Risidual valve question

[bobtile]

I had a power disc conversion kit on my car with drums on back. I recently purchased a Strange manual master cylinder to replace the power unit for weight savings. On the paperwork from Strange, it stated for drum brakes I need a 10 residual valve on the rear. I have a proportioning valve on the car from the original kit. Do I still need to put a residual valve inline?

 

[67 coronet]

if they say so then yes.normally those are built into the master,when needed,i guess theres does not have it.

 

[Propwash]

I agree with '67.....and say yes as well. Residual valve has a different function than a proportioning valve. Lotta folks make decent in-line residual valves, that are easy to plumb in.

 

[Cranky]

Drums brakes need the residual valve to keep any air from leaking into the system from the wheel cylinders.....

 

[bobtile]

I didn't know if it would have been built into the proportioning valve or not. Would I be able to see one if I looked into the old master cylinder?

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This is a picture of the prop valve if it helps.

 

[hunt2elk]

You wont be able to see it unless you pull out the brass seat where the line for the rear line attaches to the cylinder. I have one apart right now, and will take a pic of it tomorrow for you.

 

[Belv1956]

I have used a 10 ib check on many race cars with drum brakes on the rear , it retains pressure to keep the cups in your wheel cyl expanded so you do not have to pumped the pedal to get the rear brakes applied. The proportioning valve controls the amount of flow not pressure.

 

[Cranky]

I have used a 10 ib check on many race cars with drum brakes on the rear , it retains pressure to keep the cups in your wheel cyl expanded so you do not have to pumped the pedal to get the rear brakes applied. The proportioning valve controls the amount of flow not pressure.

I have an older repair book on brakes and it doesn't say anything about that. If you keep your brakes adjusted (manual or auto adjust) where they should be and the system is right, you won't have any issues with having to pump the pedal. Even without the residual valve you won't have to pump it...until air slowly leaks into the system but when that happens, you end up with a spongy pedal.....

 

[hunt2elk]

 

[bobtile]

View attachment 227833

That's interesting, thank you.

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I'll check the master that I pulled out. If it doesn't have one, i think I'm good to go.
I see the screws, but how do you remove the seats?

 

[383man]

Drums brakes need the residual valve to keep any air from leaking into the system from the wheel cylinders.....

No bascially Belv1956 is right as they maintain some pressure in the line so when you hit the pedal the pressure is instant and it overcomes the rear spring pressure faster for a good pedal that wont drop to much on the first pump. And maintaining some pressure in the line will help keep the wheel cyl cups against the wheel cyl walls as it all helps keep a good pedal. Some use the spring and cup retainers in the wheel cyl between the piston cups. Where they are located it wont really have anything to do with air getting in the system other then without them the wheel cyl cups could relax and maybe try to pull air in on the hit of the pedal. But in all my auto tech classes it was said they help keep a good high pedal since drum brakes have to overcome the brake spring pressure on the hit of the pedal not like disc where only the piston seal pulls the disc brake piston back a tad when it relaxes since they lay against the rotor all the time. Not trying to be a smart a$$ just telling what I was taught. Ron

 

[Dragon Slayer]

I agree with Ron and that is what Service manuals would say now. Otherwise the springs would retract the drum liners and as the pedal stopped under the front disc pressure the back drums would not be as engaged. Helps compensate for the spring. G

 

[Longroof]

Call Cass at Dr. Diff. Last week I ordered a master cylinder from him for my front disc swap. He told me that if you have replaced the rear wheel cylinders in about the past 10 years you probably are good. Cass said that about 10 years ago they started incorporating a residual valve in the wheel cylinders. Give him a call...