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Rollcage for chasis stiffening

I am putting a Chevy v6 in my 914 and was curious if a 4 point rollbar in the cockpit does wonders for chasis stiffening. I would use 1 1/2 inch tubing. Thanks
Old 12-12-2004, 02:20 PM
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It does stiffen the chassis up, but "does wonders"? Nope. A full-on cage will come close--one that is tied into (at a minimum) six points of the chassis, four on the longitudinals and two on the targa bar. To really "do wonders", you need to have the cage connect through the firewalls to all of the suspension pickup points.

--DD
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Old 12-12-2004, 05:32 PM
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Peter, you can go several ways of stiffining the chassis. As Dave mentioned, a simple 4 point will stiffin the chassis, and it depends on your definition of "wonders". I honestly think if mounted with gussets as far up the A and B pillars as you can go, a 4 point cage will stiffin considerably. The halo of a cage in a targa car does a tramendous amount of work aiding in the stiffining of a chassis.

The other thing you can do to stiffin if you don't like the cage (its a small compartment and can become more dangerous for head injury than helping), is to get some thick (1/8"+) steel plate bent up and then weld it along the outside of the rocker, under the rocker panel. Since all of the chassis flex is through the floor, stiffing that will get you good results.
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Old 12-13-2004, 08:18 AM
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There are also doublers you can get that are formed to the in-the-cockpit side of the longitudinals. I am told those help. You can also weld a doubling plate across the bottom of the firewall in back, and I am told that it helps a bit--but not as much as a piece of tubing in the same location.

Don, when you say "four-point cage with gussets"--do you mean a gusset to an attachment at the A- and B-pillars? If the cage attaches to both at all, it is now an eight-point cage. Four "points" on the longitudinals, plus two on each A-pillar and two on each B-pillar. BTW, I'm not convinced an A-pillar attachment does much on most of our cars, because the 914's windshield frame is not very strong...

--DD
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Old 12-13-2004, 09:05 AM
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When I did this cage, the intent was for stiffening, not saftey.
IMO, this is about the minimum needed to actually do any good....and it does.This has 10 attach points. More tubes to the front & rear shock towers will help futher.

Easiest entry/egress is thru the top
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Old 12-13-2004, 10:10 AM
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Dave, your right about the windsheild frame, I should clarify. The A pillar section below the windsheild frame is what i would attach too.

The "X point cage" is only in reference to the bottom attachment points, IE when a tube ends to the chassis. All other points are just an attachment for strengh and have no reference about the cage. In JP's second picture, where the tube ends into where the speaker grill used to be, is considered in the count for "points". But in his last picture, where the roll bar hoop mounts to the chassis tunnel, and about .5" above that is another plate that is welded to the door seam, is not added to the "points" of a cage.

Here are a few pics of a '55 356 6 point cage i made. If you look at the top of the A pillar, i attached it to the cage. If i had also attached the cage at the lower bend to the chassis, this would also not account for the "points".

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Last edited by BigD9146gt; 12-13-2004 at 12:18 PM..
Old 12-13-2004, 11:42 AM
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Hmm... I must have misinterpreted the rules that I read about roll cages, then! I always thought that, when they said "attachments to the chassis", they meant anywhere the cage tied into the body of the car. On a 914, at least, seeing as it's a unibody car.

--DD
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Old 12-13-2004, 01:48 PM
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Well Dave we could both be right depending on who's rules your reading.
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Old 12-13-2004, 02:00 PM
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