evildky Posted February 27, 2008 Share Posted February 27, 2008 if it's just ornamental for ca street car have fun, that syle bar is marginally better than nothign at all and would not be sufficient for any form of sanctioned racing, for sanctioned racing rule books provide detailed info on what is and is not allowed Quote Link to comment Share on other sites More sharing options...
bschiltz Posted February 27, 2008 Share Posted February 27, 2008 It isn't a factor of the welds breaking. The welds are VERY strong. The problem is the heat affected zone(or HAZ) which is where the base material is reduced in strength.The combination of a very hard area of metal(the weld) next to a weakened area(the HAZ) will cause any break to happen inside the HAZ. For the sake of argument, what if the entire thing was heat treated to relieve stress? Not really practical, but theoretically it should negate any advantage of a single piece, right? Quote Link to comment Share on other sites More sharing options...
MatMan Posted February 28, 2008 Share Posted February 28, 2008 For the sake of argument, what if the entire thing was heat treated to relieve stress? Not really practical, but theoretically it should negate any advantage of a single piece, right? Yes, heat treating (annealing) would releave some stress in the HAZ. There are hand coils made for tube welds (think hand-held kiln) that would suffice when an autoclave large enough for the roll bar cannot be found. Quote Link to comment Share on other sites More sharing options...
bschiltz Posted February 28, 2008 Share Posted February 28, 2008 After it's annealed would you need to harden and temper it to gain some rigidity back? I know being a low carbon steel the strength-brittleness trade off is minimal but maybe try for a spring temper? Quote Link to comment Share on other sites More sharing options...
Shift Posted March 1, 2008 Share Posted March 1, 2008 BTW. what is the authorised thickness and diameter of tubing allowed by sanctioned bodies? And does it matter if its rolled or extruded (as far as regs go). Quote Link to comment Share on other sites More sharing options...
MatMan Posted March 2, 2008 Share Posted March 2, 2008 After it's annealed would you need to harden and temper it to gain some rigidity back? I know being a low carbon steel the strength-brittleness trade off is minimal but maybe try for a spring temper? IIRC, letting the anneal cool at room temp (no quench) is the "usual" way to retain the reduced stress, but keep the strength; Annealing in this case is the "temper". John C, do you know of other heat treatment for roll cages? Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted March 2, 2008 Share Posted March 2, 2008 Shift, From SCCA rulebook: Seamless or DOM (recommended 1020 or 1025) mild steel tubing or 4130 cro-mo must be used for all roll cage structure. Cars weighing between 1701-2699 lbs w/ driver must use a minimum of 1.500 x .095 in. Main Hoop... The roll cage must attach to the vehicle structure(FLOOR PAN/ROCKER BOX) within the passenger compartment.... Quote Link to comment Share on other sites More sharing options...
johnc Posted March 2, 2008 Share Posted March 2, 2008 John C, do you know of other heat treatment for roll cages? No. With 4130 tubing sometimes the joints are normalized. Cars weighing between 1701-2699 lbs w/ driver must use a minimum of 1.500 x .095 in. Which SCCA rule book did you get this from? SCCA roll bar tubing requirements are much more specific then that are are unique to each category (IT, SS, Production, GT, etc.) Anyone building a cage for their car must get a copy of the SCCA GCR. Its free and its here: http://www.scca.org/documents/Club%20Rules/GCR2008.pdf Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted March 3, 2008 Share Posted March 3, 2008 John, I got it from the very rulebook that you posted the link to (the one I deal with on a dialy basis building rollcages with). If you have kept up with the GCR, they(SCCA) have set cage material to one set of specs. So whether it is an IT car or my GT car or a prod car, all production based cars get the same set of rules for tubing sizes. The benefits of cro-mo versus mild steel has been erased, due to the fact that they (SCCA) relied on people proving, usually with receipts, that their cage was built with cro-mo.Just different attaching points etc. Quote Link to comment Share on other sites More sharing options...
Mr.INSANE Posted March 3, 2008 Share Posted March 3, 2008 I really like the Front strut bar, It really fits in there well. As for the Rollbar, it looks good for mounting race seat belts thats about it . Keep up the work though I'm sure you just saved a couple hundred dollars building your own strut bar Quote Link to comment Share on other sites More sharing options...
johnc Posted March 3, 2008 Share Posted March 3, 2008 If you have kept up with the GCR, they(SCCA) have set cage material to one set of specs. You're right. I had only given the 2008 GCR a quick glance and assumed that 9.4 applied to GT and Production cars only. I missed the "Production Based" reference. They still include the old Section 18 as Appendix G but its just for grandfathering cars from before 1/1/08. Thanks for updating me. Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted March 3, 2008 Share Posted March 3, 2008 John, Ya its been like a giant soap opera getting things normallized. The Z in IT trim had( last year) a minimum tubing of 1.75x .095 or 1.5x.120 (whether mild or cro-mo) but then in Prod it was 1.50x.095 in mild steel or 1.375x .095 in cro-mo(with proof?? that its cro-mo). Kinda made moving a car up and not getting killed on weight an impossibility. Or you could just gut that 1 or 2 year old cage out and build a new one!! Not a bad idea for my business!! Quote Link to comment Share on other sites More sharing options...
240Z2NV Posted April 8, 2008 Share Posted April 8, 2008 'Yorgee' you might consider checking Chris Allston's Chassisworks in CA. They make ALOT of structural components for NHRA and the like. They make a custom bent main hoop for the '70-'78 Z car, and you can add-on from there. It also makes it possible to add-on in the future, when a budget might permit [e.g. going from an initial four point to an eight or six point]. Once you find their website, start with part number 7000, and go from there. I got my plates, tubes, and gussets, along with removable harness bar for under $300. The 'kit' will require cutting and forming 'birds mouths'; but, it is an alternative... Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted April 10, 2008 Share Posted April 10, 2008 Here is the above mentioned site: http://www.cachassisworks.com/ Part number 7000 is just a universal set, that is cut and fit/weld, not specifica for the S30 or any car for that matter. Quote Link to comment Share on other sites More sharing options...
240Z2NV Posted April 10, 2008 Share Posted April 10, 2008 Actually, when you order it, they ask what vehicle it will be used in, and make the main hoop from CAD [?] program to fit, perfectly, the dimensions of the interior. The other pieces are generic; but, the main hoop is the most important, AND the most aesthetically obvious part. Quote Link to comment Share on other sites More sharing options...
Slow_Old_Car Posted April 10, 2008 Share Posted April 10, 2008 so do they have the s30 design on file, or would a person need to do the measurement sheet on there website and submit it? Quote Link to comment Share on other sites More sharing options...
240Z2NV Posted April 10, 2008 Share Posted April 10, 2008 It is on file. They have sold ALOT of them. Very good customer service! Quote Link to comment Share on other sites More sharing options...
Slow_Old_Car Posted April 10, 2008 Share Posted April 10, 2008 It is on file. They have sold ALOT of them. Very good customer service! got photos of your install? i'd like to check it out... Quote Link to comment Share on other sites More sharing options...
240Z2NV Posted April 10, 2008 Share Posted April 10, 2008 I JUST bought the kit and picked it up. I am still working on the layout with the help of the experts here on the site. It'll be a while, as NOTHING on my project happens quickly [much to my frustration]. Quote Link to comment Share on other sites More sharing options...
240Z2NV Posted April 10, 2008 Share Posted April 10, 2008 I will add, however, that for simplicity, ease, and quick results, the Autopower sets are probably the way to go. They are more expensive initially; but, time is money! Quote Link to comment Share on other sites More sharing options...
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