RS4 Front Brake Disc Wear Limits

[AndyRS4Glos]

Hi,

Am hoping that someone can help with details of the front disc wear limits on an RS4 B7. When I bought the car under the Audi approved scheme from a dealer some distance away from home I specifically pointed out that the front discs looked a tad shabby and could they be checked out. Later I was assured that the discs were ok (within 60% of wear limit to sell under Audi used approved scheme) but the pads had been replaced; I then bought the car on this understanding.

Roll on 700 or so miles and 6 weeks later.......... decide to take the car in to my local Audi dealer for a "complimentary summer health check". Check picks up "brake discs close to wear limits but new pads fitted" plus a couple of other items including weeping oil cooler pipe and worn suspension bush. Anyway, moving on, I take the car back to the supplying dealer for the items to be attended to and am told that the items identified will be fixed but the brake discs are in limits and dealers typically make notes on the condition of the brakes to "upsell". Have also been given thicknesses of the discs to prove that they are within tolerance. However, I can't find any details on the web to indicate what the limits are.

Greatful for any advice as at the moment I seem to be stuck between 2 opposing views in respect of the state of the discs and any info would be greatly received. It seems strange that the discs are deemed to be fit for purpose under the Audi approved scheme but are then deemed to be "close to wear limits" some 700 or so miles later under a complimentary health check.

[spikeyboy101]

Front discs start at 34mm with a wear limit of 32mm

Audi will tend to tell you to replace if they see a lip on the edge.

I had a similar issue when i bought mine from an indy dealer - asked them to check to disk thinkness as they looked a bit shabby - i was given thickness of 32.8 mm (60% worn) on each side so no need to replace.

A week after buying the car i took it to Audi for the free coil pack change and they gave it a the once over - guess that came up - new discs needed on front as close to wear limit.

[toyneg]

this week had mine in at Audi for a health check and were told I needed new front discs and pads, but just come back from an Indie Audi specialist who I have used for yrs and they said the pads have approx 2-3k miles left and then the discs are fine to last through another set of pads at least. 2 techcies had a look and confirmed that.

[P_G]

Buy yourself a digital Vernier Caliper from Halfords for £20 or borrow one and measure yourself, easiest way.

[pDkALO]

Buy yourself a digital Vernier Caliper from Halfords or borrow one for £20 and measure yourself, easiest way.

+1

Note that you need to measure the actual thickness of the body of the disc, so if there is a lip on it the gauge will give a false reading. On mine the discs were hardly worn at all when I bought the car, but it had stood for a while so the small lip had a coating of rust which made the reading even further out - I simply sellotaped 2 small washers on the back and front of the disc, measured across them, then deducted the thickness of the washers.

Oh and by the way, whilst the "complimentary health check" is a handy thing to be offered, don't forget that it probably goes by other names on the other side of the service desk, such as "list of expensive stuff that the customer might like to pay for now rather in 2 years time when it's actually needed" etc.... I'm not knocking the dealers for offering the service, but sometimes it's best not to take those pieces of paper on face value, and instead use them as a starting point for further discussion.

By the sounds of it I'd reckon that your discs are actually OK, and the 2nd dealer has indeed tried a bit of upselling - but if they're correct though, and they really do need replacement, you'll have very strong grounds to get the supplying dealer to cough up for new ones.

[AndyRS4Glos]

Thanks all. Indeed the measurements given to me by the supplying dealer do indicate that there is life in the discs yet. But in my view the discs are badly lipped and I will invest in a digital calliper just to reassure myself.

[supersi]

To be honest I've asked our brake engineers on the OEM wear specs and was told its really to sell more rotors, I've had rotors skimed bellow the recommended limt and used and know many other owners now using at bellow the spec

[pDkALO]

But in my view the discs are badly lipped

The lip is nothing to worry about, and certainly no reason to replace the discs. The lip simply builds up because the sweep of the pads misses the outer 1-2mm of the disc - and then the lip might get a crust of rust building up on it that makes it look much worse than it is, which is exactly the case with my car (remember that rust is about 10x the thickness of the metal that it came from)

[supersi]

But in my view the discs are badly lipped

The lip is nothing to worry about, and certainly no reason to replace the discs. The lip simply builds up because the sweep of the pads misses the outer 1-2mm of the disc - and then the lip might get a crust of rust building up on it that makes it look much worse than it is, which is exactly the case with my car (remember that rust is about 10x the thickness of the metal that it came from)

Was told the lip can cause noise that's all, on a side note our disc are 362mm dia so don't get the lip, and new are 32mm thick

[pDkALO]

as a side note our disc are 362mm dia so don't get the lip, and new are 32mm thick

Good bit of design that...
Although the lip may only result in noise (if that), it's still a slightly clumsy bit of design thinking by the factory, because if nothing else it just looks a bit rough