montesa311

im working on a design for a roll cage, and i was woundering what you all thought about its ability to stifen the chassis for better handeling.. the car is/has subframe connectors, tubular front crossmember and a-arms, strut tower brace (3 point connection style) and a bunch of other goodies... but i would still like to stiffen it up a little more... the car has t-tops and i can still hear them creaking in hard cornering... so i know there is room for improvment. so to the overall question.... since im tring to design the roll cage, i was tring to figure out a way to make the roll cage also stiffen up the chassis.. i know any roll cage will make it better, but im tring to design it with the stiffining in mind... any thought would help

askulte

To start visuallizing how the car flexes, imagine taking a sheet of cardboard, and twist it. It flexes easily and doesn't have much stiffness. Now do the same to a box - hardly any flex.

Your lower plane (bottom of the box) is already stiff, from the unibody and the subframe connectors. What needs to be done is to tie the upper plane to the lower plane and brace it. By having a cage tie into the firewall and rear shock perches, you just turned your flat sheet into a box. Sure - a roll bar will help if you don't tie into the firewall bar (base of windshield), just like SFC's, but that one additional connection point will add a ton of stiffness. If you run a diagonal from the left rear shock tower to the right firewall (and give up the pass seat), that would be ideal. Not many people would do that to cars that are street driven, though. Finally - tie diagonals from the strut towers to the dash bar and the STB.

Question you have to ask yourself is how stiff do you need the car? If you're not a national caliber driver, putting the effort into drivers ed (racing schools) would probably give you faster track times than a super-cage. If you're drag racing, disregard all this!

montesa311

well the car is a kinda do everything like most peoples car, its driven on the street, goes to the stip, and out to the road coarses, on hard launches at the strip, it starts twistin up, and i can only imagine the streeses and eventual craks that will result, but on the road coarss i do, in hard cornering i can feel it shift a little, but i cant give up the passengers seat... then were are all the hot girls suposed to sit...... i guess i have to find hot girls first though..... i have some pics of the cage im working on, i'll post them later on today

1983Fbody

You have the same mods I did before I installed a 12pt. cage. You'll notice a huge difference once tied into the suspension points, no comparison really. I cut through the floor and tied into the subframes also through the firewall and onto the strut towers before boxing it all back in with sheet metal.

You could weld the cage directly to the top of the "door pillars" with a couple of added supports- which is not legal for some road racing events. To get around this some racers will press the 'cage bars up against the pillars using a jack, then weld them in the normal places(halo bar, floor pads) to add stiffness and not break the rules.

The cardboard concept explains it pretty good. I wanted to add that triangle shapes are the strongest if you can design any into your 'cage, also using gussets on all the intersections.