ct-audi-A6-3.2

Long time lurker, first time poster.

I did the rear brakes on my 2005 A6 this weekend. I did not buy the Vag-com tool as I really have no desire to change any settings or anything. Also, I do not have a laptop, so moving my home PC into the garage to change my f'in brakes really did not appeal to me. Plus, the vag-com was just too much coin $275 for the cheapest version.

Rather, I simply bought the tool from Mactools.com, part No. EPB101. It is about 1/3 the cost of the vag-com but is limited to brake jobs.

Also, I pretty much figured out that you can get the piston to withdraw without needing the Mactool or the vagcom. You can remove the motor from the caliper using a torx socket to remove the two bolts. Once removed, inserting the torx socket into the back of the caliper and turning clockwise will with allow you to compress the piston. You can see this proceedure in the Bently manual as it is what they tell you to do when rebuilding the piston seals...... see funny story below for the reason why I had to rebuild the caliper....

Now, since I had the resetting tool in hand, I can not tell what my little proceedure will do, after installing the new rotors/pads. Namely, I do not know if it the computer will recalibrate the motor to the new spacing and reset the error code. I suspect it will. However, if it does not, you should be able to hit the local autozone and have them reset the codes for you.... Also, I had the tool in had from mactools the day after I ordered it, I did not even pay for the fedex delivery, they just sent it that way.

So all told, I spent about $60 on the pads and $75 on the rotors both at genuineaudiparts.com, plus the $140 on the tool from mactools ===> $275, which is still a bunch less than the stealership wanted and now I can do them whenever I want......

My funny story about rebuilding the calipers....You've got to make sure you have NOT taken out the old pads before using the tool. When you plug this thing in, it sends a bunch of codes to the computer to see what kind of car it is dealing with. I had my calipers already off when I plugged it in because I tried to do the brakes without the tool and had not yet figured out the little torx trick I described above. In doing so, the tool caused the motor to index forward, obviously looking for the end point before retracting. With no resistance from the pads/rotors, the damn motor forced the piston right out of the caliper housing. Now my car was bleeding all over the place. Luckily none of the seals or boots were damaged, so I simply rebuilt the things. Boy was I pissed.

If you live in Connecticut and want to use the tool, send me a note offline....

BlueSander

lol, great story. I live in CT, too. Which area do you locate? I live in West Hartford. All my pads were replaced less than a few months, however, the front pads are giving brake dust like crazy. I probably have to take care of that soon. Anyways, that was a good read. Glad that you figured out how to the rear break.

pierreb

I ordered the pads today and have vag-com. I guess we'll see if I have the right tools :P

danno6

I just did my front brakes this past weekend...I got all the parts for the rear but when I took out the pads (at 65k miles), they are barely worn. So I left them.

I do have the vag-com cable and reading through the procedures in the bentley I could not figure out how to retract the electronic parking brake. Despite that I got the driver's side caliper off. Not sure when the need to retract the parking brake comes in....

I also could not figure out (but I didn't spend much time once I realized the brake pads were OK) how to get the rotor off...that is how to remove the caliper hanger (not sure the official name) to get the rotor free.The front rotors were loose when I removed the screw from the face - then I took out one of the 21mm bolts holding the caliper hanger and loosened the other enough to drop the rotor out - but the rear appeared to be stuck on the hub.

Maybe I will tackle the rears when I put the winter tires back on in the fall!

pierreb

I could be wrong, but I believe the reason to retract the parking brake the 'official' way is to prevent an error code.
there's also an automated brake pad play adjustment every 1,000km if you don't operate the parking brake after servicing the pads.

the procedure for vag-com is here, although I haven't done this myself yet.

ct-audi-A6-3.2

As you know, the piston in the rear caliper needs to be retracted whenever you change the pads and/or rotors. The new pads/rotors are thicker than the old ones, thus you need the piston to retract back into the caliper to give more clearance.

You can not just use a c-clamp or piston compression tool to move the piston inwards like on the fronts. This is because the parking brake motor moves lock nut behind the piston to prevent pressure alone from forcing the piston back in.

You could simply rotate the piston while pressing it in. However, the Audi rear piston has nothing to bite into so that you can safely rotate it. Most other car manufacturers have two offset holes on the face of the piston, which receive corresponding pins on caliper retacting tools. These allow you to compress and rotate at the same time.

Audi conveniently left those two holes off of the piston so you need to get the motor into reverse to pull back the lock nut (unless you use my trick from behind the caliper with the motor removed). You could put some channel-locks on the sides of the piston, but that seems a bit risky to me b/c that is the same surface where the piston boot seals against and I was not willing to take the risk of scarring that surface.

It is my understanding that when the motor has extended the lock nut a certain distance, it sends a signal to the computer that the rear brakes must be serviced. Thus, the rear pads do not need a wear sensor, since the motor takes care of that input.

You need the vag-com to turn the motor in reverse to allow pressure alone to retract the piston. Plus, you need the vag-com to reset the service code in the computer once it has been tripped by the motor.

The mactools tool does both of these functions and is incredibly simple to use. Push on to activate, then off when you are done. No fancy codes or software to learn. I am a gear head not a computer dude.

pierreb

I've got 2mm left on my rears and no alarm anywhere.

danno6

Pierre,

Thanks for the link....the bently instructions appear to be specific to Audi equipment, not the vag-com - hence my confusion.

Ct-Audi...thanks for the retraction explaination...now I understand. Again, since my rear pads looked real good, I didn't bother checking out how to do thus further at the time. If I can't get the vag-com to work I can try your trick (hopefully without having to rebuild the calipers!)

Dan

05whtaudia6

My rear pads were real low and i never got a warning, i dont think the rears are monitored. The only warning i got was a squeak when braking.

pierreb

only the fronts are monitored