master cylinder

[bobsmanstuff]

On my 53 customline I was thinking of going from a single master cylinder to a double for safety. What all is involved and what cylinder would work? Thanks Bob

[glennpm]

Take a look at this active thread to start.


https://www.fordbarn.com/forum/showthread.php?t=335765

[ScubaChief60]

Hello... I have the Early Ford Store single master cylinder on my '35 Fordor (after my conversion to hydraulics) and with the Bolling brothers rear backing plate setup and the E-brake activated by steel cable... I can literally skid the rear tires with the hand brake lever. That and down shifting is my plan-B in case the single MC ever fails.

[ScubaChief60]

Actually Early V8 Garage (not Early Ford Store) helped me immensely on my project. Good folks!

[bobsmanstuff]

on my 53 I have a small block that has two lines coming out to feed the front brakes and one out the rear to feed the back brake. simple set up. A lot of the doubles have a proportioning valve and some don't. Would I need that valve since there isn't one on there now?

[V8 Bob]

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Originally Posted by bobsmanstuff

on my 53 I have a small block that has two lines coming out to feed the front brakes and one out the rear to feed the back brake. simple set up. A lot of the doubles have a proportioning valve and some don't. Would I need that valve since there isn't one on there now?

If your brakes are original drums, you don't need a proportioning valve, but you will need a residual for each axle IF the new dual master does not have them located behind the tube seats.

[bobsmanstuff]

What do you mean by residual.

[V8 Bob]

Originally Posted by bobsmanstuff

What do you mean by residual.

Residual valves are required in older/vintage drum brakes to prevent air from entering past the wheel cylinder cups during fast release. Your stock '53 has one located at the end of the bore inside the master cylinder. These are sometimes called a check valve.
Drum dual masters had them located behind the tube seats up until the early '70s. Aftermarket inline 10 lb drum valves are available if there are no internal valves in the dual master you choose.

[Bob C]

Here is a link to a good video explaining the reason for a residual
pressure valve.
https://www.youtube.com/watch?v=DIVDjqniUX8

[bobsmanstuff]

good video

[V8 Bob]

Originally Posted by bobsmanstuff

good video

Well, NOT so good video. I like Wilwood products, but their explanation of a drum residual is total BS!


Why in the hell would you want the shoes to float inside a drum, with only .020"-.030" or so total drum-to-shoe clearance?? Drum shoe return springs do just that-return the shoes to their anchors, as they were designed to do.

I didn't recommend looking for residual info because there are still so many who don't know how or why they work, including some brake suppliers that should know!


Drum residuals are necessary in older drum systems because of the strong shoe return springs that can cause air to enter past the cylinder cups when releasing the brakes quickly. Production residual "check" valves ranged in pressure, but the aftermarket uses 10 lbs for drums. Wheel cylinder cup expanders made residuals obsolete by the mid '70s along with front discs.



Modern disc brakes never used residuals because the masters have all been mounted higher than the calipers, preventing any fluid transfer back to the master reservoir. However, if the master is located lower than the calipers, an aftermarket 2 lb residual will prevent any fluid transfer.

[bobsmanstuff]

Well aren't the drum brakes the same then being higher then the drums?

[V8 Bob]

Originally Posted by bobsmanstuff

Well aren't the drum brakes the same then being higher then the drums?

Master location has nothing to do with drum brake residuals. Guess I haven't explained the residual function well enough.

[bobsmanstuff]

I understand that it's a check valve.