groups N, A, B, SP)

Linky here:

http://www.fia.com/resources/documents/994546964__...

I did a text search and couldn't find anything else in those regs with regards to that drawing so it seems to me that the bar in the factory 944 turbo cup car above is within current/recent FIA regulations, there appears some freedom as to where the other end of the bar mounts. I imagine though that the idea of the drawing is more along the lines of a stay for the main hoop harness bar.

Edited by NJH on Tuesday 10th February 23:45

[NJH]

johnfelstead said:

The first picture is a really nasty cage which breaks one of the general rules of a good cage, which is don't have a bar passing it's load into the middle of another unsupported member. The door bar design and the way the centre bar attaches to the cross bar under the dash are hopeless.

Good point actually, its a basic structural design principle and is why there are rules saying various sections have to join together within 100 mm of each other.

[Nick_F]

Makes sense. Mine joins the main hoop about 50mm inboard of one of the rear braces.