I'd noticed a few small bubbles in the paint on the lower rocker panel while I was doing an earlier repair on my (wife's) coupe. Never being smart enough to leave well enough alone I went poking about with a pick and discovered the dreaded rust.

Upon further investigation I found evidence of some slap-dash previous body repair. Not surprising on a 40+ year old car but aggravating just the same. Stripped the paint from the lower rocker and this is what I found.

#1 front section

W114 rocker panel repair-1.jpg

#2 middle

W114 rocker panel repair-2.jpg

#3 rear

W114 rocker panel repair-3.jpg

Aaaarrrggghhhh!

Well, nothing for it but repair. A little history on this car. It sat for a couple of years as a shell with no interior. I got it as a package deal, the wife loved the color, it has a sun roof and her '69 W114 was on its last legs. Engine, transmission, interior got transferred and she was happy.

In the previous body repair they must not have had the access or knowledge to replace the trim retainers so they used silicone to secure the lower trim strips. It obviously worked because I've had the car for 5 years and they never fell off. Of course the hidden danger waited a few years to arise.

Notice how the rot coincides with the line of trim holes and where the silicone was in contact along the trim strip? Silicone becomes acidic as it cures. This etches the metal and opens it up for rust https://showbox.tools/. Now, not only was the metal compromised but the silicone trapped between the trim and the metal became a "dam" which caused moisture to accumulate. Every time it rained or the car was washed the water collected into the space between the plastic strip and the actual chrome trim. DON'T USE SILICONE as an adhesive on sheet steel! I shudder every time I read about someone using it. This IS what happens!

Okay, okay, enough with the sermon. On with the show. I had to decide what to do. I could replace the entire rocker panel with a new/used section but that comes with its own problems. To remove the entire rocker the car should be supported in a jig because the rocker is a structural component in the W114. The body WILL sag when you remove the rocker. I could fab one up but then the car would be immobile sitting in my work shop. You know that 20 seconds after I cut the rocker out a situation would arise which would require the access to my work shop. Murphy's Law is a constant in my world.

So I'm left with two options. I could cut the bad stuff out, use fiberglass with mesh or replace with 18 gauge cold rolled sheet metal.

Because I wasn't sure of how much of the original metal was compromised I decided to cut the bad sections out and replace with sheet. This seemed to be the best option because it allowed me to do the repairs in stages and yet I could move the car if required.

#4 The first section cut out. You can see the metal is mostly sound and if they hadn't used the silicone this would have never happened.

W114 rocker panel repair-4.jpg

#5 Fitting the first panel. Thanks to "Stretch" for the tip of using magnets to get the panels aligned.

W114 rocker panel repair-5.jpg

You can see the body filler they used to the right of the fitted panel. Sigh, something else to fix.