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Expert
Posts: 3588
   
Location: Plymouth Spaceport | I bought a 1957 Plymouth with power brakes.
It had a new master cylinder installed and the pedal goes all the way to the floor with no resistance.
The master was bench bled,and I went around to each wheel cylinder and did them as well until nothing but fluid came out.
still the pedal goes to the floor!
There are no leaks anywhere to indicate a leaky wheel cylinder or brake line,the fluid level in the master cylinder doesnt go down.
When I disconnect the line at the bottom of the master cylinder and connect it to the kit,fluid flows into the bottle,so the master cylinder seems to be working.
Anyone have any advice they can offer here?
Could there still be air trapped in the system or do you think the master cylinder is defective?
I went out and bought a fitting to screw into the bottom of the master cylinder this evening to see if it has pedal pressure when its blocked off to test the master...but If its good and has "pedal" when its blocked off I am out of ideas...other than maybe they is still air in the lines.
I was also told that for 1957 the master cylinders used on the power and manual brake cars are the same,is that true?
Edited by 1960DesotoAdventurer 2010-06-08 5:25 PM
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Expert
Posts: 3776
Location: NorCal |
Blocking the MC outlet will tell all, if the pedal still drops with the outlet plugged the MC is bypassing internally.
If you get a firm pedal with the outlet blocked, the system is needing more fluid than the MC can supply in a single stroke. Can you pump the pedal repeatedly and get a higher pedal? If so the likely problem is loosely adjusted brakes. |
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Expert 5K+
Posts: 6203
Location: Big pimpin' | I assume you are still running the old "Tea pot" single master cyl., with the original drums right? If so, how did you bleed them? With another person, or gravity?
Have you checked the adjustment of the drum brake shoes? if you "pump" the pedal, does it come back? |
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Expert
Posts: 3588
Location: Plymouth Spaceport | 57chizler - 2010-06-08 6:24 PM
Blocking the MC outlet will tell all, if the pedal still drops with the outlet plugged the MC is bypassing internally.
If you get a firm pedal with the outlet blocked, the system is needing more fluid than the MC can supply in a single stroke. Can you pump the pedal repeatedly and get a higher pedal? If so the likely problem is loosely adjusted brakes.
Hi,
No the pedal doesnt build up if I pump it repeatedly,it just goes without resistance to the floor.
I bought a block off plug today and am going to see this evening if I get a pedal using that.
Edited by 1960DesotoAdventurer 2010-06-08 6:36 PM
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Expert
Posts: 3588
Location: Plymouth Spaceport | dukeboy - 2010-06-08 6:26 PM
I assume you are still running the old "Tea pot" single master cyl., with the original drums right? If so, how did you bleed them? With another person, or gravity?
Have you checked the adjustment of the drum brake shoes? if you "pump" the pedal, does it come back?
Hi,
Yes,its still using the old single pot type master and original brakes.
I had a friend pump the pedal and used a clear tube and jar at each wheel cylinder to watch the fluid coming out and get rid of bubbles.
The pedal wont pump up.
I didnt try adjusting the brakes though...so I'll try that tonight too. |
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Expert
Posts: 2679
| 1960DesotoAdventurer - 2010-06-08 6:34 PM
dukeboy - 2010-06-08 6:26 PM
I assume you are still running the old "Tea pot" single master cyl., with the original drums right? If so, how did you bleed them? With another person, or gravity?
Have you checked the adjustment of the drum brake shoes? if you "pump" the pedal, does it come back?
Hi,
Yes,its still using the old single pot type master and original brakes.
I had a friend pump the pedal and used a clear tube and jar at each wheel cylinder to watch the fluid coming out and get rid of bubbles.
The pedal wont pump up.
I didnt try adjusting the brakes though...so I'll try that tonight too.
It sounds like the shoes are so far out of adjustment they take alot of fluid to move all those wheel cylinders at once. That could
be your problem. |
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Expert
Posts: 3588
Location: Plymouth Spaceport | I got a chance to insert the brass plug I got today into the master and guess what?....still no pedal!
So it looks like the "rebuilt" master cylinder is bad.
I should have a new one tommorow,I let you know how it works out. |
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Walter passed away on Jul 29, 2014. We will miss you, Walt!
Posts: 5358
Location: Heaven Above (Formerly Oklahoma City,OK) | Or. it may be that you are not "bleeding "the brakes correctly. You may want to search back a few months under this section as there was considerable discussion on the proper method to "bleed" brakes in a thread.
Uncle Walt
Edited by wbower3 2010-06-08 11:29 PM
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Expert
Posts: 3588
Location: Plymouth Spaceport | wbower3 - 2010-06-08 11:27 PM
Or. it may be that you are not "bleeding "the brakes correctly. You may want to search back a few months under this section as there was considerable discussion on the proper method to "bleed" brakes in a thread.
Uncle Walt
Thanks Walt,but I have done brakes on several cars before so I am familiar with the process.
The master cylinder was bench bled prior to installation by me,as was the bleeding of the brakes at each wheel cylinder,I was carefull to get all the air out.
I threaded a brass plug into the bottom of the master last night and there was still absolutely no pedal,and no resistance when it traveled to the floor...so how can it be anything but a bad master cylinder?
Edited by 1960DesotoAdventurer 2010-06-09 2:27 PM
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1957 Plymouth brake problem..no pedal! ..new master cylinder...no wheel cylinder leaks...any advice?
