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Gunk build up inside the brake lines, gunk get stuck right where the line has a bolt on clamp,fluid pressure will only go to the clamp on the hose to the brake caliber but not back to the master cylinder.Two ways to check :have someone press the brake pedel,take off master cylinder cover and have them release the pedal look at the fluid return into the reservoir,it should fill fast,if it's slow most likely the line,if no flow at all it's the caliber. Or jack the front wheels up press the brake petal when release spin the wheels if its hard to spin it's the lines,if no spin it's the caliber.Please note if your car is front wheeldrive take it out of gear regardless of make and model use Wheel Chokes and emergency brakes when checking and repairing!Do not bleed the brakes flushing is alot better.

Contaminated brake shoes or pads or an ABS (Anti Lock Brake) sensor, could cause one of the wheels to lock while braking.


If by "lock," you mean the wheel suddenly stops turning, there can be several causes:

In general, static friction is greater than dynamic friction. (Static means not moving and dynamic means moving) An example of that would be when you push something across the floor. The force needed to move the object generally decreases once that object starts moving. The same is true for your tires in contact with the road. When they are rolling, the surface of the tire is not moving relative to the road. When the tires begin to skid, they are moving relative to the road. Skidding actually slows the car less than braking just slightly below the traction threshold of the tire.

Locking due to mechanical problems: If a brake disk or drum is not uniformly shaped (warped), the braking force will not be uniform as the wheel rotates. In this case, you may find that the brakes pulse or even lock the wheels when traction is low. The solution is to resurface or replace the disk or drum.


You have a pinched brake line. Inspect them all.


Pull the wheels and look. I would expect to find a leaking wheel cylinder(s). When they leak, the fluid gets on the shoes and cause a lock-up situation. As you drive more the fluid spins out and the lock up is less severe. Are you losing fluid?


Well if you pedel goes almost all of the way or does go all the way to the floor then the master cylender is bad.

you might have a leaking wheel cylinder or a caliper that sticks and does not release properly. or if it is panic braking, its just because you may not have ABS.

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โˆ™ 2011-09-14 00:07:47
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Q: Why does the brake lock during braking?
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Related Questions

What is a EBCM failure?

EBCM stands for electronic brake control module. The purpose of this is to sense if the wheels are going lock-up during braking, and then make adjustments accordingly. If this switch fails, then your anti-lock braking system will not work properly.

When braking a vehicle equipped with anti lock brakes the driver needs to?

The driver would need to step on the brake pedal when braking a vehicle equipped with anti-lock brakes. FYI, the driver would also need to step on the brake pedal when braking a vehicle that is NOT equipped with anti-lock brakes. Hope this helps.

Abs brake system?

ABS stands for "Anti-Lock Braking System" which means that the brakes won't lock up and cause a crash or skid.

What is the ABS system in a car?

Anti lock brakes. The system uses a computer, valves, and speed sensors to control wheel lock up during hard braking.Anti lock brakes. The system uses a computer, valves, and speed sensors to control wheel lock up during hard braking.

Braking just short of lockup is known as?

The technique of braking short of lockup is known as threshold braking. Modern cars have anti lock brakes to help prevent from going into full brake lockup.

What is the first step of the threshold braking technique in vehicles that do not have anti lock brakes abs?

Pump the brake pedal

When skidding should you apply a quick motion pumping to your brake?

No, if your car has ABS (Anti-lock Braking System) do not pump your brakes. The anti lock system does this for you.

What does ABS light mean?

ABS = Anti-Lock Brake SystemIf you have this light come on while not braking, it most likely means there is a problem with the electronic controls in your brakes. If it comes on while you are braking, it means the Anti-Lock has kicked in. It should only do that however, if you are braking really hard.

What does the ABS light on the 1998 Toyota 4 runner mean?

This light warns that there is a problem somewhere in your anti-lock brake system. If the light comes on while you are driving, have your vehicle checked by a Toyota dealer asap. The light comes on when the ignition key is turned to the ON position. After 3 seconds it should go out. When the "ABS" warning light is on (and the brake system warning light is off), the brake system operates conventionally but anti- lock brake system is not assiting brake performace so that the wheels can lock -up during sudden braking or braking on slippery road surfaces. Vehicles with rear differential lock system- The anti-lock brake system does not operate when the rear differential is locked. It is normal operation for the "ABS" warning light to be on at this time.

What does Brake Assist system mean?

Basically, a brake assist system monitors the driver?s use of the brake pedal, automatically sensing an attempt to stop the car as a result of panic. It then generates very high braking power, even when the driver is only pressing lightly on the brake pedal. When this is used together with anti-lock braking systems, it results in faster and safer braking. Source:

How is anti lock braking system applied?

Push hard on the brake pedal when your moving. If the wheels start to lockup ABS will be activated.

What causes brakes to lock up during moderate braking?

Caliber is sticking. More than likely the brake fluid is contaminated with moisture which has caused the brake caliber to rust. I would recommend you have your brakes inspected and replace any caliber that is sticking. Also have the brake fluid changed immediately.

How many braking systems a vehicle should have 4 or 5?

Normally, a vehicle has ONE braking system that includes the brake pedal, the brake master cylinder, newer cars then have the Anti-Lock Braking System, then there are either disc type or drum type brakes at each wheel, and everything is connected with small metal and rubber hoses that allow the pressurized brake fluid to activate the brake pads and/or brake shoes that cause the friction necessary to slow your vehicle.

What are EBV in a car?

EBD: Electronic Brake Distribution (or Electronic Brake-force Distributor) - alters how much of the brake force goes to the front and how much to the rear. Cars always have more braking on front as if the rears lock before the front then the car will spin. How much braking you can do with the rears depends on how much weight is in the vehicle so EBD dynamically adjusts this balance. Without it, the manufacturer sets up the balance so the rears don't lock when the vehicle is empty which is less braking than is possible when the vehicle is full.

What is the proper way to brake in an emergency situation with non anti lock braking system brakes?

dont slam but push on the brake and do not turn this will make you spin out of control and get hurt even more.

Where is abs wheel sensor in Lincoln town car?

The anti-lock brake control module is located in the engine compartment on a bracket that is attached to the radiator support . It is an on-board diagnostic non-repairable unit consisting of two microprocessors and the necessary circuitry for their operation. These microprocessors are programmed identically. The anti-lock brake control module monitors system operation during normal driving as well as during anti-lock braking and traction assist cycling, if equipped.

What is the present participle of brake?

Braking is the present participle of brake.

When braking a vehicle equipped with anti-lock brakes the driver needs to?

press down hard on the brake pedal, and continue to steer the vehicle.

What does abs do on a motorcycle?

Antilock-braking-system......if you brake too hard and lock your wheel an electrically operated piston connected to the brake hose will reduce the pressure until wheel starts turning again.

Anti-lock braking systems are very good on wet roadways with less then normal or little friction?

The anti-lock braking system usually reduce the skidding that occurs when tires lock and therefore allows the driver more control during emergency braking. Having the tires on ABS can help a stranded driver to veer away from emergency situations.

Does a 1988 Volvo 240 dl have anti lock braking?

No. The Volvo 240 Series of cars did not receive Anti-Lock Braking until 1991. It does, however, have a four wheel disc brake setup with four calipers per rotor on the front axle, and two calipers per rotor on the rear with a triangulated braking circuit, as opposed to a conventional split braking circuit, which happens be found in the ABS equipped models.

If 1996 Tahoe have ABS module Then why the rear wheels lock in when brake strong?

if you are braking under 15 mph abs does not activate or it does not have 4-wheel abs

What is the first step of the threshold braking technique in vehicles that do not have anti-lock brakes abs?

Pivot your foot to the brake pedal and press firmly with your toes.

What is the proper way to use anti-lock brakes in an emergency situation?

Push down on the brake pedal and hold it there, do not pump.Apply the brakes in an even manner until the braking system starts to pulse and vibrates the brake peddle. This is how anti lock brakes tell you you are getting the most available braking from them.Keep enough pressure or force on the peddle until the vehicle comes to a stop.

Why do brakes become hot if driving in city traffic?

The brake discs get hot with frequent braking during traffic.