[TR] Clutch master cylinder.

[Dave1massey at cs.com]

In a message dated 7/15/2011 9:52:39 AM Central Daylight Time, 
tswhitez123 at hotmail.com writes: 
> When I installed my hydraulic throw out bearing I used a 5/8" bore short
> stroke master cylinder recommended by the manufacturer.  After using my TR 
> as
> a grocery getter the last few months I find the clutch pedal is too heavy 
> for
> comfortable around town driving.
> 
> If I remember correctly the stock TR clutch master cylinder is a 3/4" 
> bore.
> If I switch back to the stock master cylinder will the increased bore size
> make the clutch pedal easier to depress?
> 


Regrettably, no.  It will prove counterproductive.  The amount of force 
applied to a piston is the pressure times the cross sectional area of the 
piston.  Assuming you are not changing the slave cylinder you will need the same 
PSI to operate the clutch.  Going from a 5/8 inch diameter master cylinder 
to a 3/4 inch one will only make the required force greater.

For example, if 200 PSI is required to operate the clutch the force needed 
with a 5/8 master will be 61 Lbs. The force required with a 3/4 master will 
be 88 Lbs. (PIx(r^2)xPSI).

If you can find a larger slave cylinder you will reduce the PSI required 
and thereby reduce the pedal force needed.  But the trade off is a longer 
stroke will be needed.  If you are already engage the clutch near the floor that 
may not work, either.

Dave