after two cups of coffee, I finally get what it is that I am trying to figure out. The later model reservoir has two chambers, thus two fluid level switches instead of one, And that is easy to remedy with a little splicing. What I don't know is if Mercedes did away with a brake pressure differential switch in the later cars, or if they just moved it off of the master cylinder to some other location.

Sometimes it stinks having an early W123 loaded with weird parts that didn't see use past 75-78. I guess I will be breaking out the FSM disc to see if I can compare and contrast the electrical nonsense enough to effect a retrofit.

I will say this, though. I thought I had a caliper hanging up a little as hard braking used to lead to a bit of a pull to the left. with the replacement master cylinder, that pull is gone, and the brakes are much more sensitive overall. I guess that means I have been driving the car off and on for two years with a bad master cylinder. I had no idea that a master cylinder could cling to life for that long.

__________________
- K.C.Adams

'77 300D Euro Delivery
OM617 turbo / 4-speed swap
404 Milanbraun Metallic / 134 Dattel MB-Tex

Current status:
* Undergoing body work

My '77 300D progress thread