Clutch Master Cylinder Sizing

[Ralph Z.]

My clutch pedal on my vintage FF is pretty hard to comfortably push. I don't think there is anything really wrong with it but I would like to make it a bit easier to push.

If I want to require less force to depress the pedal do I move to a larger diameter master cylinder or a smaller diameter?

Yeah, I should know this, but...

Thanks in advance.

[mikey]

Smaller dia master will reduce pedal effort but you will need to depress further to achieve the same force at the calipers

[kea]

Common clutch master cylinder size on older F/Fords, was 3/4". This worked well with the standard OEM style clutch they were designed for.
With the racing clutch, moving down one size to .70" should solve your problem, without making the pedal stroke too long.

[Brian C in Az]

Smaller dia master will reduce pedal effort but you will need to depress further to achieve the same force at the calipers

x

[HayesCages]

Another possibility is checking the bobbin/release bearing diameter where it meets the clutch cover face. On our car I found that I could reduce the diameter over 1/2", reducing the force required to release the clutch, but taking a tad more travel at the pedal as well... We did have to make this part as the bearing is a set diameter.
Now it acts more like a normal clutch than the "on-off switch" feeling most racing clutches give.
May not work on all chassis but did for us.
Our M/C diameter is already .70".

[Ralph Z.]

Another possibility is checking the bobbin/release bearing diameter where it meets the clutch cover face. On our car I found that I could reduce the diameter over 1/2", reducing the force required to release the clutch, but taking a tad more travel at the pedal as well... We did have to make this part as the bearing is a set diameter.
Now it acts more like a normal clutch than the "on-off switch" feeling most racing clutches give.
May not work on all chassis but did for us.
Our M/C diameter is already .70".

Yes, we know that our release bearing diameter is quite large and that is the actual cause of the problem. A temporary and easier fix is to change the MC. The final solution is a new release bearing which means splitting the car. Good winter project.

[HayesCages]

Winter: That's when we did it