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.
 
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!
 
(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.
 
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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.
 
Probably China or Taiwan. Seems all brake parts are made somewhere else. Even Wagner does not make parts here. How good is our government?
 
exoilfld said:
Probably China or Taiwan. Seems all brake parts are made somewhere else. Even Wagner does not make parts here. How good is our government?
Click to expand...

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.
 
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.
 
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
 
Talkwrench said:
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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I agree with this completely. I have a O/T Corvette whose brakes were a real b*tch to bleed. After installing "SpeedBleeders", it's a 10 minute one person job.
 
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).
 
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.
 
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?
 
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 ;)
 
V8COOPMAN said:
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
Click to expand...

Not an actual check mechanism, the residual valve keeps about 10 pounds or less in the lines and wheel cylinders. The return springs are far stronger and will return any excess fluid to the reservoir.
Bill
 
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

Sent from my SM-G973U using Tapatalk
 
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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