What sort of thickness tube have people used for the bracing of their roll bar?

After seeing this post:

http://www.locostbuilders.co.uk/viewthread.php?tid=13414

I've decided I definately want it braced!

I've got some 50 x 1.6/2.0 stuff, anybody reckon that's not enough?

The rollbar itself is an MK one which is (IIRC) 3mm wall.

Cheers,

James

would think either would be well up to the job. As an aside, RAC MSA min spec (for 50mm OD) is 2mm wall so you are about right.

I read somewhere (could be the SVA book or on here) that it was 2mm x45mm seamless or 3mm 45mm ERW, can anyone confirm (may be only if the seatbelts were attached)

45mmx2.5mm and 50mmx2.0mm to suit MSA and same material for diagonals and rear braces and must be in CDS unless you want to register your own design at a cost of course.
Drag racing is 50mmx 3.00 so don't feel hard done by!

Undecided, you beat me to it with your post. A bit sad to be reading your Blue Book @ 0204 in the morning though
Cheers. Ken.

Thanks everyone!



James

James,
I used 48mm x 3mm wall "black pipe" which you can easily get hold of at steel stockholders. It's not as strong as CDS obviously but the fact that it is 48mm and 3mm thick should (hopefully) make it of comparable strength to the 45mm x 2.5 or 50mm x 2mm stuff which MSA recommend.

The other good thing about black pipe is that it is just the right size for you to use an industrial hydraulic pipe bender. I hired one from Speedy Hire for about £26 for a whole weekend. It was actually a one day hire but they are shut on a Sunday so I got it from Saturday until Monday. Make sure you keep the seam in the neutral axis (ie. the seam will follow the curve rather than being on the inside or outside of the curve) to avoid any splitting.

I also welded mine (no rivnuts here...) to the rear turrets using an extra thickness of 3mm plate on top of the turret. This is important as the turret plate must be thicker than the rollbar wall to avoid punch-through. I think I've read this in the SVA manual in fact.

Mine is braced using a horizontal bar onto which my harness upper mounts will attach. I know it would be better if it was diagonal but to be honest I don't think it is of major concern and to my mind it is more important that the harnesses are mounted properly.

I also have (Cater ham style) rear braces although these are only made from 38mm x 1.6mm ERW tubing and weld onto spreader plates on the rear 19mm top tube. I didn't see the point in having 48mmx3mm rear braces welded to 19mm x 1.6mm tubing and it would have looked very ugly. I also didn't like the look of the MSA style rear braces although these are clearly the safest option.

Glad the driver of the upside down Locost got away unhurt!

Cheers,
Craig.