Good explanation Paul. I know from experience that the free link between
the two pistons does not prevent them from working in tandem the way you
describe. I also know the 5 way connector is not a true proportioning valve
and only used the word as a descriptor, not knowing what it's actually
called. Ya gotta admit, everyone knew which part I meant.
Thanks.
Gerard
At 9:34 PM -0400 5/15/03, ptegler@cablespeed wrote:
>OK guys and gals.... it's simpler than you're all
>making it!
>The dual ckt master works like this.
>
>As you first apply pressure, the front ckt
>sees the peddle pressure you applied.
>Once the pressure is applied to the front ckt and the
>piston i nthe master cyl has passed, and closed off
>the intake hole from the reservoir...
>and as you continue to apply pressure...the pressure
>in the master cyl itself starts pressurizing the rear ckt.
>So the fronts will have pressure before the rears,
>and unless the front ckt pops a cork, the rears would
>never have more pressure than the fronts.
>
>There is no 'proportioning valve' in the ckt. The
>little do-hikky (what ever it is you all want to call it)
>activates the failure warning light when one ckt sees
>massive pressure when the other doesn't. If the
>fronts were working, and the rear leaking badly,
>no pressure is built up in the rear of the master cyl.
>So the differential valve sees high press. on one side and
>not the other, thus shuffling it off-center. And visa-versa
>rears to front. It is NOT designed to seal off the
>damaged ckt. But in many cases it seems to.
>Bleeding the brakes properly, requires you to re-center
>the shuttle IF it was knocked off-center. This Too, can
>happen if too 'robustly' trying to bleed your brakes.
>
>Yes...your brakes will work just fine without the differential
>valve in the ckt. But you'd never know that one of the two ckts
>is not working, until the second one fails, leaving you with
>NO brakes at all. Just like it sounds like what happened
>to your friend leaving the pits.
>
>Paul Tegler
>ptegler@cablespeed.com
>www.teglerizer.com
>
>----- Original Message -----
>From: "Bob Van Kirk" <racerbob70@yahoo.com>
>To: "Gerard" <pixelsmith@gerardsgarage.com>; <spridgets@autox.team.net>
>Sent: Thursday, May 15, 2003 8:46 PM
>Subject: Re: dual braking system
>
>
>> Gerard,
>> Thanks for your input. This car didn't have the
>> proportioning valve in the system. Just a line
>> connected to the master for the fronts and a line
>> running to the rears. No one has said that "yes it
>> must be on the car" but after studing the master
>> cylinder cross section and having rebuilt several I am
>> begining to think that it has to be in the system. I
>> believe that the valve of the front system needs the
>> pressure from the closed off section of the proportion
>> valve to actuate the rear system in the master. There
>> isn't a solid push rod all the way thru the master but
>> 2 rods connected by pins and a spring, sort of a
>> proportioning valve in itself? The pressure from the
>> front part, after starting to actuate the discs, then
>> pushes the rear rod and valve forcing the rears to
>> start doing their job. If you have a pressure failure
>> in the front system, as my friend did, the rears won't
>> work if the PDWA isn't there to shut off the front
>> line. In the other case were the rears fail, there
>> isn't enough difference in normal every day braking
>> for the average driver to notice thus the inclusion of
>> the warning light in the PDWA system.
>> Imput?????????
>>
>> Bob
>>
>> --- Gerard <pixelsmith@gerardsgarage.com> wrote:
>> > Cap'n (and others following this discussion),
>> >
>> > Nope, not diagonal. Circuits are front and rear and
>> > probably set up the
>> > same way front and rear without the valve.
>> >
>> > Also, I don't think the system is designed to
>> > conpensate for a leak, but
>> > rather a loss of pressure.
>> >
>> > The proprtioning valve has 5 connections, two from
>> > the MC, one to each
>> > front wheel and on out to the rear tee. One MC line
>> > feeds the front and the
>> > other the rear and front and rear are supplied from
>> > corresponding feeds. If
>> > pressure drops from one supply, it will force the
>> > shuttle valve to pop to
>> > the weak side allowing fluid to supply both
>> > branches. Unless someone can
>> > explin otherwise, I think you are still in trouble
>> > if you spring a leak
>> > somewhere.
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