Brake help

[loganzillmer]

Hi all. I need some help with my brakes.

I have a '70 Fastback. When I got it, the car had no brake pressure. None of the lines leaked, but I decided to use this issue to launch the first stage of my build project and I restored the whole front end. When I pulled the master cylinder, it was in rough shape, and I found moisture in the frame where the end of the master cylinder meets the pedal rod, so I figured the fluid was leaking out of the master cylinder itself. I ended up replacing the master cyl, all of the front brake lines and hoses, including those going from the reservoir to the master. After this I discovered the previous main line that runs to the T in back didn't like the new master, as it leaked at that connection point, so I replaced the main line as well. No more leaks.

Finally I got to bleeding the brakes. I no longer am getting any air coming out of any corner, but when I depress the brake pedal (with a partner), I get no pressure still. If I pump a couple times rapidly it builds lots of firm pressure, but when I let the pedal all the way out, the first depress of the pedal has no pressure. And unless I pump the pedal quickly to build pressure, I get no pressure.

I have no visible leaks, and no air comes out of any corner when bleeding (Right front, left front, right rear, left rear in that order), but I have no pedal pressure unless I pump quickly.

I am at a loss and could really use some help. Thanks.

[old_man]

Did you adjust your rear shoes? If you pull/set the parking brake all the way does the pedal feel change?

[loganzillmer]

[loganzillmer]

I can be a little more precise.

With the parking brake set, the first press has no pressure. If I let the pedal all the way out and push it back in, I get some pressure. If I pump the pedal, it builds lots of pressure quickly. If I let the brake pedal out all the way (parking brake still set) some/most of that pressure stays. If I keep my foot pressed on the brake pedal, I don't lose any pressure. If I take the parking brake off with my foot on the pedal, the pressure stays.

With the parking brake off, the first pump of the pedal has no pressure. If I pump it builds pressure quickly. If I hold my foot, the pressure stays. If I let the pedal all the way out, the first pump will have no pressure. If I pump slowly, letting the pedal all the way out, it does not build pressure. If I pump quickly, it builds lots of pressure quickly.

Hope this helps.

[Mike Fisher]

Fig. 9-3 in Chapter 2 of the brown Type 3 Bentley says to bleed fronts before rears! RF,LF,RR,LR in that order.
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[loganzillmer]

[Bobnotch]

Make sure you adjust the hand brake cables so that when you lift the handle 3 clicks, it starts activating the rear brakes (they stop turning by hand). This gets the cable adjustment correct.
Then like oldman was trying to say, adjust the rear brakes (at the adjusters) until they are tight to the drum. Then bleed the rest of the air out of the system. Once you've done that, then back off the adjusters so the drum will turn. You can check your work by lifting the hand brake handle about 4 clicks, and the drum shouldn't move. If so, they're set.
By having the rears tight, you eliminate any place to trap air, which sounds like your problem (having to pump multiple times to build pressure). That long line takes a couple of minutes to bleed out, as it humps up at the rear to exit the floor pan. Sometimes I'll jack the rear of the car/pan up to try and get it higher than that point to move the air pocket (get the bleeder screws to the highest point).
If you've replaced the lines and hoses up front, you might have to bleed them several times to get all of the air out of them. They need to be bled first.
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[loganzillmer]

[Multi69s]

Logan, it sounds like you are doing everything right, or at least close enough to get a decent pedal. The one thing that I stress to my students, is just because something is new, doesn't mean that it will work right. There are three different parts that are made for VWs, where the quality has greatly diminished: Condensers, Ignition Switches, and Master Cylinders.

It really sounds like you got a bad one. I've seen this quite a few times, and tried to help others with it, but most of the time it was a waste of time. In fact yesterday I just ran into someone who is having the exact same problem as you (Market Place purchase). The methods that I have tried to help others: Pump pedal and crack bleeder, vacuum bleed, and reverse bleed, (pushing brake fluid into the caliper, or wheel cylinder towards the master). Nothing would work. I pulled the master apart and in every case the "piston" cups did not have adequate pressure against the bores.

The Master Cylinder is a very simple design. Unless it is totally filled with air, you will get pedal resistance. If you don't, the brake fluid is going pass the cups, and not expanding them against the bore.
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[loganzillmer]

[BobR24]

I am having the same issue. Was this ever resolved?

[Bobnotch]

[Bobnotch]