Big problem doing rear brakes

[sjw]

Got into a big problem of my own making entirely.

New disc went on fine. Problems started when I couldn't get the caliper over the new pads. Thought maybe the piston wasn't retracted properly. Screwed the piston in as much as I could. Then...

Went to try the OBDEleven again in case that hadn't worked. Accidentally selected "end lining change mode" rather than start. Piston starts to extend, can't stop it, and it's almost like it's completely unscrewed itself. Now I'm stuck. Any ideas?? 

[sjw]

Update: I'm taking a break. The piston has screwed some of the way back in. I figure if any damage has been done, I might as well carry on and see how far I get. A little brake fluid has come out. Not dripping, but I had a few drops on my fingers. If I do get it back on, there's no guarantee the OBDEleven will be able to control the EPB. If it CAN, I'll get it to a garage to take a look at it.

[madstaff]

If you have brake fluid on your fingers the only real way for that to happen is if the piston has come right out past the seals and it is tricky to wind the piston in from there.

The piston would have to have come out along way though and would have not have easy to wind back.

[sjw]

It definitely felt like it was screwing in, but I couldn't get it in enough to get the tool in to wind and press. I think I was just spinning it in the end. I have a couple of other ideas. Going to have a look tomorrow

[sjw]

If it comes to getting a new caliper, where is the best place to go?

[EB2019]

Most motor factors stock the mk7 rear calipers these days but they won't be red unfortunately

Brake engineering (now TRW) used to stock VW calipers in the Reds and the blues but not sure if they do them in new electronic caliper.

[sjw]

Is there anything special about the performance pack caliper?

[willni]

Is there anything special about the performance pack caliper?

I think the rears on the PP are 310mm vented brakes and the standard GTI has 300mm non-vented, with different carriers but not sure about the actual caliber / piston differences.

[madstaff]

Doesn't need a new caliper, all it needs is the piston winding back in by someone who knows what they're doing.

Worst case scenario is to remove the caliper and take it to a local garage so they can replace the piston, refit and bleed the brakes.

A PP pack caliper is wider to accommodate the extra width of the vented disc IIRC.

[sjw]

Doesn't need a new caliper, all it needs is the piston winding back in by someone who knows what they're doing.

Worst case scenario is to remove the caliper and take it to a local garage so they can replace the piston, refit and bleed the brakes.

A PP pack caliper is wider to accommodate the extra width of the vented disc IIRC.

From numerous threads I've read online, by far the simplest solution is a new caliper. I can feel ball bearings in the rubber dust boot. Everyone else who this has happened to has had to replace the caliper