tube80z

.095 1.5 inch tubing should be fine. I have seen many cars built that way at a shop near me that have won many championships. For your weight target be prepared to bolt in weight. My project is an EMOD V8 powered autoxer. All the pieces (complete frame) and everything else piled on the car weighs 1640 pounds. It is built with .095 for the outer sections and main cage tubes and a lot of .064 and .049 used as bracing for sections that showed low stress in simple FEA tests. You will need to check on materials if you plan to roadrace. I'm pretty sure all the tube needs to be the same thickness in GT and DOM. Cary

Is 90 degrees a misquote? Because if that's it I wouldn't bother. A fluid recirculator would be a much better option. Cary "had glowing red rotors on my autox car this past weekend :-)"

You all should really listen to Jon. There are two types of padding I see on cages all the time. The first, often called pool noodles, really should stay near the water. The second is SFI approved and is a more rigid foam. It, HOWEVER, is intended to be hit by your helmet, not your skull. I know of no foam that is designed to deal with your head hitting a bar. Cary

I need to read the rules again. I didn't realize you could get away with such a big doubler plate. I wonder if you can flange holes in it to help make it stiffer? Cary

Reading this I see that I told you a lie. I don't do area. I've been doing 4 times the size. So for a 1.5 inch tube I've been doing a 6x6 pad. You wouldn't know I had a math degree I'll plug weld those too to make the stick better.

yep, that makes sense. I would close the gap across the lateral tubes to the floor rather than just use a couple of stands. That makes the floor a shear panel as Jjohn mentions. It would seem like it would be harder to rip out too. Figure in a wreck (worst case) that you might see some rather large forces on those mounts. And having more area will lower the load, or some my feeble thinking goes. Cary

I'm not completey sure I follow. Are you putting this tube across the car or lengthwise? If across I would use sheet metal to hook to the floor just like the stock piece, similar to what John mentions above. But I'm may not be following what you're doing here. For the tubes I try and do 4 times the area of the tube. Not sure why but somewhere along the line I picked that up. At least one of us is out in the shop working Cary "stuck at work"

What about FIA seats that don't require a backbrace?

John is right. The end links stack up and your spring analogy goes out the window, just like tender springs. This only changes the rate of change, not the rate. Cary

If you plot bumpsteer every 0.1 inches you'll get a curve. It depends on the curve whether you change the inner pivot point or the outer pivot point when trying to minimize bumpsteer. Cary

Oddly enough I've gotten it to work well. If I were to continue to run this car I would widen the front to be wider than the rear, if for no other reason having a fat but makes getting around cones a lot harder. The EMOD car is wider in front if that is any consolation. It's not normal but I thought I'd throw it out there. Cary

Hmm, I guess I won't tell you that my car looks like a 911 I would widen the front track but I've found that wider rears work for me. Cary