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Jon's 2 year roll cage saga...


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More is better. If I were doing one the .080 plate would have a 90 degree bend at the bottom, start on the floor, and basically cover the front face of the strut tower. 100 square inches can do a lot to help that strut tower.

 

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

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Take your 1" square tubing and cut one side off so its a U-channel. Contour the open end so it fits tight down on the floorpan and connects to the rocker and the tunnel while keeping the top surface sqaure and level side-to-side. Stich weld the U-channel to the floor pan' date=' rocker, and tunnel. Drill holes in the top big enough to get a 3/8" nut through the opening. Weld a 3/8" nut to a 1/2" washer, insert the assembly nut down into the hole, and weld the washer to the top of the 1" tubing.

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I gotta say, I thought 1" off the floor would be WRONG, but it turns out that this is closer than I had thought to what you need. It's like you've done this before or something John. :wink: When I tried going 2" off the floor with the sliders I'm using the seat was way too high. BTW I ended up grinding a notch in the bottom of the tube where the bump in the floor is so I'm not going to cut that 2" section out of the floor. Probably about 70% done with the mount. As with everything, this is taking longer than it should. Contouring the end of the tube was a lot easier than I thought it would be though. Might finish the frame tomorrow. Kinda tired and dirty right now.

 

Also looks like I'm going to use a piece of angle iron on top of the tube to bolt to, so won't need to drill holes and get washers, etc. I like that idea, but I'm trying to keep it simple.

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Yeah so today I welded up my angle steel :wink: to the square tube and got that all squared away. Problem I'm running into now is that the floor isn't flat. I've beaten the bent parts as much as I can. I think I'd literally have to remove the frame rail from the floor to get it any better. The frame rails are dented and look pretty bad on my car, so I was thinking about doing some subframe connectors or just replacing the stock rail where it is bent. If I could weld this frame to the floor now, but then the floor might not be straight when I went to do the subframe connectors. Or I could tack it in now, make sure I get clearance for the roll bar, then fix the floor and finish welding later. Now that I've typed all that out I think tacking it in and then waiting to finish it is my best option.

 

Got some pics, but can't upload. Is it just me???

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Update: Seat is in temporarily anyway and shoulder bar for roll bar definitely does not clear the seat back. So I'll need a curved piece to go around the seatback. It will be easier to accomodate the seat back if I move the diagonal farther away from the bend. I looked in the rulebook and I don't see a max distance from the corner bend for the diag to hit the hoop. Is there a rule? Obviously the closer to the corner that bar connects the stronger the diag will be. Looks like the Autopower bar for 944 connects pretty far away judging by John's website. Any idea how far away that is John?

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  • 6 months later...

I might set projects aside, but I always come back to them... 9 months later.

 

I think I have most of this figured out, but I want to get some advice on attaching the bar to the rocker. I've decided to do mine like katman did the cage in the old ITS article. That's what will work best with the way the main hoop is bent I think.

 

I just can't really make out exactly what's going on from this old article scan: ZcarCage2.jpg

 

I think he's made a plate to go in the corner like this:

DSCN0990.jpg

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DSNC0989.jpg

 

But then his tubing looks so tucked back in the corner there.

 

What I don't get is how the hell do you weld this in with the roll bar tube right in the way? Only thing I can come up with so far is to shape the plate, then weld the tube to it, then weld the plate to the rocker. Even then I don't think I'll be able to get the plate welded to the body in the far corner. Is that going to be a problem?

 

I've only got one hoop and no bender so I don't want to F this up. Advice appreciated.

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Your last picture sure threw me off, but when I did a headstand, then things were put in perspective.

 

I guess reading this whole thread would be ideal, but would you be able to mount the main hoop in the seatbelt retractors like I did?

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But then his tubing looks so tucked back in the corner there.

 

What I don't get is how the hell do you weld this in with the roll bar tube right in the way? Only thing I can come up with so far is to shape the plate, then weld the tube to it, then weld the plate to the rocker. Even then I don't think I'll be able to get the plate welded to the body in the far corner. Is that going to be a problem?

 

I've only got one hoop and no bender so I don't want to F this up. Advice appreciated.

 

Yes, what you've surmised is correct. The tubing is also notched to get about 50% of it on top of the rocker and the rest tapered to the side of the rocker. You can also build a box or shelf like I've done here:

 

240ZRollBar4.jpg

 

Ideally the main tube should be closer to the rocker in my picture above but my customer wanted to be able to easily re-install the interior parts, so I moved the legs in about 3". There are a couple ideas behind building a box:

 

1. Tie the rocker, the floor pan, and the rear bulkhead together beyond the existing OEM structure.

 

2. Create a horizontal (or near horizontal) area so compressive loads in the main hoop legs are more normal to the tube's vertical orientation.

 

3. Its really easy to get the main legs positioned correctly.

 

A box takes up more space (can interfere with moving the seat back), adds weight, is more complex to build, and you have to get the welding right or the box will come a part in an impact Z (or the main hoop leg will punch through).

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Looking at the picture above it looks like I'm using seamed tubing. The line you see on the tubes are orientation lines I draw to make sure:

 

1. I'm bending the tubes in the right direction.

2. The notches are oriented correctly.

3. All the bends are in the same plane (it sucks to end up with a main hoop that has a twist).

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Well, it's almost done. Haven't put in the shoulder bar yet, and I need to make tabs to connect it to the roof. Everything went pretty smoothly. Biggest problem I had was that I couldn't get the bar exactly centered, it's about 3/8" closer to the driver side than the passenger. I kept screwing with it and it wasn't getting any better. The more I messed with it the closer the bar got to the sides of the car (it's about 3/8" on the driver side and that's with that big bump inside beaten down) so I finally just said screw it and started welding. :lol:

 

This was a really scary project for me to tackle, because I had a couple hundred bucks in the material and have no easy way to fix it if I screwed up. Hopefully nobody will find major fault with it. I started thinking I was going to duplicate John's bar design on his website, ended up with something much more katman-ish...

 

Here are the pics:

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DSCN1009.jpg

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  • 1 year later...

I figure since I finally have something more to report here, might as well change the name of the thread and give the update.

 

Just over a year later, I HAVE INSTALLED THE SHOULDER BAR!!! WOO HOO!!! :lmao:

 

I guess it's not like I haven't done anything else in that time frame, but I did finally get a bender that works from http://www.speedwaymotors.com and I finally got some tube and finished up the shoulder bar. I'm happy with how it turned out, and now that I have the tools I expect to continue on with the cage, trying to get the main part done before I move, but that's going to be tight at best.

 

Some pictures:

 

DSCN1670.jpg

 

DSCN1671.jpg

 

DSCN1672.jpg

 

I guess I didn't update when I did the X brace, so here's that thread for anyone interested:

http://forums.hybridz.org/showthread.php?t=119861

 

Next up, bending the halo. I'm really a little freaked out about trying to bend this sucker, but I guess the worst that happens is I waste a piece of tubing or two or three...

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Are you going to remove part of the roof to completely weld the halo bar in place? Why didn't you wait to weld in the main hoop in until you had the hallo bars done? That way you could have dropped the cage down and finished the welds completely.

 

Also, why halo over the alternative of A pillar bars with a cross tube? Most of the cages I've seen with the halo bar have trouble fitting the halo up really tight against the roof.

 

Anyway good job making progress! That bender is pretty interesting. I'm just concerned with the amount of effort to start bends.

 

Justin

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Are you going to remove part of the roof to completely weld the halo bar in place? Why didn't you wait to weld in the main hoop in until you had the hallo bars done? That way you could have dropped the cage down and finished the welds completely.

 

Also, why halo over the alternative of A pillar bars with a cross tube? Most of the cages I've seen with the halo bar have trouble fitting the halo up really tight against the roof.

The way my main hoop was bent I don't think I could have gone through the floor even if I wanted to. It was very tight in there. Also at the time I was going to do a roll bar and not a cage. Then after a while I decided to do a full cage instead, but the roll bar was already welded in. The plan is to cut the entire roof off at the A and B pillars, after tacking the cage in.

 

Halo vs A pillar bars... I was under the impression that halo bars were stronger. I'm not married to either idea. I know bjhines was worried about putting more than 2 bends in the A pillar bars, but I haven't seen any rule in the SCCA book that says anything about the number of bends in the A pillar bars.

 

On the bender, keep in mind that I'm using about the largest tubing it's made to bend. They say its good for up to 1.75 x .134, I'm using 1.75 x .120. I'm sure if I were using 1.5 x .120 it would be a lot easier. Even as it is, I may have overstated the difficulty if people are getting scared away from it. I don't have the bender bolted down, so I'm able to hold it on the table with my left hand while pulling the handle with my right. I just thought it was interesting that it took so much pressure to start the bend, then once going didn't take as much to keep it going. So far I'm nothing but happy with the bender.

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