<VV> Dual Master comment (Disk Brake)

[Charles Morgan]

Doc, when most people talk about a "dual master cylinder" they're talking 
about a MC with dual pistons operating in a common bore.  Since the pistons 
are the same diameter, equal pressures are produced in each circuit and 
there is no front/rear adjustment.  Brake drum/rotor size is just one of 
the many factors that affect front/rear brake distribution.  Other factors 
include tire size, wheel cylinder/caliper piston size, and tire/brake pad 
friction characteristics.  Optimum braking occurs when both front and rear 
wheels are just about to lockup.  However, if lockup occurs, it's 
preferable that the front wheels lockup first.  Proportioning valves are 
designed to keep the rear wheels from locking at high rates of 
deceleration, but finding one properly sized for Corvairs is 
difficult.  When changing any component that affects braking, the effect on 
front/rear distribution should be taken into account.

Charlie Morgan
Beaver State Corvairs

At 02:11 PM 5/10/04, Doc wrote:
>I am not an expert but isn't there a balance adjustment for front to rear on
>dual master cylinders?  I suspect that the front to rear braking requirements
>are addressed on stock single MC Corvairs by the different sizes of the brake
>shoes and drums.  I would imagine that a disk brake setup would throw this 
>off
>significantly to the point that a balance adjustment would be required.  You
>don't want one set of wheels locking up in an emergency braking episode.  Is
>this correct?  If so, I would guess that you don't want to use a disk brake
>setup with a single MC.