While my 280SL is basically totally disassembled and now out for paint, as one of a thousand items that need reassembly I decided to install the clutch master cylinder in the pedal assembly. I researched our site and couldn't find guidance so I was on my own. Since the pedal assembly is out of the car it was not a difficult job at all, however, there were some interesting surprises.
As with many items on our W113s it seems that there are some variations. My car is a July 1970 build so my situation may not apply to earlier versions. The first issue was that i ended up with the incorrect master cylinder. That matter was addressed in earlier postings. So I ordered the correct one and I'm ready to go.
I didn't take any photos (sorry) but the diagram below is pretty self explanatory.
Two M6 bolts attach the master cylinder "package" in place and once out the "package" was easily removed from the pedal. The MC itself is surrounded by an alloy housing (#55 in the diagram) so you have to remove the MC from the alloy housing. During this process I also ordered a Knipex snap ring plyers. What a joy to work with. So you have to remove the snap ring (#60), then a washer (#59). Now you come to what looks like a rubber washer but in reality is the top of a rubber bushing (#58) that fits between the alloy housing and the MC. Even though the diagram only shows 2, there are actually two rubber bushings between the MC and alloy housing.
Freeing the MC from the alloy housing was the only tricky part. After 50 years of togtherness, the MC, rubber bushings and alloy housing did not want to separate. I ended up pressing an ice pick down between the MC and rubber bushing to create a little space for lube (I used WD 40). I pressed the ice pick in about 8 places around the MC each time spraying lube and working the ice pick a little from side to side.
After it set about 15 minutes I was amazed the that I could easily pull the MC out of the bushings by hand.
I cleaned up the inside of the bushings, lubed them good for the next guy, inserted the MC, installed the washer, then the snap ring. Reinstalled the alloy housing into the pedal assembly with the two M6 bolts. I also adjusted the length of the return spring to 40.5mm per the BBB. Again, this measurement may vary for earlier models. All told took 45 minutes to an hour.
I didn't have to unfasten the fluid lines and there may have been other issues that I didn't encounter since the pedal assembly was out of the car. If the pedal assembly were still in the car I'm sure the whole process would have been more difficult and time consuming.
