car brakes by itself..help.

[Slammed Assassin]

Ive searched but some have only similar problems. When i drive about five minutes the brakes start to heat up and the car dosent want to roll in neutral. And the car has a hard time to take of from a light. After five minutes of driving i can smell brakes burning and my brake pedal begins to get stiffer and stiffer to the point wheres theres almost no play on the pedal at all. one time i got out of the car and the rims were too hot to touch...the car has new pads and rotors..please help i want to roll to the bash at the end of the month too....

[Alpha Residence]

Ive searched but some have only similar problems. When i drive about five minutes the brakes start to heat up and the car dosent want to roll in neutral. And the car has a hard time to take of from a light. After five minutes of driving i can smell brakes burning and my brake pedal begins to get stiffer and stiffer to the point wheres theres almost no play on the pedal at all. one time i got out of the car and the rims were too hot to touch...the car has new pads and rotors..please help i want to roll to the bash at the end of the month too....

I've had this problem in the past, It came to the point where I had replaced everything and nothing worked.

Proportioning valve in MBC could be going bye bye, from my knowledge it's usually the culprit. Have you replaced anything brake related lately? For starters you can try adjusting the actuator rod on the brake booster or a temp fix I used was to put a couple washers between the MBC and the booster.

[Slammed Assassin]

I've had this problem in the past, It came to the point where I had replaced everything and nothing worked.

Proportioning valve in MBC could be going bye bye, from my knowledge it's usually the culprit. Have you replaced anything brake related lately? For starters you can try adjusting the actuator rod on the brake booster or a temp fix I used was to put a couple washers between the MBC and the booster.


i just changed the pads and rotors but the problem was there before i changed them. do you think that there could be air stuck in the system still?

[JRas]

figure out why your brake calipers are clamping on your rotors..

I think what your experiencing is brake fade in the pedal.. because the brakes are always clamping on the rotor they overheat... it also explains why it may be slow taking off from a stop at lights.

good luck

[Alpha Residence]

i just changed the pads and rotors but the problem was there before i changed them. do you think that there could be air stuck in the system still?

I don't think so, it seems like the brake fluid is forcing the caliper to the rotor but is not returning when you are releasing the brake pedal. If there was air still in the system, I don't think it would prevent the fluid from returning to the MBC. It would just make for a mushy brake pedal and poor brake performance.

Try unplugging the brake booster, make sure you plug the line or you'll have a major vac leak. From there try taking the car slow around the neighborhood. You're not going to have power brakes and you'll have to hit the pedal hard but if the brakes don't lock up I think you can start narrowing down the problem towards the booster. If it still locks up I would have to assume it be the proportioning valve in the MBC.

[Slammed Assassin]

thanks^^ ill check it out..

[beto300zx]

i had the same problem, i put my 300zx brakes on and the same thing happend.
it turned out to be the brake booster, just raplace it and you should be fine.

[SoSideways]

Another person here that will say it's probably the brake booster.

Happened on my wife's 89.

We'd just be driving and all of a sudden it's as if she threw on the brakes and the car just doesn't want to go anywhere.

So we'd pull over to a gas station or something and shut down the car, pump the brakes a few times, and start the car up again. From that act, I guess the vacuum pulls on the diaphragm on the booster and loosen the brakes.

[Bumnah]

I'd like to say to check the caliper as well, but it would be locked all the time.


It's okay the first 5 minutes of driving, and then it acts up?

[Slammed Assassin]

I'd like to say to check the caliper as well, but it would be locked all the time.


It's okay the first 5 minutes of driving, and then it acts up?



yes its acts up after the first couple of minutes..i notice that if i pump the pedal while at a stop it goes away for another three minutes or so then comes back..

[g6civcx]

Seized calipers would be the most common cause.

[devnull]

Pinched/kinked brake line perhaps?

[superbike81]

I had this problem on my motorcycle. The rear brake locked up on me going about 50mph and I nearly crashed. Basically the caliper needed to be rebuilt, as it heated up, it expanded to the point where it would clamp down on the rotor. It wouldn't let go until I let it cool down for about 15 minutes, another couple minutes later it would heat up and lock again.

[murda-c]

Is there rolling resistance when you first start it up? Or when the car is off?

[Howlermonkey]

Brake push rod set too tight not letting master cylinder open ports that need to be opened.

Toyotas and Lexus cars had this problem when water would cause the clip that holds the piston into the master to rust.

Once it rusted, it also swelled not allowing the brake master to fully retract.

Same symptoms.

[georgesal]

make sure none of the brake hoses are kinked take the front calipers off their bracket and have a friend slowly press the pedal down dont let the pistons come all the way out. the try to push the piston back in if they slide in smoothly your calipers should be good. also when the brakes begin to lock up try un bolting the master cylinder from the booster leave the lines connected if the brakes loosen then your problem is the booster. if you still can't pinpoint it take it to a midas we charge 25 for a brake inspection. if you do a repair its free

[Slammed Assassin]

Is there rolling resistance when you first start it up? Or when the car is off?


theres no rolling resistance at all when i first start it up. but after a couple of minutes of driving that when i get a lot of resistance. In the morning the pedal is normal not too soft but after a couple minutes of driving the pedal gets pretty much rock hard.