WTF caused this?

Author
Discussion

Wozy68

Original Poster:

5,387 posts

169 months

Thursday 31st October 2019
quotequote all
Sebro brake discs, textar pads.

Last year OPC said change your brakes as they are shagged. I went mad because the rears were only four months old and covered less than 2K miles, the fronts 12 months old and less than 5K miles..... so i didn't as I thought they were taking the piss,

This year they said the same..... I had to admit the brakes felt like they were under performing. So I took it the fella I use for all the day to day stuff and this is what he found.

The outer face of the discs wern't great but a whole lot better than the inner faces.

So what has happened here. The one disc looks like a pad had stuck in position ... but thats not the case.

In places the discs have (for a better word) delaminated .... like they've lost a layer of steel.... funny thing is I couldnt feel anything through the brake peddle.

I did have to keep the car park outside for some of the winter, but I always gave the 993 a good heavy braking to clear any rust off the discs when I took her out.



ianwayne

6,244 posts

267 months

Thursday 31st October 2019
quotequote all
I had the same accelerated wear on a 986 Boxster S a few years ago. It was down to not driving it much (apparently), under 2k miles in 1 year, and drilled discs exaggerate the problem on low mileage cars, more surface area to corrode.

Perhaps the brand of discs you had fitted didn't help? If they're OEM, I'd be complaining. Other makes also often come with warranties.

DJMC

3,431 posts

102 months

Thursday 31st October 2019
quotequote all
Giving her a good heavy braking to clear any rust off the discs when you took her out may have been too late perhaps?

When I come home in rain I drive a few hundred yards with my left foot pressing the brake pedal so as to clear any water and heat the discs to evaporate any that's lingering.

Even after simply washing the car the discs will go brown after a few hours and so I always take mine for a run after washing, so as to dry/heat the brakes once again. Still on original discs at 51k miles and RPM said there was no sign of any disc corrosion at 50k.

Mine is always garaged overnight so even doing the above routine may not save yours if left out in the damp.

Koln-RS

3,849 posts

211 months

Thursday 31st October 2019
quotequote all
I think it was a common problem on 996s and 986s.

Water holds in the holes, and then dribbles down the back of the discs, causing corrosion build up.

Apparently, most common on low mileage 'garage queens' that are washed and put away without being dried out with a good run.

Skimming is the usual solution, if there is enough thickness remaining

Wozy68

Original Poster:

5,387 posts

169 months

Thursday 31st October 2019
quotequote all
Thanks for the replies

Bizarrely (for an air cooled these days) she’s driven throughout the year and covers the max 6K miles a year allowed under classic insurance and enthusiastically at that.

Thats why I was so surprised at the condition of the discs.

boxsey

3,574 posts

209 months

Thursday 31st October 2019
quotequote all
Wozy68 said:
Thanks for the replies

Bizarrely (for an air cooled these days) she’s driven throughout the year and covers the max 6K miles a year allowed under classic insurance and enthusiastically at that.

Thats why I was so surprised at the condition of the discs.
I agree with the comments above that it's the drilled discs that exacerbate the problem. Even with 6K miles a year the standing outside becomes an an issue and not even the heaviest of braking will clean off the corrosion in the holes as it sets in. I used to do similar miles in my 964 and also used sebro/textar but the discs being solid meant they were more resistant to corrosion (it lived outside too).

Discombobulate

4,794 posts

185 months

Thursday 31st October 2019
quotequote all
Wow. They have not aged well. Do you park in the sea / use acid on your wheels? wink

Edited to add: where did you get the discs? Are you sure they are as advertised, and not cheap copies?

gsewell

693 posts

282 months

Thursday 31st October 2019
quotequote all
Most of what has been said would have equal corrosion on each side of the disks or worse on the outer face for car/wheel washing. I believe that the issue is that the brake cooling ducts direct only to the inner face and if he roads are damp then the disk is bathed in water for every mile.
I'd love to find a disk that is corrosion resistant without the expense of ceramic or carbon disks.

Discombobulate

4,794 posts

185 months

Thursday 31st October 2019
quotequote all
gsewell said:
Most of what has been said would have equal corrosion on each side of the disks or worse on the outer face for car/wheel washing. I believe that the issue is that the brake cooling ducts direct only to the inner face and if he roads are damp then the disk is bathed in water for every mile.
I'd love to find a disk that is corrosion resistant without the expense of ceramic or carbon disks.
Aye but mine only looked like that after 6 years and 35k.

Slippydiff

14,742 posts

222 months

Thursday 31st October 2019
quotequote all
Back in the good old days, discs had a certain amount of chromium in the cast iron, it made the disc more corrosion resistant and harder wearing. Unfortunately it was expensive and reduced the disc’s co-efficient of friction...

Peter911

473 posts

156 months

Thursday 31st October 2019
quotequote all
Porsche's are cars that make you smile every time you drive them.

Smile more.


C4ME

1,156 posts

210 months

Thursday 31st October 2019
quotequote all
993 does a similar 5-6K miles a year and disks are still in good condition and I can't remember exactly when the disks were last replaced but at least 5 years 25K miles ago. Car is garaged and official Porsche disks and pads. I know with these cars it is a race to wear the disks with use faster than they rust but that rusted disk does not look usual, especially at such low mileage. Do you think the callipers are not working well so that rear face is not getting worn? Have you looked at the pads to see if any are abnormally thick compared to the others indicating they are not getting pushed properly by the calliper pistons?

Armitage.Shanks

2,251 posts

84 months

Thursday 31st October 2019
quotequote all
Isn't this something to do with 'plate lift' where the pads sit in the calipers? Classic symptoms are corrosion to the inside facing disk. Usually requires a strip down of the caliper and 'plates'. If it's not sorted you'll keep writing off the discs due to failure of the inner facing.

https://www.pistonheads.com/gassing/topic.asp?h=0&...

SRT Hellcat

7,017 posts

216 months

Friday 1st November 2019
quotequote all
What is the pad wear like. Are all pads worn evenly. It might be time to have the calipers serviced

DRH986

284 posts

143 months

Friday 1st November 2019
quotequote all
Here's a thread from 2016 on the same subject in which I posted my own conclusion, which is that the cause is due to the cooling ducts flowing water to the rear faces of the discs in wet conditions. The solution is to make sure there is sufficient heat in the discs to dry them out at the end of the journey. I've personally proven this theory and haven't had a problem with my cars since.

https://www.pistonheads.com/gassing/topic.asp?h=0&...


My own discs from 2014:

https://thumbsnap.com/sc/KUgtn5hL.jpg

Edited by DRH986 on Friday 1st November 08:44

Slippydiff

14,742 posts

222 months

Friday 1st November 2019
quotequote all
Armitage.Shanks said:
Isn't this something to do with 'plate lift' where the pads sit in the calipers? Classic symptoms are corrosion to the inside facing disk. Usually requires a strip down of the caliper and 'plates'. If it's not sorted you'll keep writing off the discs due to failure of the inner facing.

https://www.pistonheads.com/gassing/topic.asp?h=0&...
Modern Porsche calipers don’t have the stainless wear plates fitted, they were a feature on the 964/993/944/968 cars.

Edited by Slippydiff on Friday 1st November 09:46

Pickled Piper

6,334 posts

234 months

Sunday 3rd November 2019
quotequote all
It's not uncommon. It could be some "plate lift" that is preventing the inner pads from contacting the disc properly.

You do have to drive them hard and brake really hard to get all the crud off the discs. Storing the car outside doesn't help.

mlsporsche

67 posts

78 months

Monday 4th November 2019
quotequote all
Rust forms at about 70% RH, it doesnt need to be wet

Wozy68

Original Poster:

5,387 posts

169 months

Monday 11th November 2019
quotequote all
What’s occurred here?

The photo shows my old discs (and others) that was thrown outside (ready for the scrappy). They’ve been sat there at least two weeks. Why has the one not gone rusty

Weird.


Porsche911R

21,146 posts

264 months

Monday 11th November 2019
quotequote all
OPC don't bleed inner nipples so air gets in the inner side and thus less pressure on the pad/disk
so if it's an OPC looked after car then they are ruining your car.

if you bleed the inner nipples on the calipers then the brake pedal is firm and the pads both sides grip equal.

OPC are rob dogs, they don't remove wheels in a service, they skimp on jobs, and thus your brakes wear before time and performance is down and they rob you for £2.5k on new disks every 2 years.

how may times have people fitted BIGGER MC to cars due to sloppy brake feel !!!

I have never felt the need, just bleed the brakes rights and the pedals firm.

or people wash cars and put them away wet !!!
or you might have to rebuild the calipers if old.

etc etc

Edited by Porsche911R on Monday 11th November 11:00