Smaller Master Cylinder

[Guest whiz]

Hi Guys to make everything fit in my S7 engine bay it looks like I'm gonna have to replace my master clyinder with a smaller one than the cortina one I'm using . Does anyone know off any alternatives that are smaller but still have three outlets 1 for the rear & 2 for the front. I don't run a servo on the car.

 

Cheers Andy

[Guest Alan_builder]

Hi Guys to make everything fit in my S7 engine bay it looks like I'm gonna have to replace my master clyinder with a smaller one than the cortina one I'm using . Does anyone know off any alternatives that are smaller but still have three outlets 1 for the rear & 2 for the front. I don't run a servo on the car.

 

Cheers Andy

 

Having walked round a number of scrap yards looking for master cylinders I think you will have a hard job. There may be some on the small jap cars but you will have to re engineer the braking system. Don't forget you need to match cylinder boor size, volume / stroke length against those in the slave cylinders to get the mechanical advantage and brake pad movement.

 

So I think you want a shorter master cylinder? Your dual circuit one has 2 cylinders one in front of the other, so wanting to keep front and rear on individual circuits stops you selecting a shorter one with one cylinder.

 

Now if you said get rid of the dual circuits, it still wont help much! Your existing master cylinder will displace twice as much oil as a single cylinder of the same size so your cylinder will need to be twice as long, back to where you started, and your break pedal will move twice as far!

 

So you double the size of you master cylinder, problem fixed - No - The force on the pedal needs to be 4 times what it was? The radius is twice what it was and cross sectional area is radius squared so 2 squared is 4, so the cross sectional area is 4 times what it was and hence the pressure in the master cylinder for the same pedal pressure is 1/4 of what it was. So now you need to make the slave cylinders twice the size!

 

 

 

I guess you are doing a Zetec upgrade? The option used is to fit twin cylinders with a balance bar and fit them inside the foot well. You need to have the povit point on the pedal between the foot and the cylinder clevis pin so the cylinders are placed 180 degrees from your existing system.

[Guest AWhite]

Are you fitting with servo? You could get a push rod from Tiger and do away with the servo. I have this set up on mine and a number of others do too. The brake feel is firmer and more direct but you don't get much assistance. Would save quite a bit of space losing the servo from the equation?

 

Alternatively you can get remote servos for placing elsewhere.

 

Andy

[Guest whiz]

Thanks Alan, christ that was like a science lesson never did get that at school. yeah its a zetec conversion the bike carbs are going to foul the master cylinder. I'm not using a servo either.Will look at the inboard option .

 

Andy