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10-18-2015, 02:15 PM | #1 |
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47 brake problems
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?
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10-18-2015, 03:21 PM | #2 |
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Re: 47 brake problems
No, I adjusted the brakes after bleeding just tight enough to have some drag but not so the wheel would not turn.
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10-18-2015, 03:25 PM | #3 |
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Re: 47 brake problems
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.
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10-18-2015, 03:28 PM | #4 |
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Re: 47 brake problems
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
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10-18-2015, 03:39 PM | #5 | |
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Re: 47 brake problems
Quote:
It sounds like you may still have some air in the system, if the brakes are all adjusted properly, and, there are no leaks. |
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10-18-2015, 04:12 PM | #6 |
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Re: 47 brake problems
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Believe me , I've been there many times . Keep on bleeding , it will come out . |
10-18-2015, 04:17 PM | #7 |
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Re: 47 brake problems
Did you bench bleed the new Master cyl first, to get the air out of it ?
.
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10-18-2015, 04:46 PM | #8 | |
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Re: 47 brake problems
Quote:
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.
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10-18-2015, 08:10 PM | #9 |
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Re: 47 brake problems
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.
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10-18-2015, 08:21 PM | #10 |
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Re: 47 brake problems
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
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10-18-2015, 08:28 PM | #11 |
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Re: 47 brake problems
If a single circuit system no need to bench bleed. also DO NOT push the pedal all the way to the floor when bleeding, put a bit of wood or something behind it. Speed bleeders are your best friend. http://www.speedbleeder.com/
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10-18-2015, 11:50 PM | #12 |
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Re: 47 brake problems
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 .
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10-19-2015, 12:12 AM | #13 | |
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Re: 47 brake problems
Quote:
Here is one bench bleeding procedure: http://s7d9.scene7.com/is/content/Ge...29488pdf?$PDF$ Here are the installation instructions for my 47 MC that includes the bench bleeding procedure: http://s7d9.scene7.com/is/content/Ge...62928pdf?$PDF$
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Prof. Henry (The Roaming Gnome) "It is good to have an end to journey toward; but it is the journey that matters, in the end.” *Ursula K. Le Guin in The Left Hand of Darkness Last edited by Old Henry; 10-19-2015 at 12:21 AM. |
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10-19-2015, 07:56 AM | #14 |
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Re: 47 brake problems
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.
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10-19-2015, 02:07 PM | #15 |
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Re: 47 brake problems
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.
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10-19-2015, 02:38 PM | #16 |
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Re: 47 brake problems
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.
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10-19-2015, 03:29 PM | #17 |
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Re: 47 brake problems
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
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10-19-2015, 03:43 PM | #18 | |
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Re: 47 brake problems
Quote:
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10-19-2015, 04:08 PM | #19 |
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Re: 47 brake problems
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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10-19-2015, 06:09 PM | #20 |
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Re: 47 brake problems
Which wheel are you bleeding first, second, etc?? How much free play in the pedal?? Original style M/C??
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10-19-2015, 06:40 PM | #21 |
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Re: 47 brake problems
I always chamfer the ends of shoes some times to long both ends, never pinch rubber lines, if you had the floor up make sure you have piston gap 1/8"
Also make sure the MC is higher then WC gravity helps bleed. |
10-19-2015, 09:16 PM | #22 |
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Re: 47 brake problems
There is a problem with chinese wheel cylinders. Now I don't know if your new cylinders were USA or chinese, but always use American made. The fluid holes in many chinese cylinders are drilled in the wrong place. I fought this for ages, four brand new chinese cylinders, did some research, reco'ed my old USA ones, instant brakes!
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10-19-2015, 10:43 PM | #23 |
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Re: 47 brake problems
(1) x 2 re bassman/NZ's comment re US made cylinders.
(2) Not expressly mentioned in this thread but bleed wheel cylinder most-distant from MC first, then next most-distant, etc, etc. (3) Do you have one or two-point brake shoe adjustment points (i.e. top and bottom). See Service Manual for correct procedure if two. Last edited by Drbrown; 10-19-2015 at 10:48 PM. |
10-20-2015, 07:58 AM | #24 |
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Re: 47 brake problems
Right rear,lr,rf,lf. Yes,original type MC.
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10-20-2015, 09:27 AM | #25 |
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Re: 47 brake problems
Any idea where the wheel cylinders are from? Manufactured? The issue is the bleed hole is miss located and does not allow for proper bleeding at the cylinders.
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10-21-2015, 08:08 AM | #26 |
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Re: 47 brake problems
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10-21-2015, 08:26 AM | #27 |
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Re: 47 brake problems
One approach is to find some rebuildable used USA manufactured wheel cylinders and rebuild them. Very simple, cheap and quick to do and you then have known good parts.
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10-22-2015, 06:23 PM | #28 |
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Re: 47 brake problems
did you rebuild the MC?
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10-23-2015, 07:57 AM | #29 |
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Re: 47 brake problems
Bought a new one and am now trying my old rebuilt one. Waiting on a replacement for a broken MC end bolt. I will post how it works out.
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10-23-2015, 08:21 AM | #30 |
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Re: 47 brake problems
exoilfld,
I've been lurking on this thread...I just rebuilt my '47 COE brakes and had a similar problem. I didn't bench bleed the master cylinder before installation. When I bled the brakes normally, I couldn't get all the air out of the master cylinder on the first try. I still had no pressure or had to pump for pressure on my test drive (blew through the first stop sign). That trapped air inside the master cylinder may be causing your poor braking action as well. Upon re-looking at the system, I looked inside the master cylinder reservoir (filler cap removed) and noticed bubbles escaping from the holes in the reservoir that feed the piston when I SLOWLY actuated the pedal. I cycled the pedal SLOWLY numerous times until no bubbles escaped. I then re-bled the brakes and now they work fine. It only took about a quart of fluid total to complete 2 bleed rounds. I must emphasize to SLOWLY press the pedal. If you do it fast while looking into the reservoir, you'll squirt brake fluid in your eye...not a recommended result. Dan |
10-23-2015, 08:25 AM | #31 | |
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Re: 47 brake problems
Quote:
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10-25-2015, 07:52 AM | #32 |
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Re: 47 brake problems
I have noticed the same thing. Got squirted in the face. Bled the MC and still had the problem. Just got the replacement end bolt and will post results with rebuilt MC(a Wagner).
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10-25-2015, 01:41 PM | #33 |
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Re: 47 brake problems
OK guys, problem solved. I took the old MC(a Wagner), honed it and put in a new repair kit, bled the system and it works like it should. I put the "new" MC in a vise and pumped it several times and it would not pump up like it should. In fact, it would never stop squirting up at the first of the stroke. So, I figure the "new" MC made in China or somewhere is just not made correctly. Stupid me thought a new one would work properly. Thanks for all the input guys.
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10-25-2015, 02:02 PM | #34 |
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Re: 47 brake problems
Here is a bit of guidance, and old Henry is the only one to have touched on it.
If you have a hard pedal, then it is adjustment. If it is a spongy pedal then you have air in it. To my way of thinking you have not assembled something correctly. I would suspect the problem is inside your brake drums. One stroke is moving fluid and making the linings hit the drums. A quick second stroke is giving you a firm pedal. Correct? If so, go back inside the drums. You have bled it enough. You might even hear the movement from the ones that have the travel? |
10-17-2020, 11:06 AM | #35 |
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Re: 47 brake problems
I ran across this thread while researching another issue and wanted to post that I have seen several replacement master cylinders that had bad or no residual pressure valves in them. They will cause the exact scenario described due to all the fluid returning to the master when the pedal is released.
The residual valve is supposed to keep 10 PSI in the lines. In our case(s) originality was not an issue so external residual valves were installed and we had instant brakes hope this will help someone maintain their sanity |
10-17-2020, 10:00 PM | #36 | |
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Re: 47 brake problems
Quote:
Bill |
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10-17-2020, 10:37 PM | #37 |
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Re: 47 brake problems
Looks like we're in this together. I didn't see this thread and posted an almost identical question. Guess I'll go get some more brake fluid... LOL
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10-18-2020, 06:25 AM | #38 |
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Re: 47 brake problems
I wonder if your master cylinder will also apply to a truck with a booster, if so the master
cylinder will not have a residual check valve, the valve is in the booster. That is shown in my 48 to 54 truck parts book. I have no way of crossing part numbers to find out if a car and light truck master cyl. are the same. could be I don't know. mark this info: |
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