Brakes still not right

[49powerwagon]

I think I could use some advice on my brakes. This is on my `49 B1-PW, but they are mechanically the same as my B3-D. A little over a year ago I replaced all 4 slaves, every hose and line, and rebuilt my master. The brakes worked great for about 8 months, then I started having to pump the brakes to get them to work. I figured the master was going bad (didn`t trust the rebuild), and was sure when it started leaking out the back as well. After being parked for winter, I just put a new master on from vintage power wagons this weekend, and I still have to pump the pedal. Once I pump it 4-5 times I have good brakes and it is hard as a rock, but as soon as I let my foot off for more than a half-second, I lose them and have to pump again. I bled the brakes and was getting no more air, and no change. Then I adjusted the shoes out against the drums to make sure the slaves were not having to travel to far, no change.

I really hope this is not another bad master. This is my work truck for getting firewood and hauling dirt and such, and also until I get it working right again, I can`t work on getting my B3-D running.

[NiftyFifty]

Any proportioning valve installed after? Any chance you have a loose line...maybe now check for air again to see if that's the issue? It's a pretty basic system with very few components and sounds like you have crossed off most with the adjustment and bleeding and inspection....so unless one of the wheel cyl's was leaking then almost sounds like you got a bad master...

Try bleeding with 2 ppl (if you didn't already do it that way) Just have one person pump up the brake then go around and crack each indv. cyl....only for a quick burb...do this about 3 or 4 times. I have never had any luck with those 1 person air systems....other then that you can leave the top off the master and leave it for a day..that also will release a lot of air.

[HanksB3B]

But something doesn't make sense to me. It would be obvious if it were leaking fluid because there'd be a puddle somewhere, or the inside of one of the tires would be streaked with fluid. It sounds like air is getting into the system somehow. I think I'd look at each and every fitting and both visually and by feel examine the lines as well. Could there be a crack in one of the lines you can't see that is allowing air to be sucked into the system.

A mystery for sure,

Hank

[austinsailor]

If it pumps up solid it's not air. One or more of your shoes has to have a problem.

With the effort you've already done, what I'd do is adjust all 8 shoes out good and tight. Wheels won't turn, but you should have a solid pedel. Assuming that goes as expected, I'd loosen and adjust as well as I could one wheel at a time. Check the pedel after each one. It should show you something - either one wheel is causing a lot of problem, or all four if it gets equally worse as you move to the next wheel. If that is the case I'm guessing there is a problem with maybe linings loose or major adjustment way out.

Something else comes to mind. Many years ago I was turning the adjusting cams the wrong way. You can actually get it to feel kind of ok doing that, but it won't last long at all. Could that be the problem?

Edited May 5, 2010 by austinsailor

[49powerwagon]

When I adjusted out the shoes, I tried adjusting all the shoes out until the wheel was locked and wouldn`t turn, with no change. After sitting over night I re-bled the lines and there was still no air coming out. Another thing I forgot to mention is that if the reservoir is over about 1/3 to 1/2 full, after you pump the pedal to get brakes and then release the pedal, the reservoir will overflow and force fluid out the breather hole.

[grey beard]

Have you double-checked your masterr cylinder piston rod to make certain that it is returning ALL the way back in its travel. There must be some free play on the pedal linkage. Anything that interfears with the ms piston travel getting full return can cause the problem you describe.

Good Luck

[Merle Coggins]

Another thing I forgot to mention is that if the reservoir is over about 1/3 to 1/2 full, after you pump the pedal to get brakes and then release the pedal, the reservoir will overflow and force fluid out the breather hole.

This tells me that it has to use up a fair amount of fluid in order to stroke the wheel cylinders out enough to apply the brakes. That was also my assessment from your initial post. There is a residual valve in the master cylinder that will hold a small amount of pressure in the lines. When you pump the pedal you stroke the wheel cylinders out slightly, the on the next pump you stroke them out slightly more, etc, until the shoes make good contact. At rest the return springs gradually overcome the residual valve and return the cylinders to their retracted position and refill the reservoir.

So, there's something not right with your shoe adjustment. You may need to pull the drums and gain access to a proper adjustment tool and work on getting the shoes properly adjusted. Which adjustment are you playing with? The eccentric pivot pins (major adjustments) or the adjustment cams up near the middle (minor adjustments).

Merle

[NiftyFifty]

This tells me that it has to use up a fair amount of fluid in order to stroke the wheel cylinders out enough to apply the brakes. That was also my assessment from your initial post. There is a residual valve in the master cylinder that will hold a small amount of pressure in the lines. When you pump the pedal you stroke the wheel cylinders out slightly, the on the next pump you stroke them out slightly more, etc, until the shoes make good contact. At rest the return springs gradually overcome the residual valve and return the cylinders to their retracted position and refill the reservoir.

So, there's something not right with your shoe adjustment. You may need to pull the drums and gain access to a proper adjustment tool and work on getting the shoes properly adjusted. Which adjustment are you playing with? The eccentric pivot pins (major adjustments) or the adjustment cams up near the middle (minor adjustments).

Merle

I agree sounds like your cyl are moving too far out to start the breaking motion, any chance you got some hardware backwards in there? I've done it before and done TONS of brake jobs so happens to the best of us...that's why I always leave 1 wheel together and do them seperately so no confusion. I'm guessing with a 1 res. master it doesn't take much to drain the sucker and loose pressure....open it all up and start again...probably the easiest

[Andrew O'Brien]

I had a similar problem on my B2G, and found the piston actuator rod at the master cylinder was adjusted too far in and not allowing the internal check valve to close. If after sitting, are you able to pump up the brakes so you have a decent pedal, without bleeding?

Andy

[Jerry Roberts]

I had a similar problem on my B2G' date=' and found the piston actuator rod at the master cylinder was adjusted too far in and not allowing the internal check valve to close. If after sitting, are you able to pump up the brakes so you have a decent pedal, without bleeding?

Andy[/quote']

And your problem could be just the opposite too . The actuator rod could be too far out . You want just a little free play between the end of the rod and where it contacts the plunger in the master cylinder . ( very little )

[Guest P15-D24]

Low but consistently firm pedal = shoe adjustment. Center and adjust, pedal will come up.

Have to pump, but comes up to normal height. Release, reapply and pedal goes back down. Pump and it come right back up=you have a leak letting air in the system. Check all T blocks for cracks in the blocks, check all connections at wheel cylinders, crack in lines. Have your replace all flex lines?

Leaks can be a bear to find. Clean off all fitting with denatured alcohol and dry. Pump and apply the brakes on and off for 5 minutes, just keep cycling them. Then take a kleenex and dab each fitting looking for traces of brake fluid to show you where the leak is. You have a leak, period. Probably a cracked fitting or line.

Edited May 7, 2010 by P15-D24

[49powerwagon]

As far as the wheels not being together right, I lean away from that theory just because the brakes worked just fine for 8 months before this happened, and the wheels have never come off, and I can lock up each wheel with each shoe, so I know they are all macking contact with the drum. I checked for free play between the piston and pushrod, as well as making sure the releif port is uncovered by the piston at rest.

I replaced all the flex hoses when I did the lines, and inspected the blocks. I would think an air leak would show up in the form of air in the system, which never happened.

Right now brainstorming is all I can doas the truck is 350 miles away right now, so I won`t be able to try again for a few weeks.

[Guest P15-D24]

You have to find it or you will never solve the problem. Beg, borrow or make a pressure bleeder. Pressurize the system to 5-7 pds through the master. Wait 5 minutes and your leak will show up. It could be on a wheel cylinder.