Locked up brakes.

[armerdan]

So here is my long sad story........

It all began 2 weeks ago when I was headed back from lunch.......

I went to stop and the brakes went straight to the floor. So I'm thinking ok master cylinder, it wasn't every time just about every 5-6th time they would just go straight to the floor with almost no braking at all.

So I replaced the master cylinder no problem at all, easiest thing in the world.

I took it out for a spin and it seemed fine till I tried out the ABS, now sure enough they don't go to the floor at all, they stop really well.....
Too well...

So well the car won't go, even when I want it to.

So I'm thinking ok, the fluid was a little (a lot) less clear then it should be, maybe there is some trash in the lines that's messing it up eh? So I completely bleed the system out replacing the fluid as I go with new fluid forcing the old stuff out with the new stuff, and I toss some SS lines in for good measure $104.00 from Summit shipped.

It drove fine until I decided to make her skid a little bit to test the ABS, They locked up good again.

Disconnecting the ABS makes no difference at all.

The only thing that works is letting some pressure out at the bleeder valve, and then it only works for a while and thy slowly lock up again as I use the brakes more, (or they quickly lock up if I slam on the brakes)

So my question is this.

Is there anything mechanical in the ABS system that could be letting the fluid only flow one way? Or could I have a bad proportioning valve? Or did I maybe just get a bad MC?

What do you think?

 

[SHOtimer]

Once you let it sit - overnight lets say does it loosen up? I had a similar issue when I replaced the calipers and lines in my car for the first time. I thought I had it bled out fine, nope. When the air heated up it expanded and caused my brakes to lock - when it cooled down they were fine. I just had to bleed the heck out of them.

You may have gotten air in your ABS system, which lets it out when you cycle it. I would bleed everything out really well.

Doug

 

[armerdan]

Yes, in fact they do unlock after it sits for a few hours / days.

I will "bleed the heck out of them" when I get home today and let you guys know.

Any other ideas?

 

[Phoenix]

Yes, in fact they do unlock after it sits for a few hours / days.

I will "bleed the heck out of them" when I get home today and let you guys know.

Any other ideas?

Pedal to the floor is

1- You have air in the system

or

2- You have a leak with the hardlines/calipers.

Bleeding a SHO is hard , bleed the **** out of it , do all 4 wheels , then repeat 4-6 times. That should be good.

 

[SHOtimer]

Bleeding a SHO is hard , bleed the **** out of it , do all 4 wheels , then repeat 4-6 times. That should be good.

Indeed.

Doug

 

[armerdan]

The pedal to the floor symptom seems to have subsided after I replaced the Master Cylinder, at this point I'm more concerned about getting them unlocked.

Of course I will bleed them again when I get home and post back, I'm just wondering what else other than air in the lines, or a leak could cause my brakes to lock up, since I'm pretty certain that I don't have a leak.

 

[armerdan]

Well, I finally got the chance to bleed them again, and I took it out for a test drive, I drove it around the neighborhood for about 15 minutes, taking it pretty easy and stopping nice and slow, then a little faster, and it seemed to be fine until I slammed on the brakes at 35. As soon as the ABS kicked in the brakes locked up again.

Any more ideas, or am I out of luck?