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
|