Power disc conversion question, residual valve... not sure if correct ?

[rustytoolss]

Bought a 62 Plymouth wagon ,with Performance Online power disc brake conversion (booster/master cylinder kit #BB-6374 and disc conversion kit #SWBKS6274) All of this was installed by last owner. This kit has the Mopar style cast iron/plastic MC . The way it's install ...the front port (near front of car) is going to an inline residual valve/ then to a manual adjustable brake pressure valve knob type then to the rear brakes......The rear port (close to firewall ) goes down to a tee connection and splits to both front calipers.
Is that residual valve in the correct place (going to the rear brakes in front of the adjustable brake pressure valve)????.... is it even needed ? Help a guy out here. I'm at a loss . Like I said bought this car this way. Thanks

 

[hunt2elk]

Those aluminum master cylinders don't have residual valves in either port, whereas the cast ones have a residual valve in the front port for the rear brakes. So I would say it is plumbed in correct although there has been debates if a residual valve is even needed, especially with new rear wheel cylinders. Are you having stopping problems?

 

[rustytoolss]

Those aluminum master cylinders don't have residual valves in either port, whereas the cast ones have a residual valve in the front port for the rear brakes. So I would say it is plumbed in correct although there has been debates if a residual valve is even needed, especially with new rear wheel cylinders. Are you having stopping problems?

Like I said, just bought this car. Replaced both rear wheel cylinders and rear brake hose. Was trying to bleed brake / could not get any fluid flow Either side of MC/ removed MC , to bench bleed , MC seamed to work fine on vise. I just thought that the Red residual valve was meant to be put inline with the front brakes to keep 2-3lbs of PSI on the front calipers ????

 

[hunt2elk]

No, the residual valve was always on the rear brakes from what I have seen.

 

[rustytoolss]

Guess I was wrong,.....don't get old, you forget stuff Thanks

 

[Dave6T4]

Residual valve on rear brake circuit holds 2 or 3 pounds pressure to keep rear pistons/cups from collapsing. Retraction springs on rear drum brakes overcome this small pressure to pull linings back from drum. Some styles of rear wheel cylinders have a weak spring in them to do this task, so no residual valve required with these. Disc brakes only have piston seals to retract piston/pad from the disc, so pressure on this circuit must drop back to zero. Therefore, no residual valve in disc brake circuits.

 

[rustytoolss]

Residual valve on rear brake circuit holds 2 or 3 pounds pressure to keep rear pistons/cups from collapsing. Retraction springs on rear drum brakes overcome this small pressure to pull linings back from drum. Some styles of rear wheel cylinders have a weak spring in them to do this task, so no residual valve required with these. Disc brakes only have piston seals to retract piston/pad from the disc, so pressure on this circuit must drop back to zero. Therefore, no residual valve in disc brake circuits.

Residual valve on rear brake circuit holds 2 or 3 pounds pressure to keep rear pistons/cups from collapsing. Retraction springs on rear drum brakes overcome this small pressure to pull linings back from drum. Some styles of rear wheel cylinders have a weak spring in them to do this task, so no residual valve required with these. Disc brakes only have piston seals to retract piston/pad from the disc, so pressure on this circuit must drop back to zero. Therefore, no residual valve in disc brake circuits.

So according to RockAuto, the rear wheel cylinder kits for my 62 Plymouth have an internal spring in between the seals . So you are saying that I "should not Have to use the red residual valve " and could remove it...correct ? will it cause any problems if I leave it in place ? ( Note I replaced the complete wheel cylinders)

 

[rustytoolss]

Those aluminum master cylinders don't have residual valves in either port, whereas the cast ones have a residual valve in the front port for the rear brakes. So I would say it is plumbed in correct although there has been debates if a residual valve is even needed, especially with new rear wheel cylinders. Are you having stopping problems?

My MC is the cast iron version/ not aluminum .

 

[hunt2elk]

https://www.doctordiff.com/aluminum-master-cylinder-kit.html
This is the aluminum cylinder that i am familiar with. This style doesn't have a rv.

https://piratejack.net/1960-1970-mopar-master-cylinder/
And this is the cast version that does have a rv.

So if you unscrew the front line on your cylinder, does the fluid run out? If it does, you don't have an internal valve.

 

[Dave6T4]

So according to RockAuto, the rear wheel cylinder kits for my 62 Plymouth have an internal spring in between the seals . So you are saying that I "should not Have to use the red residual valve " and could remove it...correct ? will it cause any problems if I leave it in place ? ( Note I replaced the complete wheel cylinders)

I don't think it is necessary to remove residual valve if you already have it. Whatever exerts most pressure will hold cups in place. I don't think the 2 forces will add to each other.

 

[rustytoolss]

https://www.doctordiff.com/aluminum-master-cylinder-kit.html
This is the aluminum cylinder that i am familiar with. This style doesn't have a rv.

https://piratejack.net/1960-1970-mopar-master-cylinder/
And this is the cast version that does have a rv.

So if you unscrew the front line on your cylinder, does the fluid run out? If it does, you don't have an internal valve.

Thanks, actually my master cylinder is the cast iron /plastic tank version, of the Aluminum/plastic tank unit. I think that the cast iron ones came out before aluminum ones were produced.