Well having little to no fabrication experience go easy on me. So I'm trying to install a comp. eng. roll cage. I got the hoop in and I started the crossbar and was doing real well and then oopppps!!! I cut it to short. It is a 1/4" short. Can I cut it in half and weld in a piece and have it be safe? They say a good weld is stronger than the orig. metal. Maybe if I "v" groove it to weld, or should I try to find some new tubing? (Which will be hard) Thanks in advance. Seann

 

ahhhh....14 inch aint that bad, hammer up the floor and get a thicker plate to go under the cage that welds to the floor

 

He cut the crossbar too short not the main hoop.

To be done properly, lengthening it 1/4" will be more problems. The crossbar doesn't need to be exactly where the bend is in the main hoop but does need to be in a specific location in relation to the driver sitting in the seat for the shoulder belts.

2 options

Install it slightly lower where it makes contact on both sides. If below the recommended location then option 2 is to buy some new tubing. 1-3/4" x .134" DOM tubing.

To cut it and make it longer, you need to install a tube that slides inside it or a sleeve to go over it. The rulebook section on frames explains how to extend a tube. All butt welds (welding 2 pieces together) must have a visible reinforcement. IE. sleeve and rosette welds.

You could always cheat and cut it right where one of the shoulder belts wrap around the bar and weld in a small section. Nobody would every see it.

 

1/4" is only an 1/8th on each end. Thats just a good weld gap. But if you cut it, sleeve it on the inside, weld it up, grind it down and finish it off nice maybe no one will ever know.

 

Grinds on a weld mean instant DQ at any local track with tech

 

I think I will just try to find a new bar. Called around and nobody has any dom tubing. I'm gonna call outlying towns and try to find some. Anyways here are some pics. Lmk if you guys see anything I might be doing wrong. I don't want to go to mid ohio, or norwalk and not be able to run. Thanks

 

Some more pics just in case I'm screwin up. BTW I did not do the drivers floor like that. I took itto a friend of a friend who said he could fix it.I went there a week later and that's what it looked like. I said if it looked like that I could do better and took the car home.

 

That must be a pretty common fix for that area that rusts out down there. Kind of looks like what I did to fix mine, except no 1/4" gap.

Is there a particular reason you have to have a piece of DOM tubing to fix your mistake? I don't know about the comp eng. cages, but my S & W isn't made of seamless tubing...it might be easier for you to find a piece of regular 1 5/8" x .134 mild steel tubing??

 

Yeah I was super poopiefaced when I went there to check out the progress. It's kinda my fault for not checking into his previous work. As far as the dom tubing I was just going by what Stephen 87 IROC suggested. I really hate to do things twice. But I hate to do it 3 times even more. I am not willing to risk that.

 

It that main hoop welded to sheet metal? All the mount points need to be welded to 6" x 6" x 1/8" steel plates that are welded to the floor. That section that the hoop is sitting on doesn't look like a 6x6 steel plate. You can heat and hammer the plates to take the shape of the floor.

Just did a quick flip through the rulebook and didn't see a specification requiring DOM but it does say for the simple roll bar that all tubes are 1-3/4 x .118" (minimum) of mild steel. Typical safe wall thickness is .134". It also says that the crossbar that you cut too short only needs to be 1-1/4" OD but minimum wall thickness is the same.

Looking at your crossbar in relation to your seat position, I don't think you would have wanted it much lower.

 

The hoop is welded to the 1/8" pieces I got with the cage kit. I cut the plates to form them to the floor. Is that bad??? Thank you for looking up the specs though as any info is good info. Where did you get the spec book? I need to order some. Hindsight is 20/20.

 

i mail order some of my metal.
try going to http://www.metalsdepot.com/
thats who i use

 

I get most of my metal from a local metal supplier. You can see if there's a branch near you. www.metalsupermarkets.com

As for a rulebook, both NHRA and IHRA have similar requirements for roll bar/cage construction. If your local speed shop doesn't carry the rulebooks, you can buy them from the sanctioning bodies or from online vendors such as Jegs. You can also join the NHRA or IHRA and you'll get one free. If you're going through the trouble to install a roll bar because you need one, you should at least install it so that it will pass a tech inspection as per the rulebook.

I can't see how cutting the plates to form them to the floor could be "bad". Nothing in the rulebook says you can't. The idea of the plates is that there is 24" of weld holding the plate to the sheet metal compared to a few inches around a tube holding to sheet metal. A tube simply welded to sheet metal can easily punch through or tear off the metal even if it's just welded. The plates give it more stability and strength.

If you want to build a spec chassis, the specs sheets can be purchased for $35 from www.sfifoundation.com but I doubt you would ever need to go that far for a while. They're more for chassis builders.

 

Took your advice stephen and bought a new tube and finished it today. LMK what you guys think.

 

Now you just need the door bars.

 

I have had SCCA tech check welds, stab bushings, and go through my car with a fine tooth comb. There is nothing you can hide from a good tech inspector.