Rear Trailing Arm

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Rusty trailing arm = death wish

How to get the 280CE approved for the road? Change the rear trailing arm since it is rusted. Not allowed to weld this critical part. So it is obviously number one priority. One can say that Christmas this year came early. I have been searching for a good used one as this for a long time and this particular one I got quite cheap compared to a new one! It even came with a good wheel bearing and the handbrake shoes with the cable. New trailing arms for the W123 from a Mercedes dealer can cost up to 3000$ and I was not up for using this amount of money when there are alternatives.

Rusted rear trailing arm
Rusted old rear trailing arm due to road salt

It weird that this one rusted and the other one is completely fine, also it rusted on a smooth curve and not on a edge.

New trailing arm for W123
New trailing arm

Like new this one! I painted it and changed the rubber bushings as well, however needed a workshop to put the new bushings on. I don’t have a hydraulic press in my basic workshop.

Welding the Front Quarter Fenders

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Why get new ones when you can use 30hours trying to fix the old ones?!?!

I wanted to weld the front fenders rather than replacing them, even though I have two replacement fenders. Why is that?

  • Welding practice
  • Stubborned idiot like myself
  • Keeping the car more original
  • No need for respraying fenders since the other ones are blue
  • Replacement fenders have hole for antenna, and my antenna is in the trunk

So I got on with that, but I might replace them in the future if I’m not satisfied with the result.

rusted front fender
Front fender rusted in the seam, like on every w123. The other one is the same..

So on to the cutting, and trying to recreate the corner, was quite painfully difficult actually.

comparing the fenders
Comparing a rust free fender with the old for reference

So then I welded and this was the result:

Front fender welded
After the welding…

It looks better than it was, turned out when i fit it on the car I needed to do a massive job with the filler, but after the result was quite nice. Good enough for now, might change the fenders in the future when doing a complete respray though, but then I will get completely new ones without old paint and stupid holes for antennas.

Welding water drains

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Water sports in pools within the coupé

I realized that the car have had a small repair on the lower section under the left side rear quarter window due to a parking ding or something in the past. How do i know that? The lower panel had no water drain holes! How is this possible to be so sloppy when fixing a repair? They must have known it would start rusting immediately when the water has nowhere to go every time it rains.

The outer car window seals are never completely rainproof since the windows are made to be lowered. Especially when the windows are lowered when they are wet they drag lots of water into the panels. This is fine since the water can escape through drains through the lower panel. However here there were no such thing like on the right side. Idiots… The result are massive amount of rust in this area, both on the inner canal panel and the outer body panel. Thankfully the welding was quite easy since it involved straight large panels. The big part was removing the panels in the interior and working in tight areas.

Lets get to work, start tearing those inner panels off, hopefully without damaging them and breaking clips.

beyond inner panel at beackseat in w123 coupe
Beyond the inner panel

Do you see that hole behind the seat belt puller? Obviously there was no hole before, no drains remember… But after removing the the rusted metal a huge hole was left, maybe a bit too much? To get access to the inside I had to remove even the window mechanism.

inside panels removed w123 coupe
All panels removed including window mechanism

The hole left was huge, all that lower panel had top be cut off and even the inner panel is rusted out and needed to be removed.

lower panel before welding
Lower panel before welding, huge hole

After cutting the inner panel and welding in a new one it looked like this. I got access through the other hole in channel to paint it, there is a large rubber plug one can open. Needed to recreate the corner there as well, a bit tricky, but very satisfied with the result.

Inside panel welded
Welded the inside panel and canal corner

What remained was to weld the outside panel, paint it, make drain holes and side trim fastener holes. Obviously paint it on the inside as wheel since all the water is going there from the window. Don’t want it to rust again.

lower side panel welded and painted
Outer side panel welded and painted, not that I made the picture before I drilled the drain holes and holes for the side trim.
lower panel finished
Finishing the lower panel, nmow with drain holes!

Now on to the wheel well, It had some rust holes spread out, and the worst part was at the point where the rubber end stop was (if the car bottoms out this will prevent the wheel hitting the upper part). I had to make a new bracket from scratch.

wheel well before welding
Was quite some rust in some areas and needed to remove the old metal and the suspension rubber end bracket

The metal bracket holding the rubber on the left side of the car was so rusted I threw it out. This is a part that is welded to the car and cannot be replaced. So I made a new one, I think my design is even better and more strongly built than the old one. The rubber can be replaced and I changed them too. In the picture under you can see the original bracket for the right side, and creation of a new bracket for the left side. They are mirrored since they are on different sides of the car.

rubber mounts for suspension w123
Making new rubber bracket from scratch.

I also made a new mount on the car out of 2mm steel plate which is super solid. The end result is under

wheel well after welding and painting
Wheel well after welding and painting, notice the rubber bracket is now mounted

Welding the rear quarter wheel arch

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Wheel arches mania

Started welding on the rear right wheel arch today, I hope to finish it tomorrow. It is hard to shape the metal to the smooth round shape of the wheel arch. Much easier if I had a replacement part, but these parts are rare and expensive since it’s a coupe and the rear section differs from the station wagon and sedan models. A part from an old wreck are hard to come by and would had the same rust problem in 99% of the cases. So better off doing it the hard way.

rusted right rear wheel arch
Rusted right rear wheel arch

Obviously I had to make a huge hole and remove the old crappy metal.

Welding metal into the wheel arch
Making some wheel arch

Cutting panels and shaping it is an art, and I’m not an artist, just a simple engineer.

Welding wheel arch
Welding first seam

Welding along the seam needs patience, the metal here is very thin.

Welding wheel arch
Welding continues

Also have to make the inner weld which I didn’t take pictures of.

Welding wheel arch
Adding lower part

This last part is a tricky one though. How will I be able to replicate the smooth shape?

Welding inner wheel arch
Welding the inner sides

Making the car water proof once again.

Wheel arch welded tight
Final polish before paint

Welding done! Think I have swung the hammer more times today than any other day in my life! An exact reshape of the arch was not possible from my side. Will need some filler to make up the last touches.

Wheel arch painted
Wheel arch painted but not done

Painting the metal and then applying filler.

Wheel arch finishing touches
Finishing the touches with some body filler to get the smooth shape, harder than I thought. Used a filler that is easy to sand.

I was quite pleased with the result, but is not as perfect as a replacement arch, will look into that in the future…maybe. So fast forward in time, here is the end result. Not bad for an amateur like myself!

Result after welding wheel arch
Wheel arch after painting

You can see the slight difference in color where the old and the new paint meet. I also think the shape of the arch is nice.