FAQ 72

Question: I have a 1973 Beetle and the brake pedal had no pressure. I changed the rear brake line, the wheel cylinders and the master cylinder. When I bled the line it appears all of the air is out of the line and I adjusted the brakes. I still do not have any pedal pressure. Do you have any ideas on what I need to look for?

Answer: You have to bleed all the lines, even if you only work on one. Start with the rear right, then rear left, the front right, and last the front left. Do not allow the brake reservoir to run dry or you have to start all over again.

If you knew all that already, then read on...

If you bleed the front brakes first, when you go to bleed the back the pedal won't go down to the floor all the way. I ran into this problem when I accidentally got air in the system by letting the reservoir run down while bleeding the rear.

I opened the front bleed screw, and bled the rear again. Needless to say, this goes through a lot of brake fluid. I think it works to have the front bleed screw open just a little bit. It may also work to slacken the front brake shoe adjuster to the front wheel cylinders extend to max - just be sure the front pistons extend too far and come out. It should be fine as long as you keep the brake drums on while bleeding.

I wonder if the late model master cylinder is different. Even after going through a couple of gallons of brake fluid, my brakes are not as firm as pre-master cylinder replacement. I only replaced the master cylinder becuase it had started a small leak.

It is also possible that since I did not turn the drums, that the small ridge on the the inner edge of the drum (inner is towards the center of the car) is hanging up. It may well be that the brakes will be mushy if the brake shoes aren't adjusted correctly.

Still, if I pump my brake twice, the pedal is lower the second time. It doesn't go down after that. Something is still no right with my brakes, and I think it has to be the master cylinder.

Early cylinders had a flow restrictor on each line. Apparently, this was machined into the later model master cylinders. It is possible that you and I both have an early master cylinder, and that the parts suppliers either don't know or don't care.

I'm sorry I don't have a more concrete answer to the mystery. My brakes are fine, but not as good as the should be. Try my suggestion about releasing pressure on the front so the pedal will go all the way down when bleeding the rear.

Also, make sure you have the proper clearance on the push rod. It should have a tiny amount of play (about 1/8 inch of pedal travel, which is about 1 mm (less than 1/16 inch) of play in the master cylinder push rod. If the push rod cannot fully return, the brake cylinder pressure return won't work, and the air will never be fully pushed out.

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