Rear brake dragging

[Cicsy]

Advice needed. Please read through and comment if you have any informed advice on what could possibly be the issue here.

 

I've the 2.0l quattro TDI and have an ongoing problem with the off side rear brake dragging. This obviously destroyed the new disk and pads I'd fitted the previous year in jig time.  

Last month I replaced the entire braking system from each wheel arch. New calipers, disks, pads, and Flexi hoses. Thoroughly cleaned all carriers, lubed slide pins with appropriate grease ensuring pins were free and unobstructed then carefully reassembled and bled brakes at each corner. 

 

Everything working great with the exception of that rear o/s which is STILL dragging and driving me to drink. I've a cheap VW specific scan tool which has identified both rear wheel sensors are shot and a further fault indicating an ABS module problem.

 

I'm no mechanic but I'm fairly competent with the spanners and would love to resolve this myself before taking it to Audi. Anyone ever had similar issues like this? Any informed advice would be much appreciated. 

[Magnet]

Hello Scott,

I like the ‘informed advice’ bit Scott! That comes via. (sometimes) experienced technicians at Audi dealers at a cost of around £120/hr. On here we do the best we can, of course, without sight of the vehicle. 
Anyway, basic question:- electric or manual handbrake? 
Kind regards,

Gareth. 

[Cicsy]

Yeah you know the score mate I was trying to avoid the usual "have you checked the........." obvious questions.

I assume one of the main points of the forum is for information sharing with people who have experienced the same issues. To answer your question it's electric hand brake. 

[Magnet]

Thanks Scott,

Is electrically disarming the parking brake on the offending side an option - so that you can eliminate any ill effects of that system? 
Kind regards,

Gareth.

[JMKC82]

Hi Scott,

So you have changed / overhauled all the braking system on all 4 corners?

4 hours ago, Cicsy said:

reassembled and bled brakes at each corner

Is it possible, to flush or push lots of brake fluid down the hard lines (especially that particular caliper), from the reservoir in case of any blockages?  Or rod the lines?

I was thinking if there is a blockage in the line, the hydraulic pressure is not going to relieve itself after you release the footbrake.

Thanks, Joe

[Cicsy]

1 hour ago, Magnet said:

Thanks Scott,

Is electrically disarming the parking brake on the offending side an option - so that you can eliminate any ill effects of that system? 
Kind regards,

Gareth.

I can retract the auger screw for the electric handbrake using the scan tool if that's what you mean. However I assume that's doing both sides simultaneously. 

[Cicsy]

30 minutes ago, JMKC82 said:

Hi Scott,

So you have changed / overhauled all the braking system on all 4 corners?

Is it possible, to flush or push lots of brake fluid down the hard lines (especially that particular caliper), from the reservoir in case of any blockages?  Or rod the lines?

I was thinking if there is a blockage in the line, the hydraulic pressure is not going to relieve itself after you release the footbrake.

Thanks, Joe

I bled each corner using a brake bleeder but yes, I have considered doing a full and thorough brake fluid flush next to see if that brings any joy. I also considered identifying the appropriate brake line as it enters the ABS module with the thought of disconnecting there to see if that releases pressure at the caliper. I'm reluctant to try that though untill I've eliminated all other options. 

[Magnet]

As I see it Scott, releasing the parking brake (albeit affecting both sides) and running the car is the logical way to test whether it is that - or not - that is adversely affecting the one rear wheel. If the situation improves, bingo there’s your answer. If it doesn’t improve, at least you have eliminated that possibility. 
Kind regards,

Gareth. 

[Cicsy]

So update, I've retracted parking brake using the scan tool and ran the car for a few miles. Rear right disk STILL hot to touch where as all other disks are cool. Guess that eliminates that suggestion. The scan tool identifies " electronic parking brake control module" as a fault . I'm going to try a complete brake fluid flush first but failing that the next logical step looks like swapping out the module. 

[Magnet]

OK Scott, so at least my idea eliminates the EPB being the culprit on that wheel- so a worthwhile call. 
Re. Logical step of replacing the parking brake module :- then I’m losing your logic, since you have already tried isolating the EPB on that wheel with no improvement.