Rear brake piston fully extended
 

Let me come right out and say: I'm not the most mechanically inclined individual you've ever met. Anyways, I brought home some brake pads for my audi A6 3.2l Quattro thinking: "hey, certainly it can't be that hard, it's only brake pads!". I suppose I should have learned by now.

So here's what happened.

1. Didn't think to research this job.
2. Removed driver side rear tire and caliper.
3. Swapped pads.
4. Opened hydraulic reservoir and attempted force piston down.
5. Uttered profanities.
6. Kicked myself in the ass and researched the job.

Meanwhile, back in the drive way my idiot neighbor determines pressing the brake pedal multiple times is clearly the only option left :mad: He's one of those guys that want's to "help" whenever he can. so as the title states I've got a brake caliper with a piston fully extended.

I've ordered a Vag-com from Ross-tech, should be here in a few days. However I'm not quite sure where to go from here. I've read through a number of diy articles, but I'm not sure what to do in my case because the caliper is not fully installed, and cannot cycle brakes etc. I think this is certainly one of those instances where the "documented resolution does not exist" and I could really use some pointers.

Additional info:

2007 Audi A6 3.2l Quattro
120k miles
has an electric parking brake
My neighbor is an eighth grade drop out.:cool:

maybe I included too many details in my original post...
 

Sorry if the first post was too much info... In short I have my rear brake caliper removed from the tire, the piston is fully extended due to the break pedal being depressed while the caliper was uninstalled, I have a vag-com on the way and hope to be able to resolve this issue.

The articles which explain the process from start to finish explain that the caliper NEEDS to be fully installed in order to run these commands and not destroy the caliper motor; mine cannot be installed and thus I need some help determining which method of corrective action I should take.

Thanks.

In most cars that use the service brake pads for the parking brake function require that the piston be turned at the same time it is being pushed back in. Trying to push it back with a C clamp will damage the worm drive gizmo that applies pressure to the pads. You can pick up a special tool for a few bucks at most auto part stores.

Wish it was so...
 

Thanks for the reply Pete, unfortunately the Audi A6 piston does not have the traditional indents found on the piston which allow the afforementioned tool to lock on and rotate the piston. I have heard that it is possible to take the motor off of the caliper and somehow retract the piston this way, however it seems to have a high failure rate. I don't think the C clamp damaged the piston, it just didn't move it. I'm really hoping I don't have to buy a new caliper.

I'm curious if using the vag-com to command the piston to disengage will be a possibility while the calliper is not installed.

C6 cars require VAGcom to retract the rear brake pistons.

In a normal R&R, once they are retracted and the calipers removed with VAG-COM they still need to be pressed in with a clamp. Turning the piston while pressing is not necessary on the C6 because of the motor drive mechanism.

Hopefully your brake pads were between the piston and the caliper when your intelligent friend did this, if not you are probably screwed as the piston may have come out of the cylinder. If the pads were in the caliper they probably would have stopped the piston before it was too late. If you are lucky and the pads were installed, I recommend that you remove the pads, get a C clamp or large vicegrip pliers and press the piston back into the cylinder. It will take some force but it should get you back to where you started, perhaps even further. Once you get back to the starting point try using the VAG-COM to fully retract the parking brake. At this point continue to use the C-clamp to press the piston into the cylinder until it is approximately flush with the housing (the rubber seal will protrude slightly). Check the rubber seal and make sure it is well seated, install the new pads and put the caliper back on the rotor.

Good Luck.

Thanks for the info, the caliper was unfortunately not installed and the pads were not present when the break pedal was pressed. I'm not quite sure what to do now, I've got the vag-com but there was no response from the caliper when trying to go through the procedures found on the website.

I'm contemplating taking the motor off the caliper and trying to manually retract the caliper, but I'm not really sure what to expect in doing that.

electric caliper bypass
 

unplug and remove electric motor off back of caliper via 2 spline bolts(motor pops off) splines locate on shaft.using a spline tool inserted into rear of caliper ,turn it clockwise while holding piston with waterpump pliers softly ,guiding piston straight into caliper ,tou may have to push on piston every few turns ,until all the way back in caliper ,resume by fitting motor back on locating splines ,and fully assemble back onto car,helps to open bleed nipple while retracting piston