EPB driven piston completely out

[foorbar]

I've got the calliper off my car, I was trying to use a gunson tool to wind off the epb but something happened that caused the epb motor to run and drive the piston right out. The piston is wobbling inside the dust cover which doesn't seem like it would be a good thing.

Does the piston screw back in somehow?

[zollaf]

you retract the piston by using a computer. if you were trying to wind it back in as with an old fashioned caliper, before electrically retracting it, then you may already have damaged it. not sure how you have managed to get it to operate itself though to push it out. but yes, if you retract the epb you should be able to wind the piston back into place, just make sure the seal hasn't been damaged in the process.

[foorbar]

I have a tool to wind back the epb but that hasn't worked as expected. Technically, the epb is just a motor on the back of the calliper so in theory it can could be wound back and forwards by powering with a battery, reversing polarity to control fwd/back movement. If I wind it back with a battery, are you saying I ought to be able to screw the piston back in?

[zollaf]

yes. there is a detailed write up of how to do it but i have no idea where it is. someone will know, i think its on martins website... or his page on here.. ?? but yes, you are correct.

[Rob69]

It sounds like the piston has come right out of the cylinder past the seal.Unless you've already got it in, The piston will have to be carefully fitted back in past the gaiter locating lip and piston seal. That's tricky enough on a straight forward caliper, I don't know if or how you'd do it to re engage the piston onto the epb screw thread. I took an old rear caliper to bits for a look inside, it's not as simple as you'd think inside.

[foorbar]

Thanks. What is martins site? If i can find the guide I might be able to fix this disaster