Thread: Breaks go to floor to stop, new brakes, no leaks.

02 GTP 90K

I cannot seem to find any problems with the breaks as far as calipers, and pads. To stop the break pedal needs to be all the way to the floor. ABS light is on but that's from my FL wheel speed sensor, I thought the sponginess was because my rear pads but I replaced them and the problem persisted. I read about internal leaks inside the break booster can cause this problem but when the car is off and I step on the breaks they are firm and don't seem to budge. Could this be a MC problem? Any help is appreciated! Thanks

try bleeding the brakes, if that dont work it could be the master, when they go bad, the pedal goes to the floor and you have no brakes really.

the bad hub will also mess your brake pedal up if its moving enough. every time a hub goes bad, my brakes feel like crap, all spongy, soft pedal feel, new hub, they are solid again.

May be a dumb question, but you didn't clarify. Is the master cylinder reservoir topped up? Has it been too low if you had to top it up? Air doesn't just get in the lines by chance. It sounds like either that, or maybe a bad master cylinder. Try what he mentioned first ^ and if you still don't have a good pedal while the car is running, and have no leaks, the master may be bad.

Scotty beat me to the other possibility, a bad master cylinder.

Yes the resivior is topped off, and Scotty how is it the breaks are effected when hub goes out, I understand that when the hub goes abs and trac are no longer functional but what changes as far as brakes and break pressure? I know the break pressure has to go through the ABS module? I will try bleeding first. Can someone tell me the order of bleeding?

What happens is, the hub and rotor and tire moves, the caliper does not, so the caliper has a hard time clamping on the rotor when it moves side to side.

Sounds like an internal seal is gone in the master cylinder.

Here's a way to tell the difference between air in the system, and a bad master seal. When the car is off, you said the pedal does get somewhat hard. Hold it down and keep applying pressure while the engine is off. If the pedal just stays there for at least a minute or so, there is air in the system. If the pedal slowly sinks, a seal is gone or there is a leak(you said no leaks, and master was full, so that's not it)

just a fyi, the master will leak from the rear of it, where it bolts to the booster, look for a wet trail under it and down the booster, mine was leaking, just a little bit, felt the pedal losing pressure if i held them for a long time. the leak was small, i cleaned it up with brake cleaner, then watched it for the next few days, and it got wet again.

I've actually heard of the booster sucking brake fluid from a leaking master cylinder. If the booster has a vacuum leak, and the rear seal in the master leaks, you can actually burn brake fluid. It sounds crazy but it can happen.

Also, a bad internal seal can cause a sinking pedal, the fluid just slips past the seal (internal leak)

Okay, thanks for all the replys guys, Navy I tried that with the pedal and it seems to not budge at all. Girlfriend has the car right now ill check where the booster bolts on and see if theres any leaks. Im not sure if it helps but when you first start the car when you go for the breaks to put it in gear it sinks straight to the floor, second pump is decent enough to shift out of park this leads me to believe something to do with the booster, it will do this the first pump with the car on or off.

if the booster was bad the pedal would be hard as a rock all the time, like when you turn the car off, you get a pump or two with power, then the pedal gets harder/ very firm.

if it gets hard after you turn the car off, id think you got air in the lines. hard means the pedal wont move but a little bit, if you can push it to the floor the master is dead.

Yes, the booster is simply helping you press the pedal using engine vacuum. It's not the cause of the low pedal.
By everything you've described, it seems there is just somehow air in the system. Bleeding from all 4 wheels should solve the problem.