heavy clutch pedal

[smithy]

hi all, hoping someone can shed some light on this for me.
i have a supra 5 speed in the FC fitted with a heavy duty clutch, problem is the pedal is super heavy to depress, i am going end up with a left leg the size of a tree stump if i cant change it
is there anyway to achieve a lighter feeling pedal operation without modifying / changing to much, do i need to change the clutch master or slave cylinder or both? eventually i want the wife to be able to drive the car and i want to be able to drive the car home after a painful day playing soccer, my knees are shot !!

cheers heaps

dean

[Glenn 'Stinky' Stankevicius]

Finally back eh? (pun intended)
I have heard of remote boosters being used to help with the clutch effort, the hard part will be finding one though.
Apart from messing with master/slave sizes which I don't think would achieve much, have you looked at the clutch fork pivot/slave location, can this be changed for better leverage?
If you do find a solution, let us all know especially me as I will be fitting a 202/Supra to the FC Wagon.

[smithy]

Finally back eh? (pun intended)

cheers stinky, back is starting to come good, returning to work tomorrow on light duties and finally going for the MRI and specialist on Tuesday...but it is still giving me the sh**s. cant do any bloody work on the car.

re the clutch, i have heard somewhere that the pedal pressure ( amount of effort needed to push it in) can be changed by using a different size master / slave i cant remember which one
i'll keep looking around.
i have sent you a pm too.

cheers
deano

[mcl1959]

Ok, there are a few things that affect pedal effort. Please note that the following dimensions are estimates only and should not be employed without a more thorough analysis of your clutch system.

The clutch - take out the heavy duty one and install a standard unit.
The slave cylinder - decrease the bore of the slave by sleeving down and installing the piston and cup from a smaller slave cylinder. Decrease by about 1.5 - 2 mm
The master cylinder - increase the size of the master - this will be more difficult because another master will have to be adapted on. You could go from 1 inch to 1 and 1/16 inch.
Change the pedal ratio - move the master cylinder up the firewall about 15 mm. Clutch pedal travel will be reduced using this fix so a stop may need to be included to avoid pushing the piston too far into the master cylinder.
Change the clutch ratio - move the clutch cylinder away from the pivot point about 5 mm - this one is not really recommended since the stroke of the slave would need to be increased as well.
Add a booster such as a VH 44, have never done this before so may be a bit hit and miss as to how much sensitivity is taken away from the "feel" of the clutch. Trucks and buses use clutch boosters regularly.

Some of these are easier to do than others and the sizes / dimensions stated are estimates only. I would need to know your pedal load and master / slave diameters as well as pedal ratios and the desired load you want to achieve in order to work out more accurate dimensions.

Hope this gives you some sort of guide on the rough proportions of what would make some difference

Ken

[smithy]

thanks ken, its food for thought. might pop into a clutch specialist tomorrow and pester him 
dean

[oldjohnno]

Ken,
To reduce the pedal effort wouldn't you want to use a bigger slave cylinder, and/or a smaller master?
My take on it is that if the clutch doesn't start to engage until the pedal is at least halfway up you can afford to trade some of the excess clutch travel for a reduced effort. And you can do this by changing the leverage ratio at the pedal or throwout fork, or by changing the cylinder(s). If however the clutch engages when the pedal is not far from the floor there is nothing you can do short of putting in a lighter pressure plate. Or taking steroids.

[mcl1959]

Yes you're right - I shouldn't write stuff when I'm tired and not thinking straight. Smaller master cylinder, bigger slave cylinder.

Ken