So here's the situation for you guys. I just finished my trans and I wanted to take it to Rider to show off a little to my friends. So I'm driving around town and everything seems fine. I take it on the highway and everything is still going good. I get to Rider 10 mins later and I pull in the campus. While I'm cruising around campus I put my foot on the brake and it goes to the floor! :eek: I freak out and think my car is going to be smashed. Oh, and last year I took out the e-brake because is was seized shut. I'm thinking, "how am I going to get home with the rear making sqeeking noises and my brakes are now going to the floor". So then, I start pumping them up. And then they get some pressure and stop. While I'm back on the highway heading home the brakes just don't lose pressure, it literality goes to the floor. After pumping for 3-4 times is gaines more pressure and slows me down. I've heard horror stories about the wheel bearings heating up and boiling the brake fluild causing the pedal to go to the floor. What do you guys think it the problem here? It makes sqeeking noises now all the time in the back. And when I go around turns it gets worse. The noise varies with the speed of the car and not with the rpm of the engine. I hope somebody can help me figure this out. I'm thinking of replacing the bearings in the front and rear, and rebuilding my front brakes. My rear ones where rebuilt like 3 months ago and they clamp awesome which is why I'm getting a little freaked out. :cry

 

Have you checked rotor runout?

 

Look and see at the same time for leaks. Fill the master cylinder.
That would scare the bejeebees out of me. Get that fixed before something bad happens.

 

Have you checked the level of your brake fluid? A low level of brake fluid would produce the results that you explained. If your brake fluid level in your master cylinder is indeed low, then it is time to start tracking down the source of the low fluid (leak). Just something to look for.

 

Only one problem guys. The brake fluid level in the master cylinder is full. Didn't lose anything. Here's the thing. I've already rebuilt the rear brakes and I haven't looked at the front brakes yet. I'm actually thinking that I may have a bad front caliper. Any thoughts?

 

I think it may time to replace the master cylinder..

 

I'm with Bill. The only way I can think of that a caliper can go bad is if it leaks (and you'd see brake fluid slung out all over the inboard side of the tire). Master cylinders is cheap.

JB

'78SA

 

I don't believe you got back on the highway with no brakes :eek: :nono:
I would have found a shop, or a tow truck to get me home,
Thiink about how unsafe this was for your life (and vette)...

Hope you find the problem soon. But Please be careful when your testing it out...
:cheers:

 

 

I'm not sure how the master cylinder could be doing this. Could someone inlighten me a little? I took it to a automotive place today. The guy got in the car and drove it around the block on the highway. He says he didn't feel the brakes go out at all. So he says, if you're still having this problem then you should pick up a IR gun and take it with you for a test. When the brakes get soft, stop the car and hit all the rotors with the gun. This will help to pinpoint which rotor is creating the heat to make the brakes go out. I think if it was the master cylinder wouldn't the problem be there all the time? Not just when it heats up? If I'm mistaken somebody please correct me. Most of the people here have more experience than I do. :cheers:

 

Excessive heat will cause brake fade. What you experienced is not fade, but failure. The pedal goes to the floor because loss of hydraulic pressure. So 1) either your M/C is intermittantly losing pressure but more likely 2) air is being pumped into your brakes by excessive rotor rouout causing your caliper pistons to wobble in and out with each turn of the rotor...even more so at highway speeds...and we all know air is compressable. If you can bleed the brakes and have a firm pedal again...then you lose your brake pedal...IMO it's your rotor runout being excessive. I don't think your boiling the fluid.

 

Hmmm...when was the last time you bled the brake fluid? It's possible (at least in my mind) that the mushiness caused by air in the system could get worse as it heats up - hotter air=less dense=more mushy. Don't know if it would put your pedal to the floor though. Maybe there's water in there that starts boiling. Just a quick fix that you might try.

 

I bled these brakes maybe 3 months ago at the most. This is looking good for the front brake rebuild. When I had the tires off last year and I was spray painting the wheel wells I noticed that the front rotors had deep scoring in them. Of course the rear rotors had much more and I rebuild the calipers and replaced the rotors back there first. It's funny that when I took the rear calipers apart I noticed that just about all the pistons where siezed in the bores. I'm wondering how this thing even stops at all :confused:

 

I had the same thing happen on my 76....Did you check the vacuum line that goes to the brake booster..I believe there is a check valve were it enters the booster....My vette use to run hot and with no charcoal filter inline with the check valve when it got hot I would lose my brakes until it cooled down....Then It would stop fine....Good luck