I was thinking of putting in a roll cage (6 point I think). My dad put in a roll cage and his has 2 bars to the trunk area, 2 by the back of the doors, and 2 up by your feet, (with swing-out sidebars), as well as the crossbar in the back. My question is, if I leave out the crossbar, will the roll cage still stiffen up the frame? It will be tied into the sfcs if I get it.

 

even if they do stiffen up the car roll cages aren't meant for that, they're roll over protection. it's a lot of extra and needless work to tie a cage to the SFCs. leaving out the bracing will significantly weaken the main loop. look at nhra rules for what is reguired to make and install a safe and effective rool cage.

 

I agree with your response except for the statement that welding the subframe connectors are a waste. If you ever make real HP like anywhere from 400-600 at the rear wheel then you will need that extra tie in to keep your car from looking like a pretzal after 8-9 passes. And yes its feasible to twist a car with subframes and a regular weld in roll cage. Its been done before.

 

are you kidding me?

roll cages absolutely do stiffen the chassis, and are intended to that.....as well as for protection. A cage is an important element in creating a stiff chassis, look at some tube frame cars....the cage is part of the super structure.....because it makes the car that much stronger and resistant to flex. thats why the car has to be plumb and level when the cage is installed or it will be twisted forever.....cause it wont flex after the cage is welded in. a 6 point cage or better (i have an 8) will stiffen your chassis alot more than subfram connectors will. I have both as well. Unless you are really going crazy you dont have to tie the cage into the subrames though.

i installed my cage about 2 months before i got around to installing the subframes.....after i was done the car was so stiff it was great....body flex was virtually eliminated. BEFORE subframes...with the cage, i could jack up the right front wheel and pull 3 of the wheels off the ground.

the cross bar behind the seat is an important structural element of the cage...it would really hurt stiffness to remove it, and structural integrity. its also required by NHRA as a seat support. its a good place to tie in your racing harness as well.

 

I put an 8 point roll bar in my Trans am and it really really does stiffen things up alot!!!!I really don't see why a 6 point would be the way to go b/c after a 6 point is in the backseat is pretty much unless for people. since you really can't get anyone in the backseat that easily you might just as well put in the last 2 bars, it will only add more strength and stiffness to the car. my .02 cents I guess.