240D Floor - W T F ?!
 

I noticed recently that my seat was a bit saggy, and when I looked there was hole in the floorboard where the seat's back left bolt attaches to the car!

Then I removed the carpet on the driver side in front and in back the seat, and started poking around, and noticed the "metal?" had a little give to it, and it didn't seem like metal at all, but more like some type of fiberglass or wood even?

The other places where the seat is mounted to the frame are definitely solid metal, and not rotten or rusted. But the back left bolt, which is mounted to the floor, is soggy.

What the hell is the floor of my 240D made out of ??

And what can I do about this hole??

I'm about ready to sell this car if anyone wants a mechanically sound 240D with a hole in the floor, PM me.

Most likely the metal is gone... and all that is left is the sound deadener. (About 1/8" thick plyable material?)

Time for some floor pans

-Chris

Wow, that's a disappointing thing to find. Sounds like it has rusted away?

There are various cheap-o things to do for a short-term fix, like pop-rivet a piece of metal over the hole or cut a piece of plywood to fit, but the seat may come loose in an accident, and that would be pretty serious. Welding in new metal is really the best course.

Hans at German Auto on Rivers Ave / North Charleston may be able to either weld in some new metal or recommend who can. Star Motors does bodywork as well, and I think you've already been there so you know them a bit.

To give you an idea what you're dealing with, check out these two videos I did of a parts car I had back in 2013. Note that this car had an extreme rust problem, and that was the primary reason it was a parts car, though it still looked pretty good above the floors:

https://www.youtube.com/watch?v=8yFa7wCzIsQ

https://www.youtube.com/watch?v=OiJSl5wdKO0

The sound deadening material and thick undercoating are often mistaken for solid metal, while in fact, sometimes the metal will rust away from between those two layers, leaving what looks like solid floor, but in fact is something that is mostly plastic and rubber, and can be broken through easily.

^ Yup.. put my foot through my passenger side rear pan earlier this week. Mines getting new pans over the winter while I've got the subframes pulled.

If you can weld and have some time, its not a bad job to replace the pans yourself.

-Chris

Yup...My rear passenger floor is completely gone, but when you lift up the carpets you wouldn't know! It looks to all be there. Even looking underneath the car all you see is a sturdy looking floor.
And then you put some pressure on it and you can see the whole damn thing flex.

These old Mercedes certainly hide their rust very well. I just remind my rear passengers to not stomp their feet too hard, lest they end up damaging their shoes what with their soles dragging over the asphalt!

In all seriousness though: if you can't weld (I can't either), call some body shops. Have a quote done if the rest of the car is still good. Rotten floorboards are not necessarily the end of the road, nor does it have to be (too) costly to get it fixed. You could even check craigslist or something, see if some local welder is offering his services in the nights and weekends...
It's a floorboard; the welds don't have to be too pretty, as long as it has fresh metal and gets rustproofed! :)

If all else fails, you can do what this guy did with his car (I actually took this picture two days ago, while sitting at a stop light during my lunch break)
http://www.peachparts.com/shopforum/...1&d=1439423525

He had his seat propped up on wood. You can tell, as it was poking through the floor.

Oh, and this is the carpet!:
http://www.peachparts.com/shopforum/...1&d=1439423525

It was raining, too. Pretty sure his socks got wet...:rolleyes:

What's the skinny on pop rivets & adhesive instead of welding in pans?

Years ago I did floor patches to a 240D with sheet steel and pop rivets. It certainly felt solid when I was done. I drove it for a year and a half like that before selling it (with full disclosure on the nature and extent of the repairs).

I gave the repairs layers and layers of paint and undercoating, not to mention seam sealer, to seal everything up. A few years later, I saw the same car for sale on eBay with a dead engine, but the photos of the repaired areas showed that the patches aged well.

I have no idea how such repairs would hold up in a crash, nor do I wish to find out. I felt comfortable driving that car. It's not something I'd do for a concours restoration, but for a beater car, I'd certainly consider it if I couldn't weld (I can weld now and now only do riveted repairs when welding would be likely to set a fire or would otherwise be impractical.

Timely thread for me. I am dealing with the exact same issue in my 300TE and the thought of selling the car isn't sitting well with me or my wife. My plan is to cut a floorboard out of another parts car and have that welded in since I don't have any welding skills.

If you're going to rivet a patch, do "wet patch" with a bead of sealant on the patch and the floor pan (I hear road signs make for great patch material). You can go an extra step and add a layer of fiberglass resin matt over the repair to really seal things up. Welding is always preferred and you can rent a welder for cheap. I was able to rent and MIG/TIG machine 3 days for $100 and wasn't charged for gas or wire.

No it is NOT....
This has been thoroughly discussed in the archives.
I will find the reference threads if I have a chance..

The bottom line until that great thread can be found.... is that welding takes away any corrosion resistance made into the metal being used.... a better plan for floor replacement... for the plug ' welding ' mentioned below there is also the chance that brazing would be more appropriate for the same reason...

proper spacing and sizing of the solid rivets combined with moisture protection will be plenty strong to hold the floor pan..... Aircraft are still put together with Rivets...Automobile FRAMES were hot riveted until unibody was invented..... not welded... for exactly this reason.. even aside from taking away any built in corrosion or strength designed into the metal used... only xrays can tell if a weld is proper....( talking airplanes )....

which is in an area prone to moisture and even salt some places..
is to find the good metal by using a ' pick' hammer...take out all diseased metal

then provide plenty of Overlap to the good metal with the new metal replacement.... then use a pneumatic plug cutter available cheap from Harbor Freight.. it also FLANGES your sheet metal for the overlap..... and turn it around and it cuts the holes for plug welding..

http://www.harborfreight.com/catalogsearch/result/index/?q=flange+tool

https://www.youtube.com/watch?v=e_4I9Kyk09Q

Note that the flanger can reach into a small space one direction and not the other.. thus you will need to plan which sheet metal is going to be offset which direction.


to make holes appropriate for plug welding .. which would be placed according to engineering standards for sheet metal...and IN Between those plug welds.... use SOLID STEEL Rivets .. no pop rivets.. the solid rivets are used by Experimental Aircraft builders ( as one example where strength is important ) to attach the overlapped metal . In getting the various sheet metal panels lined up and held exactly while accomplishing these processes.. use Cleckos in the holes which will be filled with the solid rivets... check out this catalog.. solid rivets require an ' anvil ' behind them... so plan ahead on access for proper installation....
http://www.aircraft-tool.com/

Send for their Paper Catalog also... really nice to have as reference....


The thread I am and would look for involved a discussion which Larry Bible was arguing for 100 percent welding in a new sheet metal floor plan. Larry Bible quit several times and came back under new names to get rid of infraction points he had built up...and it messed up using his name for searching...

Over the years several things have happened which may have lost that thread... at one time a huge number of threads were lost due to a hard drive failure.
At one time OP's could delete their first post in a thread and it would delete the entire thread .... TXBill did that in a fit of anger and the forum lost lots of good information. Some of us woke up one morning to find we had a thousand less posts than the day before.....

Some people have made a habit of saving to their computer informative threads... if someone has the one I am remembering please share it with us..
thanks, Greg

Welding is great and all, and not that hard, but I'm thinking that if you weld you're burning off the undercoatings on the good parts.

My thoughts were that a new floor gooped on with adhesive and plenty of paint would hold really well-lots of modern body panels are glued on.

That is another good point which I did not get to in my post... not only BURNING OFF... exposing it to corrosion effects.... added to changing the metal's resistance to corrosion... a double whammy....
but really easy to start a FIRE or create bad smoke... on a floor pan project much of what you will be dealing with is likely to have those undercoatings up in really bad to get to tight places..
I think CO2 extinguisher is mandatory for this project... even just for cooling up inside those hidden seams.... absent an actual fire... or to keep from having a fire...

Just a note that where I live, the provincial government used to not accept riveting as a floor repair on safety inspections.

They were taken to court on it and with all the might of the ministry of transport AND the provincially run insurance scheme (same folks who inspect heavy trucks inspect cars here and set the inspection rules)... they were unable to come up with a convincing argument on why rivets were unsafe.

Riveted floor pan repairs are now legal. There are specs on the rivet spacing and the repair must be sealed properly.

Wow, this is so interesting! I never thought riveting a floor pan was considered an actual sturdy repair, but I guess I was totally wrong in my assumption.
I'm now reconsidering how to fix my rotten rear passenger floor pan as well... Some good information in this thread!

What one finds in dealing with old cars and corrosion is that many times you can not really see how bad the metal is... so when you start to weld.. either oxy acet, stick, mig, Tig, etc... once you put the heat to what you thought was good metal to attach TO.. just literally MELTS away... not there anymore...
So usually best to start with a method which will preserve the strength and ' existance' of the metal you need for support... and just follow the ' rules' , in this case sheet metal rivet rules', and then seal up from further corrosion the best you are able... but that process also must follow the rules... as you do not want to encapsulate moisture in a pocket where it will be working away like termites on your structure...

and remember,,, there are lots of legit pop rivet uses... but here we are talking about SOLID STEEL..... rivets for this structural repair. Everyone ought to have a paper copy of that aircraft tools catalog... very interesting reading... and cool tools.. even though many of those tools will be available at less cost elsewhere.....

The use of Clecos.....
https://www.youtube.com/watch?v=aTQNuQlVnA0

So these are very useful all the time... but particularly when replacing a full floor pan.. you can use a few of these removable fasteners to get your floor pan positioned and measured at exactly where you need it... floor pans are hard to work on due to not being able to put your weight on them... so a few holes of the same size Clecos you have... then tweak the position.... and put more in... until you are sure you have it where you want it.... you already have flanged the sheet metal which is going together...and made plug welding holes probably.... or brazing holes... interspaced between the Cleco holes... then you take out the last of the Clecos and put in your final solid rivets......and then prep for sealing it all up....

Great Sheet Metal automotive books... look for author Ron Fournier a magician with sheet metal...
https://www.youtube.com/watch?v=aTQNuQlVnA0

Either method of repair will work.. just be sure to cut back to solid material... clean and prep....

And be ready to go back over everything with a rust preventive. Even drilling holes for rivets exposes the material to potential corrosion. Clean, Prep, Repair, then protect.