Ok, as a newbie to the wonders of the hydraulic clutch system is there any rule of thumb as to the bore size ratio for master to slave?? i've got a 3/4 bore master and was wondering if anyone with more knowledge than i posses could point me to the size of slave i need to run?
On my '46 using a stock Chevy throwout arm I have a 7/8" Lucas/Girling slave and had to up the master cylinder to a 1" bore - a 7/8" might work, but I ony wanted to buy one so went from the 3/4" master I had that did not have enough fluid movement right up to the 1". Increased the pedal effort quite a bit, but at least I can release the clutch now.
Don't under estimate the importance of bleeding those systems. Sometimes it seems as though there is not enough volume due to improper bore size...but often it is because the bleeding is not complete. I've found that many times the slave cylinder needs to be "stroked" during the bleeding process in order to get all the air out and a complete stroke of the slave cylinder for proper operation.
I used a master cylinder and slave cylinder for a '70s Ford Courier/Mazda pickup, 5/8" bore on both, 307 Chevy and T-5 5 speed. Works fine. If the MC bore is bigger than the SC bore, the piston in the SC will travel further than the piston in the MC. If the SC bore is bigger than the MC bore, the piston in the SC will travel a lesser distance than the one in the MC. SC and MC bores equal size, the SC piston will travel the same distace as the master cylinder piston.
equal bores ***umes that your throwout arm is correct for the hydralics involved. I started with equal bores and on my ex-mechanical Ford clutch and found that I could make it work, but it was fussy. And it was a race car that was appart a lot. And I got tired of fussing with it. So I got Tilltons largest master cylinder and mad a pedal stop to keep from going over center. Now I love it.
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