Soft Brake Pedal 66 mustang - Vintage Mustang Forums

 
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post #1 of 8 (permalink) Old 08-20-2016, 10:28 PM Thread Starter
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Soft Brake Pedal 66 mustang

I upgraded my single bowl master cylinder to a dual bowl master cylinder and cannot get a firm pedal. I have bench bled the master cylinder, replaced all lines and put in 4 new wheel cylinders. Put the rear end up and tapped on the MC with a mallet and still, the car has brakes but I can't lock the brakes up?? any suggestions would be appreciated
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post #2 of 8 (permalink) Old 08-20-2016, 10:49 PM
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did you bench bleed the master ? do you have a proportioning valve ? do you have a 10 pound residual valve to the rear brakes?

Welcome,by the way

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post #3 of 8 (permalink) Old 08-21-2016, 08:37 AM Thread Starter
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Are you saying these additional parts are required when you make the conversion from a single to a dual bowl MC? I did bench bleed it for hours.
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post #4 of 8 (permalink) Old 08-21-2016, 09:18 AM
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bench bleeding a master should only take few minutes I have an adjustable proportioning valve it's a good idea but mostly for tunability I'll admit I don't have a 10 pound residual valve yet, but I'm sure it will really firm up the pedal

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post #5 of 8 (permalink) Old 08-21-2016, 11:26 AM
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The 10lb residual valve is for the rear line with drum brakes and a 2lb value is used if your rear brakes are disc. This should reduce pedal travel. Also, after hooking up the MC and lines, open all brake bleeder screws, let it gravity bleed until all corners are dripping, close all bleeders, then bleed furthest from MC to closest (right rear, left rear, right front, left front). Make sure MC doesn't get too low and that you're using new DOT4 fluid (as soon as you open a bottle of brake fluid it begins absorbing moisture).

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post #6 of 8 (permalink) Old 08-21-2016, 07:36 PM Thread Starter
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I am using DOT3, is that a problem
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post #7 of 8 (permalink) Old 08-21-2016, 07:43 PM
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DOT3 or 4 is fine. 4 has a higher boiling temp so can handle more abuse. Whichever kind you've been using, though, stick with the same kind, don't mix them.

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post #8 of 8 (permalink) Old 08-21-2016, 07:44 PM
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Quote:
Originally Posted by fbovi1 View Post
I am using DOT3, is that a problem
nope, that's fine

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