e9 brake upgrade/ smallest master cylinder bore?

[daicos35]

Hi gents, i have deleted my brake boosters, and am running standard brakes with a standard 22.2 mm master cylinder.... i need reduce the size of the master cylinder bore, and/ or increase the size of the brake pads /calipers / rotors to get the right pedal feel/resistance, as it is a very firm pedal, as you would expect...

A few questions...

1- There is a formula used to determine the correct master bore ratio, compared to brake system dimensions, does anyone know where I can get info on this formula?

2- does anyone have the standard E9 brake system dimensions that are needed to calculate the optimum bore size to run on the master, for a non booster system, using the above magic formula...

3- What is the smallest bore master cylinder that is a bolt on for the e9, and / or has anyone one ever re sleeved the standard master, for a custom machined smaller bore piston...

4- if i must upgrade the brake size also (owing to the required master bore being too small for practical purposes) , has anyone had experience with the wilwood kits, or are there BMW retro fits that bolt on (i have 16 inch alpinas on the car).


thanks all for you help...

 

[Ed G]

Some good stuff here if you haven't seen it already- http://www.e9coupe.com/forum/showthread.php?t=15489&highlight=Brake+pedal

Changing the pivot points of the pedal can have the same effect of increasing pressure, but all at the cost of increasing forces at the pivot points as well as reducing total flow. The end result would be the same as a smaller bore cylinder- less force, more travel required at the pedal.

 

[Mario L.]

We did something very similar with a Gruppe II replica race car that we built.
We converted the car to dual master cylinders with a balance bar between the two and retained the same basic caliper on the car and switched to 19 mm Tilton master cylinders.
I do want to note that we used a four piston caliper in front from the E28 M5 and 2002TII calipers in the rear.
Granted our brake rotors are a much lighter larger size but our tire sizes also substantially larger.... With this set up the car stops much better than it ever did with Wilwood forged ultralight calipers!!

The change from 22.5 to 19 mm is quite substantial. There are single master cylinders available in the aftermarket they can easily be adapted to your firewall.