Plug Weld Floor Pans?

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JeremyAB95

JeremyAB95

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Originally my plan was to have a shop do the body work on my Duster, but it's pretty costly. I'm not exactly the best when it comes to body work, but the floors are so rusted I'm just removing and replacing anyway - so I don't have to fuss around making patches. I only have gas (oxy-acetylene) and stick welding equipment and experience. Is it advisable or even possible to use either of those techniques to do the plug welds in the floor pans? Do you know if it'll penetrate enough and make a solid joint - or would I have to use a MIG welder to securely and cleanly attach the new floors? Will it be difficult, and has anyone used either of these for a similar job? Thanks.
 
JeremyAB95 said:
Originally my plan was to have a shop do the body work on my Duster, but it's pretty costly. I'm not exactly the best when it comes to body work, but the floors are so rusted I'm just removing and replacing anyway - so I don't have to fuss around making patches. I only have gas (oxy-acetylene) and stick welding equipment and experience. Is it advisable or even possible to use either of those techniques to do the plug welds in the floor pans? Do you know if it'll penetrate enough and make a solid joint - or would I have to use a MIG welder to securely and cleanly attach the new floors? Will it be difficult, and has anyone used either of these for a similar job? Thanks.
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We just replaced front passenger pan on mine. It was no big deal. We used a mig. We cut the old pan out. Used it for a template to drill holes. Cleaned everything up and and welded it in
 
I have never been good enough with an ARC/ Stick welder to do sheet metal. I have a MIG with a gas attachment that makes me a much better welder than I thought I was.
The gas welder you have places too much heat to do sheet metal work.The floorpans may not be so bad though since warpage there may not be noticed. I'd still look at borrowing a MIG from someone.
 
67Signet said:
You also can glue them now.. hear it works well too
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A few years back I would have laughed at this suggestion and made fun of who said it. I have seen the light. The adhesives now have hold strength as strong as a weld with no warpage and none of the porosity that happens with weld spatter.
 
Kern Dog said:
A few years back I would have laughed at this suggestion and made fun of who said it. I have seen the light. The adhesives now have hold strength as strong as a weld with no warpage and none of the porosity that happens with weld spatter.
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Does adhesive really work that well? I'm aware modern production cars use this method for cost and time savings, but is it superior to the old-fashioned way of welding panels? I'd never even considered it. Well it be just as sturdy as a welded joint?
 
I believe GM glues their doors on vehicles now. I know that body shops glue on body panels to. I glued in my 4 speed hump. Worked great, even though I do have a Mig welder
 
As long as you follow the directions many panel adhesives are actually stronger than a traditional weld. Many cars are almost entirely assembled with it.
 
Pascamp said:
As long as you follow the directions many panel adhesives are actually stronger than a traditional weld. Many cars are almost entirely assembled with it.
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I heard the standard was to only use it on non-structural portions of the car, but I've also heard you'll never find a weld on a Bimmer or a lot of other European cars these days. Do you think it would be a good permanent or at least semi-permanent repair if I bonded the panels with the 3M goop that the body shops and such use?
 
And panel bond seals the complete seam. You do need a lap joint for panel bond. You can't butt joint.
 
I just plug welded my floor in with my inexpensive Eastwood 135 on the bottle. I am not a welder, but made it work ok- learned a lot in the process. Trunk floor is next. If you have a buddy with a MIG, see if you can borrow it or buy him a case of beer to do it for you. I do this often with my buddy that has a higher amp MIG/TIG combo.
 
We use 3M Panel Bond in our shop but not for structural areas! You still need to spot weld when appropriate and we have a massive water cooled machine for that. Panel Bond is awesome for patch panels on garage built stuff but you have to use a lap joint obviously.
 
I built a street rod model A with a 400 Chevy and TH350 glued the floor, hump, and firewall. Used strong rare earth magnets on both sides were I couldn't clamp it. It is glued continuously and sealed all in one shot. You need a 1" overlap and clamped tight no gaps to make it work.
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THis is an interesting idea. The wheel tubs in my 70 Charger have that stupid design where there is a bulge that encroaches into the wheelwell area. The tire makes contact with it occasionally and it sucks. I have no fear of cutting and fitting a smooth patch in there. It is the welding sparks and spatter that could set the interior on fire that I worry about.
 
Glue should not be used on structural, quarters included, and I definitely wouldn't use it on a unibody floor pan. I don't know of any Oem that uses glue as a stand alone on the main structure, some trunk tubs and ancillary are . Steel bodies usually use weld-bonding and aluminum usually use bonding and rivets. I have seen it fail and have seen what happens to cars that have been wrecked that been repaired that way previously. I've seen many comebacks where glue was used, and 2 different companies deny warranty. Most of these adhesives have microspheres or some other method the keep every bit of glue being squeezed out so they make for very thick edges on an overlap, and the seams raise back up over time. Once the stuff is in between panels it makes it very difficult to go back drill and do a clean plug weld. The better body shops have moved away from the stuff. We even strength tested it vs plug welding under supervision of an I-CAR instructor. The glue pulled apart before the metal failed.
 
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GeorgeH said:
Glue should not be used on structural, quarters included, and I definitely wouldn't use it on a unibody floor pan. I don't know of any Oem that uses glue as a stand alone on the main structure, some trunk tubs and ancillary are . Steel bodies usually use weld-bonding and aluminum usually use bonding and rivets. I have seen it fail and have seen what happens to cars that have been wrecked that been repaired that way previously. I've seen many comebacks where glue was used, and 2 different companies deny warranty. Most of these adhesives have microspheres or some other method the keep every bit of glue being squeezed out so they make for very thick edges on an overlap, and the seams raise back up over time. Once the stuff is in between panels it makes it very difficult to go back drill and do a clean plug weld. The better body shops have moved away from the stuff. We even strength tested it vs plug welding under supervision of an I-CAR instructor. The glue pulled apart before the metal failed.
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Would you say I should get out the air hammer and my bucking bar then? Some areas seem like they would be hard to access for rivets.
 
JeremyAB95 said:
Would you say I should get out the air hammer and my bucking bar then? Some areas seem like they would be hard to access for rivets.
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No, you need to weld it. The floor ties everything together, the rails/torsion bar crossmember to the firewall, etc. Mig is really the easiest way and probably 200 plug welds to do if your doing a full floor. Not really a place where I would short cut the job.The bonding and rivets is typically aluminum construction, and like Mercedes, they use 7 or 8mm titanium rivets.
 
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i don't know.. new cars are designed around using that adhesive... is it a good idea to use adhesive on a old car that was designed around being welded together?
 
I would NOT trust a panel bonding adhesive on a structural component at all. Small patch panels, sure. But for a structured component on a car, never. I've seen floors and quarters that were screwed/rivoted on actually flex when the car is jacked up. Now i do know the bonding adhesive are strong, but not strong enough.
I would invest in a Harbor Freight MIG welder, scan Craigslist or even Lowes sells welders. I bought a lincoln 125 on CL 6 years ago for 100.00 with everything.
 
Glue is glue period , I work at a reputable chrysler dealership with a body shop , they use glue where the oem s did and add e few stich welds for assurance , I borrowed the glue gun to re bond some reinforcements inside my hood (followed the body guys instructions sanded and cleaned both surfaces thouroughly three times) and the hood wasn t even back on the car and the bond failed!
 
Now , I did try welding floor pathes in an old caprice cop car with a stick welder . It worked but the welds were snotty (lots of grinding) and if any flux stays caught it WILL spawn corrosion (it did in my case)the only way to make sure this doesn t happen you will neen to do tacs and grind/chisel away the flux , this will be so time consuming and if you count all the grinding supplys you can probably buy a base 120 volt wire welder(usually wire included) 90 Amp Flux Welder Here is one for 99$ at 174 you can add gas , with wire feed you still have to deal with flux but even then you will have 80% less grinding to do just dont overlap welds if the flux hasn t been chipped away!Gas welding is going to put lots of heat and warp even though it is not noticeable it will cause you alingment problems on any other subsequent repairs , I have seen a door not close properly after some floor work!!!Heat applies to the stick welder too , stich slowly move to another area...Also the gas welding will cost you in oxygen that little welder!
 
Just got to comment on the bmw and mercedes posts above first off I hope it not anyones reference for quality.Just remember the old saab 900 those cars were all welded fenders too , demo derby guys beware!
 
W-Edge said:
Glue is glue period , I work at a reputable chrysler dealership with a body shop , they use glue where the oem s did and add e few stich welds for assurance , I borrowed the glue gun to re bond some reinforcements inside my hood (followed the body guys instructions sanded and cleaned both surfaces thouroughly three times) and the hood wasn t even back on the car and the bond failed!
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Yeah the stuff comes loose, I've refixed quite a few. One where the trunk floor was done and instead of absorbing the crash energy the panel sheared loose and was poking through the back seat, and a Honda where the qtr was loose under the backlight and qtr window, rockers, and wheel house, no collision, from just riding around. Both situations involved multiple insurance investigators. In a DRP situation Ins. Co's really frown on the stuff.
 
W-Edge said:
Just got to comment on the bmw and mercedes posts above first off I hope it not anyones reference for quality.Just remember the old saab 900 those cars were all welded fenders too , demo derby guys beware!
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I ran from them things man!
 
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