Residual Valve

[Carl Wiese]

Hey Mike,

while working on the 100 buck pos last time you suggested to my Dad I May want to put in a residual valve for the rear drums? I talked to Dad today and he couldnt' remember exactly what you suggested and I was wondering if you could clarify. I am going to do some work on it next week and swap on the new master cylinder for it, and since I have to bleed brakes, I May as well swap one of these in as well. It seems to me it should mount on the rear portion of the line, before the split to the drums, or would up by the master be better? From my reading for drums I believe a 10psi is what's recommended. Is this what you were recommending?

 

[Michael Mayben]

I "think" we discussed the fact the master cylinder was leaking out the rear? And it was gonna get replaced with a new one or a reman?

But even if you are gonna use it, ya need to pull the rear brake fitting out of the current master and see if there is an rpv inside. If there is, ya don't wanna add another. If there is not, then a drum system uses the 10psi version as you mentioned.

The replacement master cylinder (new or reman) May not have an rpv, that is a crapshoot these days! So verify what is there before attempting to bench bleed the replacement mc. If there is one in place, then you will good...if not, then an inline unit can be added...but in the case of a disc/drum system, it would be best to put it downstream of the proportioning valve in the rear brake circuit.

 

[Carl Wiese]

I "think" we discussed the fact the master cylinder was leaking out the rear? And it was gonna get replaced with a new one or a reman?

But even if you are gonna use it, ya need to pull the rear brake fitting out of the current master and see if there is an rpv inside. If there is, ya don't wanna add another. If there is not, then a drum system uses the 10psi version as you mentioned.

The replacement master cylinder (new or reman) May not have an rpv, that is a crapshoot these days! So verify what is there before attempting to bench bleed the replacement mc. If there is one in place, then you will good...if not, then an inline unit can be added...but in the case of a disc/drum system, it would be best to put it downstream of the proportioning valve in the rear brake circuit.

I don't have the valve in front of me, so I can't picture how the rear fitting comes out? Is there any chance it would be in the proportioning valve?

 

[Michael Mayben]

I don't have the valve in front of me, so I can't picture how the rear fitting comes out? Is there any chance it would be in the proportioning valve?

Not in the proportioning valve. It is normally either "behind" or built into the transition fitting that is screwed into the cast iron body "port". Pull that transition fitting out of the old mc and take a peek. And keep the fittings out of both ports until ya have the fresh brakes working ok, that forces the reamnner to put new transition fittings/rpv into the "rebuilt" master cylinders (unless they decide to scrap your core and send to china. It could return some day as a pump casting for cornell!