Firm brake pedal, low brakes, pump to stop bus - Solved!

[don.ville]

67 bus with dual master cylinder.
Changed a broken Right Rear wheel cylinder, new brake shoes, and other parts replaced.

Brakes don't feel the same after bleeding just the rear cylinders 3 different ways:
Slow drip .
One man bleed with the little cup
Old school pump and hold with a friend....

At speed, brakes feel firm, almost like pedal has bottomed out, with pedal at mid-travel, but not slowing down the bus, (feels like brake fade).
Release and press again and brakes feel great....

I did not mess with the front brakes at all, think I need to bleed those based on symptoms?
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[DubStyle]

Pump brake fluid from the cylinder you replaced to the MC. I had something like this happen on my 63 many years ago. I must have bled the brakes old school 50 times until I pushed fluid through. Then it worked fine.
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Anthony

SBS #1
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[ToolBox]

Bleed it more and do it the way it is described in the manual. 67's have a different bleed sequence. Then bleed it some more.

[flemcadiddlehopper]

Try this: one person works the pedal, one person at the WC bleeder.

Open the bleeder screw a fair bit. Have the pedal pushed down all the way, then just cap the bleeder with your finger. lift the pedal and push it down again, letting the pressure release with your finger. With communication between the two of you (up, down), and topping up the master with fluid, you can move a large amount of fluid very quickly. This way any air trapped in the system doesn't have a chance to settle.
Once you get good fluid flow close the bleeder and go to the pump and hold bleeding method.

Chances are you let the master run dry on that part of the circuit. Bleed all the brakes and adjust them too.

If it bleeds well and you have a good pedal feel, then after a while it begins to go back to how it felt before, one of the other wheel cylinders could be sucking in air, or the master itself is pooched.

Gordo.

[Major Woody]

You probably know this but the reservoir must be kept almost totally full during the bleeding process or you will suck air and have to start over again.

[swervyjoe]

Check for durrs on the backing plates.

[don.ville]

[flemcadiddlehopper]

Any of the vaccuum type of bleeders are not the best to use. They can be OK for starting the fluid flow for a gravity bleed, but when you suck the fluid through you are always grabbing small amounts of air that come in past the threads of the bleeder screws.
For me, no matter what method you use to start the fluid flowing (vaccuum, gravity, pressure bleeder,or old school pump past finger cap) , you should always finish with the pump them up, hold and pop bleed method. Don't stop until you are satisfied with the results.
Please check for leaks and a solid pedal. Have "Hagrid" stand on the pedal with force and watch everywhere for any signs of leaks. And don't test drive it where there is a dead end or a cliff. I know it sounds obvious , but you would be surprised what people do.

Gordo.

[don.ville]

Thinking of using my tire air pump to the vac spout and hooking the outlet of the bottle below to the bleeder screw, and push fluid thru back to MC

Thoughts?

I Plan to Flush and Bleed front brakes tonight...
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[BarryL]

[don.ville]

[DubStyle]

Sorry I didn't repy right away you need something like the one below. Also is your push-rod adjusted correctly?

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Anthony

SBS #1
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"The original & best lowered Split Bus website/club"

[Eric&Barb]

http://www.thesamba.com/vw/forum/viewtopic.php?t=525161
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[don.ville]

I am using the bleeder pictured above, and decided to get another one since mine fell into my oil drain pan and oil/brake fluid got into the hose.

Picked up the new one today and the instructions say, make sure the container is held ABOVE the the bleeder screw.

I forgot to do that.
I just let it hand from the bleeder screw by the hose and went pumping...

Rookie mistake, I will repeat the bleeding on the rears with the bottle held above the bleed screw.
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67 Standard 11 window How I Keep My Bus Alive
04 Jetta TDI Page (SOLD)
01 Mexican Beetle Hello Kitty Rescue (SOLD)
29 Ford Model A Rat Rod (SOLD)
2015 Audi A8L TDI Quattro

[don.ville]

Thanks for all the tips.

Brakes are awesome now!!! high pedal, stops firmly, even the emergency brake can stop the bus from speed.

I got a new one-man bleeder with the magnet to hold it above the bleeder screw height.
All the brake shoes needed adjusting (a lot).
There was a little air in the lines, but I flushed through about 3/4 of a large bottle of brake fluid

1. Loosened both front bleeders
2. Filled reservoir, pumped and filled, pumped and filled, until garage floor was flooded , tightened bleeders.
3. Adjusted front shoes
4. Locked rear shoes using adjusters
5. bleed each side using one-man bleeder raised above bleed screw.
6. pumped pedal until fluid in hose was clear.
7. tightened bleeder screw, backed off rear brake adjusters until wheels spun freely.

Thanks for all the tips and suggestions.
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67 Standard 11 window How I Keep My Bus Alive
04 Jetta TDI Page (SOLD)
01 Mexican Beetle Hello Kitty Rescue (SOLD)
29 Ford Model A Rat Rod (SOLD)
2015 Audi A8L TDI Quattro

[Eric&Barb]

Congrats!! Good to read all is working.
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[BarryL]

Yes, what ^^^^ E & B said. Now you're safe. Only thing I've noticed about the "one man" problem is, if you don't get back to shut the bleeder relatively quickly air will suck in past the bleeder screw threads so that every time more that you bleed it will appear there is another bubble. It still works good enough. The best way is with two people that know what's going on.

[don.ville]

[Eric&Barb]

Good to put grease on the threads of the bleeder valves, and other threads of the brake system. This probably would help keep air from being allowed in with that kind of bleeding. In our experience is really helps keep the rust away in our wet PNW weather. Nice to be able to take the brake system apart with no stuck threads after even ten years!
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[coreyajones]

Had a similar issue on a Brazilian Bus. I had a firm pedal but occasionally it had no stopping power unless I gave it a single pump first. I assumed it was a bleeding issue and bled the brakes many times having my kids pump and hold the pedal.
I had previously adjusted all the stars on the shoes when I first got the bus 5 months ago.
I realized the adjustment on the pedal didn't have the 1/8th-1/4th clearance it needed so fixed that and took it for a drive. It was worse than ever. Very little stopping power.
I came back home and started adjusting the front stars again just for shitzengiggles. I found they could all be adjusted out a little, but one of the 4 on the front could be taken out a ton.
When I got in the bus and pressed that pedal, it was higher than ever! Took it for a drive and it stops on a dime...well, maybe a half dollar.
When I got back, I found the front wheels were pretty hot so I took the adjustment in just a tad to keep the shoes from dragging too much.