Making a lightweight roof?

[Timmyevo6]

i race a mitsubishi evo 6 saloon car and was wondering, is there anything stopping me cutting out the OEM roof and bolting a sheet of 0.5mm ally in its place? i can get sheeting nice and cheap!

my series regs don't mention 'keeping OEM silowet' but i don't know regarding MSA safety regs.

the other option is carbon fibre but i don't wanna spend +£1000 on it to probably bend it at the very next race!

any thoughts please??

cheers, Tim

[Chris Y]

I'm not sure on the specifics here as I don't have a blue book to hand, but I think the regs state that if you have an ally roof, the cage has to have some sort of metal roof to it instead. That's certainly the case on a racing 2CV - the fabric roof from the roll cage is replaced by ally sheet, but in the event of a roll over, that wouldn't protect your head much from debris or kerbing or even fencing if you were that unlucky, so a thick metal plate over the top of the cage is mandated.

[Al Weyman]

Doesnt the rules also state somewhere that Sunroofs in saloon cars must be replaced with material of a similar nature to the roof or was that in SR's where I read that. Also athetically it will look pants as you would have to rivett it down to the orginal steel which you could not disquise and would immediately call up the attention of the scrut plus you would have to have it rolled to get the right shape which is not going to be cheap.

I have a bit of experience with this with my IROC-Z racecar because as with the Tomcat it came with removable shaped glass roof sections. What I had to do was take these to a a man a lot cleverer than me who cut them to shape (in steel) then rolled them through this machine to get the correct curve and a wonderful job he did as well but not cheap and we welded these in place so I would hate to hazard a guess what a whole saloon car roof section would cost or even if it was doable.

[phoenix]

Originally Posted by Timmyevo6

i race a mitsubishi evo 6 saloon car and was wondering, is there anything stopping me cutting out the OEM roof and bolting a sheet of 0.5mm ally in its place? i can get sheeting nice and cheap!

my series regs don't mention 'keeping OEM silowet' but i don't know regarding MSA safety regs.

the other option is carbon fibre but i don't wanna spend +£1000 on it to probably bend it at the very next race!

any thoughts please??

cheers, Tim

In a saloon's monococque construction the roof provides a great deal of stiffness - even with a cage in the car - so you would likely loose some rigidity. 0.5mm ally is extremely thin and would dent if you put a mug of coffee in the middle of the roof! Also, getting the curve in three dimensions to match the profile of your existing roof would be very tricky and expensive - whilst a flat sheet would look aweful!

If you are determined to do this, you could go for a GRP roof which would be way cheaper than carbon. A local glass man could take a mould from your existing roof so the profile would be an exact copy, and with some added ribs (internal) it could be fairly stiff but lightweight.

All though 'adding lightness' is always a good thing to do, I honestly don't think you would see any measurable improvement in performace from such a mod and it's probably not worth the hassle or the expense.