I installed new rotors and brake pads on my 1999.5 a 4. I used a c lamp to push the pistons back and now I have a firm pedal with the engine off but when I start the engine the bake pedal goes almost to the floor,its also a very soft pedal. I tried bleeding the bakes but didn't help when I pump them with the motor running I do get a little better pedal but not a solid pedal.

1. Did you use a c-clamp on the rear? And it worked? Not sure what you damaged - they only; screw back in with a caliper tool.

2. How did you bleed them? It does sound somewhat like air, since you can pump it up but then it gets mushy again. However, that could also be a bad Master, i would guess. Its very hard without either 2 people or power/pressure.

Grant

Its the front brakes that I changed. The brake pedal is solid with the engine off holding the bake pedal down and starting the engine the pedal goes almost all the to the floor. The pedal can be pumped up but the pedal is a little soft it stays about half way up. I've bled both front brakes starting with the right side. Using the 2 man method twice, so far I've put 1 pint thru the system. The brakes were working fine prior to pushing the pistons back with a c clamp they pushed with no restance. The only thing I forgot was to take the cap off of the reservior but the excess fuid came thru the cap.

.. you *could* have damaged the MC, but probably not

.. it still sounds like lots of air in the system. I use a motive pressure bleeder

.. if you get air int he ABS pump, only the dealer can get it out, or using a VAG-COM to activate the pump while pressure bleeding - and I dont knwo the VAG COM code or method

Best of luck,

Grant

the resivor. I am figuring there is just some air in the system If you have access to a vagcom cycle the master cyclinder. We had the problem on my wifes car.

I've bled the front both sides twice wnd got no air.What I don't understand is how air got into the system by pushing the pistons back.

When we're ready to finish a caliper,

1. The man at the bleed valve says "slow"

2. The man on the brake pedal does one more pump, but very slowly.

3. The man at the bleed valve closes it completely <b>before</b> that last stroke is completed.

This insures that absolutely no air is pulled in around the threads of the bleed valve at any point in the process of that last pedal pump and release.

Cycling the ABS with VAG COM as some of the posts are getting at. There is no separate cycling of the master cylinder.

I think hard vs. soft can likely be just the power assist effect when the motor is on.

Failing that the master cylinder may be damaged. I recall occasional reports of it happening when the pedal is pushed all the way down and the pistons inside of the master cylinder move beyond their operating range and get damaged.