Master Cylinder / Slave Cylinder Size

[blykins]

Will a 3/4" master cylinder be adequate enough to push a 7/8" slave cylinder? Or do they have to be the exact same size?

[KobraKarl]

Blykins,

It has a lot to do with your pedal leverage and lenth of stroke needed to disengage your clutch...most combos will work, but too large of a difference in favor of the master will give you a heavy pedal.......too large in favor of the slave will give you an easy pedal , but may not give you the stroke you need ...

KK

[blykins]

Is there an easy way of figuring this? The slave cylinder is a Wilwood with a 7/8" bore. They offer master cylinders with the same bore....probably should go with that right?

But what about brakes? This is the area where I really am gonna have trouble. I have no idea where to start on this...I have a bunch of questions.....

1. How big of a master cylinder do I need for each brake bias?
2. How do you know where to position the T/O bearing for a starting position back away from the pressure plate...and then how do you know how much stroke you need to completely disengage the clutch?

The tranny's in the car...just waiting on some parts...I have to fab my own mounting bracket for the slave cylinder...then all this tedious work starts.

If you any of you can lend some experience or expertise, I'm gonna need it.

[rdorman]

Generally you go with the same size master cylinder and slave. If you really want to figure it out you will need to know:
- throwout bearing to pressure plate gap as recommended
- distance that pressure plate 'fingers' need to be depressed
- measurements on the throw out bearing arm (from slave cylinder to bell house mount to throw out bearing center line) to determine how much throw out bearing travel you have for a given slave cylinder travel.

Call the manufacturer for specs or check their website.

From there you can see what you need. For instance, if for everyinch of travel of the slave cylinder you get half an inch of bearing movement and 1/4 of an inch is the total distance you need to move the throw out bearing then you will need a master cylinder that at MINIMUM will displace enough fluid to move the slave 1 inch. If you went with the minumum (I won't) then you will probably have a BUNCH of peddle travel.

Mine is one to one. I think most are. If you want a clutch that feels like a Toyota then go with a smaller master cylinder. If you want it to feel like a bulldozer, then a bigger one. Remember, the bigger the master cylinder the less peddle travel required and the greater the effort required.

As for the brakes, email me. I have a spread sheet that will get you in the right direction.

Rick

[blykins]

Rick, I looked on the website for info on my pressure plate (Hays Borg & Beck)...it doesn't really list anything about how far the T/O bearing has to move....it just suggests using a feeler gauge and setting the air gap between the flywheel and clutch disc. Have you ever done it this way? It stinks, because I'm using a scattershield....I'd have to drill a hole in the bellhousing to do it this way.....

[Roscoe]

Yes, there is a formula for determining mc size/slave size.

1) Pick up the phone
2) Dial Tilton Engineering at 805 688 2353 and ask for tech.
3) Give them the specs
4) Write down the answer.

Works every time
Roscoe

[Junket]

My experience On the slave slave you need 1-1 you are displacing equal parts fluid and you don't need a lever factor, you don't want to displace more on the slave (blow the O rings) on the mulit-disk they don't need to move as far as a single you can go under on the MC there. As far as the brake you you are not displacing the the full piston on the calipers just moving the puck a little that is where the lever factor comes in with the diameter of the MC. come in to play.
Ken