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Discussion Starter #1 (Edited)
Roll cages for fox???

Hey all,
i am thinking about building a road track car. i will not be driving it competitively, but just for fun days.
I want to put a roll cage in it and wanted to know what most people here run? Custom cage or pre-made cage(mm offers a mild cage)??
this will be for a 89 fox hatch.
thanks
 

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If it is at all possible, get a custom-made cage from an EXPERIENCED builder.

The cage is the most important part of the race car. It's there for safety, obviously, but it also functions as a chassis stiffener, if done RIGHT. I've not seen a bolt-in cage or cage kit that will do a very good job stiffening the chassis.

Second, make SURE the cage adheres to whatever rules you will be tracking under. If you have no specific rules (like for HPDE,) the you should build the cage to adhere to a racing class that you might end up racing in, or for a popular class in your area. That way, should you ever plan on selling the car, it'll be more attractive to potential buyers. Nothing sucks more than to buy a race car and then have to modify the cage to make it class-legal.

Another big advantage to a custom cage is that the cage is made to fit YOUR CAR, and not the "typical" Mustang (or Firebird, Miata, etc...) Pre-fab cages tend to err on the conservative side and end up with big gaps between the bar and the car itself, meaning the bars are closer to you than strictly necessary. This is especially obvious with the halo bar. If it's too close to your head, you'll be constantly smacking your helmet against it and getting out of the car with a helmet on is especially difficult.

This is a BIG DEAL. Screw it up and you really trash the value of the car.
 

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If you spell "cage" correctly the search function will be immensely helpful.
 

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I don't use a guage for measuring roll. If I'm lucky, someone has taken a picture of my car mid-corner and I can use the protractor function in a good photo editing program (say GIMP) to find the amount of roll using the bottom of the tires as my reference plane and some straight part of the bodywork as the roll plane. Project outwards until the two lines intersect and then measure the angle. That will be the roll angle.

I know that's not what was being asked but I thought I'd be a smart-ass. :)
 

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Discussion Starter #7
haha. wow. I don't know what I was thinking last night. I fixed the spelling. sorry. thanks to all who replied.
 

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It's prit near impossible to gauge how I roll. I got a wild and unique style. I wear All Stars with my suits.
 

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Kirk Racing here close to Birmingham offers bars and cages. I had him install a custom cage in my 97.

http://www.kirkracing.com/
They aren't too far from me, and I am considering a cage in the future. How much was it, and how close a fit are the bars to the roof and pillars? Thanks.
 

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I had a caged installed that would be AI legal. 1.75x.120 DOM, full welds and it was 1800.00. There are some braces left that I will install. I think the pillar bars are pretty close considering the roof was not removed.

I will get some better pics and update later.

Edit:http://www.flickr.com/photos/doomsday_motorsports/

Pics are not very good, maybe they will help.
 

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Thanks for posting Raznkane. It looks like they did an awesome job, and the price seems to be right. What braces are left to be installed?

I hope to run with NASA in December at Road Atlanta. If your car is ready by then, I would love to check it out.
 

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Overall the cage looks good, though I'm hardly a cage expert. Still, I have a couple of questions...

First, why wa the main hoop mounted so far forward? The harness bar looks to be bent and runs 4" or so *behind* the main hoop. It would have been better to move the hoop backwards 4" and attach it to the rear seat bulkhead, which is a major structural component of the car -- ideal for mounting the main hoop to. That would have moved the harness bar into the same plane as the hoop and made the entire section much stronger, and would have been easier to fabricate, too. As it is, there are compromises made to accomodate that offset harness bar that add weight.

Second, there are a pair of stringers running from the center of the harness bar to the rear of the car (to the shock towers, I presume.) These are not necessary and add extra weight.

I've got mixed feelings about the Petty bar running down to the passenger footwell. I'm not convinced that it does much to make the driver any safer, and it's been show in FEA that it does very little to stiffen the chassis. It does add a lot of weight, and makes it impossible to carry a student (important for instructors like me.)

I'm also seeing some "floating nodes" -- places where a bar ties into another bar and there is no other supporting bar to support the first. DSC00130 and DSC00104 are good examples of this. That door bar could have been raised up to where the harness bar attaches to the hoop to better support both tubes in a collision.

There is no A-pillar bar. This is a vertical tube that runs from the NASCAR door bars up to the top of the A-pillar tubing, where it meets the halo bar. This better supports the halo bar and A-pillar in a rollover.


If you're at all curious about cage design, here is an excellent discussion about a lot of stuff that's cropped up over the years:

http://corner-carvers.com/forums/showthread.php?t=27556&highlight=cage+design

Keep in mind that just because the cage meets the class rules, that does not mean it's a good design -- it's just good enough. This is why I stress going to an experianced fabricator. They know all the tricks to building a good cage for minimum weight.

(And no, my cage isn't perfect, either. It meets the rules, but there are places where I can make it stronger or easier to live with.)
 

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My apology to the OP for this small hijack,

Hey Robert,

Thanks for your input on this, I learn a lot from you on here and the CC.(JPope) I try to save the pics in that CC thread to help on things like this for the future.

As for the harness bar and main hoop, I am not sure why it was not put on the bulkhead. And yes, the harness bar has a slight bend at each end as it is set back. I know any bar with a bend is weakened.

The 2 stringers you see do run back to the shock towers, I believe they are there because the petty bar is there, they meet the harness bar at the same area. Honestly I wish the petty bar was not there now, it was my decision though and I have been thinking of removing it. :hammer:

The braces I spoke of in my post will be on the floating nodes that you see. I will also tie the cage to the pillars with dimple die plate. Also an A-pillar bar will be installed on both sides. These items should add much more protection in a roll over situation.

Do you see a problem with the petty bar being removed?

Also, what is your thought on leaving a cage unpainted? Pro's and con's.

Hijack off :)
 

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Do you see a problem with the petty bar being removed?
Yes, in theory. Wherever you weld on mild steel, you locally heat the steel around the weld, which can affect the steel that wasn't directly involved in the weld. This is a necessary evil, since welding his the only practical way of joining the tubing, and in practice, the new tubing added serves to strengthen the structure. However, if you later remove that tubing, the additional strendgth is no longer therre, and the remainin tubing that was welded to is slightly weaker (how much depends on the alloy used and whether the joint was heat-treated after the welding.)

So in theory the place where the original tube was connected is slightly weaker now.

In theory.

Also, what is your thought on leaving a cage unpainted? Pro's and con's.
My cage is unpainted at the moment, as is the car's interrior. It looks like crap, but it's a race car. It';s not supposed to win any beauty contests.

But there's a downside to that, too. If your car is dark colored, it makes it MUCH more difficult to see inside the car when you're working on it, particularly in the far corners and underneath the dash.

Also, if you paint your cage with cheap, brittle paint (think Rustoleum,) it will crack and flake off if there's much movement in the underlying metal. This can be usefull for detecting small cracks in things like wheels and roll cages. The Corner Carvers thread I mentioned in an earlier post has an excellent illustration of this. A BMW e30 rilled recently and you can see the paint is flaking away from a roll cage joint that cracked. the crack is so small that you can't readily see it if it were not fot the paint flaking off.
 
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