quick roll bar question

[michael92]

hey all just a quick-un, i plan to make my roll bar and obviously weld tabs on to allow my harness to be bolted on, question is... do i need the bars that go to the lower chassis to allow it to be bolted just near the fuel tank area?

Meik

[PorkChop]

I would put backstays in. As you would be moving if you were unfortunate enough to roll the car, a single hoop on its own would be more likely to deform as angled forces would be acting against it.

[baz-r]

hey all just a quick-un, i plan to make my roll bar and obviously weld tabs on to allow my harness to be bolted on, question is... do i need the bars that go to the lower chassis to allow it to be bolted just near the fuel tank area?

Meik

there is 2 ways people put the back stays in the book style with a sheet metal rear panel
or mount them to the ends of the grp mounting frame with a grp rear panel.

[mgglep]

Hi there take a look through my pics I have a few of the roll bar I made might give you a few ideas

[michael92]

cheers for the pics and stuff guys, erm don't really want to put back stays on to be honest :/ Ill ask the iva man when i see him

[Wynand]

I would put backstays in. As you would be moving if you were unfortunate enough to roll the car, a single hoop on its own would be more likely to deform as angled forces would be acting against it.

Not necessary, All depends on design and height of roll bar, material used and most importantly how it is anchored to frame...
All this done correctly, most probably the frame will suffer most turning turtle.

In this picture you can see that the roll bar sits on bases made of 5mm plate that spreads the load over a large area. The frame has added framing that is gusseted (4mm plate) to other chassis parts fitted to take the bases and was weld fast on that.
Note that the roll bar also has a camber in it for strength. The lower tube where the harness bolted to is close to base of r/b and immensely strong (no lever effect) and made from 4.5mm wall steam tube. Roll bar was made from 63mm diameter x 3.8mm tube.
R/bar welded to bases with 5 staggered filleted stainless steel welds for strength.
http://img.photobucket.com/albums/v305/wynand/Lotus7Rollbar.jpg

and here is the completed job.
http://img.photobucket.com/albums/v305/wynand/Lotus7008a.jpg

[PorkChop]

Not necessary, All depends on design and height of roll bar, material used and most importantly how it is anchored to frame...
All this done correctly, most probably the frame will suffer most turning turtle.

In this picture you can see that the roll bar sits on bases made of 5mm plate that spreads the load over a large area. The frame has added framing that is gusseted (4mm plate) to other chassis parts fitted to take the bases and was weld fast on that.
Note that the roll bar also has a camber in it for strength. The lower tube where the harness bolted to is close to base of r/b and immensely strong (no lever effect) and made from 4.5mm wall steam tube. Roll bar was made from 63mm diameter x 3.8mm tube.
R/bar welded to bases with 5 staggered filleted stainless steel welds for strength.
http://img.photobucket.com/albums/v305/wynand/Lotus7Rollbar.jpg

and here is the completed job.
http://img.photobucket.com/albums/v305/wynand/Lotus7008a.jpg

That's a meaty rollbar :D, which would help. I was imagining the OP talking about a bar closer to MSA spec (38mm diameter IIRC).

I do like that rear lid too - looks smart :)