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Chairman
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Discussion Starter · #1 ·
[Edited to change from "handbrake" to the more correctly entitled "parking brake" - especially as it is operated very firmly by one's foot!!]

The Treg was booked in for its MOT today, but the disc pad warning light came on last night so it was no surprise when the MOT man failed the car, but only the parking brake efficiency. At least everything was ok.

Did I read on here somewhere that the parking brake does not use the rear disc brake pads at all but comprises "old fashioned" shoes that fit inside the rear brake discs or was I imagining that?

I know on my 3 series Beemer this was the case and in order to ensure the handbrake held well on MOT days, my mechanic's advice was to occasionally put the parking brake on and drive the car very slowly for a couple of hundred yards to clean the metal wear surfaces up as they tend to rust.

There was also an excellent set of photos on here for changing pads and discs yourself, but the links [like so many others regrettably] have broken so if anyone [a] can answer the question above and point me to the pix . . .

Thank you in advance.
 

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Elite Member
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Original link is here - viewtopic.php?f=10&t=5868&p=61166#p52535
The pdf file has the pics.

I believe that you are right about the foot/hand brake - it uses shoes that use the inside of the disc as a drum.

I am not 100% sure but I believe that the brake pad monitor is based on the metal in the pad causing a connection or short between the disc and the brake housing.
So if you have a continuity meter you can check for a short between the disc and brake housing of each wheel in order to identify the offending pad.
 

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yeah the pad sensor is a loop of cable in a plastic shroud. As the pads wear this rubs on the disc until it wears right through, breaks the wire on comes the light. Comes on fairly early, about 2K miles left when it comes on. Mine has just come on but im waiting a while since im changing the discs too. Another thing i noticed is if the disc has a lip on it on the outer edge ( i.e where the brakes wear) it makes the light come on earlier than if the disc was brand new.
 

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Chairman
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Discussion Starter · #4 ·
I spoke to Windrush this afternoon.

Their Treg techie has never heard of a Treg failing an MOT on handbrake and has suggested there may be a lot of crud in there amongst the brake pads [he remembered I go wading occasionally which is possibly why the prop shaft failed] and as a result the auto adjustment hasn't done its job, so I'm going to remove the discs, clean out, inspect and go from there.

I can get a pair of calipers for a fiver to measure the disc thickness - 30 mm is the recommended change point so I suspect I'm looking at discs and pads. If someone can get the links on here to work so I can see the excellent pix that were posted by Hunterlees I think it was [pm sent!], I think I'll do it myself with my son's help.

The fact the disc pad warning light was on is not an MOT failure since, as the tester can still see pad material, that's fine. Personally, I'd have thought they would measure pads and discs to see if they were serviceable, but no so apparently - its a visual test only!
 

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Discussion Starter · #5 ·
Doing some research tonight, I found this:

A. For some reason German car manufacturers make their brake rotors thin. On your vehicle [Touareg] the specifications for the brake rotors are:

Front Brake Disc
Ventilated brake disc diameter 308 mm
Brake disc thickness 29.5 mm
Wear limit 25.5 mm

Brembo
18" ventilated brake disc diameter 350 mm
18" brake disc thickness 34 mm
18" wear limit 32 mm
17" ventilated brake disc diameter 330 mm
17" brake disc thickness 32 mm
17" wear limit 30 mm

Rear Brake Disc
Ventilated brake disc diameter 314 mm
Brake disc thickness 22 mm
Wear limit 18 mm
Brake drum- diameter 185 mm
Wear limit
 

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noobytoogy said:
Doing some research tonight, I found this:

A. For some reason German car manufacturers make their brake rotors thin. On your vehicle [Touareg] the specifications for the brake rotors are:

Front Brake Disc
Ventilated brake disc diameter 308 mm
Brake disc thickness 29.5 mm
Wear limit 25.5 mm

Brembo
18" ventilated brake disc diameter 350 mm
18" brake disc thickness 34 mm
18" wear limit 32 mm
17" ventilated brake disc diameter 330 mm
17" brake disc thickness 32 mm
17" wear limit 30 mm

Rear Brake Disc
Ventilated brake disc diameter 314 mm
Brake disc thickness 22 mm
Wear limit 18 mm
Brake drum- diameter 185 mm
Wear limit
I had a look on the same site after my original post and it seems to imply that only the front pads have the wear sensor fitted.
 

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Telemetrically Superb
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Strange....I changed my rear pads a few weeks ago and they deffo had the sensor - Only difficult part of the job is getting the plastic plug for the sensor to fit in its shoe

Rest of the job is easy
 

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Discussion Starter · #8 ·
Found this diagram on another VW site that I think shows the Transporter and, therefore, the 2.5 diesel rear brake / parking brake BUT THIS IS NOT GUARANTEED so it comes with a health warning!

Notwithstanding that, it shows the type of parking brake arrangement Tregs have which uses old fashioned brake shoes in a drum that sits behind and inside and is a part of the brake disc or rotor as some call it.

6-3-1.jpg[/attachment:12fg2kgx]
 

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Discussion Starter · #9 ·
Looking at the diagram above again, I noticed tonight that the disc shown is cross drilled as well as ventilated!

Me thinks it's not a Transporter then, but someting a little warmer!!
 

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Discussion Starter · #11 ·
Update on repairs:

When the rear discs came off, the internal drum that the parking brake shoes are pulled onto was a very, very dark brown with rust! There wasn't a glimmer of bright steel anywhere. No wonder the parking brake had failed the MOT!

As it turned out, the shoes were ok and just needed a bit of rust cleaned off them.

Coupled with the fact that the wear on the discs and the pads themselves was extreme, the Treg needed new discs, pads and sensors all around and the job took 3.5 hours.

Despite Hunterlees' excellent instructions, I have to admit I let my local garage do it in the end as it is years since I played with brakes on cars and I was concerned about truing the discs properly. However, since I left his instructions on the passenger seat and there are now oily fingerprints on the page concerning the parking brake, I think they were very useful!!

With the parking brake adjusted so it now only needs 6 to 7 "clicks" on the pedal to engage [12-13 previously!], the MOT was duly passed.

Interestingly, the Treg's reluctance to fully disengage the parking brake upon a swift release [activating the red light and bleeper] rather than the usual "pull to release, hold for 2 seconds and then let go" has also been cured!
 

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I never use the parking brake.
Any views on whether it's advisable to use now and again,especially after reading nooby's post?
 

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'Ow bist?
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I always use it. I've got the notion that there is a tiny little weedy pin or something that holds the car in "P".
 

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Discussion Starter · #14 ·
Nimrod said:
I never use the parking brake.
Any views on whether it's advisable to use now and again,especially after reading nooby's post?
Wurzel's right: P is definitely not enough for a two and a half tonne lump especially on any kind of a slope.

If the car was just left in P and ran away and a serious accident occurred resulting in a fatality . . . well, I think you can work out the likely consequences.

IMO, the parking brake should not be an option unless leaving the car on a level surface for a long time such as a two week holiday when it should then be chocked!

And I'm told the trick to keep the drum clean and clear of rust is to partially apply the brake and drive the car very slowly for 100 yards occasionally otherwise the only thing that is happening when applying the parking brake when stationary is pressing the pads onto a rusting surface with no friction to clean it up.
 
G

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noobytoogy said:
Update on repairs:

When the rear discs came off, the internal drum that the parking brake shoes are pulled onto was a very, very dark brown with rust! There wasn't a glimmer of bright steel anywhere. No wonder the parking brake had failed the MOT!

As it turned out, the shoes were ok and just needed a bit of rust cleaned off them.

Coupled with the fact that the wear on the discs and the pads themselves was extreme, the Treg needed new discs, pads and sensors all around and the job took 3.5 hours.

Despite Hunterlees' excellent instructions, I have to admit I let my local garage do it in the end as it is years since I played with brakes on cars and I was concerned about truing the discs properly. However, since I left his instructions on the passenger seat and there are now oily fingerprints on the page concerning the parking brake, I think they were very useful!!

With the parking brake adjusted so it now only needs 6 to 7 "clicks" on the pedal to engage [12-13 previously!], the MOT was duly passed.
Can you explain what you mean by Truing the Discs??
 

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trueing the discs means that they will rotate cleanly with no "wobble" laterally, if they don't run true you will get vibration and have to push the peddle harder to get them to work. Most garages will have a run-out gauge which measures the "wobble", normally rotating the disc on the hub will change the amount of run-out until you get within the required tolerance.....HTH
 

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Discussion Starter · #17 ·
dorset_treg said:
trueing the discs means that they will rotate cleanly with no "wobble" laterally, if they don't run true you will get vibration and have to push the peddle harder to get them to work. Most garages will have a run-out gauge which measures the "wobble", normally rotating the disc on the hub will change the amount of run-out until you get within the required tolerance.....HTH
Exactly.
 

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Due to the securing bolt which holds the disc onto the hub, for the Treg there is only one possible alignment of both.
This applies front and rear.

As an aside, some years ago when I was rallying, a fellow competitor had his car fail scrutineering due to lack of a mechanical parking brake (as the handbrake had been converted to hydraulic operation). His solution - punctured a hole through the transmission tunnel and inserted a long screwdriver through the yoke of the propshaft - Result - passed!

(same car failed another time as horn not working - visit to a cycle shop produced a cycle horn, screwed to dashboard -passed again!)

Alasdair
 

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Discussion Starter · #19 ·
hunterlees said:
Due to the securing bolt which holds the disc onto the hub, for the Treg there is only one possible alignment of both.
This applies front and rear.
A very good point.

One should still check for trueness of rotation though.

A few thou out at the hub if a bit of dirt or whatever is trapped between the mating faces will magnify up to 100 times at the outer edge of the disc.
 
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noobytoogy said:
hunterlees said:
Due to the securing bolt which holds the disc onto the hub, for the Treg there is only one possible alignment of both.
This applies front and rear.
A very good point.

One should still check for trueness of rotation though.

A few thou out at the hub if a bit of dirt or whatever is trapped between the mating faces will magnify up to 100 times at the outer edge of the disc.
I honestly had to read this twice, If making sure the hub where you mount the Disc onto is free off rust and dirt is beyond your ability then yes you should Definitely leave it to the professionals.

Ask how many garages use a dial gauge after fitting every set of brake discs and you'd probably get the answer virtually never, esp if the vehicle came in for just a general wear and tear replacement of the discs. Personally i think you've just chickened out
 
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