unpredictable brakes

I have a 1970 Bug with standard drum brakes.

Recently I replaced the master cylinder, then pressure bled the brakes and readjusted them.

Now, the brake pedal works normally *most* of the time, but occasionally it sinks almost all the way down to the floor when pressing the pedal very slowly & gently. Any ideas on what might be causing this unpredictable (& somewhat alarming) behavior?

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Chip San Francisco, CA

I don't trust the "new" M/C.

Very suspicious.

Speedy Jim

I just started driving a 69 beetle thats doing the same thing , It seems that my rear right wheel cylinder is leaking. Look to see if you have any wetness on any of your inner rims.

Does it seem like your losing any brake fluid?

Also look at the area around your pedle assembly, I have dealt with many that have small leaks do to rust in the main line running to the rear brakes.

Mario Vintage Werks resto

I second that! If you don't have any fluid leaks get another M/C!

"dave AKA vwdoc1" schreef in bericht news:BScoi.27194$ snipped-for-privacy@newssvr14.news.prodigy.net...

Is it possible that he just didn't bled the brake "good" enough so there is still air inside? I've had something simmular; if I braked to stop (for a trafficlight or so) and than took my foot of the brakes and then braked again I felt the brakepedal sink deeper. After bleeding the brakes again it all was good...

Roger

Sounds likje an internal bleed inside the master cylinder. A piece of dirt or a rust flake somehow got in there and gets jammed between the bore and the piston seal?

Jan

snipped-for-privacy@aol.com wrote:

That actually sounds more like the problem I've experienced.

Jan wrote:

OK. So before I start grumbling about having to replace the MC again, it sounds like a thorough leak inspection and a more careful brake bleeding would be a good place to start.

Also, since I started working on the car again, I've noticed that the emergency brake sometimes causes the rear brakes to freeze against the rear drums. Taking off the drums & checking on the wheel cylinders is something I have to do anyway - I may just need to do it a little sooner than I expected. And, come to think of it, the rubber hoses haven't been replaced in more than a decade.

Thanks for your suggestions / brainstorming! I'll let you know what I find.

Chip San Francisco, CA

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