Hi tech gods (robin),
having some trouble with audi A6 brakes. Pedal was a little bit soft, and felt like it needed pumped to get any real assistance from the servo. Pads were a bit low, wondered if it was to do with that, so i asked them to change them at service, They did this, and bled the brakes also.
Have the car back now, and pedal is far softer than it was before, even after being bled. I have bed the pads in, and they now bite firmly, but only on the second push of the pedal. i.e depress brakes, car slows a little bit, lift and depress pedal again to same depth and car stops on its nose.
Any idea's?? I am guessing master cylinder, and garage reckon it could be that too. they have told me to bring it back in and they will rebleed the brakes.
car has done 111,001 miles. audi should be better than this surely?
Audi brakes. NLC obviously
If you switch off the engine, pump the brakes until the servo is drained of vacuum (if it even works that way!) then see how the pedal feels - if it still can be pumped up then I would suspect air in the system. A faulty master cylinder would give you a sinking pedal. Pumping the pedal up is compressing the trapped air at which point the pedal then goes hard again until you release pressure, air expands and back to soft pedal.
Now as to how that air is getting in there, that's another question - as the brake fluid gets old it absorbs moisture; then that boils when given rough love; then you get vapour which is easily compressible. So when it's water vapour it's usually only when hot that you notice any real problems (but a fat tank like yours probably gets its brakes hot quite quickly).
Now if they've replaced all the fluid and done a good job, you should have no air and no water/vapour. If they didn't maybe you still have water vapour or maybe they introduced some air.
But I know nothing about Audi specifically - for all I know they use electric brakes
Robin
Now as to how that air is getting in there, that's another question - as the brake fluid gets old it absorbs moisture; then that boils when given rough love; then you get vapour which is easily compressible. So when it's water vapour it's usually only when hot that you notice any real problems (but a fat tank like yours probably gets its brakes hot quite quickly).
Now if they've replaced all the fluid and done a good job, you should have no air and no water/vapour. If they didn't maybe you still have water vapour or maybe they introduced some air.
But I know nothing about Audi specifically - for all I know they use electric brakes
Robin
I is in your loomz nibblin ur wirez
#bemoretut
#bemoretut
Mac,
An air leak in the system would give him the opposite problem - that the pedal was rock hard but you need to be iron man to make the car stop (i.e. like an elise pedal, but on a 2 ton car!).
His problem is the pedal is soft (like most servo systems) but he has to pump the pedal to make the car stop.
If the servo were to blame, pumping would make it worse, not better.
Likewise if the ABS was playing silly buggers I think it would make the pedal hard (because it would lock out the brake line).
The pumping required symptom has to be caused by either:
* a straight fault in the master cylinder (though I don't know what that would be)
* air/vapour in the system (likely, except the Audi boys are meant to have bled the system), the air/vapour needs compressing before the brakes will work.
* really warped disks pushing the pads back each time you release the pedal, so you need to pump the pedal to get the pads back onto the disks before there is any action.
Cheers,
Robin
An air leak in the system would give him the opposite problem - that the pedal was rock hard but you need to be iron man to make the car stop (i.e. like an elise pedal, but on a 2 ton car!).
His problem is the pedal is soft (like most servo systems) but he has to pump the pedal to make the car stop.
If the servo were to blame, pumping would make it worse, not better.
Likewise if the ABS was playing silly buggers I think it would make the pedal hard (because it would lock out the brake line).
The pumping required symptom has to be caused by either:
* a straight fault in the master cylinder (though I don't know what that would be)
* air/vapour in the system (likely, except the Audi boys are meant to have bled the system), the air/vapour needs compressing before the brakes will work.
* really warped disks pushing the pads back each time you release the pedal, so you need to pump the pedal to get the pads back onto the disks before there is any action.
Cheers,
Robin
I is in your loomz nibblin ur wirez
#bemoretut
#bemoretut
) so i dont think it could be warped discs.