Pedal Assembly Restoration
I didn't think much about the pedal assembly, as the car's previous owner supposedly had rebuilt it. But like many things Porsche, a "rebuilt part" is often not what I would consider a real rebuild. The assembly had new bronze bushings, but that's about it. There was a lot of rust in and around the assembly; I'm surprised I didn't notice it in earlier projects. Eventually, however, a little water leaked in, caused some additional rust, and the brake pedal froze up. Thus, the restoration.
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The pedal assembly is harder to remove than it needs to be. It is attached to the body by two sets of nuts; the rearward ones are accessible from the passenger compartment and are easy to remove. The front ones, however, double as a mounting point for the brake master cylinder and must be accessed from under the car, after the protective panel is removed. The clutch cable, accelerator pedal rod, and the accelerator rod in the tunnel also must be disconnected. The assembly can then be removed.
The pedal assembly has a frame that supports a central shaft, which in turn supports the pedals. The clutch shaft is inside the central shaft and the brake pedal assembly is mounted on its outside. Both ride on sintered bronze ("Oilite") bushings. Finally, riding on another set of bronze bushings, is the pivot for the accelerator. Two return springs are used, one for the clutch pedal and one for the brake pedal.
Wearout of the bronze bushings is the usual reason for rebuilding the assembly, but, in this case, rust from water infiltration was the reason. The bushings were still fine.
Close-ups of the assembly show how it goes together. The left picture below shows the accelerator pivot and the connecting point for the clutch cable; the right picture shows the clutch pedal attachment.
The accelerator pivot comes off easily, along with its bushings. The clutch shaft is removed from the pedal by driving out the roll pin visible in one of the previous pictures; then the spring is loose and the shaft simply slides out.
The brake-return spring should be released at this point. It looks harder to remove than it is.
The central shaft is attached to a bracket on the left side of the assembly. It should come off easily when the nut is removed, and the central shaft should then slide out. But because of the rust, mine had to be encouraged a little. When the shaft is out, so is the brake pedal.
Finally, here are all the parts. The bushings are in the jar of oil in the top left part of the picture; I soaked the bushings in oil for the couple of days it took me to restore the pedal assembly's pieces. New bushings must be oil-soaked, but it's not a bad idea to repeat the soaking whenever the assembly is taken apart.
I cleaned and derusted the parts in phosphoric acid. Some paint and a little rust were left, which I tried to remove with a wire brush. The best way to derust the parts would be to use an abrasive blaster, but unfortunately I don't have one. I checked the clutch shaft carefully for cracks, which sometimes form around the hole for the split pin.
The phosphoric acid leaves the steel surfaces coated with iron phosphate, which is actually a good surface for paint. Because I planned to replate them, and the iron phosphate would interfere, the clutch shaft, central shaft, and brake actuating rod were sanded.
I masked, primed, and painted the parts of the assembly with Rustoleum products. I masked the area inside the cylinders where the bushings fit on the brake pedal and central shaft, then sprayed in some paint. I doubt that coverage was perfect, but I think it still should inhibit further rusting.
Once cleaned, the frame was painted with Eastwood Rust Encapsulator. It is not pretty, but it should be well protected from further rust.
Here are the pieces, all painted.
I nickel-plated the clutch and central shafts, the brake actuating rod, and the threads on the rod for the clutch pedal. Zinc plating (galvanizing) was an option, but I expected nickel to have better wear characteristics for the surfaces that mate to the bushings. To remove any remaining iron phosphate, before plating the parts, I gave them a brief "pickle" in dilute hydrochloric acid.
In the picture below, the pieces are finished, plated and painted. There is a little pitting on the central shaft, but not enough to prevent its use. New clutch shafts are available (about $90 each), and Stoddard offers new central shafts ($136), which appear either to be unplated or hot-dip zinc galvanized. Traditionally, the accelerator pivot is zinc-plated and chromated, but I think that paint is simpler and just as good.
Reassembly, as the shop manuals say, is the reverse of disassembly. The picture below shows the clutch pedal installed, but I found it easier to mount the assembly in the car without it in place.
Reinstalling the pedal assembly was largely straightforward. In order to get enough slack in the clutch cable, I had to disconnect it at the engine. I found the reinstallation easier without the clutch pedal attached; it is easy to reinstall after the assembly is in place.
Finished, it looks good and works smoothly.
