Classic Mustangs List Archive
66 Master Cylinder Questions answered....
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This read-only message was archived from a public mail list.
Mail From: Wal Marshall (email redacted)
There has been a lot of discussion on this topic but to my mind one or two
points seem to have been missed.
As another who has suffered a sudden brake failure on a single MC car
(fortunately all that happened was that my wife drove right through our
garage door after coming in the driveway!!), I feel the following is worth
stressing.
Dual master cylinders have DUAL RESERVOIRS. This means that a (relatively)
slow loss of fluid for example over hrs or days, (the usual case) will leave
a single cylinder car brakeless, but a dual cylinder car will only loose
fluid from one or other circuit leaving the other still functioning.
Another point concerns junction blocks/proportioning valves/metering valves.
As I understand it there are several basic types and each has a different
role.
1. Simple junction block. Contains no internal components and simply
distributes fluid. Suitable only for all drum brake cars.
2. Metering Valve. A development of the junction block which contains a
spring loaded valve which in the event of a sudden total loss of pressure to
the front or rear brakes, moves and blocks off the fluid to the side that
can not sustain any fluid pressure. Preserves some braking action in the
event that there is a sudden loss of pressure eg a ruptured hose. But if all
the fluid is gone (i.e. a slow leak) with a single M/C you are still in
trouble!
3. Proportioning valve. Further development of the metering valve, and
required by disc/drum set-ups for the reasons noted by Chris in a recent
post. i.e. the need to get the rear drums into contact before the front
discs are activated. Front and rear circuits are retained fully independent
within the valve so that a slow loss of fluid on either circuit doesn't
drain both M/C reservoirs. I understand this is achieved by applying M/C
pressure initially only to the rear cylinders, with the front circuit
blocked until the rear reaches a predetermined pressure. At this point a
sliding valve then moves against a spring unblocking the front circuit
allowing fluid to flow through to the front discs. This is the set up that
I have on my 70..
Of note also is that the actual pressure applied to the brakes is a function
of the bore size of the master cylinder, vs. the bore size of the wheel
cylinders. These need to be carefully balanced to ensure sensible foot
pressures and correct front to rear brake balance. Care needs to be taken
when swapping items from model to model, that the final result is properly
balanced..i.e. cylinder sizes are correct at both ends of each circuit.
Hope that's helpful
Wal Marshall
----- Original Message -----
From: Chris Stephens <(email redacted)>
To: <(email redacted)>
Sent: Wednesday, February 23, 2000 6:06 AM
Subject: Re: [CM:20440] 66 Master Cylinder Questions answered....
> Billy,
> Your 66 has a single MC with all drums right? Well all the drums on
your
> car needs the same amount of volume and pressure at the same time to
> correctly activate at the same rate. Therefore you shouldn't need anything
> but a distribution block.
>
> The way I understand the drum/ disc metering is that because of the
> spring action and design of the rear brakes, the drum takes a little more
> fluid at first ( to overcome the action of the springs moving the shoes to
> the drum )and then less pressure ( because drum design causes it to get
> tighter on its own as the wheel turns) to operate. So you need a
Metering
> valve for the front disc that sort of holds off the pressure ( while the
> drums overcomes the springs) and a proportioning valve for the rear
> because the disc needs more pressure). Disc brakes take more pressure to
do
> the same thing as drums. What makes them better is that they cool off
faster
> and dont hold water in the enclosed assembly like drums do. If you have
> power this is no big deal but you can overcome some of this with a smaller
> bore, longer stroke MC like the Granada.
>
> In my 70 I did the Granada swap using the granada MC. The only thing I
> used was a summit proportioning valve going to the rear and simply a " T "
> for the front two. Now I can " feel" the front catch in before the rear
but
> its no big deal you need more braking in the front anyway. What I have
done
> to help is just to adjusted the proportioning valve so that the rear will
> not lock up first . I think if I find a metering valve for the front that
I
> would have more braking power but I haven't decided which to use yet.
>
> Oh, now to answer you question. You can just " move the rear line
from
> the metering valve to one of the m/c outputs? Then plug off the
> open fitting on the metering valve" Or go by NAPA and get a " T "
fitting.
> After this you still need a proportioning valve to keep the rear from
> locking up. The one I got is from summit racing
> summitracing.com/index.htm part # sum-g3905 for $39.50.
>
> Sorry this thing got a little long but I have done a lot of research
on
> brakes in the past year and figured Id pass the knowledge to the list.
Also
> I wanted to add that I am NOT a mechanic or expert on this sort of thing
> this is simply opinions based on my reading and asking my own questions on
> this and other ford lists. And I welcome comments to further or correct my
> knowledge.
>
>
> > Currently, my 66 has what I call a junction block that all the brake
lines
> > connect to. Maybe it's correct name is metering valve, but it appears
to
> > just connect all the lines together. There doesn't appear to be any
> > metering going on. There is one line that goes to the rear brakes, two
to
> > the front brakes, and one to the m/c. Why couldn't you just move the
rear
> > line from the metering valve to one of the m/c outputs? Then plug off
the
> > open fitting on the metering valve. This would give separate front and
> rear
> > systems. It might not look as 'factory' as some would prefer, but it
> should
> > function the same.
> >
> > Billy
>
>
>
>
> ------------------------------------------------------------------------
> All the list info you'll ever want: antler.moose.to/~server/cm
>
------------------------------------------------------------------------
All the list info you'll ever want: antler.moose.to/~server/cm
Mail From: Wal Marshall (email redacted)
There has been a lot of discussion on this topic but to my mind one or two
points seem to have been missed.
As another who has suffered a sudden brake failure on a single MC car
(fortunately all that happened was that my wife drove right through our
garage door after coming in the driveway!!), I feel the following is worth
stressing.
Dual master cylinders have DUAL RESERVOIRS. This means that a (relatively)
slow loss of fluid for example over hrs or days, (the usual case) will leave
a single cylinder car brakeless, but a dual cylinder car will only loose
fluid from one or other circuit leaving the other still functioning.
Another point concerns junction blocks/proportioning valves/metering valves.
As I understand it there are several basic types and each has a different
role.
1. Simple junction block. Contains no internal components and simply
distributes fluid. Suitable only for all drum brake cars.
2. Metering Valve. A development of the junction block which contains a
spring loaded valve which in the event of a sudden total loss of pressure to
the front or rear brakes, moves and blocks off the fluid to the side that
can not sustain any fluid pressure. Preserves some braking action in the
event that there is a sudden loss of pressure eg a ruptured hose. But if all
the fluid is gone (i.e. a slow leak) with a single M/C you are still in
trouble!
3. Proportioning valve. Further development of the metering valve, and
required by disc/drum set-ups for the reasons noted by Chris in a recent
post. i.e. the need to get the rear drums into contact before the front
discs are activated. Front and rear circuits are retained fully independent
within the valve so that a slow loss of fluid on either circuit doesn't
drain both M/C reservoirs. I understand this is achieved by applying M/C
pressure initially only to the rear cylinders, with the front circuit
blocked until the rear reaches a predetermined pressure. At this point a
sliding valve then moves against a spring unblocking the front circuit
allowing fluid to flow through to the front discs. This is the set up that
I have on my 70..
Of note also is that the actual pressure applied to the brakes is a function
of the bore size of the master cylinder, vs. the bore size of the wheel
cylinders. These need to be carefully balanced to ensure sensible foot
pressures and correct front to rear brake balance. Care needs to be taken
when swapping items from model to model, that the final result is properly
balanced..i.e. cylinder sizes are correct at both ends of each circuit.
Hope that's helpful
Wal Marshall
----- Original Message -----
From: Chris Stephens <(email redacted)>
To: <(email redacted)>
Sent: Wednesday, February 23, 2000 6:06 AM
Subject: Re: [CM:20440] 66 Master Cylinder Questions answered....
> Billy,
> Your 66 has a single MC with all drums right? Well all the drums on
your
> car needs the same amount of volume and pressure at the same time to
> correctly activate at the same rate. Therefore you shouldn't need anything
> but a distribution block.
>
> The way I understand the drum/ disc metering is that because of the
> spring action and design of the rear brakes, the drum takes a little more
> fluid at first ( to overcome the action of the springs moving the shoes to
> the drum )and then less pressure ( because drum design causes it to get
> tighter on its own as the wheel turns) to operate. So you need a
Metering
> valve for the front disc that sort of holds off the pressure ( while the
> drums overcomes the springs) and a proportioning valve for the rear
> because the disc needs more pressure). Disc brakes take more pressure to
do
> the same thing as drums. What makes them better is that they cool off
faster
> and dont hold water in the enclosed assembly like drums do. If you have
> power this is no big deal but you can overcome some of this with a smaller
> bore, longer stroke MC like the Granada.
>
> In my 70 I did the Granada swap using the granada MC. The only thing I
> used was a summit proportioning valve going to the rear and simply a " T "
> for the front two. Now I can " feel" the front catch in before the rear
but
> its no big deal you need more braking in the front anyway. What I have
done
> to help is just to adjusted the proportioning valve so that the rear will
> not lock up first . I think if I find a metering valve for the front that
I
> would have more braking power but I haven't decided which to use yet.
>
> Oh, now to answer you question. You can just " move the rear line
from
> the metering valve to one of the m/c outputs? Then plug off the
> open fitting on the metering valve" Or go by NAPA and get a " T "
fitting.
> After this you still need a proportioning valve to keep the rear from
> locking up. The one I got is from summit racing
> summitracing.com/index.htm part # sum-g3905 for $39.50.
>
> Sorry this thing got a little long but I have done a lot of research
on
> brakes in the past year and figured Id pass the knowledge to the list.
Also
> I wanted to add that I am NOT a mechanic or expert on this sort of thing
> this is simply opinions based on my reading and asking my own questions on
> this and other ford lists. And I welcome comments to further or correct my
> knowledge.
>
>
> > Currently, my 66 has what I call a junction block that all the brake
lines
> > connect to. Maybe it's correct name is metering valve, but it appears
to
> > just connect all the lines together. There doesn't appear to be any
> > metering going on. There is one line that goes to the rear brakes, two
to
> > the front brakes, and one to the m/c. Why couldn't you just move the
rear
> > line from the metering valve to one of the m/c outputs? Then plug off
the
> > open fitting on the metering valve. This would give separate front and
> rear
> > systems. It might not look as 'factory' as some would prefer, but it
> should
> > function the same.
> >
> > Billy
>
>
>
>
> ------------------------------------------------------------------------
> All the list info you'll ever want: antler.moose.to/~server/cm
>
------------------------------------------------------------------------
All the list info you'll ever want: antler.moose.to/~server/cm
|
., Online, USA
|
|
., Online, USA
|
This read-only message was archived from a public mail list.
Mail From: (email redacted) (email redacted)
Yes, basically it IS just a distribution block, but the name "metering" is just a name for that very same block..
Anyway, I just use what Ford used...It's easier.
Use any '67-70 Metering (distribution block) valve out of any '67-'70 Falcon or Mustang, a 69 Falcon Master cylinder (non-power), and fabricated your own front lines..
Why make it harder?
Why use anything else?? Ford did the work for you already..
Tony.
------------------------------------------------------------------------
All the list info you'll ever want: antler.moose.to/~server/cm
Mail From: (email redacted) (email redacted)
Yes, basically it IS just a distribution block, but the name "metering" is just a name for that very same block..
Anyway, I just use what Ford used...It's easier.
Use any '67-70 Metering (distribution block) valve out of any '67-'70 Falcon or Mustang, a 69 Falcon Master cylinder (non-power), and fabricated your own front lines..
Why make it harder?
Why use anything else?? Ford did the work for you already..
Tony.
------------------------------------------------------------------------
All the list info you'll ever want: antler.moose.to/~server/cm
|
., Online, USA
|
|
., Online, USA
|
|
., Online, USA
|
|
., Online, USA
|
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