poor braking

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changed from stock front drum brakes to lightweight front disc brakes and used master cylinder required 1-1/8 bore brake pedal is hard as a rock car does not slow down checked the ratio on the brake pedal measures perfect the car is a 72 dart any help is appreciated

[Dan Fahey]

Originally Posted by back for more

changed from stock front drum brakes to lightweight front disc brakes and used master cylinder required 1-1/8 bore brake pedal is hard as a rock car does not slow down checked the ratio on the brake pedal measures perfect the car is a 72 dart any help is appreciated

Have a used once Wilwood Master cylinder for sale.

Dan

[Larry Hill]

On our 72 charger when we changed breaks from power to manual the linkage under the dash had to be changed to a different hole to give us more of a mechanical advantage. I want to say the bore in the master cylinder was smaller making it easy to build psi.
Good luck.

[Rory McNeil]

Like Larry said, at least on Fords, the manual brake cars came with a different brake pedal, with a pivot for the master cylinder pushrod closer to the pivot for the pedal itself, for more mechanical advantage. Again, with my Fords, manual master cylinders a re usually a smaller bore, like 7/8" or 15/16" diameter, compared to over 1" for a power brake application.

[Tom Goldman]

As was mentioned pedal ratio is critical .If the car originally had power brakes the ratio was only around 4 to 1 ,a ratio of 6 to 1 is considered ideal . also ,If you are only using discs on the front and retained the drums on the rear ,a master cylinder with a smaller bore will help.
On a disc /drum car I usually use a 1 3/32 bore master cylinder which wit the 6 to 1 pedal usually will yield around 1000 psi with reasonable pedal pressure.

[Gmirza]

On my ‘71 Duster, I used an aluminum master cylinder that came on the Volare/Aspens. I have Strange fronts and stock 10” rear drums and factory proportioning valve also from Volare/Aspen. Never a problem stopping or holding the car. You could have a bad brake hose or a stuck caliper. Make sure too use the braided front brake hoses.

[Doug Domm]

Originally Posted by Gmirza

On my ‘71 Duster, I used an aluminum master cylinder that came on the Volare/Aspens. I have Strange fronts and stock 10” rear drums and factory proportioning valve also from Volare/Aspen. Never a problem stopping or holding the car. You could have a bad brake hose or a stuck caliper. Make sure too use the braided front brake hoses.

Any particular reason to only use braided front brake hoses?

[GTX JOHN]

All our A bodies have 7/8 or 15/16 Cylinders
The large one would not let my elder legs hold
the two step or stop quickly.
We try for 7:1 and sometimes redrill the brake petal
itself and relocate the master if need on several of our
different stockers. Particularly on the two Aspens F Body cars.

You will figure it out.
PM me if needed.

[GTX JOHN]

The rubber fatigues and expands producing
a spongy petal.

At a minimum replace the stock lines every few
years.

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thanks for the info does anyone have the part number for the volarie style master cylinder? would i be better off going back to the stock master cylinder? also i was told to delete the proporting valve all together was that a bad idea?