Cage Design, Are they really worth it in an auto-x Options

[jhadler]

David,

I like those designs. One other idea to add is a neat trick that I've seen used in IT and SS class racers. Run a bar along the door sil as close as possible. The trick was, clamping the bar tightly to the door sil while it gets welded to the verticals in front and back. The reinforcement this gives is quite substantial. But you have to get the sil bars _clamped_ down while they're being welded.

-Josh2

[Brett W]

Those cages will do very little for actual chassis stiffness, nor will they fix the safety issues with the chassis.

Look at the cage Gagnon's car.

http://www.pbase.com/9146gt/dr_gagnon_porsche_9146_gt

This is one of the better "bolt in" bars.

[groot]

Those drawings show things that "may" help improve the chassis stiffness through the passenger compartment, and they should do a decent job of occupant protection. IMHO they won't do much to improve your car's overall stiffness.

Again, IMHO it's pretty easy to fix that for the front of the car, just need to tie in your suspension points and triagulate to get the strength. The difficult part is getting real stiffness improvement in the rear. Sure, it's easy to do vertically by running tubes from the shock towers to the upper part of the main hoop, but what about horizontal stiffness and the stiffness of trailing arm attachments? That's the difficult part. My personal solution involves making the engine support bar a stressed member of the rear chassis and relocating the trailing arm mounts to accomodate attachments to the cage.

[Brett W]

Kevin is right, about the lateral stiffness. Keeping the car from folding up is fairly easy. Stressing the engine mount bar is a good idea, you have to carry the item might as well make it do something useful.

Wohoo, you finally gave in and moved the rear pickup points. What made you change your mind, (other than it is what needs to be done).

[groot]

(IMG:style_emoticons/default/laugh.gif) I'm not doing the "arbitrary raise the pickup points".... this is my new design trailing arm deal.

[Brett W]

Just jerkin' your chain.

[Dave-O]

Ok, I understand what you guys are saying. Next question...is there any way to really ad any beneficial bracing to the car with a cage that does not extend out of the drivers compartment (required in our AX classes)?

[Joe Ricard]

(IMG:style_emoticons/default/popcorn[1].gif)

[914forme]

Now I have thought about a much simpler solution, called bolting down the top. But that involves reinforcing the front windshield pillars and building a metal frame and cross bars into the roof. And making it them pin and bolt into the car and a Roll bar hoop. Bolt in a petty bar, and a couple of door bars and I should be good to go.

Factory did it with the GTs and it would not be hard to do. 916 they just made it a coupe to help solve the issue. One problem is it adds weight up high, but then so does a cage. I run with my top on anyway. Nobody wants to see me topless anyway. (IMG:style_emoticons/default/biggrin.gif)

I will have to get onto the other computer and build a diagram of my idea. Have had it sketched since the early 90s....

[Brad Roberts]

The single biggest improvement I have found over the years:

Single main hoop with a Petty bar that runs to the right front inner fenderwell where the frame rail welds to it. I use a bolt in bar solution. You can feel the difference simply by placing your hand on the bar in a corner. You can feel the bar load and unload in the corners. I feel this is a simple *easy* solution. Careful use of scab plate material and you can cover a lot of ground.

Something else to think about:

Engman kit. This kit was designed to be "hidden" under some thin carpet. Run it. It helps with both issues (twist and fold)

B

[J P Stein]

Ok, I understand what you guys are saying. Next question...is there any way to really ad any beneficial bracing to the car with a cage that does not extend out of the drivers compartment (required in our AX classes)?

You betcha.
This door bar helped quite a bit....I'm making a few improvements to it.

[Joe Ricard]

Hey those are ULF pics. Now that seems like a LONG time ago.
Geez I just looked at my post count and member number.


What I don't like about that design JP is the bar coming down so far back that I know I will never get my feet out of the car with out doing some serious folding of limbs.
I want to pierce the dash and run down to where the heater tube is / was.

[J P Stein]

Heh....I climb out the top....and I ain't all that agile (IMG:style_emoticons/default/sad.gif)
No worries about kicking off the fuse cover....

Had I planned that cage knowing where I'd be today, I'da done "things" different.
Shit happens.....but the bar stiffened tha car nicely. More would be gud.
Stay tuned.