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  #1  
Old 03-29-2014, 10:48 AM
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Floor rust repair W123 sedan

I noticed a "crack" in the undercoat when I was having a tire changed. Turns out that my passenger side floor is rusted at the seam between the rocker panel and the floorpan. About 3" of metal are "crunchy" along the seam between driver and passenger seats. It seems to have rusted from the outside in, not from the inside due to water intrusion.

Questions:
(1) Can anyone recommend a body shop either near NYC or near Morristown, NJ that will undertake this sort of repair? The previous guy that did this type of thing for me seems to no longer be in business.
(2) What should be the cost of fixing this if I grind away the bad metal myself?
(3) The rusty strip is within about 1" of the outboard rear suspension mounting bolt. The metal around the bolt, in front of it, and inboard of it is good (passes the screwdriver-and-hammer test). Should this area be reinforced in some way, perhaps with an L-section welded to the rear seat box and to the captive nut in front of the rear seat?
(4) The rusty area of the floor is basically flat. Has anyone had any luck buying a MIG welder and doing the repair himself? I have a space to work in outside the city, so this won't be a problem.
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  #2  
Old 03-29-2014, 10:58 AM
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I bought a mig and some repair panels from Klokerholm and did the rust repairs on my 81. IN both sides I had simialr to what you are describing except mine was in both the rocker panel and the floor panel. Especially around the seat brackets. Once you get past the learning cruve of mig welding very thin sheet metal as long as you have the right tools (body hamers and anvils, angle grinder, welding clamps, etc) it was fairly straight forward. Getting the hang of making good butt joints is 3/4 of the battle. My floors are super solid now.
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Old 03-29-2014, 11:03 AM
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Are the repair panels worth it for a 3" to 5" gap, or should I just bend/hammer sheet steel to fit? Not doing the entire pan, just a section that's about 24" x 5". It doesn't look like there are any stamped reinforcements there, but I may be mistaken.

If I'm doing the welding myself and working outside, the metal of the W123 is most likely galvanized steel. Are there any precautions I should take to avoid metal-fume fever?
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  #4  
Old 03-29-2014, 11:52 AM
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There is thread in the Peachparts bodywork forum describing the repair of my 300D floorpans and other parts!

At one point, i thing it digressed into a mig welding discussion.

With the rust you described, might be worthwhile checking rest of firewall, floors, hinge pockets

http://www.peachparts.com/shopforum/body-repair-restoration/326615-300d-w123-weld-repair-rusted-chassis-floorpans.html.
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  #5  
Old 03-29-2014, 12:40 PM
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Quote:
Originally Posted by Graham View Post
There is thread in the Peachparts bodywork forum describing the repair of my 300D floorpans and other parts!

At one point, i thing it digressed into a mig welding discussion.

With the rust you described, might be worthwhile checking rest of firewall, floors, hinge pockets

http://www.peachparts.com/shopforum/body-repair-restoration/326615-300d-w123-weld-repair-rusted-chassis-floorpans.html.
Thanks. I did check over it. It's basically a solid car apart from:
(a) that place
(b) front fender -- will also patch if I get a welder
(c) one rear fender, but not serious
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Old 03-29-2014, 02:10 PM
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Originally Posted by spdrun View Post
Are the repair panels worth it for a 3" to 5" gap, or should I just bend/hammer sheet steel to fit? Not doing the entire pan, just a section that's about 24" x 5". It doesn't look like there are any stamped reinforcements there, but I may be mistaken.

If I'm doing the welding myself and working outside, the metal of the W123 is most likely galvanized steel. Are there any precautions I should take to avoid metal-fume fever?
Yes, breathing the Fumes when welding Galvanized Steel is hazards. You should be able to get more info on that hazard on the internet.

You should also have a Fire Extinguisher or a Water Hose ready to go.

You can buy bare unplanted Sheet Metal. Regular Hardware store may have it.
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Old 03-29-2014, 03:51 PM
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If you have never welded, and never used a Mig Welder. I suggest you do a lot of practicing on the same gauge metal as the car, before you jump in and start burning holes in the metal.

Take a Welding course at your local JR College.


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Old 03-29-2014, 04:27 PM
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Quote:
Originally Posted by spdrun View Post
Are the repair panels worth it for a 3" to 5" gap, or should I just bend/hammer sheet steel to fit? Not doing the entire pan, just a section that's about 24" x 5". It doesn't look like there are any stamped reinforcements there, but I may be mistaken.

If I'm doing the welding myself and working outside, the metal of the W123 is most likely galvanized steel. Are there any precautions I should take to avoid metal-fume fever?
Its not galvanized, but you will have fume concerns from all the burning vinyl. I wire wheel back 1 to 2 inches all around the weld area, but there are collection areas full of vinyl coating that will burn. Keep a spray bottle full of water with you, that will put out the 101 little vinyl fires as you weld. Wear a chemical respirator, not the dust masks, but a full on anti fume one with cartridges

I wouldnt bother with the klokker panels for the floor. Its half the thickness, and the klokker 123 floor pans are notoriously crappy panels. Just buy some sheet steel from a local metal supply. 18 or 20 gauge works for me

Im gonna be doing this exact same repair on my 240 this summer too. Passenger floor is rusted and needs surgery. Worth doing though, took these cars 30 years to rust that bad, assuming you coat the surface properly, probably get another 10 to 15 years out of a good repair
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Old 03-30-2014, 08:41 AM
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I had an almost identical problem two years ago. Used steel epoxy and sheet metal. Everything is still solid after two winters.
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  #10  
Old 03-30-2014, 04:48 PM
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Quote:
Originally Posted by aieeegrunt View Post
I had an almost identical problem two years ago. Used steel epoxy and sheet metal. Everything is still solid after two winters.
Which steel epoxy product?
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  #11  
Old 04-02-2014, 07:44 AM
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Use cold rolled steel
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  #12  
Old 04-02-2014, 09:17 AM
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Despite the galvanised metal and welding hazard you are better off with zincor plate (or such like it) as it is more malleable than the more "normal" cold roll steel sheets. (Commonly given tip from the guys over on MetalMeet - for Metalshaping Enthusiasts & Professional Metalshapers)
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  #13  
Old 04-02-2014, 09:30 AM
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Quote:
Originally Posted by NC-Diesel View Post
I bought a mig and some repair panels from Klokerholm and did the rust repairs on my 81. IN both sides I had simialr to what you are describing except mine was in both the rocker panel and the floor panel. Especially around the seat brackets. Once you get past the learning cruve of mig welding very thin sheet metal as long as you have the right tools (body hamers and anvils, angle grinder, welding clamps, etc) it was fairly straight forward. Getting the hang of making good butt joints is 3/4 of the battle. My floors are super solid now.
Seconded. There is a mental hurdle and a learning curve to overcome, but mig welding these repairs yourself isn't too difficult or costly. For the record, I'm repairing my floor pans and rockers with steel upcycled from some old Jeep Cherokee doors as well as some fresh steel. I'm using a cheap Harbor Freight flux core mig welder (it's all I can afford). I would advise to NOT use the welding wire that comes with the unit.

If you can spring a few extra bucks, get Hobart flux core wire. I noticed a night and day difference between the HF flux core and the Hobart. The Hobart welds much cleaner and with much less spatter.

I just repaired my rear quarter panel lip with sections from a new Klokkerholm panel and was able to do some reasonably clean and very strong butt welds with this setup. A grinder is a must.

In all, it really isn't too bad a process. I'm learning more and getting better all the time.


The only other tip I have is to coat all sides of the repairs as best you can to help prevent the return of rust.
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  #14  
Old 04-02-2014, 09:48 AM
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IMHO, a mig welder is the easiest welder you can work with. I knew some very basics when I bought mine to restore my 1965 VW Beetle. I am currently doing that, replacing both heater channels and floor pans. In reality it seems scarieer than it actually is, it will take some practice but overall is very easy.
Common sense laws apply, do not weld/grind metal near anything combustible, specially fuels, buy a good mask and gloves and practice some before starting.
If you decide to buy a MIG welder, I'd advice a decent one like a miller or Lincoln. I have a Lincon 180 (240V) and I would advice against flux welding. Using an 80% Argon mix will give you a cleaner weld and make things easy on you. I am not terribly far from you, PM me if you want to stop by one day to try mine and see it for yourself. Now that the weather is getting nicer I'll be starting again, possibly next week.

Good luck
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  #15  
Old 04-02-2014, 09:54 AM
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Quote:
Originally Posted by 65aircooled View Post
IMHO, a mig welder is the easiest welder you can work with. I knew some very basics when I bought mine to restore my 1965 VW Beetle. I am currently doing that, replacing both heater channels and floor pans. In reality it seems scarieer than it actually is, it will take some practice but overall is very easy.
Common sense laws apply, do not weld/grind metal near anything combustible, specially fuels, buy a good mask and gloves and practice some before starting.
If you decide to buy a MIG welder, I'd advice a decent one like a miller or Lincoln. I have a Lincon 180 (240V) and I would advice against flux welding. Using an 80% Argon mix will give you a cleaner weld and make things easy on you. I am not terribly far from you, PM me if you want to stop by one day to try mine and see it for yourself. Now that the weather is getting nicer I'll be starting again, possibly next week.

Good luck
I second the advice on going for a higher quality gas-shielded welder if you can afford it. I use the welder I have because it was cheap and as such, a great way to get into welding.

When budget allows, sometime in the future, I'll be doing as 65aircooled says.
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