What Type and Gauge of steel should I use to repair a seam rusted open in my passenger side floorboard along the edge next to the front and rear passenger side doors?
Can you please consider that a beginning welder will be welding this? Also should i weld from the top or bottom? I haveheard you should weld from the bottom in floorboard work. I get pretty obsessed with strength sometimes. I want to avoid welding 100 pounds of steel and girders into the seam.

I have already removed the passenger side seat. The rusted open seam extends from rear of the front door to rear of the backdoor. Sometimes I (jokingly) worry that one day I will be driving along some bridge and my carpool partner will literally fall out of the car and disappear into the river if I don't fix this seam before it turns into major cancer.

I would use whatever sheet metal I could find. 16 gauge will be harder to work with, but if it works out that the spot needs very few bends or curves, then the added thickness would be easier for a rookie to weld and will take longer to rust through.

Make sure you trim back as much of the cancered floor as possible and get back to something substantial enough to weld to. Make sure the metal where you will weld is COMPLETELY clean using abrasives of some kind.

What kind of welder do you have to work with?

Good luck and have a great day,

If you are a beginner, you are going to have trouble welding sheet metal, use the MIG process. The heavier the gage, the easier it is to weld and the harder it is to shape. One other thing - use cold rolled steel, hot rolled must be seriously cleaned before painting. If you are using scrap sheetmetal anything that is painted will likely be OK.

Stronger steel is used in the roof of many cars. I cut the roof out of an old SAAB from the late 70's and used it to replace the floorboards in an old Ford pickup. That repair lasted through many years of hard use.

Cleanliness will make an easier and longer lasting repair.

After years of using recycled sheet metal to repair things, recently I actually bought some virgin sheet metal at the local hardware store. I quickly overcame the pain and suffering associated with actually PAYING for metal because it was such a treat to work with clean, straight metal. 18 ga is about 1.2mm thick which was about right for the floor spots I repaired.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

BTW if you have this extensive of damage to your car, be sure to inspect the rest of the auto for other such bad rust. You defintely don't want to patch up your floor and find out the unibody is shot!

Just wanna be careful....

you may be able to buy the panel new or cut one out from a wrecked vehicle.try to find a dismantler in the south where they maybe rust free

What about buying aftermarket floor pans? I know for like Mustangs you can get them cheap. I think their is a company called K&K maybe that makes MB sheet metal.

At least that way if your a good welder it would be very close to factory.

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1999 SL500
1969 280SE
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Mercedes Benz I generally use 18 gauge sheet metal.

It depends upon which gauge matches vehicle panel thickness best, and needed structural support in the area.

The toughest repairs are double or triple layers of sheet metal to reinforce structural points.

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I have had good success with 16/18 gauge metal and a Hobart 135 (now 140 I think) model MIG welder. Best practice is to weld about an inch or less and let it cool to prevent warping (and fire). All my welding has been from the top, because that's where the metal fit best in terms of the junction seam with the rest of the car.

The driver's side of Cinderella has a new floor pan that I will guess is 18 gauge steel. That's the side where the seat was propped up with a 2x4 wood stick so the driver would not fall out. The passenger side is going to get sheet metal patches instead of a new floor pan because it has rusted out only along the areas you describe.

Cinderella's floor rust is mostly the result of blocked hood drains, and so it is from the inside out. Fortunately, this means the rocker panels are still in quite good shape. On the driver's side they were opened up enough when cutting away bad metal that a good POR-15 treatment was possible.

I have given some consideration to having a custom license plate for little Cinderella: "POR 15"



Ken300D

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1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

floor repair is normally done with rivit gun rather than welder.

maybe, but Rich seems to take his repair work seriously and wants to do it right.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Rivet joints are not strong at all, especially for a unibody.

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

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Blue Ranger is absolutely CORRECT !
There are other threads on sheetmetal where I go into the reasons for that...

WBain, that is a silly statement and you should do your research quickly, determine that it is a silly statement and delete it as soon as you can... for the sake of your own reputation....