Guest Anonymous Posted July 21, 2002 Share Posted July 21, 2002 back in the mid 90's when i was building my 240z turbo, i remember reading some articles on seam welding unibody chassis. has anyone here done this to their z? i was thinking of doing it to stiffen the chassis while ive got it tore down. any suggestions? nic Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted July 22, 2002 Share Posted July 22, 2002 Seams to make sense that it would help. Seams like a lot of work, though. Seams that I recall a neighbor of mine who raced Camaros in SCCA did the same thing. Quote Link to comment Share on other sites More sharing options...
v8dats Posted July 22, 2002 Share Posted July 22, 2002 thats a heck of alot of seams!! Quote Link to comment Share on other sites More sharing options...
Dave Posted July 22, 2002 Share Posted July 22, 2002 Seams to me that it will work. Seams that this is not going the way it seams it should. Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 22, 2002 Share Posted July 22, 2002 I did some of that - mostly the hat section unibody "frame" area under the back of the car. You have to wonder how much the metal gets weakened by all the heating though. I did an inch at a time here and there until it was all seam welded. I seam welded most of my frame rail and subframe connectors to. Lots of weld wire and lots of sheilding gas, and lots of wire brushing and lots of Oxi-solving to get the oxidation off. That's alot of "and lots" Quote Link to comment Share on other sites More sharing options...
Guest 320Zeven Posted July 23, 2002 Share Posted July 23, 2002 Its Done in rally a lot to add rigidity to the car in other terms i also makes it tougher. but i gues the down side would be your factory crumple zones are **** if you do this. if you are hit your car will not crumple the way it should and absorb the shock which could mean the diference between life or death. but really i have know idea about how the Z car behaves in an accident. and i guess if its strictly a race car it doesnt matter? What do yah think Pete? Thomas ZONC member 1973, 72 240z Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted July 23, 2002 Share Posted July 23, 2002 I dunno about you guys, but I have very little faith in ANY early Z-car, as far as crash safety and crumple zones go. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 23, 2002 Share Posted July 23, 2002 well, unfortunatly ive wrecked a couple of z's....... got rearended hard in a 77..... got a nice ambulance ride for that one, crumpled the rear corner pretty bad. i got banged up pretty good even thou i was wearing seatbelt. also spun a 83zxt.... wrapped it around an embankment. it warped the chassis so bad you couldnt open the driver door..... and the pass door had about an inch gap. i dont think these things were built with that much safty intended. ps.... luckily for the other 2 z's i owned, they got sold and not wrecked Quote Link to comment Share on other sites More sharing options...
katman Posted July 23, 2002 Share Posted July 23, 2002 Originally posted by 320Zeven:Its Done in rally a lot to add rigidity to the car in other terms i also makes it tougher. but i gues the down side would be your factory crumple zones are **** if you do this. if you are hit your car will not crumple the way it should and absorb the shock which could mean the diference between life or death. but really i have know idea about how the Z car behaves in an accident. and i guess if its strictly a race car it doesnt matter? What do yah think Pete? Thomas ZONC member 1973, 72 240z I don't believe seam welding is gonna stop a first gen Z from crumpling. I also doubt it adds any measureable stiffness. What it does do is reduce the local stresses on the spot welds, which is more of a fatigue thing than a static thing. On the downside you fry the primer between seams which give your old Z another excuse to rust. If I was a little more anal I'd disassemble the entire unibody and reweld it with the bonding agent they use on new cars which can be spotwelded through. Good seal, glued together, very strong. Wait, I am anal enough to do that... Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted July 23, 2002 Share Posted July 23, 2002 Hey Katman. Are you ever going to give us the recipe for the ultimate street cage? Quote Link to comment Share on other sites More sharing options...
katman Posted July 23, 2002 Share Posted July 23, 2002 Originally posted by Jim Powers:Hey Katman. Are you ever going to give us the recipe for the ultimate street cage? Anybody remember the Sperry UNIVAC mainframe? As old as the Z. Lost my old HLS30 unibody finite element model on a tape somewhere. Since I have to re input it, may as well put it in CATIA and PATRAN, eh? Haven't forgot, still getting the geometry in in my spare time. May as well have a tool for exploring the age old questions about chassis stiffening for V8's, strut bar effectiveness, NASCAR door bars versus X-door cages, etc. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted July 23, 2002 Share Posted July 23, 2002 Thanks. Looking forward to it. Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 24, 2002 Share Posted July 24, 2002 I agree with katman that the seam welding is probably of little use. I only did a little bit of it. Katman, I do remember the Univac. I used to program on one with cards - yes, the good old computer cards. Thank goodness I never did anything like do an FE model on cards though! Talk about a nightmare! PATRAN huh. I used to use that when it was it's own company. If you do it, how about a FEMAP translation so us people with access to that can "borrow" it . Just kidding. How detailed are you getting with this model? There are alot of little details, like the spot welds, beads, etc. that would take forever to model. Of course, the problem is always finding what to do in detail and what to simplify. I usually erred on the detail side since since I hated doing convergence studies for lots of iterations. I'd LOVE to see a wireframe or shrunk element view or two of that when you get it done! Quote Link to comment Share on other sites More sharing options...
johnc Posted July 24, 2002 Share Posted July 24, 2002 > I also doubt it adds any measureable stiffness. True, but it does give you back the stiffness that may have been lost over the past 30 years. And I learned a month ago how to seam weld any car and not have it detectable. Seems that the SCORE offroad racers have been doing it for years and getting away with it. SCORE finally gave up trying to police it. Quote Link to comment Share on other sites More sharing options...
katman Posted July 24, 2002 Share Posted July 24, 2002 Originally posted by pparaska:Katman, I do remember the Univac. I used to program on one with cards - yes, the good old computer cards. Thank goodness I never did anything like do an FE model on cards though! Talk about a nightmare! PATRAN huh. I used to use that when it was it's own company. If you do it, how about a FEMAP translation so us people with access to that can "borrow" it . Just kidding. How detailed are you getting with this model? There are alot of little details, like the spot welds, beads, etc. that would take forever to model. Of course, the problem is always finding what to do in detail and what to simplify. I usually erred on the detail side since since I hated doing convergence studies for lots of iterations. I'd LOVE to see a wireframe or shrunk element view or two of that when you get it done! Dang Pete. You're even older than me! We still had some card decks when I started but I didn't have to use them. I had a teletype daisywheel hardcopy terminal that we thought was the cat's meow, until we got a bona fide CRT. Monochrome of course. These kids today, just don't know what goodies they missed. The ole UNIVAC had a 36 bit word which I always liked for scientific work. 'Course the Cray's had 64 bit words but they were a pain to talk to.... FEM will be in NASTRAN, so Femap will read it in, yes? I ain't including the spotwelds, this is an "airframe level" internal loads model, local stresses we'll have to do by hand (keeps the riff raff out of the stress analysis business), but overall deflections and gross stresses no problem. Quote Link to comment Share on other sites More sharing options...
katman Posted July 24, 2002 Share Posted July 24, 2002 Good grief. Ignore this one. Netscape and SGI Octane 2's just don't get along... Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 24, 2002 Share Posted July 24, 2002 Originally posted by katman:Dang Pete. You're even older than me! Hey, I'm only 40! I just went to a small college that had old computer stuff. We also had hardcopy terminals but they were hard to get on (lots of waiting lines) - CRT - well, they wouldn't let us sophomores use those! FEM will be in NASTRAN, so Femap will read it in, yes? FEMAP can read almost any FEM format in or out as far as I know. I haven't used it in years but it's hella popular and NASTRAN (MSC?) is too so I'd think it has great support for that. I ain't including the spotwelds, this is an "airframe level" internal loads model, local stresses we'll have to do by hand (keeps the riff raff out of the stress analysis business), but overall deflections and gross stresses no problem. Sounds good to me! I guess being an aircraft dude, you have a few tricks up your sleeve for modeling the fixity of spot welded joints. Damn, I'd love to get back into that stuff. I look forward to seeing that model once you solve the Netscape/SGI issue. Those SGI's rock. I started using them 13 years ago and they were always the best thing for 3D graphics work like FEM pre/post processing. Quote Link to comment Share on other sites More sharing options...
ZROSSA Posted July 25, 2002 Share Posted July 25, 2002 John, Are you going to share this new found knowledge? Douglas Quote Link to comment Share on other sites More sharing options...
pparaska Posted July 25, 2002 Share Posted July 25, 2002 John I'd like to see that too, just for grins. katman, I suppose you've looked into modelling the difference between leaving the spot welds and seam welding? Even though Z's rust from the inside out, as I was working on the terrible rust in my Z, I found that the spot welds were still quite strong, but the steel around them was the problem. Kind of like, if there's a weld that's nice, but what's it holding together? SInce there can be rust in the metal, say under the area that's overlapped (and rusted ) and spot welded, I'd think that seam welding outside of that area where it's not rusty might tie the car together better. Quote Link to comment Share on other sites More sharing options...
katman Posted July 25, 2002 Share Posted July 25, 2002 Originally posted by pparaska:John I'd like to see that too, just for grins. katman, I suppose you've looked into modelling the difference between leaving the spot welds and seam welding? Even though Z's rust from the inside out, as I was working on the terrible rust in my Z, I found that the spot welds were still quite strong, but the steel around them was the problem. Kind of like, if there's a weld that's nice, but what's it holding together? SInce there can be rust in the metal, say under the area that's overlapped (and rusted ) and spot welded, I'd think that seam welding outside of that area where it's not rusty might tie the car together better. Yeah John, I wanna see too. Spotwelds versus seamed, same problem as fastened versus fused when it comes to modelling. As we say in our best Colonel Klink accent, "Vee haf Vays". Pete hits on a phenomenon I too have seen, having repaired countless wrecked race cars and having cut up an entire HLS30 into wittle bitty pieces, which is that the spot welds don't rust but the region around them does. This would be typical of the technology available at the time. Any protectant on the parts before welding is cooked off, and any treatments after welding don't quite wick down between the parts at the spotweld. Sad, but true. John's statement that seam welding might restore strength lost due to age has merit and it does relieve some of the stress around the spotwelds where the rust is most likely to have started. Pete, I'm sorry to hear you're only 40. I'm 43 but don't feel a day over 39. Quote Link to comment Share on other sites More sharing options...
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