Soft brake pedal after replacing rear brakes and master cylinder 2003 Audi A4
Changed rear brakes in vehicle, afterwards had a soft pedal. Suspected it was a bad master cylinder, replaced master cylinder. After replacing and properly bleeding master cylinder, problem still persists. Soft pedal. Removed calipers and there is no pressure to the rear brakes at all. Very lost on this one. Any advice would help!
My car has 102000 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
Hello. If you have no pressure to the rear calipers at all and if the master cylinder is new then you may have forces some debris into the ABS unit when you compressed the pistons in the rear calipers. In some cases the system can be pressure bled to fix it but it may need a new ABS unit.
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You need to double check the installation since you may have put the brake booster rod on the brake pedal wrong causing binding of the brake switch and causing the system to not bleed correctly. Also make sure the brake booster to the brake master cylinder push pin is adjusted with the proper clearance.
Air in the brake line(s) is the most common cause of a soft/spongy brake pedal. If air gets into the brake lines, it can prevent brake fluid from flowing properly, causing the brake pedal to feel spongy or soft. If the brakes are soft or spongy, this is a good time to change or flush the brake fluid.
The master cylinder is the usual suspect due to the internal seals having failed. This can usually be diagnosed when a somewhat soft pedal gets worse. Pump the pedal gently and then hold the brake pedal.
If your car has rear drum brakes and the brake pedal goes to the floor, the rear brake shoes could be out of alignment. Sediment. Sometimes when new brake pads are installed, sediment can inadvertently be pushed back into the hydraulic system. This sediment can damage the master cylinder.
After you change your brake/clutch master cylinder kit or replace the master cylinder assembly, you must bleed air/fluid to prevent `trapped air` in the system after installing. There would be an `air pocket` in the line.
When your ABS system malfunctions are can also cause a spongy brake pedal. Your ABS system is designed to allow the driver to maintain more control of the car in a high-speed stop.
The rear brake may normally feel soft because of the longer cable allowing more space for the oil to expand into when you press your lever as compared to the shorter cabled front brake.
Unscrew the brake master cylinder reservoir cap. Using a funnel, slowly pour the brake fluid into the fluid reservoir while keeping the brakes pressed down to create pressure and push out any air bubbles forming. Be careful not to exceed the maximum brake fluid level.
A spongy brake lever, or a brake lever which has to be pulled a long way before you feel the brake start to work, is a sure sign of air trapped in the brake system. Some brakes can be more troublesome to bleed than others. Even after multiple bleeds air can remain trapped inside the caliper.
Usually, your brake pedal will sink if the ABS or master cylinder cannot maintain the proper hydraulic pressure. This inability to maintain hydraulic pressure will not only make your brake pedal sink to the floor, but it will also make it much more difficult to stop your automobile.
Symptoms include: poor parking brake operation, when the handle or pedal travel is excessive without adequate function; a low brake pedal that must be depressed farther than usual; or mild pulling to one side during stops.
Go to the brake master cylinder, and all you have to do where the brake lines are, is loosen all the lines. Then, if you go down, and the wheels spin freely, that means that master cylinder was sticking because when you open those lines that would take any pressure off the master cylinder.
Go to the brake master cylinder, and all you have to do where the brake lines are, is loosen all the lines. Then, if you go down, and the wheels spin freely, that means that master cylinder was sticking because when you open those lines that would take any pressure off the master cylinder.
This can be due to a number of problems: a leak in a brake line, a loss of pressure within the master cylinder itself due to a failed seal, or air being introduced into the braking system. Your first reaction to encountering spongy brakes should be to rapidly pump the brake pedal with your foot.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
Soft brake pedal after replacing rear brakes and master cylinder 2003 Audi A4
ANSWER : Hello. If you have no pressure to the rear calipers at all and if the master cylinder is new then you may have forces some debris into the ABS unit when you compressed the pistons in the rear calipers. In some cases the system can be pressure bled to fix it but it may need a new ABS unit.
Low brake pedal and anti-lock brakes are not kicking in.
ANSWER : The brake pedal is working to stop the vehicle, but there may be air in the controller unit causing the ABS brakes to not function. I recommend bleeding the brake system from the farthest location from the master cylinder to the master cylinder including the ABS unit. If the brakes are still spongy after a full bleed, then the controller will need to be replaced. If you need further assistance with your brake pedal being spongy, then seek out a professional, such as one from Your Mechanic, to help you.
Changed brake master cylinder, bled 10 times, and the pedal is soft The rear brakes are not locked but close. Truck now running rough.
ANSWER : You will have to bleed the brakes from the farthest location all the way to the master cylinder. There is still air in the lines causing the issue. Check the vibrations on the vehicle to see if the engine mounts are damaged or if the brakes are not releasing causing the engine to run harder than normal to overcome the braking force. If you need further assistance with your vehicle’s brake system, then seek out a professional, such as one from Your Mechanic, to help you.
I just replaced my brake master cylinder and the brakes still feel soft. What do I need to do after I replace the master cylinder
ANSWER : From what you’ve described you will have to bleed your brakes. Also, I believe you may have a leak in one of the lines. You may want to use a wrench and tighten the lines a little more. If you’re unable to fix this yourself, consider YourMechanic, as one of our mobile technicians can come to your home to bleed your brakes, diagnose the Check Engine Light, and help you make the appropriate repairs to your car.
Hard brake pedal and rear brakes locking up.
ANSWER : Hi. I will help you with this issue you are having with your 2001 Durango. Unless you bled the master cylinder, it is possible there is still air in the system. If you car is equipped with ABS, air could have also gotten trapped in the ABS modulator. If ABS equipped, a bi-directional scan tool would be essential to manually activate the ABS system to clear air from that segment of the lines while you are bleeding the system. It is also possible that in all of this work somehow the proportioning valve has been affected causing the desired pressure differential, front versus back, to get out of spec. Using a 2,500 PSI gauge, you can check the pressures at each wheel and that will definitely give you a clue as to which brake circuit is the issue (or both), whether the proportioning valve is working properly and whether the line pressures at each wheel are within spec. Should you need a second opinion, by all means feel free to contact YourMechanic for assistance and we will diagnose and repair the issue for you.
hard brake pedal with engine off no pedal when started replaced all brakes rear clyinders and master cylinder no air in lines
ANSWER : From the description provided, my first step would be double checking the connections at the master cylinder as well as double check the flexible brake lines at each wheel. A small leak can duplicate the brake pedal falling to the floor. If you are 100% certain there is no air in the system, it is very possible that your F-250 may have a faulty brake master cylinder.
The brake system on the your 1987 Ford is pretty basic and if there are no leaks, then it is VERY likely the master cylinder is the problem. If you are performing the work yourself, you may want to try exchanging your brake master cylinder for a new one.
Be sure to properly bench bleed your brake master cylinder before installing it on to the brake booster as well. I would then bleed the entire brake system at each wheel just to be sure there is absolutely no air in the system.
Of course if you did not perform the work yourself, or if you feel like you’re stuck, then I would recommend enlisting the assistance of a certified technician. They will be able to quickly determine the reason for your brake pedal falling to the floor.
Supportive bar attached to brake pedal interrupts proper braking process
ANSWER : It’s possible to have someone alter the brake pedal or adapt a brake pedal from a different vehicle. You may call around to some customization shops to see if anyone is interested in taking on the project. But first, I would try reaching out to the selling dealer with your concern – especially since it is a new model. Good luck.
Rear brakes not grabbing – 1995 GMC K2500
ANSWER : Hello. It is not in the ABS, but may be the proportional valve not giving the correct pressure split front to the rear. The vehicle never had enough pressure for the rear brakes. Have the rear shoes adjusted properly if you have drum brakes. You should check to see if there is an updated part to replace the old one. If you would like to have this done, a certified technician from YourMechanic can inspect the brake system and let you know what repairs are needed.
