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Someone asked exactly how the rear caliper parking brake adjuster works and as far as I can tell, there aren't any explanations out there which show how it works so I took a video.

Basically, there's an adjuster that rides on a screw inside the caliper. The piston can move a little bit and the adjuster can move a little bit. The adjuster is clipped inside the piston but there are holes for fluid to move through so there's a little play.

Not using the parking brake doesn't push the adjuster out all the way. The caliper will pull it out but not using the parking brake can result in a softer brake pedal because of that tiny bit of play. The adjuster is mostly for the parking brake - it keeps the engagement of the parking brake even as the brake pads wear down. When you pull the handbrake, it can only move the piston out a little bit. Keeping the hand brake well adjusted keeps the parking brake authority for holding the car.

It was getting dark yesterday so I think my camera gave everything a blue tint because of the blue gloves. I used it anyways because it was the best audio track I was able to do after 10 takes.
http://www.youtube.com/watch?v=nPRNbn9bdJghttp://www.youtube.com/watch?v=SKseK_k7YfM
 

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Brake Piston Self Adjuster

Had wondered how this mechanism worked - really useful thanks.

Can I ask a dumb question? I've seen windback tools advertised with left-handed and right-handed threads. Are these required for offside and nearside calipers or do both sides have a single-direction thread - so the windback tools are required for different vehicles rather than different sides of the same vehicle.
 

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Yes a lot of manufacturers use these windback rear calipers. I was repairing a cockup at work a few weeks ago. We have a Ford Mondeo and the student had wound the piston out not in. I had to remove the caliper to fix it easier. They had been playing about with it for half an hour which caused a burr on the quick start thread, its similar to a starter motor bendix. Its a left hand thread on the Ford by the way, thats why they were screwing it the wrong way.

There are windback tools avaliable Brake Caliper Wind Back Tool Kit but with a bit of improvisation you can make your own.

Nice video chitty. ;)
 
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