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Counter Of Beans
Trainee


Joined: 10 May 2018
Posts: 99
Location: Hampshire


PostPosted: Thu Aug 09, 2018 3:34 pm    Post subject: Gen 2 rear disc corrosion Reply with quote

Just returned from Portsmouth OPC where I had the sports mode retro-fitted (expensive, but transforms the car, love it!). Anyway, they insist on doing this inspection thingy, and even email you a video with comments. One of which was that the insides of the rear discs are rather rusty, and they recommend new discs and pads at a cost of several million pounds.
My questions are as follows:
Will corroded discs result in a MOT fail? I should add that the discs aren't cracked, braking is fine, and the pads have plenty of remaining life.
Should this even be happening after only 34k miles (and 7 years)? I appreciate that rear discs don't do much work, but surely their service life is longer than this?
And finally, if I do get new rear discs and pads, where's the best source for gen 2 parts? Every seller on Ebay seems to only offer discs and pads for gen1 cars, or are they all the same anyway?
TIA, Mike.
 
  
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Magic919
Imola


Joined: 05 Jun 2013
Posts: 826
Location: Berkshire


PostPosted: Thu Aug 09, 2018 3:38 pm    Post subject: Reply with quote

They can rust without the car moving anywhere, so age and miles don’t matter.

Service life is dictated by thickness.

Just drive the car and try some harder braking. Rust on the discs is part of Porsche ownership.
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997.2 C2S PDK
997.2 C4S PDK
 
  
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FZP
Indianapolis


Joined: 18 Jan 2015
Posts: 2488
Location: Cheshire


PostPosted: Thu Aug 09, 2018 3:59 pm    Post subject: Reply with quote

What they're referring to I imagine is rust on the inside of the hat. It looks bad but I don't think it's all that bad. The one bloke to confirm is Demort. He'll be along shortly I'm sure
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997.2 Carrera 2S GT Silver/Cocoa.
 
  
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Jam911
Barcelona


Joined: 31 Oct 2010
Posts: 1411



PostPosted: Thu Aug 09, 2018 4:51 pm    Post subject: Reply with quote

I had a MOT advisory for exactly this.
I did nothing but drive lots.
Next year, the corrosion had all gone.
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Ex '99 2.5 Boxster
 
  
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deMort
Zolder


Joined: 21 Mar 2015
Posts: 5158
Location: Brighton


PostPosted: Thu Aug 09, 2018 7:02 pm    Post subject: Reply with quote

Its pretty common for the inside face of brake discs to corrode .. i would only start to be concerned if the face material was actually coming off ...

Even then it wont fail an MOT .. its done on brake roller efficiencys these days .

Rear brakes are pretty much only 25 % of the stopping force so the same on the fronts would be a little more important.

They will have given you a video of the inspection and it will show the rear brakes .. if you can give me the link or email me the video i can give you my advise on the condition .

De.Mort@virginmedia.com

Without seeing then atm im leaning towards dont worry .. but its nice for me to see a picture or a video to be 100 % .
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Mechanic

7pm - 9pm
At an Indy these days !
 
  
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Counter Of Beans
Trainee


Joined: 10 May 2018
Posts: 99
Location: Hampshire


PostPosted: Thu Aug 09, 2018 8:07 pm    Post subject: Reply with quote

Wow, thanks deMort, that is very good of you. Have sent pm and email.
Cheers, Mike.
 
  
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Monkeynutz
Nürburgring


Joined: 05 Oct 2016
Posts: 445
Location: Peterborough


PostPosted: Thu Aug 09, 2018 8:31 pm    Post subject: Reply with quote

I just did my front discs and pads because the insides of the discs were bad despite them looking fine from the outside and the pads having a good few mm of life yet.
My indie told me it was common on both the front and the back for this to happen and driving it 'properly' is a good preventative measure Wink

I got them changed and it made a dramatic difference but that's unsurprising given what DeMort says so one might have expected as much.

OPC will want to charge about 100% more than your indie using original parts. I think deals can be had on Euro car parts at times.
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willy
Silverstone


Joined: 01 Jul 2012
Posts: 120
Location: Cheshire\Wales Border


PostPosted: Thu Aug 09, 2018 9:10 pm    Post subject: Reply with quote

Have recently replaced my disks and pads all round due to MOT failure.

Outside of disks looked fine, but inside of the disks were scary. Can't see how a pad could sensibly make contact with it.

All replaced for ~£210 parts plus either DIY or small labour from indy.
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1998 996 Carrera Ocean Blue
 
  
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