1978 Master Cylinder Upgrades?

[Old ITW]

I am in the process of rebuilding a 1978 911 and the master cylinder needs to be replaced. The original stock master cylinder part number is 911 355 011 12. I'm interested to know if others have tried upgraded, larger piston, master cylinders. I read somewhere that a Mercedes Benz master cylinder has been tried. Are modifications needed or do the upgrades bolt on as is?

[IROC]

Increasing the master cylinder piston size without increasing the amount of piston area in the calipers (so...installing calipers with more/larger pistons) won't result in any 'better' braking performance. It will just result in less pedal travel and more pedal pressure.

Is that what you are looking more? More pedal pressure?

[Bill Verburg]

Originally Posted by Old ITW

I am in the process of rebuilding a 1978 911 and the master cylinder needs to be replaced. The original stock master cylinder part number is 911 355 011 12. I'm interested to know if others have tried upgraded, larger piston, master cylinders. I read somewhere that a Mercedes Benz master cylinder has been tried. Are modifications needed or do the upgrades bolt on as is?

There is a 23.8mm ATE m/c that was used in some Mercedez trucks but it isn't compatible w/ the "78 SC brake setup.

You could use a ''78-89 930 23.8mm m/c, the travel is reduced, and the leg effort is increased commensurately, some track guys do use this setup, even un-boosted,

The benefit is exquisite control in threshold braking

Most would find this setup overly taxing in normal street use.

[Old ITW]

IROC and Bill, thank you both I appreciate your comments. I would prefer to eliminate the booster and more pedal pressure is not an issue for me.

Additionally I have access to 1990 C2 brakes, but have not looked at potential issues for putting them on the "78.