Guys,

I fixed my driver's side rocker panel in this thread in the winter:
W123 - Advice needed on jack point rust

That fix has held up wonderfully - I couldn't be happier with how it came out. The car has proven to be great, so I am investing the time to do the passenger side. The driver's side is rust free.

The rocker panel damage isn't as bad, but the floor along the channel near the rocker is rusted out like other side, and about 20% of the rear floor pan is rusty.

Anyone ever drop a whole new floor pan in? I am considering buying the entire aftermarket floor pan just so I can cut my donor pieces directly off it. Seems like kind of a waste but it sure would save me time fashioning my own patches.

Any advice on fixing floor pans?

This should be a lot easier - I dont have to learn to weld this time around

Pics to come.

dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Where's the pics?

__________________
1981 240d aka "The rust bucket"

*viewer discretion advised* if you are scared of rust. Come for a journey!

Pic #1: What I started this project for. I knew there was some rust under the floor and it needed to be addressed.

There is rust all through the passenger front and rear floor pans.

Pic #2: Rust through front rocker area

Pic #3: Rust in front floor pan

Attached Thumbnails

     

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Pic #4: A look at the floor pan in the rear. Its trashed.

Pic #5: Another look. At the rear floor pan.

Pic #6: A look at the battery box area - see the previous owner's repair attempt. Thats 22 gauge and rivets - not too bad.

Pic #7: Removed center console.

At this point I remove the center console and ordered new floor pans from KK manufacturing: http://www.kkmfg.com/ They are great panels and the folks there are fantastic.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Pic #7: Time to go to work fixing instead of feeling sick to my stomach uncovering rust. This is the front rocker area with rust cut out.

Pic #8: Bye bye rear floor. Cut it out almost entirely.

In the mean time the new floors came. I decided to fit the new floors in, cutting them as necessary, and then weld them in.

Currently I have begun welding the new floors in, more pics to come in a few days.

Attached Thumbnails

   

__________________
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

while we are on this subject i have an OEM drivers side floor plan FS if anyone needs one

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Okay, at this point I start getting the think back together again. This is no small task!

Pic #9: I have the new floor pans - here is a pic of what I cut out next to what has to go in. This is the rear floor section. Now comes the complicated, time consuming task of fitting the new piece in with the old.

Pic #10: Rough test fit of the new floor in the car. Lots of adjustment to go.

My main technique here is just to go slow. I use a silver sharpie to make the markings and make small cuts with the dremel or with a bench grinder. The goal is an 1/8" gap or less. Its all done by eye and feel. Sometimes using construction or poster paper to get a shape down is useful - especially for for small stuff. These big floor pans just take time and patience to get right.

Pic #11: For the areas up near the battery tray and along the firewall a ptach already existed. I decided to mostly leave it in place. I ripped all the silicone caulking done the the previous mechanic. I applied POR-15 to the whole area to seal up any rust and prevent more from starting. I then reinforced the entire area with POR-15's epoxy putty. This was so much easier than welding in new metal here. To weld in new metal I would have had to remove the dash and at least some engine compartment stuff. A LOT more work than I was already doing.

So I used the putty and I am really happy with the results. I used POR-15's 'power mesh' fiberglass fabric painted with POR-15 as sort of a mold and 'rebar'. The result is very strong...I have smacked it with a 2 lb sledge and it holds no problem.

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__________________
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

The irony of most autobody welding projects I have learned is that the welding is really quick if you have done the prep right. All told, I only spent a couple hours under the arc actually welding. The rest is prep, grinding, cutting, lining up, clamping...

So with a LOT of hand waving and time lapse...

Pic #12: On the areas I will not be able to get to later with POR-15, I spray in a Weld Thru primer to prevent rust out.

Pic #13: 3m Weld-Thru II that I use. Be prepared, its pricey at $22 a can, but lasts forever.

Pic #14: The rear floor welded in. Still some cleanup to do, but its mostly there after a long day of work.

Pic #15: The front area welded in. Again, cleanup to do, but its in there.

Some tips:

-BACK THE UNDERCOATING AWAY FROM THE WELDS with a wire brush on your grinder. Its catches fire really easy. If for some reason you cant back it away, have an extinguisher ready. Dont burn your car to the ground!

-Where gaps exist I use 3/16" TIG rods as filler. I get them at my local welding shop. They nicely fill the gaps so I do not have to bridge huge gaps with weld. It saves so much time and makes things turn out much better

- Dont over heat. Tack the whole piece in in 1" increments darting all over the piece. Then weld in one inch at a time moving all over the piece. Dont go six inches at a time! You'll warp the snot out of the panel and it wont line up anymore.

- Clean the edges: Make sure to get any rust and paint out, or else your welds wont be good. It will be hard to make an arc.

- This is tough welding. When welding on thin metal with big variable gaps things are not going to go smoothly, especially for a hobby welder like yours truly. You'll burn through, need to do lots of slow passes. It takes practice and experience, Id describe more but im no pro welder.

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__________________
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Looking great! The bad part about these types of repairs is that when you are finished, nobody ever sees them and if you do it properly, nobody even knows they are done!

Oh well, the key thing is that YOU know they are done.

Oh yeah, isn't welding sheet metal FUN!

So you can apply the epoxy putty over the the POR-15 paint?

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1983 240D 3.0T 4-speed manual, now sold

1989 Subaru GL Wagon 5-speed Touring Edition

You shouldn't but many times, due to where the rust is, it is better than the alternative of just partially encapsulating the rust.

If you can get it to shiny metal then use the putty first.