1 fast z Posted January 3, 2008 Share Posted January 3, 2008 Ok, I want to build a cage for my 2+2 Fairlady. I dont know much about the tech portion of what is needed to be legal. I want to be able to be teched to a 10.00-11.50 class for NHRA, as well as possibly 8.50-9.99 class, if I ever get my car that fast. I also will be autocrossing the car. I am mainly building the cage for saftey, as this is a daily driven car, and am affraid of dumb people on the road, broad siding me. From what I gather, atleast from NHRA rules, you have to have .120" wall, and it doesnt matter if it is Chromoly or Mild steel. Bars do not have to go into the engine compartment? How many point cage does it need to be? Pictures would be nice also. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
getZ Posted January 3, 2008 Share Posted January 3, 2008 I'm not so sure you really want a full NHRA cage in a daily driver, mostly because climbing over that side bar is a real pain. You can make the side bar removable and most tracks will allow it ( I'm pretty sure firebird and speedway will allow it), but those guys allow a little more slack in the official NHRA rulebook. Here's some basic guidelines: http://www.nhra.com/contacts/tech_faq.html. If you are going to build it yourself, I would get a copy of the rule book. They go into much more detail about floor mounts (bolt in versus weld in), seat belt placement, side bar placement, motor plates, etc. If the budget allows it, go chromemoly, it's much lighter (because they allow a thinner tube wall) Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted January 3, 2008 Share Posted January 3, 2008 jegs has "a kit" for the datsun that is nhra legal. heavier tubing. but since you have the 2+2, a standard kit will not work without mods. its not like you are afraid of doing any mods. jimbo Quote Link to comment Share on other sites More sharing options...
Challenger Posted January 3, 2008 Share Posted January 3, 2008 Yeah 1fastZ isnt known for custom fabrication... TonyC has a original 2+2 roll bar with a detachable rear bar (so you can get into the back seats), Id maybe pm him for some details. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 3, 2008 Share Posted January 3, 2008 The link above is is a helpful guideline, but as recommended, join the NHRA and buy the rule book. Any car under 10.00 seconds needs a full cage and I suggest 1 5/8" .125 wall DOM tubing. NHRA is pretty strict about wall thickness and a lot of the tech inspectors sonic test the roll cage in the bends where the wall thickness drops a bit. If the tubing in a bend goes below .118" wall thickness you won't receive a cert. Also, using 4130 tubing will save some weight but the fitup needs to be close to perfect and NHRA will require the whole cage be TIG welded and the welded joints normalized after welding. You'll also need a SFI certified flywheel shield, driveshaft loop, rear axle retention plates for floating axles, catch cans for the diff, trans, and engine, and a number of other specific safety items. Again, buy the rule book. Quote Link to comment Share on other sites More sharing options...
jimzdat Posted January 4, 2008 Share Posted January 4, 2008 jegs has "a kit" for the datsun that is nhra legal. heavier tubing. but since you have the 2+2, a standard kit will not work without mods. its not like you are afraid of doing any mods. jimbo Actually, Jegs has 2 different kits, one of which is designated for a '78 2+2: Jegster 942604K - Jegster ''Datsun'' Roll Cage Kits 4 and 8 point roll bars manufactured from 1-3/4'' x .134-wall mild steel tubing 10 and 12 point roll cages manufactured from 1-5/8'' x .134-wall mild steel tubing Includes 6'' x 6'' x 1/8'' mounting plates Some tube ends in some kits are notched while most tube ends are not notched for a better custom fit in your particular set-up. This ''extra material'' provides you some leeway for a great fit and easier installation. 8, 10, and 12 point cages exceed NHRA and IHRA standards Complete, easy-to-follow installation instructions included Welding required Datsun 2+2, 1978 550-942604K 10-Point Roll Bar Kit $224.99 I only know this because I currently have one of these kits in my garage, waiting for me to get off my butt and install it--I see no reason it won't fit the earlier 2+2 models, since the main difference was the raised false floor in the back Jim Quote Link to comment Share on other sites More sharing options...
getZ Posted January 4, 2008 Share Posted January 4, 2008 If you are really going all out, I'd do what the super stock guys do. They cut the roof off and part of the body, build the cage on to the frame and tack the body back on the frame. It's much easier to weld and get a tighter fitting cage. There a few places here in town that can build you a complete chasis. You might try asking Danny at Spanky's where he got his cage welded for his Nova. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 4, 2008 Share Posted January 4, 2008 Building a cage for a 10.00 cert isn't that big of a deal, faster than that it gets alot more complicated. Having built one in a z you'll find that completing the welds without cutting access holes is pretty tricky. Removing the roof isn't necessary unless you want a close fitting cage. Going into the engine compartment would be necessary for an 8 second car. Hinged door bars are legal so I wouldn't worry about that. If you join NHRA for $70 for a year you get $400K insurance going to and coming from any NHRA race plus National Dragster and a rule book. Cheap for $70 IMHO. Quote Link to comment Share on other sites More sharing options...
tkach Posted January 6, 2008 Share Posted January 6, 2008 jimzdat I've heard that the jegster cages dont fit well. Have you had any issues with fitment? I'd like to see some pics of the cage installed. Quote Link to comment Share on other sites More sharing options...
Clifton Posted January 6, 2008 Share Posted January 6, 2008 Also, using 4130 tubing will save some weight but the fitup needs to be close to perfect and NHRA will require the whole cage be TIG welded and the welded joints normalized after welding. Hey John, I've never tig'd anything. What's normalized after welding? Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 7, 2008 Share Posted January 7, 2008 My Roll Hoop was an over-the-counter JDM bolt-in item, and is not NHRA legal by any stretch of the imagination. I'm getting closer to pulling it out of the rafters guys...really I am! The last three months have been unbelievably busy for me with work. Dammit. The big thing about my roll hoop is it makes a nice template. Bryan, if you want John to make up some prebent stuff, I might be able to tow my 2/2 over to his shop and let him notch and pre-assemble something, and then just ups the parts to you for final assembly. The Hoop is the pain to bend, after that, straight tubing and notching is usually all that is required. I agree, read the rule book, it answers a lot of questions. And "normalizing" is not due to the welding process (TIG) it's due to the metals being used. Cr.Moly is specific in the way it likes it's structure aligned for maximum strength and impact resistance. Normalizing is kind of like 'heat treating'---it usually means heating the joint to relieve stresses and then letting it air cool. Annealling is 'the same but different' and usually occurs at a lower temperature. If you don't normalize a Cr Moly weld, the chances of it failing at the HAZ or in the weld itself is significantly higher than after normalizing. Mild steel does not usually require normalizing, due to it's structure, but following the normalizing procedure would not cause any harm. That's why most home cages are best built from heavier mild steel tubing, no special procedures are required. Make a clean weld with proper fitup and move to the next joint. Anybody remember Oxy-Acetylene Welding the "Three Sticks" in Cr.Moly tubing? Anybody have one of their's mounted as a trophy? LOL Quote Link to comment Share on other sites More sharing options...
1 fast z Posted January 7, 2008 Author Share Posted January 7, 2008 Thanks for the help and suggestions guys. The thing I dont like, is that it is a street car and getting in and out of the car with the weld in door brace is going to be a PITA. I really want the saftey, as well as be able to run MULTIPLE times at the track below 11.50's, but also do not want the hassle of that cross bar. I think what I MIGHT do, is make that bar removable for 90% of the time, and when I go to the track, I will just weld it in, as I guess now that bar has to be welded, and not hinged? That way I can still have the head on impact collision, and saftey, but not have to climb over that bar when I daily drive the car. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 7, 2008 Share Posted January 7, 2008 http://www.mechanicalengineer.cc/mechanical-engineering-archives/9-NORMALIZING-OF-STEEL-,-Normalizing-of-Steel.html NHRA requires normalizing of TIG welded 4130 (CroMo) thin wall (under .125") steel structures. The FAA and no other race sanctioning body requires normalizing for thin wall 4130 materials becuase normalizing has no affect with thin wall materials. Its a step that a lot of hot rodders erroneously started doing based on AWS and ASTM recommendations for thicker walled 4130 steel weldments. Its not necessary for properly welded roll cages and in practice most weldors do not get the weldment hot enough (1650 F for 4130) when normalizing for microstructure changes to occur. What is critical to welding a 4130 roll cage is to not put a lot of heat into the welded joint. Quote Link to comment Share on other sites More sharing options...
JustinOlson Posted January 7, 2008 Share Posted January 7, 2008 I am attaching the NHRA rules for 2007 that cover the rules for cages. Regards, Justin Quote Link to comment Share on other sites More sharing options...
Cable Posted April 2, 2010 Share Posted April 2, 2010 Another run at the top.... Quote Link to comment Share on other sites More sharing options...
piston Posted April 3, 2010 Share Posted April 3, 2010 i have that heavy ass jegs cage in my car. of course it doesnt fit well since not all z's are the same anymore anyways so a bit of cutting here and there will be required. you will also loose your spare tire with the jegs cage since it drops right in there but who needs the spare anyways when your probably going to be running fuel cell/tank? my welds are ugly but it holds. its NHRA legal if you weld it to their specs 6x6 plates to their specs. mine is just for safety purposes like you mention just in case a dumb driver comes along. Quote Link to comment Share on other sites More sharing options...
doublexl240z Posted April 8, 2010 Share Posted April 8, 2010 1 Fast, Are you willing to wear a helmet on a daily basis? Having a bar,let alone a poor fitting one(JEGS), running along side your head will do more damage to your noggin then that idiot t-boning you!! Just something to consider. Quote Link to comment Share on other sites More sharing options...
piston Posted April 17, 2010 Share Posted April 17, 2010 lol. the jegs one can be welded in any spot to your needs. as far back as you want, or up high as you want. only a dumb ass will weld it in how it comes(hopefully not any of us here). again, its base off a basic fitment on a 240z chassis. its not made to loop right over your head. mine is a bit up(im shorter), and there is still a 6" gap between my head and hoop. as for me, its better to have a hoop closer(clear helmet) than having the roof crushing your head and the hoop saving your seats. as far as t-boning, your pretty much ass out and wear a helmet at all time because if your not hitting the hoop, your head is swinging through the window. Quote Link to comment Share on other sites More sharing options...
johnc Posted April 17, 2010 Share Posted April 17, 2010 mine is a bit up(im shorter), and there is still a 6" gap between my head and hoop. as for me, its better to have a hoop closer(clear helmet) than having the roof crushing your head and the hoop saving your seats. I have no idea what this means? Quote Link to comment Share on other sites More sharing options...
piston Posted April 25, 2010 Share Posted April 25, 2010 everyone that see's my hoop says its too far up and i should have it sit back 1-2 inches from the dome light thingy. i sit up closer to the steering wheel and if i put the hoop in the lower roof area and further back away from my head area. i didn't like the idea of the hoop a whole foot back away from my head if there was to be an accident and leaving plenty of area for the roof to cave in where my head actually sits. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.