jeromio Posted September 28, 2001 Share Posted September 28, 2001 I have no pictures which would probably help explain my question, but here goes anyway. I am going to create a K style crossmember for my car (as discussed previously for installation of my LS1). I am settling on using some DOM tubing (since I already have some) rather than steel box tubing. This is mainly to do with weight issues. My rough guesstimate is that the 1.5 X 2.5 box tubing that I have is about 25% heavier than the 1 3/4 inch DOM round tubing. The wall thickness is about the same. Can anyone offer any informed opinions about this material choice? My second issues is the attachment method for the new "legs" of the crossmember. I can either: A- Weld the new legs to the existing crossmember and bolt the leg ends to the cast, strut rod humps B- Make a a more complete assembly out of the legs that bolts to the existing crossmember as well as the strut rod humps. C- Make the same assembly that bolts to the existing cross member but is welded to the strut rod humps. A or C would be the easiest to fabricate. B would be the most modular, flexible solution. Since the humps are kind of an awkward shape, coming up with a matched surface for bolting would be a challenge. Which makes me lean towards C. The fact that this extra cross member would then be sort of permanent bothers me slightly. I don't necessarily envision having to remove it for any reason, but you never know. On the other hand, it might be pretty hard to bolt/unbolt with the strut rod in the way anyway. And since the motor will effectively be resting on these legs, it probably makes more sense structurally to get a good, welded mating of the legs to the chassis. Anyone have any opinions? Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 28, 2001 Share Posted September 28, 2001 If I were to undertake this venture, I would weld ears of the appropriate design and strength to each of the four points, and then bolt the X member onto these ears. Construct the X member, bolt the ears to this piece, and then position this "assembly" where it should go, and then weld the ears in place. Of course the ears will take some work, but you WILL want to make this removeable in the future. I have never regretted a removeable piece vs a permanent piece since I've messed with cars. "B" is the way I see as the best. Quote Link to comment Share on other sites More sharing options...
ZROSSA Posted September 28, 2001 Share Posted September 28, 2001 I have always been told that round tubing is stonger than square for the same weight. I really like the idea about tieing in the compresion struts. This looks like a week area on the early z. I think if i were doing it, I might yet, i would wld to the crossmember and make "ears" that the strut could bolt through that then was atached with aditional bolts at all four corners. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 29, 2001 Share Posted September 29, 2001 Where the tension rods are attached to the frame is very strong laterally. The firewall is there to take the side loads. That area is weak longitudinally. The car bends like a hinge at the bottom of the firewall/tension rod attachment area. That's why connectors tying the top of the front strut towers to the firewall and through to a roll cage are so effective. Another trick is to weld the doors closed, but that makes getting in and out a real bitch... Quote Link to comment Share on other sites More sharing options...
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