And my rollbar is finished!

"BiTurbo228 - Dr Frankenstein of Spitfires" (biturbo228) 02/18/2016 at 16:27 • Filed to: Spit6

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Well, fabricated and tacked into place in the car that is. Looks good, no?

Currently wondering whether to extend it forwards into a full cage. I could quite easily hide the bars coming forwards over the tops of the doors in a little channel in the hardtop, but the bars coming down the windscreen would be harder.

Through a little muckup I’ve actually made it out of tubing too small to pass MSA specs, so I won’t need to worry about making it properly compliant which will help with design.

As I plan on welding a steel hardtop to the body, I could run some smaller diameter tubing inside the a-pillars to reinforce them and stiffen the whole thing...

Bonus pic of the car as it is now:

daender > BiTurbo228 - Dr Frankenstein of Spitfires 02/18/2016 at 16:35

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Nice! Are you planning on running a bar across the bottom of the floor to connect the bottom ends of the rollbar?

Takuro Spirit > BiTurbo228 - Dr Frankenstein of Spitfires 02/18/2016 at 16:36

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Needs more Unistrut. And rebar. TO THE FP!

BiTurbo228 - Dr Frankenstein of Spitfires > Takuro Spirit 02/18/2016 at 16:41

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Saw a picture of an upper wishbone made of rebar once. It was nicely triangulated but I’d bet it would crumple as soon as any real force was applied to it. Pretty certain I could bite through rebar...

BiTurbo228 - Dr Frankenstein of Spitfires > daender 02/18/2016 at 16:43

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I wasn’t no. I was going on the requirements from the MSA rulebook and anything more than this is optional.

If I do a full cage I’ll likely revisit that but at some point you end up just adding weight for no real gains...

daender > BiTurbo228 - Dr Frankenstein of Spitfires 02/18/2016 at 16:47

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I only recommend that bar position because I’ve seen floors get pinched and pushed up into the cabin from the car being compressed in a sideways collision. Yeah, it’s excess weight but it’s a minor sacrifice for a little bit more of extra safety.

BiTurbo228 - Dr Frankenstein of Spitfires > daender 02/18/2016 at 16:50

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Interesting. A side impact’s also far more likely to happen than a full rollover.

I’ll see if I’ve got some tubing left. If not, I do need to order some more as I was going to make door bars for the fibreglass doors I’m hopefully getting.

daender > BiTurbo228 - Dr Frankenstein of Spitfires 02/18/2016 at 16:54

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Door bars a huge plus in my safety book! As for that floor bar, it might also be worth running one up front when you go to a full cage setup to further prevent the front of the car getting compressed around your feet/legs. I just like seeing thought-out cages that tie everything in together to prevent the body/chassis from crumpling in around the driver.

crowmolly > BiTurbo228 - Dr Frankenstein of Spitfires 02/18/2016 at 17:36

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Looks nice, but you need one of these:

BiTurbo228 - Dr Frankenstein of Spitfires > crowmolly 02/18/2016 at 17:39

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Thanks :) What for though? Can’t see that triangulating anything :S

Unless it’s for harnesses in which case I’ll stick some small bars across the diagonal at the back :)

crowmolly > BiTurbo228 - Dr Frankenstein of Spitfires 02/18/2016 at 17:41

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Harness bar and seat brace.

BiTurbo228 - Dr Frankenstein of Spitfires > crowmolly 02/18/2016 at 17:44

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Ah gotcha :) i’m keeping it fairly basic at the moment as interior space ia at a premium. I'll definitely bear that in mine if and when i make a race GT6 :)

phillipmp > BiTurbo228 - Dr Frankenstein of Spitfires 02/18/2016 at 23:03

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BiTurbo228,

You could do much worse than read through this roll cage thread . I understand that you’re in between making a ROPS or a proper cage. I believe the thread will aid you either way.

By MSA, do you mean this is your g overning rule set ? Have you read any other cage design protocols or rules for other racing bodies? Supplementing the MSA could greatly enhance the safety of the car in the event of a crash.

Remember the entire point of caging a car is to achieve maximum safety in the WORST CASE SCENARIO. Note that a side impact can also be a roll-over. I was working F&C at that same track where a BMW E46 M3 crashed in a similar fashion, but rolled over after hitting the tire wall on driver’s right.

Would I be correct in assuming yours is a right hand drive car? Where are you mounting the seat? Will your seat back protrude rearward past the plane of the main hoop? If not, I suggest adding a horizontal cross bar for both mounting your harnesses and bracing the back of your seat. Additionally you could have a diagonal bar in plane with the main hoop terminating at the node nearest your head, similar to this option here. Note that is for a left hand drive car.

If you choose to cage the front half of the car please consider a dash bar spanning the firewall. This aids the firewall from keeping the engine out of your lap on a bad day. Similarly, terminate the front hoop as forward as possible in the footwells, or have tubing extensions doing so. That would prevent your feet getting crushed by the floor board.

For side protection I recommend you consider NASCAR style side bars. Many of my road racing friends favor these for these reasons:

Maximum space for the driver - nascar bars typically arc away from the driver and into a gutted door skin

Ease of access and egress - the top of the nascar bars are a handy seat or step when getting out in a hurry, ie fire

Lastly, consider installing FIA bars from the front floor to the roof. When done correctly, these triangulate the roof supports and greatly enhance roll-over protection.