Do I Really Need New Brake Discs With Only 0.5mm Wear ?

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RAA
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Post by RAA » Thu May 05, 2022 12:41 pm

I've now had my Macan S for three years since new, having just done 37,000 miles. The brake pads needed replacing, and the OPC said the car also needed new rear discs. When I went to a local MoT garage, they ordered the new pads and discs in from Porsche UK, and I had the work done last Friday. I asked for the original discs to be left in my car boot: when I got back home, I measured the amount of wear, as being approx half a millimetre (0.5mm). Surely, half a millimetre of wear is not enough to warrant the discs needing changing (?)

What should the depth of wear be, before the discs really DO need to be changed ? (A friend of mine who is a senior technician with the racing branch of a well-known super-car manufacturer in Surrey, took a look and feel of my rear discs last week, and reckoned they DIDN'T need changing. Two other friends told me the same. My brother who has owned a Cayenne, Audis and Jaguars etc., tells me the same.)

I'm keeping my old discs to be used again ! What do other forum members think ?

(Bob, Surrey)

Percymon
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Post by Percymon » Thu May 05, 2022 12:57 pm

If you use Brembos website as a guide then the rear discs are 22mm thick when new and have a min thickness of 20mm - so 2mm of useable surface thickness.

OPC use brakes as a nice money earner. Any dealership will always err towards advising change of wear components if there is any chance they may wear out before the next service (2yrs these days for most). Your MOt garage were little better, they could have told you to keep hold of the new parts for another year.

Having said al;l that at 37k miles i would expect the rear pads to need replacing or not far off, more so for cars with ACC or PTV systems - Porsche will always advise pads and discs at same time, but you can often run two sets of pads for one disc

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Nuclear Nick
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Post by Nuclear Nick » Thu May 05, 2022 1:20 pm

+1. Some Brembo discs have the minimum thickness stamped on them.
Nick

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CharlesElliott
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Post by CharlesElliott » Thu May 05, 2022 1:53 pm

Front wear limit for a Macan S is 32mm and 20mm for the rear. Start is 34mm and 22mm.
Macan GTS: PH1UFLL8

bigbaldybloke
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Post by bigbaldybloke » Tue May 10, 2022 11:13 pm

At approx 35k miles in my previous S I needed new discs and pads on the front but only pads on the rear, this was at the supplying dealer.
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RAA
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Post by RAA » Sat May 14, 2022 10:08 am

Thanks everyone for your views and experiences.

Bob

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Tim92gts
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Post by Tim92gts » Sat May 14, 2022 10:19 am

If you want to check yourself there's a little notch in the cover just below the calliper.

Slip a micrometer in and if you have spoky wheels take a photo with your phone to read the measurement.
Tim
PP Turbo, LED PTV ACC Pano 20"Macans collected 6th September 2017
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HertsMacan
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Post by HertsMacan » Sat May 14, 2022 1:13 pm

RAA wrote:
Thu May 05, 2022 12:41 pm
I've now had my Macan S for three years since new, having just done 37,000 miles. The brake pads needed replacing, and the OPC said the car also needed new rear discs. When I went to a local MoT garage, they ordered the new pads and discs in from Porsche UK, and I had the work done last Friday. I asked for the original discs to be left in my car boot: when I got back home, I measured the amount of wear, as being approx half a millimetre (0.5mm). Surely, half a millimetre of wear is not enough to warrant the discs needing changing (?)

What should the depth of wear be, before the discs really DO need to be changed ? (A friend of mine who is a senior technician with the racing branch of a well-known super-car manufacturer in Surrey, took a look and feel of my rear discs last week, and reckoned they DIDN'T need changing. Two other friends told me the same. My brother who has owned a Cayenne, Audis and Jaguars etc., tells me the same.)

I'm keeping my old discs to be used again ! What do other forum members think ?

(Bob, Surrey)
Good for you using an independent garage but genuine Porsche parts to carry out your repairs. Like you, I am not prepared to pay the OPC's silly prices for routine and basic service requirements. Do enlighten other members on the small fortune you undoubtedly saved. Garages use the exact same tactics with tyres. They "recommend" they are changed when there is still 75% of the tread left. Its a nice little earner, as Arthur Daley would say. Totally agree, keep those old discs and use in future.

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