Which Brake Master Cylinder?

[John S]

I need to replace the brake master cylinder on my '74 3.0 csi #4340036. It looks like I have two options to choose from:

34-31-1-120-479 (22.2 mm bore)

OR

34-31-1-120-832 (23.81 mm bore)

Is there any advantage to using one over the other? Are there any other options available?

Thanks,
John

 

[61porsche]

The former

or 22+mm is the latest version shown in the bluebook technical section.

Presumably, when the rear caliper pistons increased in size. But that's my best guess.

 

[John S]

23.81mm it is

I now realize that my question was a silly one. I was looking more carefully at my current brake master cylinder and there's a 23 clearly cast into the side of it. So, I'll go with the 23.81mm model. Mesa Performance steered me in the right direction.

34-31-1-120-832 (23.81 mm bore)

Thanks,
John