Dartanjang
Member Since: 20 Dec 2014
Location: Mountain Strokes
Posts: 77
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| Parking Brake One-Sided Binding |
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I have changed discs and pads all around, following the brake bible. There was plenty of material left on the parking brake shoes so I left them in place. After this, the right side parking brake binds, not so that the wheel is stuck but it builds heat. To a damaging level after a few miles.
If I remove the disc, put it back on and don't touch the parking brake then it's ok. But if I activate and release the brake once, it binds.
So I took the right hand side parking brake shoes totally apart and made sure that everything was clean and moving easily. Reassembly and calibration. No change.
So I replaced the old shoes with new ones and new springs. Assembly and calibration. No change.
It's like the right hand brake wire doesn't release fully after a cycle. Like that the wire sticks in its cover or the PB unit doesn't return its movement fully for the right hand side.
One thought I had was that the left hand side was too loose and required extra travel and that when the tension in the PB unit was released this assymetry could lead to a remaining pull on the right wire. But this should be remedied by calibrating the brake shoe positions on both sides with the PB unit put in its mounting position by the Nanocom. But that didn't solve it.
The parking brake has always worked flawlessly up till this. And the EPB unit sounds ok, it manouvres the brake and reports normal live values on the Nanocom when used. And the parking brake works as it should, with this one-sided light binding as the exception.
The only out of the ordinary thing that happened with the parking brake during the disc change was that the EPB unit was set to its mounting position with the Nanocom. But how that could lead to this behavior escapes me.
So I am at a loss here. What haven't I thought of that can cause this? Do I need to open up the EPB unit? What can logically be wrong in there that explains this? What else can I try?
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 11th Jun 2017 10:28 am |
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Dartanjang
Member Since: 20 Dec 2014
Location: Mountain Strokes
Posts: 77
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No, it doesn't look like it. There is some rubbing, but nothing alarming. A noticeable mark but most of the plastic cover remains.
My suspicions are more and more towards the EPB unit. The only thing out of the ordinary during the whole brake change operation was setting the EPB to the mounting position. I then pulled the EPB fuse, changed the discs and pads. After that this behavior developed.
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| 11th Jun 2017 8:12 pm |
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swansty
Member Since: 21 Sep 2008
Location: Northern Ireland
Posts: 918
  
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Have you tried adjusting the brakes using the knurled adjusted?
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| 12th Jun 2017 7:44 am |
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Dartanjang
Member Since: 20 Dec 2014
Location: Mountain Strokes
Posts: 77
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Yes, that adjustment is what I in my post above call calibration.
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| 12th Jun 2017 8:03 am |
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ItSmee
Member Since: 05 Nov 2015
Location: Berkshire
Posts: 34
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Did you also do the wedge adjustment with a 4mm Allen key?
After changing the rear discs you will also have to perform the bedding in procedure. Have you had a look at Bodsy's Brake Bible? Originally written for a D3 but the brakes are not that different from a D4. I recently used it to change my D4 rear discs whilst keeping the original shoes (I did replace the springs and clips though).
http://media.disco3.co.uk/gallery/albums/u...1.4sml.pdf
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| 12th Jun 2017 7:39 pm |
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Dartanjang
Member Since: 20 Dec 2014
Location: Mountain Strokes
Posts: 77
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Yes I did. Follow Bodsy's bible, that is. Thanks for the suggestion.
And I can say that due to the binding issue that it is more than properly bedded in 
As the left side is working properly and the right side binds after an activation cycle, the behavior is as it would be if the brake wire sticks in the cover and the springs don't have enough pull to retract the shoes from the drum. The car is not my daily drive so I'll let it be until I get the spare time to crawl under and open up the EPB actuator and take a look. The least I will do is to detach the cable and see whether it sticks in itself and needs replacement.
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| 12th Jun 2017 8:28 pm |
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daftlad
Member Since: 12 Jun 2016
Location: Worksop , Nottinghamshire
Posts: 712
 
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I recently had the wheels off to check the shoes and adjust as preventative maintenance
Found newish shoes had been fitted must have been when it was serviced at the LRMD last year before I got it
Any way did the bodsys bible to the letter and Evey now and then if I drive slow just after releasing the EPB I get a tiny catching noise but no heated hubs
Remember them well from my old D 2 
Doesn't do it every time just when I think it's gone, it pops up
It's just been serviced and the indie didn't find anything wrong or single says
Phil
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| 12th Jun 2017 8:46 pm |
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ItSmee
Member Since: 05 Nov 2015
Location: Berkshire
Posts: 34
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You could try taking the shoes off the side that is binding and resetting the wedge adjuster as this could be holding the spreader plate out.
With the shoe in your hand loosen the 4mm Allen key and push the wedge adjuster as hard as possible against the butterfly spring then retighten. This puts the wedge adjuster back to the as new position. Make sure you keep hold of it as you undo the Allen key. Then refit and adjust.
It's a long shot but might be worth trying before going for a new EPB.
Good luck
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| 12th Jun 2017 8:52 pm |
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Dartanjang
Member Since: 20 Dec 2014
Location: Mountain Strokes
Posts: 77
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Good thinking. I did exactly that to make sure that the spread would be minimal. And when I have removed the disc and have reset the shoes and refit the disc, it initially does not bind. But when I have cycled the EPB once, it starts to bind.
I have replaced the disc a number of times as I thought that the problem cause originated from the wheel assembly. But as repeated remounts doesn't help I start to think that the cause must be elsewhere.
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| 12th Jun 2017 9:10 pm |
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daftlad
Member Since: 12 Jun 2016
Location: Worksop , Nottinghamshire
Posts: 712
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the only other possible culprit that I could think of was that I may have a little brake calliper drag
soon know in the winter if it seizes up in the salty grime we get on our roads
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| 13th Jun 2017 7:20 am |
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Barn1e
D3 Decade
Member Since: 28 Aug 2006
Location: Mid-sussex
Posts: 2021
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I know this is stating the obvious, so pls don't shoot the messenger! Is it possible one of the two springs are incorrectly fitted and binding when brake applied/released. 2005, TDV6 S, Auto, 190k miles, owned from new, V8 Brake Upgrade, Nancom Evo, RLD protector, BAS EGR blanking & Remap, separate ATF cooler, changing all the fluids ahead of time.
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| 13th Jun 2017 7:41 am |
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Dartanjang
Member Since: 20 Dec 2014
Location: Mountain Strokes
Posts: 77
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Everything is always possible, no offense taken. But this is probably not the problem. The parking brake worked well before the disc and pad change. And at first, I did not touch the shoes on either side. I only released the knurled adjusters on both sides to be able to switch discs, and then re-calibrated after the new discs were mounted. Then the binding started.
So I took off the right disc and removed the shoes. Cleaned everything up, lubricated and re-installed the old shoes. Binding again appeared after first activation cycle.
Next I switched to new shoes, springs, the works. After one activation cycle, binding.
During all this, the left side works a charm.
So it's like the right side wire does not retract fully when the brake shoe springs attempt to pull it back on brake release. And I associate this with having set the EPB unit to the mounting position as this is what has been new compared to normal operation. Whether this theory is correct or not, I will have to verify by opening the EPB and see how the wire runs when the parking brake is operated. At least this is what I assume, or is there another and simpler way of checking the wire without having to do EPB unit surgery?
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| 13th Jun 2017 9:10 am |
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shlaptop
Member Since: 20 Feb 2010
Location: Cornwall
Posts: 1
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Hello
Was there a solution to this problem. I'm getting the same thing, EPB binding on the passenger side (LHD vehicle). After say 50 miles there's a juddering. I can pull over, engage and release the EPB then it's OK for another 50 miles. Also the EPB light is on and can't see the fault.
Many thanks!
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| 23rd Oct 2017 3:38 pm |
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Dartanjang
Member Since: 20 Dec 2014
Location: Mountain Strokes
Posts: 77
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My bad. I should have reported back. Yes, I solved it. And as always, when every possible reason has been investigated, go back to the most logical one.
Turns out that it wasn't the park brake. It was the disc brake. With new pads and disc, the brake piston was pushed back into the caliper and to a position that hadn't been used since the car was new. Even though the piston wasn't rusty it stuck just so much for it to develop heat. I polished the piston end, lubricated it and exercised it back and forth in the caliper extensively. After that everything worked.
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| 23rd Oct 2017 6:27 pm |
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