Drax240z Posted August 23, 2000 Share Posted August 23, 2000 I'm about to redo my front subframe, just got all the stuff stripped off them today. Pete I know you said you used 2.5" .093" wall sq. tubing. .093" seems really heavy to me. But, you are more of an engineer than I am. I'd like to know your opinions on using something thinner than that, given that the car will one day see 400hp, and will be partially triangulated up front, with pipe run from: the top center of the firewall to the top of the strut towers, as well as the top of the front side of the strut towers through the inner fenders and down to the front of the frame rails. (close to radiator) Also a cross brace between strut towers will be offering support. I'm trying to stiffen up the chassis (obviously) without adding too much weight. ------------------ Drax240z 1973 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
Guest Drewz Posted August 24, 2000 Share Posted August 24, 2000 In my car I used 14 guage steel bent into a flanged u shape and welded as far forward and rear as possible. At the rear I built a small side to side box section behind the seat. Of course the floor was rotten so I made 18 guage floor pan sections and welded them in first. The car is very rigid now. Before the frame rails went in I took it to a frame shop and had a pull done to insure the car was straight before completion. Sorry no pictures of it in progress as they were lost in my recent move. ------------------ Drewz Quote Link to comment Share on other sites More sharing options...
Mikelly Posted August 24, 2000 Share Posted August 24, 2000 I used 2"X3" boxed steel. It is heavy, yes, but gives you a foundation that is unbeatable for chassis stiffening and added reinforcement for the extra HP and Torque. Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 24, 2000 Share Posted August 24, 2000 Drax, I can't remember the exact length, but I guessed the engine rails are 36 inches long. For 2 of them in 2.5x2.5x.093wall, they weight 19lbs combined. I wouldn't go much thinner, maybe .085, but that only saves a couple of pounds for the pair. Any thinner does doesn't seem worth the tiny decrease in weight. Remember, these things take some serious point loads and having a decent wall thickness is important to keep things like sway bar mounts, etc. from pulling out, fatiguing, etc. I used this size because that's what a buddy could source from a scrap pile at work and they seemed like a great candidate. Hope that helps. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 25, 2000 Author Share Posted August 25, 2000 19 lbs is lighter than I expected. .093" sound good to me too. Unfortunately I am going to have to order it... I found my rails are a bit longer than 36", more like 38" (I think).... I guess I'll try to get a 10' length and go from there. I think for the underfloor extensions I might take the 2.5" and split it down the middle, then use a 2.5" x 1.25" U-shaped half on each side. Not as strong as a box, but when welded to the floor boards it will form a box. Thanks for the info. ------------------ Drax240z 1973 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
Drax240z Posted August 25, 2000 Author Share Posted August 25, 2000 Oh yeah, I'm also thinking that I might get some of that structural foam to put in the center of the rails. What have you guys used to rustproof the inside of your rails? Hopefully with the foam put in shortly after welding them in, they'll never have a chance to get wet on the inside. ------------------ Drax240z 1973 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
alsil Posted August 25, 2000 Share Posted August 25, 2000 Well, I'm using just some 1"x3" square that I had laying around to make subframe connectors, just to stiffen up twisting, but I am also using a crossmember to mount the engine, which will stiffen up the front, also. Other than that, strut tower braces are a good idea. ------------------ Quote Link to comment Share on other sites More sharing options...
Mikelly Posted August 25, 2000 Share Posted August 25, 2000 ...Well being that I did not put my own sub-frames in and I'm not happy with the welds (Looks like crap, but works) I had planned to re-do mine and I'm going to go with a 1" X 3" boxed as well. They will be stiff enough, if tied in properly. I'd thought about rust proofing the inside, but since the caris going to be re-done, I'm not worried about it.. I'm thinking por15 would be a good safe bet.. Get a cheap spray gun with a wide nozzle and just throw it away when you are done.. Por15 is hell on sprayers.. Mike ------------------ "I will not be a spectator in the sport of life!" mjk 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.