some good roll cage buidling guides

oh yea the building takes place in novato (40 minutes closer) and that would be awsome if you made it up here after xmas !
Lina

now I totally see it Bob, the inner rocker panels (new) in your hand out of the car had me confused for a sec... very nice, thanks for the elaborating. the feet locations and design is probably one of the first steps to take -
and I like like like not having to cut holes in the floor... wont have to weld them back up with rat droppings later hahahha

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john vanlandingham
When the car's FIA homologation runs out, you enter the car in whatever NATIONAL class it fits in. Same car, same cage..

John - part of the problem is FIA cert'd cages no longer come with FIA papers after the homologation expires. When I enquired about their offerings for the Compact, Custom Cages UK told me I'd get MSA papers. I ran that up the flag pole at both RA and NASA and got the same answer. No FIA papers, no way a T45 cage would be legal in this country.

If I had to use CDS or DOM, I saw no reason to pay the premium for a pre-bent cage...especially when roll cage tech has come a long way since 1995.

If that's wrong...when the first chassis is done, maybe I'll consider trying to find some other tech guys...T45 cage = 100 lbs, CDS/DOM = 170 lbs.

Dave

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DaveK

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john vanlandingham
When the car's FIA homologation runs out, you enter the car in whatever NATIONAL class it fits in. Same car, same cage..

John - part of the problem is FIA cert'd cages no longer come with FIA papers after the homologation expires. When I enquired about their offerings for the Compact, Custom Cages UK told me I'd get MSA papers. I ran that up the flag pole at both RA and NASA and got the same answer. No FIA papers, no way a T45 cage would be legal in this country.

If I had to use CDS or DOM, I saw no reason to pay the premium for a pre-bent cage...especially when roll cage tech has come a long way since 1995.

If that's wrong...when the first chassis is done, maybe I'll consider trying to find some other tech guys...T45 cage = 100 lbs, CDS/DOM = 170 lbs.

Dave

You can save some weight in the cage construction by utilizing 1.5 tube in all the places that 1.75 is not required. So is 50 lbs savings worth the strength lost to the T45? Not in my book.

Some places you can even utilize 1" tubing.
Like bottom of main hoop to rear stays near strut tops.
Things that are optional can be sized smaller if desired.
Or if you're really worried about weight, minimum spec cage.
Brian Moody said it best though. In rally cars we obsess over weight reduction up until the point the cage is going in. Then after cage is done, you can obsess some more. Safety > weight every time.

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phlat65
You can save some weight in the cage construction by utilizing 1.5 tube in all the places that 1.75 is not required.

Already did that and based on tube length estimates, the Compact cage came in around 170 lbs. I forgot to weigh just the chassis, so didn't have a chance to do a real before & after.

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phlat65
So is 50 lbs savings worth the strength lost to the T45? Not in my book.

If the T45 stuff is so unsafe...why is it allowed by the FIA? When I built my evo a few years ago, I looked around at options and was under the impression that T45 FIA approved cages were the pinnacle of what a privateer would put into a car. Pricing wasn't much more than a shop built one-off, so I went for it. My only disappointment with the cage is that there aren't sill bars.

Dave

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DaveK

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phlat65
You can save some weight in the cage construction by utilizing 1.5 tube in all the places that 1.75 is not required.

Already did that and based on tube length estimates, the Compact cage came in around 170 lbs. I forgot to weigh just the chassis, so didn't have a chance to do a real before & after.

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phlat65
So is 50 lbs savings worth the strength lost to the T45? Not in my book.

If the T45 stuff is so unsafe...why is it allowed by the FIA? When I built my evo a few years ago, I looked around at options and was under the impression that T45 FIA approved cages were the pinnacle of what a privateer would put into a car. Pricing wasn't much more than a shop built one-off, so I went for it. My only disappointment with the cage is that there aren't sill bars.

Dave

IDK, I watched a few WRC crashes, and the cages deform alot! I am not in a position to put the seat in the middle of the car to give me as much crush space.

I watched some in car of Henning doing a slow roll, and when the car teters on the roof, you can see the roof bars deflect in at least an inch or so, just from the weight of the car! I seriously doubt my cage would do that built with .095 DOM

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phlat65
IDK, I watched a few WRC crashes, and the cages deform alot!

Hmmm... its almost like they were designed to deform and absorb energy.

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phlat65
I watched some in car of Henning doing a slow roll, and when the car teters on the roof, you can see the roof bars deflect in at least an inch or so, just from the weight of the car! I seriously doubt my cage would do that built with .095 DOM

So it will pass that enegry to the first thing that moves around - the occupants and their innards.

Another thing to consider if you're prone to obsessing about cage weight. You will easily have 100 pounds of mud stuck to the underside of the car by the time you're halfway through the first stage (on a wet rally, anyway.)

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Doivi Clarkinen
Another thing to consider if you're prone to obsessing about cage weight. You will easily have 100 pounds of mud stuck to the underside of the car by the time you're halfway through the first stage (on a wet rally, anyway.)

Agreed - but the T45'd car will still weigh 70 lbs less.

If you're building a car that can be built to come in well under the weight minimum, I could having a heavier cage becomes less of a negative. But, if you've gutted and stripped a car pretty far and you're still 100 lbs over the minimum weight, fitting that lightweight cage starts to look more attractive.

I'm still curious about the reasoning that DOM is the preferred material vs. T45 (or other chromoly) when the rest of the world seems to think T45 is just fine.

Dave

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Morison

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phlat65
IDK, I watched a few WRC crashes, and the cages deform alot!

Hmmm... its almost like they were designed to deform and absorb energy.

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phlat65
I watched some in car of Henning doing a slow roll, and when the car teters on the roof, you can see the roof bars deflect in at least an inch or so, just from the weight of the car! I seriously doubt my cage would do that built with .095 DOM

So it will pass that enegry to the first thing that moves around - the occupants and their innards.

I understand energy absorbing structures and all that Keith, but should the Roof X deflect 1-2 inches just from the weight of the car?

I anin't no dummy.....

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Morison

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phlat65
I watched some in car of Henning doing a slow roll, and when the car teters on the roof, you can see the roof bars deflect in at least an inch or so, just from the weight of the car! I seriously doubt my cage would do that built with .095 DOM

So it will pass that energy to the first thing that moves around - the occupants and their innards.

This is something that I've heard before as well. I've kinda viewed the T45 cage as sort of a throwaway if you're in a big accident whereas a DOM car might not suffer the same destruction. I guess at some point, there's a tradeoff in which is better....but no idea what speeds or circumstances represent that point.

I'll say that some of the wrecks we see at the top levels are pretty f'n bad looking. Despite the cars shredding parts and crumpling into a ball, I'm still constantly amazed at what people are able to walk away from.

Dave

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phlat65
I watched some in car of Henning doing a slow roll, and when the car teters on the roof, you can see the roof bars deflect in at least an inch or so, just from the weight of the car! I seriously doubt my cage would do that built with .095 DOM

Do you have a link? I'd love to check that out.

Also, side question - are WRC cars allowed to gut the interior sheet metal? I've seen some top level time attack builds that just about everything but the outer skin is removed, so that would make the car structure quite a bit weaker...putting more of the load on the cage. Curious because I'm wondering how a WRC car would compare to GroupN type car.

Dave

I dont think they trust the welding process on T-45. Dom welds can be looked at and have a good idea if the strength is there. T-45 welds can look awesome and break from an improper weld.

Every body in America seems afraid of law suits and base rules on if if if what ever happens were done. This is just what Ive found when I asked the same question.

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phlat65
I understand energy absorbing structures and all that Keith, but should the Roof X deflect 1-2 inches just from the weight of the car?

I don't know the video you are talking about but I would be extremely reluctant to judge something like cage deflection from in-car video.
Got a link?