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Old 04-22-2012, 04:53 AM
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Proper Master Cylinder?

Hi, I have a 31 Model A rod, it has 11" drum brakes rear, and disc up front. These are manual, and I want to be sure the master cylinder was correctly sized for this car. I have soft pedal, and want to start from the beginning eliminating each possible senario which would cause this issue....(just purchased car)...Thanks in advance.

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Old 04-22-2012, 03:23 PM
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Soft pedal can be from many variables.. Usually air trap. What front brakes? Are the bleeders in correct position? I have had setups come in that had to be bled with caliper/ cylinders unbolted from the car, using a dummy rotor. Proportioning valves? Residual valves? Present master size? Many people use a master with too large bore. Keep it under 1" for light car. In many cases. The smaller the master bore, the more pedal force to the wheels.
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Old 04-22-2012, 03:54 PM
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If it has the underfloor master setup you most likely will need to have residual valves as well.
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Old 04-22-2012, 04:36 PM
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Quote:
Originally Posted by BOBCRMAN@aol.com
Soft pedal can be from many variables.. Usually air trap. What front brakes? Are the bleeders in correct position? I have had setups come in that had to be bled with caliper/ cylinders unbolted from the car, using a dummy rotor. Proportioning valves? Residual valves? Present master size? Many people use a master with too large bore. Keep it under 1" for light car. In many cases. The smaller the master bore, the more pedal force to the wheels.
I will have to look for these answers, since I've had the car for only a week or so.
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Old 04-22-2012, 04:37 PM
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Quote:
Originally Posted by LATECH
If it has the underfloor master setup you most likely will need to have residual valves as well.
It does have under floor master, but no clue if there are porportioning and residual valves....where SHOULD they be located?
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Old 04-22-2012, 05:06 PM
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Quote:
Originally Posted by 31ROC
It does have under floor master, but no clue if there are porportioning and residual valves....where SHOULD they be located?
Here is a page on brake valves. If you have an added on residual pressure valve(s) it can be in the brake line anywhere between the master cylinder and the caliper/slave. You can also have a built-in residual valve. This can be in the MC itself or in the combo valve if equipped w/one.
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Old 04-22-2012, 07:36 PM
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want to start from the beginning eliminating each possible senario which would cause this issue....(just purchased car)...Thanks in advance.
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