rusting brake discs

[dave cullen]

as a first time boxster owner, im looking after mine like a baby, but as i dont commute in it, choosing to use it at weekends, i notice a lot of brake disc rusting;
having read an article by james may in the telegraph where he gives porsche hell for corroding discs, im a bit worried about having to replace all my discs simply because i dont do a big mileage, does anyone have any views on this? thanks

 

[Dave Wilkinson]

I really don't think this is a Porsche-specific issue. Every car I've ever owned that had disc brakes has rusted the discs if you don't look after them properly. By the very nature of the materal they are made from, if they are left damp or wet they will rust - end of story.

The secret is to ALWAYS take the car for a 10 minute drive after you wash it, making sure you using plenty of braking action as you do it. THEN put the car away and, if you can, leave the handbrake off. It won't stop the rust completely but it will stop the heavy build up. The surface rust will disappear the first time you use the brakes.

The REALLY annoying thing - which is what I suspect James May is on about - is the rusting bells, the bit around the hub. AFAIK Porsche paint the bells but many of the aftermarket discs come unpainted and they will generally rust quite badly.

Regards

Dave

 

[oliver]

Common problem caused by lack of use, and made worse by cleaning the car and garaging it without drying off the brakes.

Not Porsche specific, but worse on cars with drilled discs. Discs can be skimmed if they are still thick enough.

 

[Laurence Gibbs]

Some interesting views. Not a lot of help to those of us that have cars that sit outside in all weathers(unless we want to go out and use the car for 10 mins everytime it stops raining !) . Not sure i totally agree that it's caused by lack of use either. I do 9k a year in mine but still had to replace mine due to rust rather than wear. I found the outer edge of the disc seemed to suffer most and that's the part that does'nt get cleaned off by the pads but just relies on heat from braking to burn any water off. I think maybe the "vented" design does'nt help as it allows water to sit in places that a solid disc would not have. By contrast my skoda rapid has solid discs that have sat outside for about 8 years, a stearn wire brushing brought them back to almost as good as new!

 

[Dave Wilkinson]

Laurence,

I take your point about sitting outside but I don't think that's a big issue. The discs tend not to get so wet if the car is just parked and if it's being driven the heat build up gets rid of the water anyway. It's that washing that's the problem - lots of water and no heat.

Rust in the ventilation fins is not a big issue either - the car will never fail an MOT for that - it's on the braking surface that matters and it's often the inside surface that gets the tester's attention because that's the side you don't often, if ever, see. I always reckon a good old fashioned "Italian Tune-up" is a good idea now and again - particularly before an MOT.

Regards

Dave

 

[Laurence Gibbs]

Rust seems to build up on mine without washing it. It does get left for weeks at a time but it also gets used too. It's not that the vents rust it's that the disc corrodes from the inside out where the water sits inside the vented portion of the disc. Removing the rust from under the pad area is easy it's the outside edge that's the tricky bit. When this corrodes lumps of the outside edge can fall off (especially when doing a pad change!)leaving you with a fairly imbalanced disc. If i get some time i will take a photo of mine so you can see what i mean.

 

[Laurence Gibbs]

best i could do with camera i'm afraid

 

[dave cullen]

guys thanks very much for advice, my car sits outside, (i do leave handbrake off), and basically when it does go out at weekend, it gets a good run and as its always washed at a "brushless" valet centre, i have to drive it 10 mins back up the road, so brakes are dried off;

have to say though, the discs on my trusty old mitsubishi which lay in drive for almost a year at one point, didnt look rusty at all!

dave

 

[Timbo2]

This isn't a Porsche specific problem, I've replaced countless discs as a result of corrosion, most discs will get a covering of rust overnight if the air is damp. I do however feel that the quality of steel used isn't as good these days, don't remember having to do this so much back in the late 70's. Talking to an MOT tester, providing the car passes the brake test the condition of the discs is not necessarily a fail item. My car recently passed an MOT but while having some work done on it I noticed that the inner surface was incredibly corroded, I've since replaced them.