Brake wear

[Rupert]

Hello folks,

Yesterday I got around to measuring my brake discs. The results are..
Fronts... 58% worn,
Rears... 34% worn.

So... I might be able to get 34k miles out of a set of front discs? (I'm on 20k now).

I also measured my tyres, plenty of tread in the middles, I measured 4.7mm on the nearside front - but the inside edges of all tyres is not acceptable. So I'd say these tyres have done at least 15k (that's how much mileage I've put on the car since buying it).

Quite pleased!

[MartynC]

What thickness should the discs be Rupert? I just wondered how you've come to those figures. Anyone know what thickness id allowed on a 6 Plus before disc replacement is required assuming no other problems?

MartynC

[Rupert]

The standard 6 dimensions are:

[Rupert]

Use the 365 and 355mm diameters.

[DrB]

Does that mean a disc can only wear 2 mm before it is at its limit?

[MartynC]

Thanks Rupert, 2mm?? Seems like not a lot!

MartynC

[Rupert]

2mm is correct. Also, if you have drilled discs, keep an eye on any cracks as they should be replaced if a crack runs from one hole to another (it's also an MOT failure).

It's easy to measure your own discs with a micrometer (I have 0-25mm for the rears and 25-50 for the front, and vernier calipers for the pads).
Get the digital ones as you can then use them without taking the wheel off.

The 911 turbo was recently in for a service, they lumped the wear together by saying "Your brakes 70-80% worn". When questioned, he said "pads and discs".

The pads may be 70-80%, but the discs were only 55% worn!

In the past (on another porsche) I was told the discs were 66% worn. 10k miles later at the next service (and a different porsche garage) I was told they were only 50% worn! Work that one out!

[MartynC]

Thanks Rupert! I ahve a micro so I'll give it a go soon. Thanks for the info.

Martyn

[AntS4]

Interestingly I had my drilled discs measured today and was quite surprised at the results.

Fronts
New: 34.0 Wear limit: 32.0

N/S/F: 33.25
O/S/F: 33.11


Rears
New: 22.0 Wear limit: 20.0

N/S/R: 22.40
O/S/R: 22.39


Now, what is strange is that when I look at the front discs they look more worn than 0.75 of a mm. In fact they look worn by at least a 1.0 mm on each side of the disc, making in my opinion 2.0mm of wear, hence getting them checked! But a nice surprise nevertheless.

However, on the rears you will note that the discs are thicker than what they should be new... which makes me worry that there might be a possibility that the micrometre that they used at Listers may need calibrating?

Do such things need calibrating over a period of time? Unless of course drilled discs are slightly thicker in the first instance.

Does anyone have experience of such matters that may be able to shed some light on this? Does anyone going to the meet on the 30th at Bobs have a micrometre?

[Rupert]

The micrometers normally come with a standard length bar, so you can check they read 0 and some other length. Mine is a Mitutoyo digital type and has a 0.130" bar. I'll be away on the 30th

[installer69]

I'd quite like mine measured if I make the 30th if anyone will be there with a micrometer.

As an afterthought - can you imagine how anal we would look gathering our supercars in a car park and measuring brake disc thickness!!! My wife would count her suspicions as proven.

[AntS4]

So too did my wife laugh at me regarding the meet next Weds. I thought I had managed to convince her that this was a proper RS6 owners club meeting and as her father is an avid member (and past president I think) of the Aston Martin owners club I would have her understanding and enthusiasm for my being present. As it transpires she has been giggling at me every time I mention next Weds and then she pretty much fell off her chair on enquiring as to the location when I said we were meeting at the Bicester Village car park. I think she was expecting AMOC type meets where they hillclimb/sprint followed by 5 course meals at Le Manoir!

Thank god she doesn't know the web address of this forum and see what we really talk about!

I for one however can't wait and look forward to lots of admiration of our wares, comparing notes and maybe having a pint.

[SteveH]

Thats pretty much exactly the same for me.

[SteveH]

Car had its first MOT today, I expected the call mid-day to inform me "sorry sir, your RS6 has failed its MOT as it clearly needs new rear disks", as my rear disks look absolutely shot to me.

Imagine my surprise when firstly no call was forthcoming, secondly it had passed its MOT and finally to be told, "your FRONT disks dont have much life left in them". Fronts!! They are practically shiny and new, less than a year old, whereas the rears look horrendous and in all probability, given the corrosion, are the original discs when manufactured in 2003, turns out they are cosmetically poor but still perfectly functional and 10,000 miles left in them. Whereas my "new" fronts have 4-5,000 miles left.

I forgot to ask what the actual readings were (must buy a micrometer myself), but that will be about 20K miles out of this front set that I put on in October. I think I will get full set though when I change the fronts.

Bizarelly I am getting better mileage out my PS2 tyres than my front disks!, even wear all round and plenty of tread left. Wonder if Michelin could make me some brake disks?

[MartynC]

Bet you're washing the car too often and rusting the discs Steve.

Amazed those rear discs passed though!

MartynC