50th Anniversary Restoration challenge

Started by gurrier, 12 January 2022, 11:51 AM



I am recommencing the restoration process on a 1973 350SE first registered in Ireland on the 30th of May 1973 - chassis no. 008241.
I have owned the car since 2009 and began work on it then but am only now returning to the effort.
I am using the upcoming 50th Anniversary of the W116 launch as motivation to progress.
The first area that I want to pay attention to is the well-known rust issue in the bulkhead/firewall in the area behind the fuse box.
This has caused substantial rust in the drivers footwell.
My one is a RHD so the area I first want to work on is the area where the floor joins the inner/outer sills, the bottom of the bulkhead and the closing panel on the front of the sill.  Quite complex where several skins of metal intersect-partially at least.
As part of the area is totally gone, I must use means of establishing a datum.  I am using the shield for the gap between the front wheel well and the wing which presumably covered off a mud trap in the area and the closing panel for the front of the sill.
The attached is a mock-up of the two parts together.
[img https://www.dropbox.com/s/0tlduzxqdq2bq0z/wing.jpg?dl=1/img]

As I stated all the area is gone so I have little to go on.   I have a donor part but that to is significantly rusted in one critical area also.
The shield is attached to the structure by three screws.   One of the locations where the screws go through are highlighted in white.
I found the below online and through shown as being for a W124 to me they look like something that would fit mine to secure the shield.
[img https://www.dropbox.com/s/5ayzv6i2lcq05k1/sill.jpg?dl=1/img]

If I get the location of the shield and attached sill closing panel correct it will go some way to help in aligning the other panels which I will buy/make.
I am aware of the repair panels available for the front of the sill - luckily the adjacent jacking point proper is intact though the outer sill is not.
Any comments would be greatly appreciated.
1973 350SE



I will need to go back to the drawing board with regard to the linking of pictures.

Please bear with me
1973 350SE


Sounds like a great project.  It is a lot of work as you know. Have you removed the front fenders? If the sills are gone up front then that is needed to access everything.

I made up a bunch of jack points if you need some.

Can you post pictures of your starting point?
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550, '16 AMG GTS


This reminds me I still haven't shared some of my restoration pics with you!
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE


Here's a couple of shot that hopefully will help you. Note the first photo all the rust is covered up and reveals itself beneath the undercoating. This area has double and triple walls that create rust pockets.
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550, '16 AMG GTS


Thanks rumb,
Below is a view of the front driver's side of mine.

[img https://www.dropbox.com/s/s824a9jb7nlp93p/Sill%20-%20Copy.jpg?dl=1/img]

Your photos and viewing the below (which I found on German eBay-unfortunately
the vendor would not ship outside of Germany) have given me a good reference as
to how the structure is constructed here.

[img https://www.dropbox.com/s/pdbi00o46d0yt26/bh.jpeg?dl=0/img]

[img https://www.dropbox.com/s/tuvxpcdyf7p7uv6/bh2.jpeg?dl=0/img]
1973 350SE


Ireland is noted for its green countryside.  One of the main reasons for the lushness of our island countryside is the abundance of rain.
As we all know moisture and steel are not a good mix.  One of the main reasons that comparatively speaking very few older vehicles,
classic or vintage survive here.  Many vehicles in the scene here are imports from our near neighbours the UK. 
Mine is an Irish registered one with thankfully its original owner from 1973 still with us.

Unfortunately, the W116 week spot for rust progression-the front air plenum is very apparent here, viewed from below.

[img https://www.dropbox.com/s/1279x87d2yb0ghr/Plenum.jpg?dl=0/img]

On the way down it moves forward into the bulkhead/firewall surrounding the fuse box.

[img https://www.dropbox.com/s/c5htnpw1z815djg/fuse%20box.jpg?dl=0/img]

Moisture is trapped in the material behind the sound deadening and this leads to a trail of rust moving downwards.

[img https://www.dropbox.com/s/ech1hyopd5dk0qy/footwell.jpg?dl=0/img]

This is where I baulked the last time.

Daunting but doable?
1973 350SE


Wow that is some brutal rust  :o  worst I've seen in that area by the gas pedal.
1977 450 SEL 6.9 - Astralsilber


What's with the Germany vendors not wanting to ship anything?  Most I have asked have said yes despite  their advert saying no.

You certainly have a big job ahead, but broken down to steps is very doable.

Would finding a parts car be a good way to find a better starting point for the entire firewall?
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550, '16 AMG GTS


Wait until I show the area around the bonnet release cable on the passenger side
at a later stage. !!!

The actual chassis, the 16 gauge and it appears 14 gauge in places, appears sound.

For donor I have the 'skeleton' of a burnt example, unfortunately rusted in most of the same places.

The fuse box area is better so I will use that

[img https://www.dropbox.com/s/fjq6pge7z8i4tjj/donor.JPG?dl=0/img]

Big problem here is no donors / body parts available- as suggested on another thread
probably only about 10 known roadworthy examples in the country.

Even offered the vendor X2 what he was looking for the repair panels
but declined.
1973 350SE


Hello all,

The main area of concern that I have is where the anti roll bar
secures onto the chassis.  There is what is described as a torsion
bearing in the area.

[img https://www.dropbox.com/s/h6u5hi0o8zfwiax/Torsion%20bearing.jpg?dl=0/img]

That bearing is present and attached in mine but perilously close to corrosion.

Is there anyone out there who has done work in this area and who could advise me as
to how to best handle repair.

Thanks for reading.
1973 350SE


Best to cut it out and weld in a new patch. That's a safety related feature. I wouldn't want to risk it detaching while on the road.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE


I have not had to deal with that particular spot, but the repairs take the same course.

First take pictures and make a drawing with reference points and critical dimensions. You need to dissect each damaged portion to see how MB put that area together - meaning is there double or triple wall sheet metal in that area.  Cut out an area that will extend into what looks like solid metal. You may have to peel each layer out, or if not possible then go ahead and cut the entire area out. Remove all rust and make up patch panels for each layer.  Use weldable primer between each layer. It's easy enough to make small panels with a dolly and hammer , vise, or small hand brake to bend larger pieces. I first make a pattern out of thick stock paper.  I find a pneumatic shear to be best to cut out panels to size and then fine tune with 2 or 3"sanding wheels - pneumatic driven.  Weld slowly to prevent warping!!!

If your torsion bearing bracket is still good after removing that is good, otherwise the one you show can be used. you will need to determine if plug and edge welding bracket back in is required to transfer forces.

Repeat the same process on the next rust area..........

https://forum.w116.org/test-drive/my-6-9-s/210/  pictures of rust removal on my Jeep recently.
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550, '16 AMG GTS


Many thanks for the input.

Attached is view of the passenger footwell.

[img https://www.dropbox.com/s/32ul1b4wc94ziui/Passenger%20Footwell.JPG?dl=0 /img]

Views on welding procedures are very much appreciated.  Seeing that there is a substantial area
involved in my firewall/bulkhead I am tending towards doing lap as opposed to butt joints.

I have a joggler tool so this may help in doing neat work.

Again thanks for interest shown.

1973 350SE


Hello all,

I am proceeding with repairs where I have manufactured panels available.

It can be a distinct disadvantage to be (ever so slightly) OCD by nature when you undertake such work.

My questions are:-

In this first photo does the front of the repair panel (top in photo) finish flush with the inside or outside of the wheel well.

[img https://www.dropbox.com/s/mcsuwfd9xou1tk0/Rear%20Left%20Passenger%20boot%20floor%20Inside.jpg?dl=0  /img]

In the second is the side downward lip of the repair panel welded in spots or is it welded continiously
to the structure beside the spare wheel compartment.

[img https://www.dropbox.com/s/od9fzbxr9itxma2/Rear%20Passenger%20Boot%20Floor%20Side.jpg?dl=0 /img]

And lastly is the repair panel supposed to finish flush with the lip (partly gone in mine) on the bottom of the panel which comes down from the
bumber.  There is a very small protrusion on the quarter panel repair panel which can just be seen (rust colour -surface!) which
looks like it was designed to line up with the repair panel.

[img https://www.dropbox.com/s/urovv5f19sozv0m/Rear%20Passenger%20side%20Boot%20Floor%20outside.jpg?dl=0 /img]

If this level of detail required is annoying please forgive, as I said (ever so slightly) OCD!.

Thanks in anticipation.

1973 350SE