danman Posted November 8, 2003 Share Posted November 8, 2003 I was asking my friend who is restoring an old fire truck about using his welder to fix weak points in chassis caused by rust. He said that you can easily burn hole in unibody, in addition area around weld could be weakened. SO I had an idea . Why couldn't you clean metal bear, sand to rough and epoxy thin sheet steel that has been pounded to fit contours. If they make epoxy that bonds metal to metal well a thin steel plate would give a shear wall type of effect greatly improving stiffness. You might have to scratch steel to get good bonding. I know this would increase weight, but welding on steel reinforcing can't be light either. What do you guys think, might be good alternative to welding already weakend chassis. Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted November 8, 2003 Share Posted November 8, 2003 If your talking about JB welding or some similiar expoxy, I would say stay away from that. You pretty much Glueing a patch into a area, which is by no means as strong as welding it. A weld actually melts the 2 metals being welded and fusses them together. With any car, your chassis is going to flex some, and be put under tension and pressures. You use a expoxy to patch a structural area and I would say it'll fall off or fail after awhile of flexing and strains no matter how scratched or scuffed the area is around the patch. As for welding on a unibody car, you can burn through the metal, if the settings are wrong and too much current causing the arc is used. I don't think that welding a patch in will weaken the surrounding area to cause concern, unless you use water to cool the welds very quickly, which will cause the welds to be brittle and more likely to have stress cracks form. I weld all my patches, and would not recommend using a expoxy to patch anything related to the chassis. I could be wrong, but using a bunch of metal screws and going to town on the unibody patch would be better than expoxying a patch in. People are using expoxies to patch in 1/4 panels and such nowadays for body work, but I still support welding it. You have to take safety into consideration also....if that patch you glue/expoxy in fails and its in a structural area, you have a chance of more failure of surrounding area. One thing leads to another and your car is taking a dump on you and you may pay royally. Unless there have been miracles made with "Crazy Glue" welding it in is my recommendation. Chase Quote Link to comment Share on other sites More sharing options...
johnc Posted November 10, 2003 Share Posted November 10, 2003 He said that you can easily burn hole in unibody, in addition area around weld could be weakened. True if you dont know what you're doing. False if you know how to weld. Go look at any new vehicle (except the aluminum chassis ones) and see how they are put together. Its only recently that various types of non-welding attachment have been used and only for joints that are designed for that type of attachment. Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted November 10, 2003 Share Posted November 10, 2003 .... I would say it'll fall off or fail after awhile of flexing and strains no matter how scratched or scuffed the area is around the patch. How do you explain all those fiberglass body part that are still stuck on after so many years? Quote Link to comment Share on other sites More sharing options...
jonzer12 Posted November 11, 2003 Share Posted November 11, 2003 I am a novice welder and pretty much suck but in most simple welding applications you can simply fill in your mistakes or just cut out the welded part and start over till you get it right. If you have a good rig you can make some decent welds pretty easy. Or just take a class like I am doing. Pretty cheap and lots of fun. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted November 11, 2003 Share Posted November 11, 2003 BTW...many body panels on new car are 'glued' together. So are many parts on the wings and fuselages of aeroplanes. There are products out there that will work. Do a search on KENT autobody products. If you really have a problem getting something welded and its not a main structural member (like patching a rust hole in a fender or floor, the make a patch panel and bond it on. If it's not in a visible area, then before applying the 'glue' drill the holes for rivets, glue it, thenm rivet it too. Tim Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 11, 2003 Share Posted November 11, 2003 Makes me wonder if I should "stitch glue" my subframe... In the end I think JohnC is probably right when he said that the pieces need to be made to be bonded, but it is kind of an attractive option if it would hold. Grind the spots to epoxy, get the right epoxy, mix it up, and you could do the whole car in a few hours. Jon Quote Link to comment Share on other sites More sharing options...
Guest oldZguy Posted November 11, 2003 Share Posted November 11, 2003 I've got some of the glue and have used it in various places. But you can't use it in place of structural welds. You could use it to say glue on a fender, but not a part of a unibody where stress is designed to be transfered. The instructions with the glue show "recommended" areas of use and areas that are to be welded. Also if you use it to "glue" in a patch pannel in an area that is not stress related, like fixing a hole in a fender, the glue, even after set will move "expand" with heat. So the panel will move and crack paint later. The fix here is to glue in the panel and then drill and install sheet metal screws, grind the head of the screws off and finish like normal, the screw studs keep the patch from moving. Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted November 11, 2003 Share Posted November 11, 2003 Wouldn't counter-sunk rivets be better? Quote Link to comment Share on other sites More sharing options...
Guest oldZguy Posted November 11, 2003 Share Posted November 11, 2003 Yes probably but the guy that has the experiance that passed all of this to me was a big time body man, time is money and the screws work and don't require anything but a drill and a screwdriver to install. If I was to use it for that I like the idea of flush rivets! Quote Link to comment Share on other sites More sharing options...
johnc Posted November 11, 2003 Share Posted November 11, 2003 A hypothetical conversation with an insurance claims adjuster after the accident: Adjuster: So, explain to me again how that part of the vehicle came apart. Gluer: I bought this space age epoxy and used it, very carefully according to the instructions, to glue the chassis together. Adjuster: Wasn't it spot welded from the factory? Gluer: Yes, but welding causes weakness and you can burn holes through the metal. Adjuster: And when did you receive your mechnical engineering degree? Gluer: Huh? Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted November 11, 2003 Share Posted November 11, 2003 How do you explain all those fiberglass body part that are still stuck on after so many years? If you reread my 1st post, I am agreeing with you, tomohawk, with the use of the glues or bonding agents on 1/4 panels and cosmetic work, but I don't think that a Zcar is designed to be glued in structural areas and I stated.... People are using expoxies to patch in 1/4 panels and such nowadays for body work, but I still support welding it. I still think welding is better, for structural or cosmetic/body work, thats just me. I'm not bashing the use of bonding agents or glues on bodywork, but I wouldn't use it on lets say the area of frame rail where the "K" member that supports the motor and steering bolts too. Too much of a chance if you ask me. I think if Danman specified the area he would be using it on, it might be up for more controversy. If its the floor pans, I don't think it would hurt to use a bonding agent as long as its not my Z . I've got some of the glue and have used it in various places. But you can't use it in place of structural welds. He just summed up my entire 1st post into 1 sentence. I also enjoy John's last post about the insurance agent and Glue user....good one. Chase Quote Link to comment Share on other sites More sharing options...
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