Guest jens Posted October 9, 2003 Share Posted October 9, 2003 Is it only seamless pipes that is legal for a cage? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 9, 2003 Share Posted October 9, 2003 I don't think that there is a class that wouldn't allow heavy pipe, like schedule 40 or thicker. GET A RULEBOOK! The main advantage to DOM (seamless) is that you can run a thinner wall with the same strength and a lot less weight. Jon Quote Link to comment Share on other sites More sharing options...
johnc Posted October 9, 2003 Share Posted October 9, 2003 The SCCA, NASA, and other United States road racing sanctioning bodies all specify ERW or DOM tubing with DOM (Drawn Over Mandrel) preferred. Schedule 40 pipe is specifically excluded (brittleness) and they've stopped grandfathering older race cars that used it. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 9, 2003 Share Posted October 9, 2003 So JohnC, I thought the downside to DOM was brittleness vs pipe. Was I mislead? I think I was reading that in "How to Drive Faster" or some such book. They basically said that DOM tubing was stronger thickness for thickness, but more brittle and pipe was softer so it would bend instead of crack. I already know I had the schedule 40 thing wrong, but what about the other? The book also said something to the effect that pipe was preferred if weight was not an issue and there was a possibility of multiple impacts (which I took to mean circle track racing). Oh, and what material is your cage made from? I've heard people talk about .095 wall and .125 wall 1 3/4" DOM. The .095 wall was on a recently done 510, not sure if that would be thick enough for SCCA or NASA on a Z. I suppose I need to follow my own advice and get a rulebook too. I think this project is in the near future for my Z. If I were to prepare it for a class of roadracing it would probably be an EP car, that is what it is closest to at this point. Thanks, Jon Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted October 10, 2003 Share Posted October 10, 2003 I used chromoloy (4130) tubing for my cage. I purchased it from http://www.chassisshop.com/index.html They have the best prices and selection of chromoloy that I've seen, plus they can do mandrel bending. The chromolly has a higher yield stress than the mild steel, but is a bit more expensive. However, by the time you finish the cage install, you will realize that the material costs are a small fraction of the overall cost of the cage install. The tubing inside the car is 0.120 wall (with some 0.083), and the tubing ahead of the firewall on my car is all 0.083 and 0.065. Another drawback(???) to chromoloy is that it must be TIG welded(pretty welds). Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 10, 2003 Share Posted October 10, 2003 Do you have any idea of the total weight in tubes that you've put it? I just sold my 50lb Autopower rollbar to Auxiliary, I was kinda hoping to get a full DOM cage for about the same weight. The guy who did the all .095 cage in the 510 said he could do a 10 point in a 510 that weighed less than my rollbar. Jon Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted October 10, 2003 Share Posted October 10, 2003 If you go to the ChassisShop web site they list the weight per foot of tubing for the various OD and thicknesses. I am using the following 1.625 x 0.120 1.9 lbs/ft 1.625 x 0.083 1.4 lbs/ft 1.625 x 0.065 1.1 lbs/ft I haven't added up the total weight of the cage, but I do know that the car is 100 lbs lighter than before the cage install. However, a lot of thing were removed during the process(carpet, sound deadening, undercoat, bumper mounts, HVAC, etc...). Also, my cage involved cutting off the entire front end and building a tubular front end. If you look in my personel album, I have several pictures of the install Quote Link to comment Share on other sites More sharing options...
Guest Aaron Posted October 10, 2003 Share Posted October 10, 2003 ... my cage involved cutting off the entire front end and building a tubular front end. And you should see it in person. Wonderfull work! Quote Link to comment Share on other sites More sharing options...
rc's240z Posted October 10, 2003 Share Posted October 10, 2003 Again, the best advise is to consult your rulebook. SCCA rules are available on disc... The guys at PDK Fabrication can make some recomendations on what is necessary depending on the class you are racing... Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted October 10, 2003 Share Posted October 10, 2003 Another drawback(???) to chromoloy is that it must be TIG welded(pretty welds). You can also do it with a torch, some people feel this is the better way of doing it: http://www.tinmantech.com/html/faq__tig_vs__gas.html Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 10, 2003 Share Posted October 10, 2003 74, that is sweet. Jon Quote Link to comment Share on other sites More sharing options...
johnc Posted October 10, 2003 Share Posted October 10, 2003 SCCA doesn't give you a wall thickness break anymore for 4130 steel. Its gotta be just as thick as DOM (.120 wall for our 240Z weights) so there's no reason to pay the extra money for 4130. My roll bar is .095 4130 and .065 wall 4340 and was built back in 1995 when there was a break in wall thickness for using CroMo. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 10, 2003 Share Posted October 10, 2003 Good to know. Thanks, Jon Quote Link to comment Share on other sites More sharing options...
Guest Zachb55 Posted October 10, 2003 Share Posted October 10, 2003 About that custom front end, what are your plans for reattaching the fenders and hood? you gonna make your own fiberglass ones or build mounts for the stock stuff? looks very nice, i bet that things gonna be extremely stiff and handle like a beast! -Zach Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted October 12, 2003 Share Posted October 12, 2003 I have built mounts for the stock fenders, and they are mounted on the car. I am not happy with the quality of the fenders (aftermarket repre steel), and I want some more room for tires. I will soon get the Subtle Z fiberglass kit after my bank account heals from doing the chassis. Here are some pictures taken of the car at the last reynolds event. http://www.dirtcheaprims.com/ztuff/sezs3/pics/5point0Z.jpg http://www.dirtcheaprims.com/ztuff/sezs3/pics/5point0Z2.JPG http://www.dirtcheaprims.com/ztuff/sezs3/pics/5point0Z3.jpg I also have a 3D Solid AutoCad model of the cage that I have been promising to post for a while now. I just got the file recovered after my old computer died, and I will post it if someone wants to host it. Quote Link to comment Share on other sites More sharing options...
Michael Posted October 14, 2003 Share Posted October 14, 2003 Back when my roll cage was being buit, I was warned about the drawbacks of chromoly. Even if the welding is done properly, with heat-relieving the welds etc., the material is still brittle. DOM mild steel was the suggested material for all but the most weight-conscious applications, because it will deform plastically before failure. But this is a long-running debate. Incidentally, I heard that 0.120" DOM tubing is typically around 0.118"-0.119" from most suppliers. That sounds like a silly difference, except that NHRA inspectors have been known to reject nominally 0.120" cages when the main-hoop wall thickness was anything less than 0.120", even by one thousandth! So, many cage builders will use the next larger size, 0.134", just to be safe. Quote Link to comment Share on other sites More sharing options...
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