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Took my 2006 VW Touareg in for servicing and had the dealership replace the rear brake pads and discs. In a post-replacement test drive the dealership discovered that one of the sides has a stuck caliper, and the brake doesn't want to let go.

The dealership called to check if we had experienced sticky brakes in the past. Having ruled that out as a possibility, they are now recommending to have the caliper replaced, and if that doesn't fix it the ABS unit as well - all at my expense.

I'm reluctant to believe that the caliper failed at the same time the brake hardware was upgraded.

By suggesting the ABS unit, I believe they're simply insuring themselves against liability claims in the future ("we told you so").

The brakes were fine prior to the servicing and brake hardware refresh, so what could possibly have happened to cause one of the brakes to stick like that? Could the presence of excessive brake fluid explain this?

With this question I'm looking to elicit technical reasons for what could be causing one of the brakes to bind.

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    I'm not interested in comments regarding what the dealer should or should not be doing here; the business rules and norms in my part of the world are pretty different – Zaid Jul 5 '15 at 14:43
  • Also try soaking it with lubricant there are pins inside that can get stuck closed because it won't slide back from rust etc. lubricant and work ur brakes free. If ur pads are shot I think it fails to dissapate heat and starts bindi g together – GettingNifty Jul 5 '15 at 21:13
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It sounds to me like they cocked the piston in the caliper sideways when they collapsed it during the brake job. This could be caused from a worn caliper piston. It may or may not have been their fault, but would be hard to prove. My suggestion is to have the caliper replaced. This should fix the issue.

I don't see any way this could be related to the ABS unit, unless they think the brake fluid is not being allowed to migrate back up the lines after braking. I've not heard of a unit creating it's own one way check valve, though.

I'm not sure how the Toureg's brakes transition (slide). This may be an area of concern as well. If the slides are rusted or otherwise obstructed, this could be causing an issue, but would assume the mechanic would have picked up on this.

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    I'll provide an update as and when I get more information – Zaid Jul 6 '15 at 1:50
  • It turned out to be miscommunication in the end. They were referring to intermittent sticking on one of the front brake calipers which only manifests itself under heavy braking. It had nothing to do with the rear brake job they had performed. – Zaid Jul 26 '15 at 8:15
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As brake pads wear, the piston is pushed further and further out of the caliper. Around the edge of the piston is a rubber boot but this sits flush with the caliper so as the piston rests further and further away from this, it can corrode.

When fitting new pads, the piston must be pushed back into the caliper and the exposed areas can be awkward to get back in cleanly which can cause them to sit proud and thus push on the pad and cause the brake to drag.

If you don't want to pay main dealer prices for a replacement caliper assembly, consider taking the car or just the caliper to a company which reconditions brake calipers. They will replace all the seals plus reface any corroded components (or replace them) so you effectively get an as-new caliper. Some of these places will hold a small stock and even provide calipers on an exchange basis.

I would be very surprised if a faulty ABS module would cause just one of the brakes to drag.

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If nothing else works.... Look into the "Master Cylinder" I owned an 03 VW Passat... And my brakes would lock up on me and I would continue to drive... Melting all calipers rotors... The computer will not recognize this problem, as I went to 4 different VW certified repair shops... None could find the source of my problem... in fact they replaced all parts... only for them to melt together again. It was the most frustrating auto problem I've ever dealt with. I brought it to 2 over non VW auto shops... They also could not find the source... So It was up to me and my buddy who knew only what he self taught himself ( I didn't know anything about Fixing Cars) We went to work doing hours of research on the issue... Only to find that no one on the internet reported a similar problem.. then we turned into engineers (even though we are not lol). We looked at blueprints etc and we both came to the conclusion that it seems something is wrong with the "MASTER CYLINDER" So we went to work and removed and lifted what was needed and replaced the Master Cylinder... reattached all parts... and Took it for an hour drive. The car was finally FIXED!!! One of the joyous moments of my life, as sad as it sounds it felt rewarding fixing something many professionals could not... After 3k in costs total and the car was still broken... It took a total of under $200 to buy the part and me and my buddy installed it.

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