My W123 saloon / sedan old accident repair (and a bit of rust repair) thread
 

G'day Folks,

Well it started with a wonky driver's seat (http://www.peachparts.com/shopforum/detailing-interior/273449-w123-wonky-drivers-seat.html)

http://www.peachparts.com/shopforum/...pictureid=2136

Then I noticed the poor fitting wings / fenders (http://www.peachparts.com/shopforum/detailing-interior/280613-w123-front-wing-fender-question.html)

http://www.peachparts.com/shopforum/...2&d=1278494072

Then when taking off the doors to paint I found that the driver's side had new ones...

http://www.peachparts.com/shopforum/...1&d=1306182952

You would have thought that the penny would have dropped by now... (and it almost had!)

Nasty discovery
 

I knew from messing about with the driver's seat that there had been some repair work to the floor as one side sits up higher than the other. The front seat height was adjusted by adding washers under the seat rails... but that fix was never really going to be a good long term one.

I discovered that it is much easier to remove the floor pan coating (a combination of tar and some sort of fibre) after several warm days so I decided to search for rust and clean up the bottom of the floor pan.

As usual I found more than expected - yes folks one of these days I'll learn not to take everything to bits!

Here's a picture along the length of the car (doors off)

http://www.peachparts.com/shopforum/...1&d=1313573482

It doesn't look too bad eh?

But inside you can now see more of what has been going on

http://www.peachparts.com/shopforum/...1&d=1313573555

Here it is evident that a repair piece has been welded on top of the old floor (hence the height problem with the driver's seat) and they have butchered the cross member in the bottom of this picture by making it not as wide as it should be... Note the weld in the bottom right hand corner of the picture...

The driver's side is banana shaped
 

I can now see that the driver's sill (some of you say rocker - I don't know why!) has been seriously bashed and the repair hasn't been done too responsibly...

Putting a plumb line along the length shows how much it is bowed:-

http://www.peachparts.com/shopforum/...1&d=1313574054

This is the best measurement I can show with a camera in one hand... it is more like a 2cm discrepancy...

You can see how the sides of the car are kind of pulled in at the rear here:-

http://www.peachparts.com/shopforum/...1&d=1313574182

It isn't quite straight but you can't see it with the sill covers on...

So what to do next?
 

...well I spoke with an accident repair specialist - someone who I've come across before - and he said at Dutch labour rates he'd be changing at least 5000 euros to fix it.

Hmmmmm

I didn't have to think long and hard about that option!

He was worth talking to though 'cos now I understand why the door rubbers were cut and knackered (so that the doors would fit); why the driver's door was slightly too high and ever so slightly slanted; and why the front wing was shoved up hard against the firewall...

I doubt if I can find a rust free chassis here so I'm now looking into doing the repair myself.

Looking at the parts drawings:-

http://www.peachparts.com/shopforum/...1&d=1313574838

http://www.peachparts.com/shopforum/...1&d=1313574878

This construction looks quite simple.

I have loads of experience riveting aircraft structures so for me resistance spot welding seems like a good approach to repair. (This is the reason for this thread - as I don't think anyone has been spot welding here just yet)

So that's all for now folks I've got to go and remove some more bits to get to the spot welds.

I'll update my progress and show some plans for supporting the structure before I drill out the old spot welds and cut out the floor.

EDIT:-

I forgot to say I had previously made loads of measurements of the "straightness" of the chassis =>

http://www.peachparts.com/shopforum/2539504-post5.html

Everything seemed fine... so despite the aggressive repair it seems that the four corners of the car at the suspension points are all in the right places...

Some repair links made by others who have gone before

http://www.peachparts.com/shopforum/bodywork-repair-paint-tools-tips-tricks/143078-technical-issues-associated-welding-floorboards.html

http://www.peachparts.com/shopforum/diesel-discussion/106997-cold-heat-soldering-gun-2.html

http://www.peachparts.com/shopforum/bodywork-repair-paint-tools-tips-tricks/145705-beginning-welder-tackles-floorboard-repair-sets-car-fire.html

(great replies from Greg!)

http://www.peachparts.com/shopforum/vintage-mercedes-forum/83194-replacing-floors-ponton.html

Mini update
 

I'm still getting the floor clear and I've got the blower motor / heater box out so I can get at the sound proofing on the bulkhead, and see how the floor pan is made.

The picture I posted above suggests that the floor pan comes in two parts - not so =>

http://www.peachparts.com/shopforum/...1&d=1313586956

And I forgot to show another bit where the car has been cut and shut. This time on the rear bulkhead bit under the rear seat...

http://www.peachparts.com/shopforum/...1&d=1313587046

I've got the following parts on order

2 X end caps for the sills / rockers / longerons
2 X outer sills / rockers / longerons

1 X Internal cross member that sits under the front seat rails (this seems to be a dealer only bit)

These are expensive dealer sourced parts - I'm hoping that they will be worth the extra cash as they are visible...

1 X imitation floor made by Klokkerholm who seem to be the only manufacturer who do the whole floor (part number 5 in the first parts picture I posted above) instead of little front and back sections.

Adjustable axle stands
 

I'm going to need some adjustable axle stands so I can get the car as level as possible before I drill out the spot welds. I plan on getting something like this:-

http://www.caravanaxlestands.co.uk/i...primary-st.JPG

It uses a screw thread to allow for height adjustment

http://www.caravanaxlestands.co.uk/products_1.html

Anyone out there with a better idea?

There is no way I'm taking the spot welds out with the car on wheels.

The motor is already out as is the transmission and from the pictures above you can see that the interior is out too. Doors are off, front and back windshields are also out. I'd like to cross brace those holes.

Anyone with any ideas? I was thinking turn buckles attached to mole grips...

I'll probably cross brace the sunroof hole too as the sunroof is also (you guessed it!) out.

I'm going to have to work out a way of holding up the central door pillar - I plan to attach something to the hinges - so that that doesn't sag and pull the roof out of shape. But I will also need some pretty good access to the sill area...


...any ideas?

Oh dear part number 5 isn't available any more...

http://www.peachparts.com/shopforum/...1&d=1313574878

Why w123 underseal is hated so much
 

Here's the result of cocooning your underside in rubber!

http://www.peachparts.com/shopforum/...1&d=1313861223

http://www.peachparts.com/shopforum/...1&d=1313861273

http://www.peachparts.com/shopforum/...1&d=1313861309

http://www.peachparts.com/shopforum/...1&d=1313861343

Update:-

I'm stripping off as much of the under seal junk as possible so I can drill out the spot welds and dismantle the structure.

The caravan type adjustable axle stands should be here on Monday - then I'll be taking off the differential and the rear subframe again - happy days!

Working out how it was made
 

I've been looking at the structure of how it has been put together.

I'm not entirely sure if the roof together with the middle door pillars were fitted together first, but the middle door pillar and the outer sill definitely were spot welded together first before the spot welds between the lower edge of the outer sill and the floor pan were fixed.

http://www.peachparts.com/shopforum/...1&d=1313929969

http://www.peachparts.com/shopforum/...1&d=1313929969

The spot welds on the floor pan and outer sill joint were never treated to a coat of seal sealer. Which means that if the inside of the car gets wet then the floor pan not only rusts through in one place but the water travels along the whole joint as shown in this picture I posted previously

http://www.peachparts.com/shopforum/...1&d=1313861273

I consider this to be a design fault!

A 30 year old car, 160,000 KM's, probably one of the wettest countries in Europe and some rust is a "design flaw"?:rolleyes:

C'mon over to the Detroit, Michigan area and see new cars rust in 2-3 years with 30,00 KM's on them.:D

I get what you mean. And in a way - yeah sure right... but that is comparing with the lowest common denominator...

How long has mankind been doing this sort of thing? Building any structure whether it is on wheels or not that is out in the elements involves water management - most of the rain goes one way - if you can't get that right then I say you need to go to the back of the line => 0/10 see me after school!

Ouch!:eek::D

Err sorry Mike I'm assuming that a Mercedes is a superior vehicle... well it is certainly emptying my wallet like a superior vehicle... so I guess it is one!