Posted by Glen
on 4/27/2009, 9:05 am, in reply to "Re: proportioning valve"
98.77.54.17
Tim that valve is the pressure differential warning switch. There is a little shuttle valve inside that is balanced when both sides of the system have pressure. If either half loses pressure (ie a leak), the valve will slide over & trip the switch, and the brake warning light will (maybe) come on.
Of course, the brake pedal going halfway to the floor is also a clue as well....
HTH
Glen
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:
:
: --Previous Message--
: Tim these cars don't have a
: proportioning
: valve. The front to rear balance is
: determined by the master cylinder bore
: sizes, all else being equal. The
: primary & secondary systems are
: completely independent of each other,
: the primary works the front calipers,
: the secondary the rear cylinders. If
: any bore size is changed (m/cyl,
: caliper, wheel cylinder), it will
: increase or decrease the effectiveness
: of that half of the system, which will
: then affect the front/rear balance. (An
: example would be an increase in bore
: diameter (master) will result in less
: pedal travel (more fluid displaced for
: a given amount of pedal travel), and
: less effectiveness (due to the ratio
: change). Also a slight change made
: usually won't be evident until the
: brakes are working close to the limit
: of tire adhesion.
: HTH
: Glen
:
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:
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: ... not a stupid question.
: IIRC the bore diameters are different,
: and the later cylinder is metric.
: You could possibly make it work, but
: the proportioning would be changed;
: there was also a rear wheel cylinder
: diameter change at the same time.
: HTH
: Glen
:
:
: --Previous Message--
: OK, Is this a stupid question? Why
: can't
: you use a 1976 to 1980 brake master
: cylinder instead of the expensive 1970
: to 1975 model? What is the difference?
: I don't understand.
:
:
:
: Glen, how would this effect the car? As
: long as it goes to the proportioning
: valve, what would be the difference? I
: don't understand? Thanks, in advance
:
:
:
: Glen, Thanks for that info. I thought
: that there was a proportioning valve
: that the mater pipes too, with the wire
: connected to it. Not a brake guy, so
: just learning. I can rebuild brakes,
: but just don't much about the Master
: cylinder and stuff. So, when the brakes
: are applied it starts pushing fluid
: down both pipes, but as they are
: applied harder, it looks like the front
: get more? Is that what I see?
:
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