Q2 Rear Brake Discs Rusting

[Old Nick]

After just 22,000 miles the rear discs are rusting and showing great signs of wear. Two local dealers are saying that it is normal wear and tear despite the fact that the front brakes are perfect.

Has anyone else had the same problem?

[Crasher]

Rust on the bells? The rear brakes on the modern VAG cars wear as much as the front which are twice as thick to start with.

[Old Nick]

But there is no wear on the front brakes!

[Crasher]

After 22k there must be some front wear but it will not be as obvious, but message me the REG number and I will see if I can dig anything up as interestingly on cars made after 7/10/2016 there were some odd changes made to the rear brakes on cars with PR-1KE and I imagine there is a TPI notice to go with this. I can’t dig deeper until Monday when I get back.

[Old Nick]

Hi I much appreciate your comments re the front brakes and your offer of help. The registration is CU66WBG and I have an AA report that might be of interest to you but the .jpg file is too large for this forum! My email is nick.ward@ntlworld.com If you send me a quick email, I will send you the report.
Regards
Nick

[Old Nick]

Hi again.

I thought that I better explain that this Q2 is not mine - it belongs to a very good friend of mine who has not got very far with both the local Audi dealerships or as you will see below Audi UK.

Dear Sir

Thank you for taking the time to speak with me regarding your concerns with the condition of your brakes/pads/discs.

We understand that you strongly believe that there is a fault of some sort with the rear brakes as a whole, despite being advised by two different Audi Technicians (MK Audi, and Audi Bedford) that it is wear and tear, and that the pads/discs require changing, advice which you have not followed up to now despite putting yours and others safety at risk.

As you have had two separate Audi Technicians advise you of the same diagnosis, we have no choice but to agree with their findings, and recommend you change the brake pads/discs immediately to ensure safe braking. You have advised that you will be seeking a report from a third Audi Centre, and you will be requesting to be present during the inspection (We do not know if that will be allowed). I have advised you that regardless of the outcome, the brakes are covered by six month wear and tear warranty, which has expired a long time ago, so you will be required to pay for the replacement of your brake discs and pads as you are the owner of the vehicle and responsible for the maintenance.

Once you have obtained your third report, you can either respond to this email directly, or use the telephone at the foot of the email.

I hope to hear back from you soon.

Kind regards


Mikki Elliott
Executive Customer Relations Manager
Audi UK
T 0800 699 888
E executive.office@audi.co.uk (executive.office@audi.co.uk)
Internet: www.audi.co.uk (http://www.audi.co.uk/)


Thanking you again for taking the trouble to look at this problem - I personally cannot believe that a quality vehicle requires new discs and pads after 22k miles of normal motoring!

Regards
Nick

[Crasher]

It was built 27/09/2016 which is before the 07/11/2016 change of brake disc and pad specification for new build cars. For the purposes of pad/disc replacement on pre 07/11/16 cars, the original discs are superseded but the pads are not and unfathomably the calipers and carriers didn’t change when the discs and pads did so I need to look deeper into this at work and see if there is a TPI about it, something was wrong here that they are either covering up or are not aware of locally.

[Old Nick]

Again much appreciate you taking time to look at this problem. My friend thinks that both Bedford and Milton Keynes Audi did not bother to remove the rear wheels to check on the full extent of the wear. Neither dealers stated the the vehicle was unsafe to drive which must pose the question as to why Audi UK thought it was!

[Crasher]

Neither dealers stated the the vehicle was unsafe to drive which must pose the question as to why Audi UK thought it was!

Because the dealers could see the car and Audi UK could not so to Schütze deinen Arsch, they overreact just in case

[vwcabriolet1971]

Most of the braking is by the front brakes because of the weight transfer during braking. Rear brakes don't do much of the braking and the disc surfaces can become become somewhat rusty or grooved on low mileage vehicles or where the brakes are only used lightly. The depth of the lip on the outside periphery of the disc is more pronounced on the front discs indicating more wear on the front discs but the disc surfaces are generally free from surface rusting. The only way of measuring disc wear accurately is with an engineering micrometer or caliper. A visual inspection can be misleading. Of course the wheels need to be removed to use the measuring instruments which most dealers can't be bothered to do.

[Crasher]

Of course the wheels need to be removed to use the measuring instruments which most dealers can't be bothered to do.

Indi’s and dealers alike would probably be quite happy to take the wheels off during a service, the problem is the VAG schedule does not allow the hour it takes to remove four corroded on wheels that have not been off in at least two years, then clean the bell and wheel faces with a wire wheel, paste up the faces, clean and paste the bolts and then refit the wheels, drop it on the deck and double torque check 20 bolts to the specified torque, one of a grease monkeys greatest fears is a wheel coming off so if you don’t remove it, that is unlikely to happen and when the service sheet asks for a visual indication of pad wear, are you going to take an hour to check something you don’t get paid for but have to accept all the risks? That hour does not included the twenty minutes trying to find the wheel bolt key under layers of crap in the load area. On top of that, try telling the average customer it has cost them £70>£120 to have the wheels removed and re-fitted, have you ever had a customer spit feathers with incredulity over the cost of a task they don’t understand?

[KevTrem]

Indi’s and dealers alike would probably be quite happy to take the wheels off during a service, the problem is the VAG schedule does not allow the hour it takes to remove four corroded on wheels that have not been off in at least two years, then clean the bell and wheel faces with a wire wheel, paste up the faces, clean and paste the bolts and then refit the wheels, drop it on the deck and double torque check 20 bolts to the specified torque, one of a grease monkeys greatest fears is a wheel coming off so if you don’t remove it, that is unlikely to happen and when the service sheet asks for a visual indication of pad wear, are you going to take an hour to check something you don’t get paid for but have to accept all the risks? That hour does not included the twenty minutes trying to find the wheel bolt key under layers of crap in the load area. On top of that, try telling the average customer it has cost them £70>£120 to have the wheels removed and re-fitted, have you ever had a customer spit feathers with incredulity over the cost of a task they don’t understand?

Its not the first time I've been laid on my side under the back of a car kicking, and then resorting to hammer a wheel off the rear of a car. 1 wheel took about half hour. I fully understand your comment above Crasher.
To be fair you can probably get a set of callipers or micrometre over a disc if not through the wheel then from behind the wheel especially up on ramps removing the need to take wheel off.

[Crasher]

With most modern wheels you can check the outer pad and disc face in seconds, Many modern VAG rear back plates make it impossible to check the inside face of the rear discs, even WITH the wheel off and as for rear bleed nipple access....:aargh4:

[vwcabriolet1971]

Some disc manufactures used to M/C flat bottomed holes in the disc faces to indicate the limit of disc wear. These were not balancing holes ( balancing is done by M/Cing in the middle of the disc periphery).

[Old Nick]

Hi
I wonder if you have come up with any more info. It sounds as though you might have a working knowledge and connection with Audi or VAG?
Regards
Nick

[vwcabriolet1971]

There are commercial disc thickness measuring ( digital) calipers specially designed to get into the limited space between most brake caliper and the discs. In the case in question in would only need one rear wheel removal to gain the necessary access.
Its a shame that most garages (& dealerships ) don't have brake skimming in-situ lathes. These M/Cs can skim discs ( both sides) on the vehicle obviating the need for new discs in a lot of cases. Almost all American brake Specialists ( brake & clutch outlets) have these M/cs. Our garages would sooner sell you new discs.

[Crasher]

I wonder if you have come up with any more info. It sounds as though you might have a working knowledge and connection with Audi or VAG?

38 years as a VAG group specialist... I would have served less time for murder, twice over! It is too new for my free to use system, I would have to log into ODIS to get deeper info and that costs me 10 Euro an hour.


Some disc manufactures used to M/C flat bottomed holes in the disc faces to indicate the limit of disc wear.

Brembo used to do that but they stopped because people would complain that the discs was damaged, it caused so much grief that people stopped using Brembo.


Its a shame that most garages (& dealerships ) don't have brake skimming in-situ lathes.

The problem is that most discs are below minimum thickness even before skimming. Setting up and running an on car disc skimmer costs more money due to time than a new set of discs. The reason garages like to fit new discs is not just a few quid profit but also the wheel face is then clean and true so saving even more time and they know the likelihood of noise related comeback is reduced to almost nil, garages don't like doing job twice.

[vwcabriolet1971]

I'm not sure about the economics of skimmming versus disc replacement. If the Americans can justify skimming why can't we ? . Ed China on the wheeler dealer Tv show saved a considerable sum by skimming 4 porche discs. Most scrap rear discs I've seen are scrapped because they are rusty not because they are thin. The big advantage of skimming , if done properly, is that there is minimal run-out as the M/Cing is done on the main hub bearings.

[Crasher]

Wheeler dealers is notorious in the trade for not taking account of labour and proper Porsche discs are expensive, most normal VAG discs don't cost a great deal. Also the typical VAG disc is only allowed 2-mm of wear so 1mm per face and that is THE limit, not a fresh pad install limit where the typical skim takes off 0.5-mm on a discs already worn down 1-mm or more. The initial cost of these machines is huge, I can't find out how much because none of the UK suppliers seem to want to tell you but there was a used one for £4K and they say that you should charge £40 per pair of discs.... which is roughly half the price of a new pair of typical discs, I would rather spend that on new discs!

[warp_speed]

Actually I have a similar issue with my Q2, 2016, 16k miles on the clock, I just recently bought from an independent dealer (Ford, Arnold Clark). Audi advised rear disks and pads to be changed but the dealer ignored their advice. Don't think the Ford Dealership had VCDS to rewind the calipers.

Anyway muggings here bought pads and disks from Audi and changed them myself. I've been changing my own disks and pads for over 20 years and these look really bad. However even after 200 odd miles the rear disks still don't look like the pads are doing much, I've made sure the pins are greased and sliding freely (used the grease from a TRW caliper service kit so its the correct pin grease), together with the seating points on the caliper. Perhaps there is an underlying issue with the calipers, even although the piston moves without issue?

[FrenchAudi]

I have experienced pedal "bouncing" and bad vibration on braking with skimmed discs, even when they had been machined off the car. This was presumably due to the two faces not being parallel, caused either by wear in the machine used, or operator incompetence/error.

Accurate machining on the car would depend on the condition of the wheel bearings, which could not be guaranteed. I also wonder where the swarf ends up?

I remember machines for balancing wheels on the car, which seem to have disappeared, probably for the same reason.

[Crasher]

I was told many years ago that on the car balancing machines would not work on driven wheels with cv joints as when the suspension was at full travel off the floor, the drive shaft angle caused vibrations.

[vwcabriolet1971]

It doesn't matter whether the discs are M/Cd on or off the car or whether new discs are fitted any significant wheel brg run-out should be attended to 1st or there will be wheel braking "wobble". In my experience having the M/Cg done off the car is fraugtht with danger. Most machinists do not have a mandrel that replicates the wheel hub mounting and will attempt to M/C the discs on a 3 jaw lathe chuck and will not spend the time to get the disc running true or removing all the rust from the disc mounting surface

[Crasher]

Many years ago I was at the shop of a now retired engineers for some engine machining work and Arthur, the owner, showed me a pair of discs that a taxi driver had brought in to have skimmed, he said their original thickness was 12mm and the minimum was 10mm but when brought in for skimming they were at 4mm.... needless to say he told the chap to go and buy new ones.

[FrenchAudi]

Years ago I was at a friend's garage in Spain, when Keith, the owner, showed me a car which had been brought in for attention to the brakes, which were pulling badly to one side.

At the front, on one side the pads had almost disappeared into the disc, on the other side the pads had met, and the remaining outer ring of metal was hanging on the caliper.

He said he was having a problem convincing the owner to pay for new discs and pads.

[mumutley]

Hi All,

I note when reading through this post that most of the Q2 vehicles mentioned are 2016 year vintage with between 16,000 > 22,000 miles. With the national average being 10,000 per year the stated mileage for these vehicles is lower.

Then the low mileage vehicle is used less than expected the rear discs do seem to suffer from surface rust (I have heard the same for several VAG group vehiles, Jaguar and Ladn Rover all with lower than average mileage) Higher/Average mileage vehicle do not appear to suffer from the same concern.

And the vehicle manufactures seem to follow the same recommendation'Rplace the pads and discs'

[Crasher]

All cars with Hybrid or full electric drive are going to have to go back to drums as cast iron discs are too exposed and non ferrous discs far too expensive. As with a lot of electrification of transport, there are lessons to be learned along with a realignment of expectations.

[mumutley]

I am sure expectations will be changing over the next few years!!

With car manufactures always looking to save money and maintain the good looks of the vehicle the best route is back to good old fashioned drums!!