Thanks TT.

How about a baseplate welded to the frame and drilled and tapped for a bolt in setup? Would have another plate welded to the bars. How thick would work for this?

 

bolt in? are you goling for a show cage or the real deal?

I think my plates are 3/16 or a little under that. Don't remember exactly.

 

Are your plates flat? I don't want to have to be bending anything with a torch.

Are they necessary? They won't be easy to do with the body on.

And now that I have gas and it setup good my welds are perfect!

Do you go in a coin pattern or zig-zag? Going straight seems to work the best. I have my edges tapered in to get full penetration.

 

Still thinking about going bolt in so I can get my speaker box in and out, still going to drive this car on the street off and on. Bolt in is good to 10.00 with a full bodied car and a 5 point roll bar, and with a IRS u can't go faster than 11.00 anyway if I am reading the rules correctly. Wonder how a Dragvette girdle or Tom's IRS is viewed by the NHRA?

 

Chris, they are curved to the frame contour but you won't need a torch, a big hammer and a vise go a long way. Just bend it, move the bend line up, hammer some more until you have a nice curved plate that fits the frame

Are they necessary, no. Are they better than welding the pipe straight on the frame? Yes, they spread the load. The frame really isn't that thick and you could buckle the frame when you need to rely on your cage. Indeed they're not easy to do w/ the body on.


You don't taper the edges when welding these things on top of each other, when you're doing a corner joint or a butt weld on heavy gauge then you need the chamfer to get full root access. With the plates laid on top of each other and fitting properly you already have a full accessible weld root.
No i don't zig zag or go in coins, the material isn't thick enough to require weaving (unless you have a puny little welder) I go forward and back uo a bit, then forward and back...and so on.

Dave, you have to make up your mind on what you want. You can't have it all like that guy on american hot rod w/ the red c2, hw wanted a race car, luxury cruiser, street racer and what else and at the end it was a little bit of nothing. If you want a serious cage, weld it in. Modify the speaker setup so it's removable if necessary.

 

I see what your saying TT. The NHRA does allow bolted in 'roll bars', good to 10.00 in a full bodied car. I could always weld them in later if I decide to go 10 point, I am thinking, as long as I make the down tubes correctly (30 degrees from vertical minimum).

 

Regardless of what the guys say here a base plate welded to the frame and then another plate welded to the bar and securely bolted to this base plate is just as strong. A threaded fastener is just as strong if not better then a weld.
I agree you can not bolt a cage to the frame without welding a secure mount to that frame.
Two pipes that come together if a properly welded flange is put on the end of each tube and then bolted securely together is will hold as much as any any welded joint.
Rules might not agree, they make the rules for easy enforcement and the tech guys don't need engineering degrees to interperet it and you might get a hassel.
But if you want the protection of a cage, the rigidity of a cage a properly bolted in cage will lack nothing and make life alot easier.
Major metal structures are flanged and bolted. And yes I know the twin towers came down because the bolts let go.

 

What about the nuts for the bolts? How would I do that? Was thinking about going 3/8 steel plate welded to the frame and then tapping some threads into that, but I'm not sure that would be as strong as what your talking about Norval...

 

Maybe I'll put a plate down now

 

How much thread engagement do you need before the nut is as strong as the cross section of the bolt? 4 or 5 threads is all. A 3/8th plate is plenty strong. You can always increase the number of bolts if it bothers you. Put in 6 if you feel 4 is not enough. I went with 4. My base is securely welded to the frame, alot of area for weld and the load is spread out. To this secure frame I then welded a flange to the tube and then bolted this flange to the frame mount.
Yes you can weld the tube directly to the frame but that is really pushing it. The small contact area, the wimpy weld. You are better with a plate welded to the frame or in this case a plateform to bolt the flange to.
Unibodies require I believe a 6 inch by 6 inch plate but we have frames.
Mig is the only way to go here. Lots of buildup, quick, easy and not a problem with burn through.

One of the problems with a cage on a street car is the DOT can complain that in the event of an accident they can not get the victum out of the car. They can demand the cage be removed and in this case I can quickly remove it, present the car for inspection and then bolt it back in. I know the blower sticks through the hood but since I can see both fenders clearly they can not charge me with obstructed view.

 

So, after you crash the car you quickly remove the frame before the emergency services come, or you know when you're going to crash and take out the cage before you go for a spin? Come on, that's BS!!!!

Also, a bolt may be as strong w/ 4 threads engaged but that's in tension, not shear. If you have 2 flat plates bolted together w/ 4 bolts it'll never be as strong as the 2 plates welded together. You will need some kind of dowel engaging deal to unload the bolts in shear

 

your kidding right?? or do you really live in a town called DREAM LAND??
...redvetracr

 

I finished my cage tonight. I just need to paint it and weld it to the frame.

 

Cool, looking forward to the pics. Mine is on hold till I get my poly body mounts and sling to lift the body (next week). I want to make certain the top of the roll bar is as tight as possible to the roof and I have no idea how much the new body mounts are going to lift the body.

DW

 

 

Welding it is pretty dam hard

Base plate to the frame should be a bit easier

 

That looks great Chris! I hope my welds turn out as good.

Hey Norval, I really appreciate all your help and pics, I have them all saved on my computer and reference them a lot.

 

Just put in alot of practice on scrap pieces. It's hard to get used to it. I have to do about 4 different beads for each joint.

Yours looks like it fits a little closer on the sides. I'm not sure though. I'll have to put the panels on and see.

 

I actually had to rewire my garage for 220 for this project, lol. I'll have to do some practicing with the heat/penetration on some scraps too, heh.

 

You people need to lighten up. Norval has always offered nothing but helpful, friendly, clear and knowledgeable posts, and always respectful of others, regardless of their knowledge or abilities, he doesn't deserve this crap.

Why don't you take a break from working on you cars and work on yourselves. Like TT's car, it'll never be finished because it's a life long project.