Guest plainswolf Posted May 8, 2004 Share Posted May 8, 2004 Guys I have a late 74 260 and the floorpans and framerails seem fantastic except for two places. The first is on the driver's side floor pan drain hole, which doesnt have the plug and so it rusted around the hole perimeter making it almost twice as large as it should be, though not all the way through. The second place is on the passenger side core support rail, on the outboard section you can see by looking in around the rear of thr front tire and the sheet metal right above the core supprt rail is rusted through making a rust hole about 3 inches long by 1 inch high. All of it is above the frame rail but still.. It can't be seen from inside the the engine bay, but only from the outside inside of the wheel-well. Other than that the frame rails look fantasic and completely undeformed anywhere! As does the floor pans except for that one spot. Now I live in western nebraska which is just shy of a desert! (semi-arid enviroment) and there is NO salt ever used on the roads here. And the car is origionally from this area as well. I have contemplated just installing new floor pans and frame rails including core supprt, but after speaking with a few guys who I work with that are welders(better than me), and one is a former body-man, they say just repair the bad spots... that it looked perfect enough everywhere else underneath so why cut it up unnecessarily? I told them about puting my 327 into it and they just recommended connecting the frame rails to the rear and tower strut braces. Now my engine is only in shortblock form now but will put out between 330-360Hp when installed. I still plan on connecting the frame as well as stich welding the unibody a little better than factory. Now I have to admit I even wondered if it truly would need them replaced since the rest of the underneath is uncannily clean and sound... but I also know how rust can fool a person on the inside and not be visible yet.. I've banged away at the framerails pretty well with a peen and it appears very sound throughout.. Guess I can't decide... any suggestions? Quote Link to comment Share on other sites More sharing options...
SSflyer Posted May 8, 2004 Share Posted May 8, 2004 My advise would be to patch your existing floors. I'm in the middle of replace my entire floorpans, and it's a HUGE job. I'd cut my patches large enough to overlap the holes and weld then from top and bottom. If your car has undercoat you might want to do some scraping to make sure nothing is being hidden, especially around the support rails. The other big plus to patching is the cost. A sheet of 18ga will run maybe $20, but new floors are over $400! Quote Link to comment Share on other sites More sharing options...
Guest plainswolf Posted May 8, 2004 Share Posted May 8, 2004 Ahh thank you!... I'd say there isa only about 35-40% of the undercoat still left and mostly in the trans tunnel area.. which I should check as you said... the areas where there is none is perfect.. just the factory paint which is sort of a light greenish gold color (the body of my car is the factory brown) But took another look at it today and noticed how perfectly straight most all of the frame rails are.. and I mean perfectly straight and level except very slight push ups near the very rear end of the frame rails.. I appreciate the advice.. one of the guys that looked at it when it was up on ramps said he wouldn't even begin to think about new floors as the origionals seemed exceptional to him... but I was just considering that it is 30 year old metal.. but they are the 280 style full length frame rails as well. I think I will strongly consider your advice especially in leui of what a huge job the new pans sound like they are.., I'll just cut out the two bad areas maybe and weld a good patch around it.. Thank you! Quote Link to comment Share on other sites More sharing options...
wheelman Posted May 8, 2004 Share Posted May 8, 2004 The other place you want to check real good is the foot wells on both sides. I cleaned the undercoating from the inside and outside of my floors. Everything looked great until I got to the drviers side footwell where I found the floor was not rusted through yet but was very thin. I used an air chisel to clean the coating from the floor and it went through at the thin spot. I haven't cut the spot out yet becuase I've been working on the passenger side battery box, fender well and firewall. This area was pretty badly rusted so I cut it all out and just started welding the new stuff in today. I thought it was going to be realtively easy but it's not, I didn't practice near enough before I started and I've burned though a couple spots and will have a big job grinding the extra filler flat. Anyway the jist of all this is to be thorough in your search to find all the rust and get rid of it when you find it. Next Z I buy is definitely going to be as rust free as I can find. I live in south eastern Washington which is also a desert environment but gets some snow in the winter so I should be able to find a decent Z if I'm patient. I'm not looking right now but a friend of my son has expressed an interest in having me build him a Z while He's stationed in Italy with the Air Force. Wheelman Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted May 14, 2004 Share Posted May 14, 2004 Wheelman, How did your floors come out? I am thinking of replacing mine. Quote Link to comment Share on other sites More sharing options...
wheelman Posted May 14, 2004 Share Posted May 14, 2004 Evil, I'm still working on it. I have most of the battery box welded in and still need to fill in some more on the passenger side footwell right above the seam. Once that's complete I'll cut out the drivers side. I was back under it yesterday measuring the tranny mount for fabrication and found more rust on the drivers side. I'm going to need to cut across at the seam between the floor and the firewall up about 3 or 4 inches and all the way across the drivers side footwell to get rid of all of it. This will give me a good look inside the drivers side frame rail so I'm not to upset about it. I'll post some pictures when I get more of it done. I'm just learning to weld so it's been quite an adventure replacing the battery box. So far it's turned out OK but I need to fill a couple small holes where I burned through. I have a Hobart Handler 135 MIG with gas, does anyone have some advice on how to prevent burn through when welding this thin metal? I have used both solid wire with gas and the self-shielded wire and had problems with both. I also think the regulator I've got is junk. As the pressure in the bottle drops the flow rate increases so I end up using a lot more gas than I should and wasting it. Any suggestions about this as well. Wheelman Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted May 14, 2004 Share Posted May 14, 2004 I have a Hobart Handler 135 MIG with gas' date=' does anyone have some advice on how to prevent burn through when welding this thin metal? I have used both solid wire with gas and the self-shielded wire and had problems with both. Wheelman[/quote'] Use thin (.025) solid wire with gas. MIG welding butt welds on the thin stuff are nearly impossible to get right, so I hardly bother. Make an overlap seam. Immensely easier to fabricate and weld. Don't be afraid to go/weld slower. When you burn through your natural tendency is to go faster, thinking you will apply less heat, but going slower will actually help this. I find that when I have my machine setup to make the best welds, I am actually burning thru a lot, but as it burns thru, the weld is built up and the hole filled at the same time so the heat is better distributed into the weld material and it comes out looking very good. If there is a corner or edge, they will be more prone to melt away to I like to start my welds there and then move to the places with more thickness or surface area. If you do burn through, holes are easily fixed. Move around the edge of the hole with short 1 second bursts to build up a lip. Once the lip is there, it is easily filled without the hole growing. Also I find that I like to set my heat quite a bit higher and feed rate quite a bit lower than the manufacturer recommendations for the material thickness, making the welds less proud. I bought a good rebuilt regulator at the welder repair shop here in town. The one that came with the welder was junk, so it died after a few months and leaked all my gas out pretty quickly. I can't say that the better regulator resulted in better welds though. Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted May 14, 2004 Share Posted May 14, 2004 Look forward to seeing some pics Wheelman. Grammercyjam, thanks for the welding tips. I too have had some problems with burnthrough. I have a very cheap Harbor Freight welder and was blaming it on that. Fluxcore is hard to weld sheet metal with but it is extremely strong. I have been wanting to try a thinner wire, I let you know if it helps Wheelman Evil Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted May 14, 2004 Share Posted May 14, 2004 I don't know that you will be able to overcome the cheap welder problems. They work OK on angle iron, but you really need rock solid wire feed and heat control to weld thin sheet metal well. I remember it was a bear trying to weld exhaust tubing with a cheap MIG and flux core .034 wire. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 14, 2004 Share Posted May 14, 2004 I just got my Millermatic 135 off ebay with Hobart helmet and a pair of gloves for $607 and free shipping. Here's the company's items for sale right now: http://cgi6.ebay.com/ws/eBayISAPI.dll?ViewSellersOtherItems&userid=weldfabulous&completed=0&sort=3&since=-1 Add $230 for an extra spool of wire, CO2/argon tank, a nice wire brush and a better regulator, and I tell you, this thing welds AWESOME. Much better than the cheapo welders I had used before that didn't have the infinite wire speed and voltage controls. I'm REALLY happy that I paid the $$$ to get a better quality welder, and the price really wasn't as high as I had thought it would be. I'm a very inexperienced welder, limited to what I learned in high school auto shop 12 years ago and a few lessons from friends while fabricating this or that coupled with a couple minor projects (weld this bracket, weld this exhaust pipe, etc), but I can weld like a pro with this thing!!! Quote Link to comment Share on other sites More sharing options...
SSflyer Posted May 15, 2004 Share Posted May 15, 2004 I wonder if there really is such a thing as a rust free Zcar. I've done the floors, firewall, battery tray (all 3 panels), both door sills, both rear quarters, and still have a couple of spots to patch on the inner fenders right above the front crossmember. The good news is that I'm getting real good at making panels, but the bad news is that it's taking FOREVER. I bought a 'rustfree' car on EBAY, fool that I am, and haven't even gotten to the engine work yet. Oh yeah, there's still the marker light, air vent, and antenna holes to fill in. I guess the key is to think of this as a work in progess, and the journey should be more fun than the destination... Quote Link to comment Share on other sites More sharing options...
Z-TARD Posted May 15, 2004 Share Posted May 15, 2004 A good way to control burn through is to clamp a chunk of brass flat stock to the back of your weld area. You'll be able to run longer beads, and they won't look like seagull poop on the other side when your done. Don't worry about welding the brass to the sheetmetal, it'll never happen. Just make sure to wire brush all the slag and contaminates off of the brass before you move it to the next weld area to prevent them from contaminating your next weld. This works really well for TIG as well, as it tends to trap the argon purge gas around the backside of the weld, your bead will look the same on both sides of the sheetmetal. Even though you won't actually be welding the brass, it will absorb quite a bit of heat, and will stay hot for a long time so make sure you wear heavy gloves when handling it. Mike Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted May 17, 2004 Share Posted May 17, 2004 Z-Tard, don't you mean copper stock? Quote Link to comment Share on other sites More sharing options...
Mike Mileski Posted May 17, 2004 Share Posted May 17, 2004 I live in Tucson, Arizona and I bought my 1971 240 in 1990 from the original owner, a lady from Missouri who received it as a high school graduation present in the summer of 1971. She drove it to Tucson at the end of that summer to attend the University of Arizona and it never left the state after that, until I bought if from her. It truely is a rust-free Z. Mike Mileski Tucson, AZ Quote Link to comment Share on other sites More sharing options...
SSflyer Posted May 17, 2004 Share Posted May 17, 2004 Oh fine, rub some salt in the wound! My poor car spent the last five years sitting in a field in Oklahoma, and on top of that the goofball who owned it left the drivers window down about a half inch. Just a few repeated soakings and snowings. Bottom line, I've learned how to break a spot weld with only one or two whacks. Quote Link to comment Share on other sites More sharing options...
Z-TARD Posted May 17, 2004 Share Posted May 17, 2004 Copper would probably work as well, but brass has a higher melting point and is less likely to melt and contaminate the weld. I've used aluminum too. Pretty much any metal that can't be welded (by normal methods) to steel will work, but for me at least brass seems to be the best. Mike Quote Link to comment Share on other sites More sharing options...
Z-TARD Posted May 17, 2004 Share Posted May 17, 2004 Any metal that can't be welded to steel, except for lead Quote Link to comment Share on other sites More sharing options...
gramercyjam Posted May 19, 2004 Share Posted May 19, 2004 I haven't ever seen any brass O/A or MIG welding tips. They are always copper. I am guessing this is because brass sticks more than copper. Quote Link to comment Share on other sites More sharing options...
tannji Posted May 19, 2004 Share Posted May 19, 2004 I think they are copper because they get hotter, and have far less mass than the heavy piece of brass.... I dont weld yet... but I have brased and soldered, and I know how heat sinks work. Its the same thermal dymanic principles that allow you to boil water over an open flame in a paper or wood container.... the material is flammable.... but the heat transfers to the water too readily for the container to reach the combustion temp. The chunk of brass isnt in the optimum position to take a weld bead.... so it just absorbs excess heat from the weld area. You would think that copper would work "better" as it is a better conductor, but it would seem to me that brass would be good enough, heck, just about any massy chunk of metal would be good enough, as long as it didnt react with the material being welded. Quote Link to comment Share on other sites More sharing options...
Z-TARD Posted May 20, 2004 Share Posted May 20, 2004 Yeah, thats the idea. I've almost always ended up using brass, because thats whats available on a ship, which is where I have done most of my welding. I've noticed that brass is very hard to get a puddle on with a tig torch set to weld on steel. The amperage required to run a bead on brass is just insane, count on turning a few pairs of gloves into bacon in the process. Copper, on the other hand, melts pretty rapidly under a tig torch. You don't want a metal with a low melting point as a backing material, copper won't fuse to steel readily, and will just crap up the weld. Aluminum works up to a point, but once it absorbs a certain amount of heat it will start to contaminate the weld as well. Brass seems to have an almost unlimited ability to absorb heat in this application, I've never had it contaminate a full penetration weld yet. You can weld on 16 gauge sheetmetal with almost 80 amps with little difficulty. Keep the clamps close to the weld zone, and only weld about an inch at a time and you will get very little warping or distortion as well. Mike Quote Link to comment Share on other sites More sharing options...
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