samsamsam

Hello,

My B7 A4 avant 6-speed got a seized caliper on the driver side rear. the rotor has rusted surface since caliper pad is not making contact. Once I press brake pedal the car vibrate like crazy. and steering also shaking as well. Not to mention the hand brake feels very weak, I have tried 30 mph and apply hand brake just feel a little bit brake...

I did some research, but I still not able to figure out some of my concerns:

1. If i replace caliper without bleeding, then go to dealer few days later ( so hard to make appointment at my place) to reflush brake system includes all brakes and clutch. Will that damage my new caliper? ( I know I will have few days got only 3 brakes, but it has been about two weeks.)

2. based on picture do I need a new rotor and pad? the pad still got decent amount left.

3. Could the soft hand brake caused by the seized caliper? or I still need to re-adjust the hand brake tension screw.

4. I found steering wheel shake while braking normally caused by front brakes. if I flush the whole system could that solve the problem?

I appreciate for any input. sorry for many questions all together.






Thanks!

Audishiva

By the look of the rear rotor, your car has been sitting a long time, so vibrations in braking are to be expected when the bakes are applied.

1. Not recommended. Air in the line means a soft pedal feel. Bleeding the bake line is not a big deal.

2. What does the inboard pad look like? Is the rotor under the minimum? Have you removed the caliper and rotated the wear compensator on the caliper? What about the caliper slides? You might be able to clean up the disk with a wire brush but the way the brakes have been described maybe you just might want to replace them........

3. What is a soft hand brake? Most of the adjustment in the hand brake is by rotating the wear compensator on the rear caliper pistons.

4. The likely cause of steering wheel shake is from the front rotors being warped or rust between the wheel hub and brake disc rotor. Again, how long has the car been sitting? While changing the brake fluid is a maintenance item with a 3 year maximum interval recommended, it will not do anything with regards to warped rotors or rust issues. It will prevent your calipers from seizing and the brake system from rusting out though.

Some additional details about your car would be appreciated. How many Kms on it? How long have you owned it?

samsamsam

Thanks for the input, I owned this car for over two years. about 130K km. The caliper start been seized about half years ago now the caliper just totally seized and will not touch the rotor even if brake applied. you know the rotor will be very easy to get rust is no pad rubbing.


1. the reason I am ask about the bleeding and flush is because the place helps me installing caliper want double the labor if I ask them to bleed. I will visit dealer in a few days and ask them to reflush whole system, can I just wait till the reflush to save some labor since I guess "flush" will include the bleeding process?


2. the rotor still got decent thickness, I do not know the condition of the inboard pad. the outboard pad still got more than half left. one additional question is do i necessary need to change the brake per axle or it is ok to change individually.


3. If I drive for 60 kmh and pull the hand brake, I can only feel very slight brake force. I dont know if there are anything I can adjust the hand brake


4. I feel the front rotor, does not feel wraped. and I do noticed sometime the steering viberating is stronger sometime is weaker.


I feel bad for not fixing the rear brake for so long. just get too busy for the past few month...




Thanks

Audishiva

1. When a flush is done on the brake system, each bleeder screw is opened so that the old fluid drains and is replaced by clean fluid, so theoretically air is purged from the lines at the same time. If you replace the caliper however, air will enter the brake line and the caliper will not operate correctly. Potentially, you will compromise the brake system completely by not doing a bleed which could cause you to crash.

2. You have to measure the rotor thickness with a micrometer. If you replace parts on one side, then you should do the other side at the same time for equal performance. That is why pads are sold in sets, not individually. It sounds to me like your other caliper is seized or the pads are worn out too.

3. The rear brakes are automatically self adjusting for wear. You only have to make adjustments if you have replaced the caliper, rotor or pads.

4. To check for a warped rotor, you need to remove the wheel and use a dial indicator to check the run out of the disk. You can't feel it with your hand because a variation as small as 0.001" is all that is required to cause a bad steering wheel vibration or shake.

samsamsam