Dual master cylinders use a floating piston which is pressure balanced
(do the free body diagram)
There is no increase in force required (other than minor additional
spring forces and seal drag) to actuate a dual master cylinder.
On Fri, 1 Feb 2002 23:47:30 -0700 "Louis & Laila" <bwana@c2i2.com>
writes:
> Just so you will know, adding a dual master cylinder will INCREASE
> the
> pressure at the brake pedal, required to apply the brakes. Here is a
> breakdown of exaclty what happens when we make adjustments to the
> brakes.
> 1. Increasing the bore of the master cylinder requires MORE leg work
> to
> acctuate the system. Increaseing the bore diameter of the slave
> cylinder
> lessons the pressure.
> 2. If you add a dual master, you are "doubling" the force. It is not
> a true
> case of doubling since the shaft decreases the face of the piston,
> and some
> of the masters have a built in proportioner which I have just
> recently
> discovered and ruined my plans for a Honda unit.
> 3. Larger bores move more fluid, therefore the stroke is shorter to
> get full
> brake pressure. Conversely, the smaller bores requires more stroke.
> If you
> use a smaller bore master, then your stroke would be the same as the
> larger
> single.
> 4. Lengthening the brake pedal will decrease the amount of force
> required to
> depress the pedal, In a Sunbeam, this isn't really possible, other
> than a
> half inch to an inch, depending n you feet size.
> 5. Moving the master closer to the pivot of the foot pedal decreases
> force
> required at the pedal, though this is not really possible if
> retaining the
> original parts.
> 6. Decreaseing tire diameter requires less force on the pedal, since
> the
> tires act as levers. It is the same thing as getting a pipe and
> putting it
> over a wrench to appply more torque on a bolt. It follows that
> increaseing
> tire diameter requires more force at the pedal.
> 7. Increaseing the diameter of the disks has the opposite effect,
> for the
> same reasons. The series I & II had small discs, 9.5 inches I think.
> Series
> 3 &IV had 10.0 nches, and series V had 10.3 inch discs. The larger
> diameter
> allows more torque to be applied to the wheels, therefore reducing
> the
> amount of pressure required at the pedal.
>
> With all that said, once manufacturers started using power assist,
> they
> started using dual systems so they could move more fluid, decreasing
> stroke
> of pedal, and increasing safety and comfort. Bore size is just not
> an issue
> for them to consider when designing a car because they have more
> room for
> error. With that said, the real question is what does that mean to a
> Sunbeam
> owner who wants the best possible brakeing system without a servo
> assist,
> while still maintaining originality?
>
> If you say that originalty can be fudged to using genuine Rootes
> parts, but
> actual year of manufacture is not an issue, here is the system:
>
> 1. Use a Series V front axle with larger discs.
> 2. Use the rear slave cylinders from a series I or II since their
> bore is
> larger.
> 3. Use a series I or II master. If safety is a concern, then use the
> series
> 3, IV, V master, but it will require more force. Using the series I
> or II
> rear slaves makes a good difference on its own.
> 4. Find a very small diameter dual master cylinder. There are not
> many that
> can be made to work. The VW is 17mm and can be made to work. There
> are just
> not to many others that can work. Lou
> ----- Original Message -----
> From: <Fritzwich117@cs.com>
> To: <bmounce@bellatlantic.net>; <alpines@autox.team.net>
> Sent: Sunday, February 03, 2002 7:36 AM
> Subject: Re: 3 questions
>
>
> > Bill...
> > The tanks are not difficult to remove. You could pull them along
> with all
> > the connection pipes and hardware for clean up, inspection and
> replacement.
> > The tanks could be taken to a radiator fit-it shop where they
> could be
> > "bioled" out and sealed. Then you could paint the exterior and
> reinstall
> > them.
> > We are still looking for a dual-bore brake master to adapt to my
> Series 5,
> > thinking that it will have a similar effect as a booster.
> > Talk to you soon,
> > ...Rich
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