bacdoc

on my 2005 A8L. Do I need to do anything special with my VAG-COM, or can I just replace the motor.

mishar

If one of your motors was not working for a longer time that parking brake mechanism is out of sequence with the other one. If you just replace the motor it will throw the code and take quite a few on and off cycles of parking brake to synchronize two sides. To avoid this when you take the old motor off you should manually (triple square or Torx wrench no force) bring the mechanism to the piston so it will be in the same position as the other one.

bacdoc

So manually adjust the torx stud on the motor to meet the piston? Is the other option to use the vag-com to synchronize the motors and if so, hook up a battery charger to the battery?
Thank you.

mishar

No. Not on the motor. On the caliper. Inside the cylinder is a screw (fourth from left on the bicture below) and nut (third from left) that press the piston. You should manually bring the nut in contact with the piston. VAG-COM can't help you here.

bacdoc

ok, thank you. Probably easier to do with the caliper off.

mishar

Actually it may be easier with caliper on since you don't need to hold it while unscrewing. Be careful with harness. Old Audi plastic is a bit brittle.

dvs_dave

Make sure the parking brake is off, then when you swap the motor, manually adjust the screw so that it's fully wound out then drop the new motor on. (System works by counting number of motor revolutions between motor stall current draw spikes at the extremes of travel) Both sides will then both be pretty much in the same position so will re sync quickly, or most likely will be within tolerance and just work. Either way, a few cycles will sort.

mishar

I think you are wrong this time. If you listen to the motors recalibrating you can hear long unwinding, long winding and short unwinding. Just enough to release brakes. If that is right than working motor would be in that position. Broken side, depending on millage out of order and pad wear, would be further opened. So it should be winded all the way in. Manually, no force.

Does that sound right?

bacdoc

I don't know if this helps, but when the right motor failed, I pulled the fuses, so the left side has not been operational since the right one has not been operational.

jandreas

The motor is not available separately or at least I had absolutely no luck finding one, you need to replace the entire rear brake caliper for between $416(Sunset Imports)-$560(MSRP). You might want to check for cracks in the housing of the right motor. If the motor has seized it is possible to undo that, replace the housing o-ring and repair the crack in the housing.