drum brake proportioning valve

[Silent Thunder]

First, I do not know if the brakes where better before because I just bought the car and had it delivered to the garage. I did not want to drive the car with a single cylinder. The valve could cause a pedal to go to the floor (not like there is no pressure but you press real hard on the pedal and it looks like its near the end of the pedal when you stop) If you do not have the valves in place in line or on the master cylinder air enters the system at the wheel cylinder and that causes a strange pedal. The mechanic that worked on the car said the back brakes were brand new and the front were in good condition.

1 The valves or lack of, have no bearing on the current problem

2 Your statement about "excessive travel" is OPPOSITE of what you should have if the master cyl. is "too big," causing harder pedal compared to old master.

SO.................

Did the brakes work "better" before you switched the master?

Did you do ANYTHING else, IE replace shoes, turn drums, replace wheel cylinders, etc, when changing the master?

 

[chryslerfat]

Ok if the master is correct then start by pulling the drums one by one and use a screwdriver on the front and one on the rear shoe. When someone pushes on the pedal it should push the front and rear shoe out if the wheel cylinders are not frozen. If not replace them. The next step is to be sure you dont have the primary and secondary shoes in the wrong spot. This will cause more pressure and distance to stop if it is wrong. The long lining should be on the rear and the short on the front. After we are sure you have this correct we can check further. I have been ASE certified and worked as a licensed mechanic for 28 years so if the master is right these are your next steps.

 

[pishta]

Make sure they are adjusted properly. I drove a 63 300 with NO brakes but everything was new. We just didnt adjust them properly. You should have a rock hard pedal within about an inch or you got air in the system or a bad MC. Bad MC is more of a sinking pedal though. Smaller bore equates to more travel and higher pressure with same output, larger is smaller stroke but less mechanical advantage. Bleed again. gravity bleed if you got time, crack all four cylinders and put a cup under each drip. Keep eye on MC level over a few hours of football. That 10lb residual valve is old school, as stated it was for piston sealing, new ones have integral springs that do the same thing. Dual drum should have 2 of the same fittings, disk.drum usually have 2 sized fittings and one res larger than the other (disk one) as they displace more fluid. Oh, and of course the elusive "turned drums and new shoes that were not radiused" equates to reduced contact area.

 

[67Dart273]

First, I do not know if the brakes where better before ...................... The valve could cause a pedal to go to the floor (not like there is no pressure but you press real hard on the pedal and it looks like its near the end of the pedal when you stop........................ The mechanic that worked on the car said the back brakes were brand new and the front were in good condition.

I think in that case you are chasing your tail

IF the pedal has "excessive travel" BUT is HARD at the end of travel, then you have shoes out of adjustment

IF you have a hard pedal, and poor brakes, you probably have a drum/ shoe problem

Glazed heat damaged shoes

Drums turned too large, shoes don't fit, and have been glazed in the center of the lining.

Grossly improper lining quality

If you don't have (and need) residual valves, the ONLY thing the lack of them will cause is a deteriorating, mushy pedal over some period of time, that is, you will bleed it, and have a nice hard pedal, and after some amount of actuations, the pedal will start to get more and more mushy.

Another possibility, is, have you driven it enough to determine that ALL FOUR wheels are braking? Maybe you have the front piston in the master bottomed out, and are only operating off the rear piston.

The changing of the SAME BORE "single" to a tandem master should not have changed anything as applies to brake effort on an otherwise properly working system

 

[Silent Thunder]

My pedal is rock hard not spongy it is just rock hard near the bottom of the swing. This has all been helpful. The car is in for paint now and when I get it back I now have a direction to go in and I will let everyone know how I make out.

Make sure they are adjusted properly. I drove a 63 300 with NO brakes but everything was new. We just didnt adjust them properly. You should have a rock hard pedal within about an inch or you got air in the system or a bad MC. Bad MC is more of a sinking pedal though. Smaller bore equates to more travel and higher pressure with same output, larger is smaller stroke but less mechanical advantage. Bleed again. gravity bleed if you got time, crack all four cylinders and put a cup under each drip. Keep eye on MC level over a few hours of football. That 10lb residual valve is old school, as stated it was for piston sealing, new ones have integral springs that do the same thing. Dual drum should have 2 of the same fittings, disk.drum usually have 2 sized fittings and one res larger than the other (disk one) as they displace more fluid. Oh, and of course the elusive "turned drums and new shoes that were not radiused" equates to reduced contact area.