DUDE Posted June 4, 2011 Share Posted June 4, 2011 I have gutted out the car wiring and all and before I put it all back together I want to do some spot welding that I have heard could help my 72 240z. So could anyone tell me how to figure out where the best spots to add spot welds? Then if anyone happens to know what "brand" that would be the most inexpensive to use since this would be a one time only job? Quote Link to comment Share on other sites More sharing options...
emeraldlion Posted June 4, 2011 Share Posted June 4, 2011 You might want to search a little more. Not sure if you're talking about seam welding but that is what it sounds like. To properly seam weld it takes quite a bit of work, and I'm not sure that it is something I would want to undertake unless I had a completely stripped shell on a rotisserie. As far as the equipment, I am still learning about what is acceptable for welds and what is not, but for something like unibody seam welding I would want at least a gas shielded mig welder. Again, the search button is very helpful on this forum. If you search the chassis subforum for seam welding you will get plenty of info. Quote Link to comment Share on other sites More sharing options...
palosfv3 Posted June 4, 2011 Share Posted June 4, 2011 There is no true spot welder available that has the ability to properly produce a spot weld on a household electrical power service. Most good spot welders used in todays repair shop require a minimun 220v 3phase power source. The old style Blair panel spotters that have been around the shops for decades just dont cut it and have been lying around in the back of many shows a cou[ple of weeks after purchase. Many of the good repair shop spot welding machines today start in the $10K range and go over $35k for new machines. Trying to double up spot welds on old existing flanges will probably not work to well with all the years of contamination and corrosion that can be present in between the panels. Your best bet may be purchasing a small MIG machine and learning how to do a correct plug weld . Quote Link to comment Share on other sites More sharing options...
emeraldlion Posted June 4, 2011 Share Posted June 4, 2011 If we're actually talking about spot welding here, I don't understand how that's going to help the 240. Maybe someone can clue me in. Quote Link to comment Share on other sites More sharing options...
DUDE Posted June 4, 2011 Author Share Posted June 4, 2011 You might want to search a little more. Not sure if you're talking about seam welding but that is what it sounds like. To properly seam weld it takes quite a bit of work, and I'm not sure that it is something I would want to undertake unless I had a completely stripped shell on a rotisserie. As far as the equipment, I am still learning about what is acceptable for welds and what is not, but for something like unibody seam welding I would want at least a gas shielded mig welder. Again, the search button is very helpful on this forum. If you search the chassis subforum for seam welding you will get plenty of info. Thanks for the info I guess I had it wrong I was told that spot welding would help the ridigity of my S chashy. Quote Link to comment Share on other sites More sharing options...
DUDE Posted June 4, 2011 Author Share Posted June 4, 2011 There is no true spot welder available that has the ability to properly produce a spot weld on a household electrical power service. Most good spot welders used in todays repair shop require a minimun 220v 3phase power source. The old style Blair panel spotters that have been around the shops for decades just dont cut it and have been lying around in the back of many shows a cou[ple of weeks after purchase. Many of the good repair shop spot welding machines today start in the $10K range and go over $35k for new machines. Trying to double up spot welds on old existing flanges will probably not work to well with all the years of contamination and corrosion that can be present in between the panels. Your best bet may be purchasing a small MIG machine and learning how to do a correct plug weld . Well I guess I was told some incorrect info I just wanted to make my S chasie stronger but if seam weling is the only way then I will have to hold off on that becuase that seem like a pretty big job thanks for the info Quote Link to comment Share on other sites More sharing options...
Nelsonian Posted June 4, 2011 Share Posted June 4, 2011 While my car was in the shop having other major surgery, I decided to have the engine bay, front rails and shock towers stitched for rigidity. The shock towers were stitched from the inside of the wheel housing side. Quote Link to comment Share on other sites More sharing options...
DUDE Posted June 7, 2011 Author Share Posted June 7, 2011 While my car was in the shop having other major surgery, I decided to have the engine bay, front rails and shock towers stitched for rigidity. The shock towers were stitched from the inside of the wheel housing side. Are those the only spots on a 240z that could benifit from stitch welding? Or are there other spots that could use it also if you happen to know? Quote Link to comment Share on other sites More sharing options...
emeraldlion Posted June 7, 2011 Share Posted June 7, 2011 There is a thread on modifications to do to the shell/chassis to improve stiffness that you should search for. The entire chassis could benefit from stitch welding where panels overlap and are spot welded. The problem you run into is that any of those seams should be blasted and seam sealer removed before welding which is a monumental task from what I've read(I haven't actually performed this myself). I didn't see that my car would benefit from this seeing as I do not plan on any heavy racing. Quote Link to comment Share on other sites More sharing options...
DUDE Posted June 8, 2011 Author Share Posted June 8, 2011 There is a thread on modifications to do to the shell/chassis to improve stiffness that you should search for. The entire chassis could benefit from stitch welding where panels overlap and are spot welded. The problem you run into is that any of those seams should be blasted and seam sealer removed before welding which is a monumental task from what I've read(I haven't actually performed this myself). I didn't see that my car would benefit from this seeing as I do not plan on any heavy racing. Great I will check it out and see if it will benifit me or not since I will be doing light racing in the future. Quote Link to comment Share on other sites More sharing options...
redneck1545 Posted June 12, 2011 Share Posted June 12, 2011 (edited) Having just completed a ton of seam welding for my car I can assure you the words monumental task does not do you justice on how difficult and time consuming seam welding is. I decided to sandblast (not with sand of course) me entire chassis. Body panels were DA'd as to prevent warping. Even with renting an industrial tow behind 210CFM air compressor the blasting still took me the better part of the weekend. Not to mention my car is on a rotisserie which took me an enitre other weekend to build. After blasting the cars seams where seam welding was planned to take place was taped off with masking tape and the entire interior and undercarriage was painted in zero-rust black. I towed it back down to my house that weekend and have been seam welding steadily for the past few days. Its going pretty good but I can assure you without sandblasting you will not want to even attempt to seam weld. Even the seams where just a smidge of seam sealer remained it makes welding at the spot almost impossible. Hope this helps Edited June 12, 2011 by redneck1545 Quote Link to comment Share on other sites More sharing options...
MuGumBo Posted July 8, 2011 Share Posted July 8, 2011 Is there anyone on here that does body work and welding as a trade? I have been doing it for 15 years and grew up in a shop watching my dad do it. I'm not saying any of the answers above are wrong but seems like most of the information is half complete. You DO NOT have to sandblast to seem weld. Sandblasting is a great option but not a required part of the process. The biggest issue that no one has addressed is EVERY single spot you weld will rust if you do not use correct corrosion protection when complete. If you can't get to the back side of a weld you have done it will rust. Still good information here but be careful because you could do a lot more damage than good. Check out my restoration project out at 1DollarZ.com Quote Link to comment Share on other sites More sharing options...
redneck1545 Posted July 10, 2011 Share Posted July 10, 2011 ^^^ I decided to sandblast. Wire wheeling and sanding didn't appeal to me in the least seeing as how I needed to prep the whole chassis anyhow. Point being, while yes, sandblasting is not required to seam weld, whats the point in seam welding a car your not going to fully prep and repair properly??? You are correct in the fact that BOTH sides have to be properly protected from rust and corrosion. I think the end all be all the the OP's question is at what point would one consider seam welding? My solution was simple as I had way too much rust to want to pursue any other option. Sandblast the entire CHASSIS, not body, and start there. In the mean time while I had a stripped bare metal body I decided why not seam weld everything that I could get to. I think the OP was trying to decide if he was going to seam weld at all. My suggestion, if your not going to strip the enitre car to the point where complete stripping or blasting could take place then seam welding should not be considered. Quote Link to comment Share on other sites More sharing options...
nissun1 Posted July 14, 2011 Share Posted July 14, 2011 Im interested because what kind of corrosion protection would you use for inner seam welds...sometimes its not even remotely possible to protect that side. Quote Link to comment Share on other sites More sharing options...
TheExpert Posted September 8, 2011 Share Posted September 8, 2011 Spot welding is a process in which contacting metal surfaces are joined by the heat obtained from resistance to electric current flow. Work-pieces are held together under pressure exerted by electrodes. Typically the sheets are in the 0.5 to 3 mm (0.020 to 0.12 in) thickness range. The process uses two shaped copper alloy electrodes to concentrate welding current into a small "spot" and to simultaneously clamp the sheets together. Forcing a large current through the spot will melt the metal and form the weld. The attractive feature of spot welding is a lot of energy can be delivered to the spot in a very short time. Quote Link to comment Share on other sites More sharing options...
johnc Posted September 8, 2011 Share Posted September 8, 2011 I think the OP is confused by the terminology. What he wants to do is seam welding and: 1. It does help the S30 chassis 2. Its a lot of work 3. You can seam weld without having the car sandblasted but you would be a masochist to do that 4. You have to paint/seal the welded areas Quote Link to comment Share on other sites More sharing options...
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