Brakes to the Floor, Also

[SuperG]

As I finished up running some errands last week after work, I came to a stop sign in my neighborhood, when suddenly there was this Pshsh and I had no brakes! The pedal was to the floor and I was barely slowing down...thank goodness I was taking it easy and there wasn't a car in front of me.

I drove up a slight hill and re-established brake pressure, but as I pulled into the driveway, it sounded like there was a nasty kind of grind from the front...I was too tired to look at it when I got home.

The master cylinder is still full and I can't find any leaks. I took the pads off the front end and one of the pads appears to have simply disintegrated. So this could be the culprit. Perhaps enough space developed such that the caliper piston moved so much, that the brake pedal travelled all the way to the floor, right?

So with a new set of pads (thanks lifetime warranty at O's), turned rotors, and bleeding the brakes, you'd think I have new life in the brakes...Nope!

Pedal still mashes to the floor, although the brakes seem to engage. I can pump the brake 3 times to get pressure and normal feel, but as soon as I let off the brake and re-apply the pedal goes straight to the floor.

Is it possible there is still air in the lines (I heated them up pretty good at the track - back in May!)? Tonight, I'll bleed the brakes without relying on the inline check valve on the bleeder setup, but close the bleed screw after each brake pedal push.

After that, I am at a loss. I don't know how to check the MC for proper function, but it seems more and more that the MC is bad. Any ideas on where I should have this replaced?

Thanks for the help!

 

[Speedy_91_SHO]

Is there any chance you boiled the fluid and got air in the lines? Have you bled the lines to make sure there is no air in the lines? It sounds weird, but tok off the MC and look in the booster if there is fluid in there, get it out and that should do it. Other than that, the MC may be bad.

 

[Ishodu]

IF you did indeed have a pad crumble there will be a few pumps of the pedal before it would push the piston out to take up the space. After that it should get hard again.

 

[SuperG]

Well, new pads are back in and the piston and pads are now against the rotors. So I don't think that's it...

I will bleed the brakes tonight and check the booster.

Thanks!

 

[SHO SPD]

Sounds like the MC to me.

 

[Bob Gervais]

Was this problem ever solved? I ran into the same issue with my 91, after doing the 96 upgrade. Replaced the master, bled a bunch of times (with the ABS tool as well), and I'm still having the same problem.

 

[SHO SPD]

is your pedal going right to the floor? Did this happen only after you installed the 96 brakes? Do you have a brake warning light on? How was the master cyl bled? you might want to try bleeding the master again.

 

[SuperG]

I still have WAY mushy brakes after bleeding, so I am leaning toward replacing the MC...

 

[Allmostall]

Bob,
Glad ot see you are still around. Still waiting for my FSTB!!!
Best Regards,
Bruce

 

[jessemachone]

Sounds like the master cyl is bypassing internally to me. I've seen it before. I would start there if I were you.

 

[SuperG]

Here's an update on my brake problem...The right, front brake pad's anti-vibration clip jumped out of the groove and was preventing the outer pad from squeezing the rotor, hence the mushy feel and "rub rub rub" sound.

I consider myself both lucky and stupid...the problem could be seen through the wheel...all this time and frustration over nothing!

Everything is back to normal and I am ready for some high speed runs again...