Clutch Master Cylinder Size

[Ferrino]

Trying to figure out which clutch master cylinder size to use for a Duratec conversion. I will be using the standard Ford slave cylinder. There appear to be two options: 0.625" and 0.7". What would be standard fitment by the factory on a Duratec car, please? My understanding is the smaller cylinder will give a longer throw for the same movement of the slave cylinder and it sounds like this would give more feel for the bite point? Thanks.

[John Vine]

I asked this very question of CC some years ago after my m/c failed.  They recommend the 5/8" (0.625") for a Duratec using the standard Ford slave, as the 0.7" risks over-extending the slave.  Apparently, the Sigma cars do use the 0.7" m/c.

JV

[Ferrino]

Thanks! How confusing! Surely if you fit a well adjusted clutch stop, you can avoid the over-extension problem in either case?

[7 wonders of the world]

0.7" of a Duratec is fine running the stock Ford Mondeo V6 CSC - however all CSC cars should run a positive clutch stop to prevent over extention - once  fitted your fine.

I run this set up and it gives a firmer but shorter pedal based on the nomal AP clutch set up.

[Ferrino]

Thanks all. I'm going to go with the 5/8" as I like to have more clutch control (and a lighter clutch) for road use: theoretically the smaller cylinder should give me that.