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Opeler
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Discussion Starter · #1 ·
Just thought I'd keep everyone updated on progress, slow as it may be. Did some roll cage work tonight though - whataya'll think?
 

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Looks good, I posted a tiny pic of my in the gallery. Are you going to run a fuel cell or the stock tank? You might make sure that you can get it in and out before you put too much of the cage in.
 

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I like the way the front down tubes match the car's A-pillars very closely, that's a nice detail that I'm sure was a PITA to make.

So I'm curious, is that a 'rolled' radius, or is it the result of numerous small bends with a typical tube-bending die?
 

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Opeler
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Discussion Starter · #6 ·
The bends on the front are the result of a lot of small bends, and yes it was a real PITA. I actually scrapped my first attempt at the A-pillar, welded them together, painted them pink and sold them to a local art gallery. OK, I didn't but I thought about it.

If you can't tell, I'm running a pretty low budget shop here- the tube bender is just the $60 harbor freight hydraulic bender, and you can only get about a 45 degree bend out of it before it starts to cave the .095 tubing.

I did put in the braces for the main hoop, but instead of putting one running diagonally across, I put 2 running from where the torque tube attaches to the corners of the main hoop. Rallybob- you think this would be a problem for an inspector if I wanted to take the Opel on a hill climb or tarmac rally (like the tarmac express in Chatttanooga). (I don't think I want to take the GT on a full-fledged romp through the woods- spent too much time on the bodywork!

BTW this is my first roll cage, and I'm taking forever getting it done as I have to learn as I go. As for attaching it to the body, I don't know if that showed up in the pics, but I'm pretty much welding it the length of everywhere it touches the body, which I would guess is about 80% of the main hoop and hoops across the front. The front comes to the floorboard right at where the floorboard makes a <45 with the firewall, and then that's welded to a box steel brace to the frameish looking piece of structure that houses the tranny. All this is probably overkill for a relatively conventional 3.4L V6, but in the event that I can figure out a way to put 400HP under the hood, I'd like the body to be ready for it. Downside is I'm now on my 3rd roll of flux! Ah well, I'm keeping Rural King in business.
 

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Opeler
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Discussion Starter · #7 ·
Oh yeah- I almost forgot, about the dash, though I've not really done much yet, the plan is to create a mold out of my parts car dashboard, making a clear-out for the a-pillar tubes and the dash bar. I was planning on bondoing that up so it has a smooth surface, spraying mold release on it, the fiberglassing over that to create a female mold to use to make a prepreg carbon fiber dash. Again, this will be a learning experience as I have not personal experience with the CF either, but I have a friend who is planning on using the prepreg to make fenders and interior parts for his Lotus 7 kit car. Maybe between the 2 of us we'll get it sussed.
 

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Old Opeler
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Plates

Can't see the ends of your tubes - have they got a 3" X 6" plate between the ends and the body work? If the tube ends are just welded to the floor without plates to spread the load they will punch through in a shunt whe they are most needed.

Love the idea of pink tubes! Might even look good on the ones in the car:D
 

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Sporqster said:
I did put in the braces for the main hoop, but instead of putting one running diagonally across, I put 2 running from where the torque tube attaches to the corners of the main hoop. Rallybob- you think this would be a problem for an inspector if I wanted to take the Opel on a hill climb or tarmac rally (like the tarmac express in Chatttanooga). (I don't think I want to take the GT on a full-fledged romp through the woods- spent too much time on the bodywork!
I doubt the tech inspectors for a hillclimb would give you grief, but SCCA inspectors *might*. They generally want to see the car comply with either rally specs or Improved Touring specs if you run the Tarmac Express.

For rally specs, you could either run a full diagonal in the main hoop, or in the rear stays, and still be compliant (well, last time I checked anyway!). Now's the time to make a few phone calls to the tech guys while it's still in the building stages.
 

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Opeler
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Discussion Starter · #10 ·
about where the ends of the tubes - I have a 1/8 plate at each of the ends where it attaches to the body work, as big as possible at each point (the rear 2 are about 2.5X4 inches, the main hoop is pretty small, as it come down in a hole kinda, I would estimate 3X3, but it is also welded all the way up the B pillar to the bottom of the window. the braces I have running to the torque tube attachment point have a big plate, at least 6"x4", which is also being used to reinforce that suspension pickup. where the tubes attach to the front at the corner of the floorboard and the firewall, they go through a 1.5" hole cut in box steel which runs the width of the footwell. they're then welded to the box steel, and the box steel is welded to the body.) Seeing as how about 70-80% of this cage is actually seam welded to the body, I don't think that the small footprints at the base of the tubes would matter all that much, but I guess I would have to convince the inspector of that one. There just isn't realestate in flat surfaces on the body for a big square foot at each point where the tube ends.

About the fuel cell - as it is now, it will still fit between the two braces I have on the main hoop. If I have to put a full diagonal brace on the rear stay, I think I will have to make the speaker shelf removable and put the fuel cell in through the rear window.

Again, the dashboard is a future challenge - and if prepreg carbon fiber doesn't work, then it'll likely be fiberglass.

Just so no one gets the wrong idea - this is NOT a serious race car - just something that I can drive to work that LOOKS like a serious race car. It'll be autocrossed, and might do some hillclimbing and/or tarmac rallying, maybe a track day or three. Planning on keeping the car licensed and insured for street driving, and I'll probably drive it to work in the summer. Nothing like a full cage and 5-point harness to intimidate your way out of carpool duty!
 

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Sporqster,

The cage is looking good. It's great to see how different people come up with different solutions to the same problems when they aren't just trying to meet 'minimum rule requirements'.

In my cage, which is still a work in progress, I came up with a different solution for the base of the main hoop. Here's a couple pics.

-Travis
 

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Here's a photo of the roll bar configuration in my GT. In a few weeks, the car is getting a 2.4 engine (a la Rallye Bob -- 1.9 - 2.4 conversion). I felt that with the additional HP, I need the added stiffness and safety provided by the roll bar. It's constructed of 1.62" x .095 DOM tubing. The fuel tank can be removed by removing the horizontal bar under the package tray -- the only bolt-in piece. The upholstery will be replaced -- thus, the reason for the gap between the main hoop and door pillar. It is intended primarily to be a street car, but I plan to drive in "timed" road course and solo events.

On that note ... I'm looking for a "street" racing seat -- one that's adjustable, but with openings or cut-outs for the shoulder harness. Is anyone using something like that or have suggestions?

Thanks ...

Ken
 

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another silly idea

Travis, is the mounting plate you used a piece of folded flat stock or a cut away piece of box tubing? I ask because the general shape you used could be made with say a cut out piece of 2x6x1/4" box tubing fairly easily. If you went that route, why not go along the entire lower edge of the door, front to rear? It would give you a VERY strong place to anchor both ends of the roll cage as well as almost all the suspension stuff in the rear, and you could do some very easy welds along the pinch weld the entire way on the top.

Not too obtrusive, weight below the wheel centerline, and should certainly help stiffen the chassis. Might even be a good starting point for the guys cutting the top off their GT's.

I think I have the starting point for my roll cage in the wagon figured out at least.
 

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Oldopelguy, that's a piece of 4"x2"x.125" box tube. I hadn't considered running it all the way to the front. My goal was to build a solid platform for the base of the main hoop without creating an oragami of plates connecting everything from the floor, to the 'shelf' , to the side of the car below the b-pillar. I'm pleased with what I came up with.

BTW, the design of my cage doesn't rely on the stiffness of the rocker.

-Travis
 

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Yes, Travis, listen to Stephen and then look at Speedway GT's rocker panel closely. It is 4" by 4" by 1/8" tubing with enough of one side cut out to perfectly fit over the verical lip seam on top of the original rocker panel. Welded in place top and bottom, goes the entire length of the rocker panel.
From there mounts the main hoops.
It is wicked strong...
Also I might suggest you copy my brace that goes from the main hoop back and down to the floor just above the coil springs.
It puts all spring force into the rollcage, not the twinky little "frame" back there.
I realize what you're doing is less dramatic than what we need for stock car racing, using smaller pipe than we do is good, but part of the main objective is to create an extremely stiff chassis that will not twist or give anywhere between front spring and rear springs. We go a little further because of safety concerns, it is a fairly good bet that Speedway GT might be instigating oops I mean involved in some pretty exciting contact with other cars of similar build... somehow that's what the fans want, and bottom line is they are paying for it all!!
Let me know if you want more pictures of all the details, we have zillions of them...
 

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Forgot to mention your seat. Look at the aluminum racing seats with the snap in vinyl cover/padding. Installed and belted properly, no one could ever question it's safety. And they are comfortable, too. The aluminum can be bent to fit you very nicely and gives your body something to lean on during hard cornering.
They can be had cheap or expensive. Take your pick. Mine cost about $150, is about middle of the road as racing seats go I think.
Fits beautifully in a GT, we have ours moved back as far as possible, which required moving the pedals way back too, but you can do it in stock location too of course...
 

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Jeff,

Here's a pic of my cage design

http://www.opelgt.com/photos/showphoto.php/photo/2375/password//sort/1/cat/all/page/1

If you look at the load paths you'll see that the side shear planes are quite stiff and will gain little if anything from reinforcing the rocker. Also note that I've tied in both the front and rear suspension pick up points. You obviously can't see all the tubes but trust me when I say things are properly triangulated.

BTW, I've already got my seat. It's a Corbeau Clubman. Relatively cheap, very light (13.5lbs), quite comfortable and more pleasing to the eye than most of the aluminum seats.

-Travis
 
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