Dual Master cylinder Size ?

[osdmike]

Hi!

I have Wilwood 340-1287 Forward Swing Mount Dual Master Cylinder Brake Pedal with Balance Bar.

Pedal Ratio is 7:1

http://www.wilwood.com/Products/005-PedalAssemblies/002-FSMP/fsmdmcbp/index.asp

I contacted Wilwood about MC size,and they recommended 7/8"
bore in front and 1" bore in rear.
http://www.wilwood.com/Products/006-MasterCylinders/003-HVAMC/index.asp

Calipers are Forged Billet Dynalite 4 piston 1.75" , both front and rear .

Usually You would go 1.38" in the rear , but according to Wilwood there shouldn´t be a promblem when using the bias bar.


Front discs are 10.75" / .81" .
Rear discs are 12.19" / .81" .

Brake lines are 3/16 all the way , with Russel Braided Stainless Steel Hose (DOT) connected to the front calipers.

The problem is ,that I have to press brake pedal very hard , to make the car stop.
To lock up the front wheels, I have to press really hard.

I noticed that Wilwood also have a 3/4" master cylinder available.
Would 7/8" in the rear , and 3/4" in front help ?

What am I missing here ?

Any suggestions ?:dunno:

"Osdmike"

[chicane67]

A 3/4 front 7/8 rear would reduce the amount of pedal effort required... but at the risk of making it too sensitive... which I dont think you will have an issue with, considering your current issue with the pedal effort as it sits... espically with the noted 7:1.

This is a pressure to volume issue that is for sure. If you have the means... I would swap the masters for the smaller pair. But then again... with running the same caliper both front and rear... I might even consider using the same size front and rear. The balance bar will give you enough bais adjustment to do just that.

[osdmike]

Hi!
Thanks for the info.
I have been driving the car for a while now, and I´m getting used to the brakes the more I drive it.
They´re not so bad after all.
I still have some adjustments to do ,until I learn how the bias bar works.

"Osdmike"

[dannyho]

here's a spreadsheet i found and posted a while ago. It's made for using a dual master cylinder setup. I've been usign it to figure out what I'm going to do. It does a lot of things in metric, except for bore sizes, but I added some things to it to make it a little easier to understand.
https://www.pro-touring.com/forum/showthread.php?p=190896

[osdmike]

OK !

Thanks.

"Osdmike" :cool: