47 brake problems

E

exoilfld

Senior Member
On my 47 pu, I have new drums, shoes, wheel cyls., line, hoses, and master cyl. Adjusted the shoes as tight as I can make them and bled the system 3 times. the first stroke of the pedal goes almost to the floor. The second stroke gives a good hard pedal. The only other adjustment I can think of is the master cyl rod. I left about 1/8 inch or less play before it starts pushing the cyl. Anyone have any ideas?
 
No, I adjusted the brakes after bleeding just tight enough to have some drag but not so the wheel would not turn.
 
The brakes on 47 do not have an adjustment at the bottom, just the upper adjustment. I wonder how the MC rod should be adjusted.
 
I would adjust the shoes to the same amount of drag as you did.....BEFORE bleeding. A 1/16" on the pushrod should be sufficient. Make sure pedal and push rod completely retract via spring. DD
 
exoilfld said:
The brakes on 47 do not have an adjustment at the bottom, just the upper adjustment. I wonder how the MC rod should be adjusted.
Click to expand...

If the pedal positively returns to it's stop (with a return spring), a 1/32"-1/16" push rod gap is all you need. The actual gap, times the pedal ratio, equals the pedal "free play", so you want to keep the gap as small as possible.
It sounds like you may still have some air in the system, if the brakes are all adjusted properly, and, there are no leaks.
 
As V8 Bob said - you still have some air in the system .
Believe me , I've been there many times . Keep on bleeding , it will come out .
 
Lanny said:
Did you bench bleed the new Master cyl first, to get the air out of it ?.
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That was my thought too, not air still in the brake lines. If you had that the brakes would not be a "hard pedal" as you said on the second push. They'd always be "spongy".

Having to "pump up" the brakes with two pushes as you describe sounds like a shoe somewhere is still not adjusted up close enough to the drum.
 
I guess I will bleed some more. Don't know how to bleed the MC, just at the wheel cyls. I might try adjusting the shoes until they lock the drums and see what difference that makes on the pedal. Sounds like I have about the right adj. on the push rod.
 
I don't think that's a wise way to try to bleed the system. You may end-up not being able to get the shoes to retract to the nominal adjustment spot because of the EXTRA volume (in each wheel cylinder) downstream of the check mechanism. Adjust the shoes precisely (barely rubbing), then bleed! DD
 
I put a Wagner rebuilt Single Pot master cyl in a '64 Comet a few years
ago, and the instructions said to bench bleed it before installing in vehicle,
was Wagner wrong :confused:









.
 
Lanny said:
I put a Wagner rebuilt Single Pot master cyl in a '64 Comet a few years
ago, and the instructions said to bench bleed it before installing in vehicle,
was Wagner wrong :confused:

.
Click to expand...

That is the same instructions that came with the master cylinder I bought from NAPA for my 47.

Here is one bench bleeding procedure: http://s7d9.scene7.com/is/content/GenuinePartsCompany/1229488pdf?$PDF$

Here are the installation instructions for my 47 MC that includes the bench bleeding procedure: http://s7d9.scene7.com/is/content/GenuinePartsCompany/1262928pdf?$PDF$
 
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For me, if I already have working brakes and am just replacing the master cyl, I have found that a bench bleed will almost always eliminate any further bleeding.
 
I give up! I have adjusted and readjusted the shoes and bled 5 gallon of fluid through the system and I still have to pump the pedal to have brakes. I had no problem with my 41,38, or 40, but this one has beat me.
 
Any way you have a wheel cylinder(s) leaking, that is a fairly common issue with the newer ones? There is a procedure for installing them to over come this.
 
I always adjust the brakes first when done should have slide drag. Then make sure you have a returns spring on pedal. What I do is crack the bleeder little so to leak out and pump and see good puddle of fluid on ground don't let pedal go to floor and keep mc full, close the blender and do the same to other ones. Test drive
 
George/Maine said:
I always adjust the brakes first when done should have slide drag. Then make sure you have a returns spring on pedal. What I do is crack the bleeder little so to leak out and pump and see good puddle of fluid on ground don't let pedal go to floor and keep mc full, close the blender and do the same to other ones. Test drive
Click to expand...

Soooo.......you're sayin' you just crack the bleeders one at a time, let it squirt out some, and just end-up with four good puddles of fluid on the ground? Don't get no simpler 'n that. DD
 
Just read a thread from a senior member from 2011, said he was having the same problem. He thought it was defective MS's(had replaced 2 new ones). I messaged him and asked how he resolved the problem. Have not head back yet.
 
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