The calipers float - there are two pins that allow them to move back and forth. If they hang up one pad will stay in contact with the rotor and drag. They need to move easily with the pads in slight contact with the rotor.

If both pads are squeezed against the rotor something is wrong with the master cylinder because the hydraulic pressure is not releasing.

As someone sugested a tight eBrake cable can cause things to lock up. Also the eBrake lever on the caliper (it has a return spring) can get gunked up and cause the brakes to not release even when the cable is loose.

Since you said it is only one side I would makes sure the capiper and eBrake are free to move.

It's not rocket science -- Find someone that knows Audi --

 

Only a couple things in my experience can cause the problem. First and already mentioned, the pistons can rust/corrode and not retract. The calipers continue to keep pressure on the pads and they contact the rotor. I used to have this problem in Florida all the time with my motorcycle, when I did not run it regularly. If you remove the wheel and peek where the rotor meets the pads, you may find the wheel(s) that is not releasing. You should be able to gently pry the pad/piston back with a screwdriver, but the solution is to disassemble and clean, or possibly rebuild, the calipers.

Another potential problem is the brake master cylinder. There's a valve in there that allows the fluid to flow back to the reservoir when the brake is released. If the valve is sticking, the fluid pressure cannot be relieved and the pads cannot retract.

 

The parking brake cables and caliper levers need to be checked. Replacing the seal on a rear caliper will not fix the problem with the stuck lever. You need to get rebuilt rear calipers, if the levers get stuck. Also, the caliper piston has to be screwed back in to the caliper with a tool.

 

I'm betting on this or bad calipers.. they can look 'shiny' and be bad.

 

Tnx for all the ideas..im gonna take the rear brake apart and check everything.

as for the master cylinder, as an audi serviceman explained, atleast 2 brakes would be effected, in my case the rear left and the front right. as all other brakes are fine and release normaly i guess (and hope) the master cylinder is not the problem.

im trying to arrange a visit from my mechanic.

ill post another msg when i will take the brakes apart.

tnx for now.

oh and, if you havent dealt with brakes to this extent before it might as well be rocket science or quantum physics

regards, zw

 

Rocket science is about moving at a high rate of speed and quantum physics is about little stuff. Brakes are about lowering speed and they are big.

 

Hehe, i know what they are about - was using that as metafor. meaning it can be as complicated as quantum physics..if you dont know how to fix it..

Well ok heres what happend, i took both rear brakes apart and went to my mechanic. he checked everything twice and found nothing wrong..i went to get a second opinion, and still nothing wrong.
Then i went home, put it all back together (which for a first time took ages), and to my suprise everything worked ok! then i just did a break test, and the left rear break wouldnt release again (i slamed the brakes on HARD).so i went back to my mechanic with the whole car and with the rear left break almost on fire...he hit the calippers with a hammer and they let go..took em apart again and again nothing was wrong..
for the moment, the brakes are fine, but since this happend to me the 3rd time now, i know its going to happen the 4th,5th...

im starting to think that everything is ok and that im cursed

any ideas guys?

regards, zw

 

Buy new/rebuilt calipers... As said, they can look fine and still not work. Dunno why. I had the same prob on an Intrpid @ 180k miles... rebuilt them myself, nope. Had a shop do it, nope. Bought cheapies, work fine.

Go figure.

 

Yep -- get a rebuilt caliper for the side that is hanging up.
Guys like Force Five have them for a bit over $100.

 

O'Reillys have remanufactured OE ATEs for around $ 60 (after you get back the core charge).