[Mgs] Brake failure - What caused it?

[Andrew B. Lundgren]

  You have a slow leak some place.

Last week I had to replace a frozen front caliper.  One piston was 
frozen out and it was leaking very slowly internally behind the piston. 
I didn't catch it in time and ruined a disk.  I got the car in '96; as 
of last week the remaining pads were still only about half gone.  I now 
have new pads, rotors and one rebuilt caliper it breaks just like it did 
before the failure.  (I was hoping for some new stopping power as the 
old breaks were probably 20+ years old.)

My dad taught me to pump the breaks when they don't work the first 
time.  I am very thankful for that as it is a horrible feeling when the 
pedal goes all the way down.

On 08/24/2010 07:16 AM, Charley & Peggy Robinson wrote:
>  Here's a little trouble-shooting exercise for ya, gang.  I got my '69 
> B out of the garage after it had been sitting undriven for several 
> months.Backed her out, hit the brakes and the pedal went to the 
> metal!  Wound up on the grass next to my driveway, fortunately an 
> uphill slope.  So I look in the master cylinder and the front chamber 
> is almost dry - my bad, should have kept it topped up.  So I fill it 
> with Dot 4, do a little bleeding and get a nice firm pedal with no 
> leaking down.  Drove the car a few times in the cool of the morning 
> with no problem.
>
> Couple days later I'm pulling slowly into my garage, got to stop and 
> the brake pedal goes to the metal!  I almost yanked the handbrake 
> lever off the floor!  So after I changed shorts, I looked in the 
> master and it was still full.  Hopped in the car and tried the brakes 
> again and they worked fine with a firm pedal.  Brake lights work too 
> and there are no discernible leaks.
>
> I think I know what's wrong.  What's your take?