speed Posted August 20, 2009 Share Posted August 20, 2009 (edited) Ok guys, here is the relevant info.. Car is a 1979 280zx. Parts of the floorboards, firewall and both frame rails need to be replaced. Because of the power of the engine going in, I am considering using 4 x 2 x .083 rectangular tubing for the frame rails. Is this over kill? Is it not enough? 3 x 2 x .083 is also available but under the circumstances... when the car is done I don't want to be wondering if it is all going to stay together when I am playing around. This is a serious inquiry as the car is in my shop, the engine is mocked up, and I am looking to get the tubing. Having never attempted anything of this magnitude before, I am cautiously optimistic. All the inspiration a man could ever need is on this site, and there is some remarkable talent here. The way that I work allows me 14 uninterrupted days at home to finish the honey do list and play in the shop. The only limiting factor is finances.(It tends to run out after the first week off). Thanks for any suggestions and any advice that you have learned from your own project that you feel may be helpful. john Edited August 20, 2009 by speed added picture Quote Link to comment Share on other sites More sharing options...
280ztracked Posted August 21, 2009 Share Posted August 21, 2009 I think the larger tube would be overkill. If you plan to use the rectangle tubing you are adding a lot more metal than was orignially there. I just finished doin this to my 1979 280zx and I left the tube complete as a tube. the 2x3 worked great and made it very rigid. I have been out on the track recently with it and can feel the stabilty that it added. I am not running the horsepower that you are but I can tell it could take a tremndous amount. PM me if you have any questions i would be glad to talk to you. Matthew Quote Link to comment Share on other sites More sharing options...
johnc Posted August 21, 2009 Share Posted August 21, 2009 (edited) 3 x 2 x .083 is overkill. You're looking at what... 600 ft. lbs / 2 (300 ft. lbs.) spread over a beam that's 18 to 24" long? According to Machinery's Handbook 26 a 3" x 2" .083" ERW tube can support 4,500 lbs at the mid point of a 24" span supported at each end. You can also look it up here: http://www.steeltubeinstitute.org/pdf/brochures/beam_load_table_bro.pdf Edited August 21, 2009 by johnc Quote Link to comment Share on other sites More sharing options...
speed Posted August 21, 2009 Author Share Posted August 21, 2009 (edited) Johnc, you caught me showing my ignorance regarding structural integrity about steel tubing, or any steel for that matter. Thanks for the link. Great information and I saved it for future reference.. I have spent a decent amount of time looking through the older posts and finally came across this one http://forums.hybridz.org/showthread.php?t=115656 that helped shed more light on this endeavor. Matthew, I appreciate the invitation and will likely contact you in the future about certain aspects of your modifications to your vehicle. At the moment I am at work so it will be 22 days before I can get back on the project anyway. Thanks guys for taking the time to comment. john Edited August 21, 2009 by speed I am an idiot. Quote Link to comment Share on other sites More sharing options...
280ztracked Posted August 21, 2009 Share Posted August 21, 2009 JohnC nice link. I wish I had have had that link before I did my frame rail on the 280zx. I know it was overkill with the 3x2 but I had it in the floor of the shop and het lets just say I wanted to get out on the track. I will use that link you posted next time. No need to wory about my frame rails then, LOL. Speed anytime man. Keep me posted love to see some pics when you begin. Quote Link to comment Share on other sites More sharing options...
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