I already have a rear hoop. I'm thinking of adding a short hoop under the dash up aginst the firewall. Would this help with side impact protection? What wall and size tube could I get away with. 1.5" x .120" wall? Thanks
Yes of course anything helps. If it were me, and you had the space make the side bars curve at the end to meet the hoops. It will change how the force of a side impact is transferred. Rather than caving toward the driver and pulling the hoops in. They will try to splay out a bit and drive the hoops away from the impact.
Here's what we put in the driver's door of our 33 Chevy. They ar curved to match the door skin pretty closely. The main hoop is on otriggers to allow it to be as wide as the body. 1-1/2" 0.95 wall mild steel tubing, mandrel bent.
I can't see the pictures because they are routed to another site that I can't get on at work. Sorry. thanks for posting though
Hey John,is your car a dirt track car? Jp, you still haven't said what you intend to do with your car. Although I guess at this point it might be self evident.
Hey JPMACHADO, Is this for your monstrosity of a roadster? Did you end up keeping the mustang II/straight axle front suspension? Why do so many of your posts that ask questions if this or that is alright end up with you defending and justifing what you already did? I don't know why I am lashing out now but I can't keep it back any longer. PS-nads was right! Brick
Yeah, ran New York State ovals in the late 60's....here's a link to many more pictures: http://www.jalopyjournal.com/forum/showthread.php?t=165476
I haven't done anything yet. How can you look at this post and say that I'm trying to defend a cage I have yet to build? Also, why are possibly keeping tabs on what I'm doing? I could care less about you. The post from Nads was over a year ago. Don't you have anything better to do than think about me? take some of that negative energy have towards me and build something for yourself.
Thanks to everyone else. I apologize the thread deteriorated with the last post, but I don't know what Brick's problem is. I garuntee he'll never HAVE to drive my car. I got just the info I wanted. My only other question is, if I can't get a hold of a bender can I cut the ends at 90 degree elbows and then gusset those for the curved ends? Thanks again to everyone.
You could cut "pie" shaped pieces out so that the tubing could be bent, then weld up the gaps. 45degrees would be better than 90. It's kind of considered crude by today's standards...but was common back in the 50's and 60's. The rollcage that cme out of my 33 Chevy was made out of driveshaft tubes and water pipe. The builder evidently felyt that the u-joint saddles made a nice cradle for the main pipe across the top of the rear hoop....but he had so little confidence that it would pass tech, that he padded it and taped it up so no one could see it.
I know what my problem is, I'm a jerk! The reason I have followed your build is because it seems that many of your posts have titles that suck me in and that I might be able to offer some help but then after reading the actual question and what you have already attempted in most cases I don't bother. I can't understand why so many people just ignor the visual disaster your building and encourage you to continue. I have seen you get some very good advice in the past and it seems to have been ignored. Brick
Main Entry: ob·ses·sion Pronunciation: <TT>äb-'se-sh&n, &b-</TT> Function: noun 1 : a persistent disturbing preoccupation with an often unreasonable idea or feeling; broadly : compelling motivation Man I don't know you and don't want to know you. Get some help and leave me alone.
alrighty. that set up won't offer much for side impact at all...here's why. you have nothing connecting the midsection of your main hoops to one another. looking at a conventional 'cage, the reason the main hoop has a crossbar it to stiffen it from the side. the reason (according to N.H.R.A. that it is placed where it is is to provide as much protection to the driver as possible.-between the shoulder and elbow, with the driver in a seated position. ) what you have (including the frame, which it has to be tied to) is an "empty box" which can collapse from under- and the fact you have 3 bars would probably amplify the effect. you would be better offadding a bar front and rearm midway down the hoop, and instead of 3 parralell bars, cross them into an x- thus providing the most strength right in the center of the car, probably just above your hips. the "3 in a row" set up only works with bracing in between (looks like a fence) and I think the basic math says every 10 or so inches. but you still need cross bars to make it work. and the roundy-round coupe looks good. little different than my "school" (go fast in a straight line.) but sturdy as hell.... I have a question (because I don't know...not throwing rocks) why 1 1/2? smallest "we" can run is 1 3/4. ( inch and 5/8 for some...) is it chromoly or something?
true...but only if truly from the side- if frome slightly "above" (Think f-350) I think it's goin' over on him.
This sounds like great advise, and makes sense. Could you possibly post a picture, even a crude drawing, of what you mean. I'm having trouble picturing how you think it should tie into the frame. Thanks a lot though I will definitly cross the bars. Also, is square tubing an option? I'm trying to take everthing possibility for material into account. If I need to go with round tubing I will bump it up to 2" as per your suggestion. Thanks again
Square tubing is a serious no-no. Round tubing has the same strength from every direction. Square tubing, only 2. watch a dragster wreck or circle track wreck in slo-mo. suffice to say, you will wanna stick with the round stuff. A good bender is gonna be required to make it happen. Surely in your neck of the woods, someone is building cages, and therefore, has access to the neccecary tooling. a good tubing notcher will make the task at hand ALOT easier. okay. as far as pictures are concerned, when you get home, look at the pics of the 33- you will see the cross bars we're refering to.(on the hoops.) as far as the sides are concerned, a good 'ol intercecting x is the ticket. they're a bitch to build, but you only need to cut the "intersecting" pipe once,dig? the angle on one side matches the other...make sense? picture cutting a 2/4 with a skilsaw at an angle. then place another 2/4 inside the cut to form an x. am I making sense, or out in Luxville, population,me again? anyhow. I think it would greatly benifit you to read "Chassis Engineering" by Herb Adams before you start this part of the project. I cannot explain this well enough for you to stay safe in text, and can't draw how (i think) it needs to be done. it will also help you out with the rest of your chassis build for maximum strenght with minimum weight. it reads about like Stereo instructions, but it has helped me ALOT through the years. (my copy looks like hell.) Roll cage design has alot of ins and outs, and going about it blind can be dangerous, or simply add a couple hundred pounds of useless weight to your car.
JP there's a number of good pics here. You might go and check out a shop or stock car track pit area, to see how these are braced and installed. The Bonneville SCTA rulebook had some tube dimensions and material types that they require. All good advice. http://www.racingcages.com/main.html
As an innocent bystander also an e-mail friend of jpmachado I take offense from your bashing of his car, it goes without saying the car is SCRATCH-BUILT a claim few if any of us can make ! I've seen videos and pictures of the car it works and drives, more than I can say for some of us, my 2cents...
I've got Chassis Engineering by Herb Adams. I read it to build my intital ladder style frame. I have a big "X" member like on page 89. This book is what gave me the idea of using the square tubing since he said square tubing was stronger, but it sounds like he meant it differently than I thought. I can see what you're saying about the round being the same strength in every direction. What picture are you talking about with regards to the crossed bars. I see a picture similar to my original on page 90, but I'd like to see what you're pointing out because I think you're making a lot of sense. Also, if I only need to bend the bars at a slight angle can I use my cheap harbor frieght style bender? I called today and the bends alone are going to be $100.00 before material. I'd need about 14 bends to do it the way I think you've described.
I don't think I'm obsessed with you. I'm obsessed with doing things correctly and not making excuses. Now please have the last word.
The tubing diameter was chosen for the 33 Chevy based on several factors. The first factor was availability of an adequate mandrel bender. I was able to borrow a nice Greenlee rigid conduit bender and the 1/14" die fit 1-1/2" OD tubing perfectly. The second factor was the fact that almost all of the modified stock cars currently being raced in our area are constructed from 1-1/2" mild steel tubing. We've seen those cars torn up in really bad, high speed wrecks without any distortion to the rollcages. The third factor was that we plan to have many areas of the rollcage fit very closely inside the body skins...actually replacing the original wooden framework...and the body skins, firewalls, etc...are going to be welded to the rollcage to increase overall rigidity. The finished product will be much like a "uni-body". If I were building a simple stand-alone rollcage to fit inside a body, I'd probably go with 1-3/4" 0.095" main hoops and 1-1/2" 0.125" support bars. 2" rollcage tubing, in my opinion, is too big and cumbersome. Also, increases in OD without increasing the thickness doesn't necessarily result in additional stregnth when you get into the lager diameters of tubing. As far as square tubing for roll cages....I've seen many older stock cars done with square tubing. It was once fairly popular, but the stregnth is much less unless all joints are plate gusseted with very large (heavy) plates. Also...some good rollcge design diagrams here: http://www.jalopyjournal.com/forum/showthread.php?t=160501&highlight=60%27s+design
Thank you again to everyone. I have a good idea now on what I need to do from all the posts here. The 33' looks awesome. I wish I'd of thought to hide my cage like that. Thanks again
now you're cookin! now take the "middle bar"from the "x" and run it from the top of the front hoop to where the cross bar meets in the rear hoop. this is the bacic assy (without the "bathtub" and rear section or top) of a funny car cage.
Killer info Josh. my limiter circle track experience stops at imca class cars, and those things are more like jungle gyms.... just tell me you won't be riding around with a fuel pump sitting on your nuts.
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