Author Topic: Rear brake discs rusted/heavily scored  (Read 2102 times)

Offline Deeps

  • Sr. Member
  • ****
  • Posts: 395
  • Located 20mins NW of Stuttgart, Germany
  • Body: SUV
  • Colour: Crystal White Pearlescent
  • Engine: 2.2L 150ps
  • Fuel: Diesel
  • Model Grade: SE-Lux
  • Transmission: Automatic
  • Year: 2015
Rear brake discs rusted/heavily scored
« on: January 17, 2018, 03:07:22 pm »
I wonder how many forum members have looked at their CX5's rear brake discs recently and noticed the uneven wear across the width of the braking surface? I first noticed what I believed to be an issue in early 2017 when it was noted that the discs (both sides) had alternate bands of rust, shiny surface and heavy scoring. When pointed out to the dealer during a routine winter > summer tyre change it was stated that this was probably caused by road salt particles becoming trapped between the discs and pads and that prolonged braking over the summer period should see the wear return to normal i.e. a complete shiny disc as is the case with the front brakes.
 
However, this has not been the case and in fact the situation has deteriorated to the point that only approx 50% of the available disc surface is actually making contact with the pads whilst the remaining 50% of disc is completely rusty and this has occurred despite the fact that the vehicle has not been in contact with any salt etc at the time of writing this. Further more, the scoring cannot simply be put down to a stone becoming entrapped between the disc and pad resulting in the scoring because the deterioration on the N/S matched exactly that of the O/S.

My own opinion is that the rear brake setup has been badly designed as with a lighter vehicle but especially so with a relatively heavy SUV it should be the front pads/discs that wear first as the physics of the braking motion places a greater braking force on the front hence the larger discs up front.

Anyway, without further rambling (sorry) this problem is well mentioned over on the German forum and receiving mixed results from Mazda (Germany) by way of response. Some vehicles appear to have travelled considerable distances with rear and front discs/pads showing acceptable wear all things being equal whilst some low mileage cars (older as well as new models) being indicated as suffering exactly the same problems of unequal wear/scoring as mine which has only travelled some 15,340km and is just over 2 years old. From what I read, Mazda's response has fallen far short of consistent as repairs have been carried out against the guarantee or goodwill in some instances whilst in others they have put discs/pads down to being wear and tear items thereby not falling within the scope of the guarantee. Photos have been taken by the dealer in my case and I am currently awaiting a response from Mazda (Germany). It will be interesting to see upon which side the coin falls in respect of my claim. Should I have to replace the discs/pads at my own cost (they won't pass any MOT in their current condition) then I shall seek to have the old items returned to me and take legal advice.
Mazda CX-5 Exclusive Line 2.2D (150PS) 6AT AWD tugging a 2016 Hymer Eriba Troll 542 Caravan (1300kg).

Offline twabrigs

  • Sr. Member
  • ****
  • Posts: 288
  • Body: SUV AWD
  • Colour: Crystal White Pearlescent
  • Engine: 2.2L 175ps
  • Fuel: Diesel
  • Model Grade: Sport Nav
  • Transmission: Manual
  • Year: 2013
Re: Rear brake discs rusted/heavily scored
« Reply #1 on: January 17, 2018, 05:12:32 pm »
Interesting, we had some posts about this back in March 2017 when I needed new pads and rear discs

Offline kiakid2

  • Newbie
  • *
  • Posts: 36
  • I NEED TO UPDATE MY SIGNATURE!!!
  • Body: SUV
  • Colour: Soul Red Metallic
  • Engine: 2.2L 175ps
  • Fuel: Diesel
  • Model Grade: Sport Nav
  • Transmission: Manual
  • Year: 2017
Re: Rear brake discs rusted/heavily scored
« Reply #2 on: January 19, 2018, 12:29:43 pm »
My Kia Sportage was the same and to overcome this I used to regularly apply the handbrake to clean the rust etc.
Unfortunately, with the electric handbrake, that can’t be done on the Mazda, so I try and use the car any time I see rust spots forming on the disc, in an attempt to reduce the corrosion aspect.
I am the laugh of the street when I cover the wheels when the car is not in use for 2 weeks or so in the winter

Offline Deeps

  • Sr. Member
  • ****
  • Posts: 395
  • Located 20mins NW of Stuttgart, Germany
  • Body: SUV
  • Colour: Crystal White Pearlescent
  • Engine: 2.2L 150ps
  • Fuel: Diesel
  • Model Grade: SE-Lux
  • Transmission: Automatic
  • Year: 2015
Re: Rear brake discs rusted/heavily scored
« Reply #3 on: January 19, 2018, 01:26:26 pm »
My Kia Sportage was the same and to overcome this I used to regularly apply the handbrake to clean the rust etc.


No, I think that you're misunderstanding my post kiakid2. The effect that you are describing can often be observed on vehicles that have been left stationary on the dealers forecourt for a period of time i.e. surface rust on the discs which can be removed by the method you describe namely running with the brakes held on for a while. Brake cleaner will also do the job without leaving an oily residue.

However, the running with the brakes on method relies on the pads being parallel to the discs so that the braking effect is spread evenly across the entire surface of the disc.

The latter is NOT the case with my CX-5 and neither is it with a lot of other users from what I am reading. Here it would appear that for whatever reason the pad is either grooved in some way or is not set up parallel to the discs or it's something to do with the calipers I don't know. The end result though, is that only part of the pad is making contact with the disc creating uneven concentric circles along with relatively deep scoring although this is not easy to ascertain from the image as it's not in 3D LOL.

« Last Edit: January 19, 2018, 04:04:28 pm by Deeps »
Mazda CX-5 Exclusive Line 2.2D (150PS) 6AT AWD tugging a 2016 Hymer Eriba Troll 542 Caravan (1300kg).

Offline rmvf

  • Sr. Member
  • ****
  • Posts: 343
  • Body: SUV
  • Colour: Reflex Blue
  • Engine: 2.0L 165ps
  • Fuel: Petrol
  • Model Grade: Sport Nav
  • Transmission: Manual
  • Year: 2018
Re: Rear brake discs rusted/heavily scored
« Reply #4 on: January 19, 2018, 06:53:24 pm »
My rears do the same Deeps, as for burning off during summer I think you agree that's a load of rubbish. I sometimes drive slowly for a 100 yards with handbrake just applied to clean up one the old one, but no remedy for EHB version
« Last Edit: January 19, 2018, 06:56:20 pm by rmvf »
Also running a pearl white petrol sport nav from 30/04/ 2012

Offline Deeps

  • Sr. Member
  • ****
  • Posts: 395
  • Located 20mins NW of Stuttgart, Germany
  • Body: SUV
  • Colour: Crystal White Pearlescent
  • Engine: 2.2L 150ps
  • Fuel: Diesel
  • Model Grade: SE-Lux
  • Transmission: Automatic
  • Year: 2015
Re: Rear brake discs rusted/heavily scored
« Reply #5 on: January 23, 2018, 01:22:48 pm »
Just a quick update to my posts. Mazda have looked at the photos submitted by my dealer and have authorised the replacement of rear discs and pads to be carried out under the terms of the warranty. Car booked in for next Wednesday.
Mazda CX-5 Exclusive Line 2.2D (150PS) 6AT AWD tugging a 2016 Hymer Eriba Troll 542 Caravan (1300kg).

Offline p38cyq

  • Jr. Member
  • **
  • Posts: 79
  • Belgium
  • Body: SUV
  • Colour: Meteor Gray Mica
  • Engine: 2.5L
  • Fuel: Petrol
  • Model Grade: Sport Nav
  • Transmission: Automatic
  • Year: 2017
Re: Rear brake discs rusted/heavily scored
« Reply #6 on: January 23, 2018, 05:25:52 pm »
Super service from Mazda I would say.

Offline rmvf

  • Sr. Member
  • ****
  • Posts: 343
  • Body: SUV
  • Colour: Reflex Blue
  • Engine: 2.0L 165ps
  • Fuel: Petrol
  • Model Grade: Sport Nav
  • Transmission: Manual
  • Year: 2018
Re: Rear brake discs rusted/heavily scored
« Reply #7 on: January 23, 2018, 06:04:30 pm »
Result ;D
Also running a pearl white petrol sport nav from 30/04/ 2012

Offline misfire85

  • Newbie
  • *
  • Posts: 11
  • I NEED TO UPDATE MY SIGNATURE!!!
  • Body: SUV
  • Colour: Soul Red Metallic
  • Engine: 2.2L 175ps
  • Fuel: Diesel
  • Model Grade: Sport Nav
  • Transmission: Manual
  • Year: 2015
Re: Rear brake discs rusted/heavily scored
« Reply #8 on: May 01, 2018, 10:46:59 am »
mine looked like that originally then I got the tpms light and dragging rear brake problem , took it to the dealer and they replaced the disks /pads /calliper's  a known cx5 problem ....

Offline grokling

  • Newbie
  • *
  • Posts: 1
  • I NEED TO UPDATE MY SIGNATURE!!!
  • Body: SUV AWD
  • Colour: Liquid Silver Metallic
  • Engine: 2.2L 175ps
  • Fuel: Diesel
  • Model Grade: Sport Nav
  • Transmission: Automatic
  • Year: 2016
Re: Rear brake discs rusted/heavily scored
« Reply #9 on: May 30, 2018, 08:14:11 am »
Just a quick update to my posts. Mazda have looked at the photos submitted by my dealer and have authorised the replacement of rear discs and pads to be carried out under the terms of the warranty. Car booked in for next Wednesday.

Hi. How did you get Mazda to look at your photos? did you send them to someone?

I'm asking because I have recently taken delivery of a 2016 CX-5 and have the same rust signs on the rear brakes. I've sent photos to the dealer from whom I bought the car and they've said it's entirely normal and nothing to worry about (Croydon Mazda). However, I'm not convinced, and I still have a 12 month warranty.

Any advice would be appreciated.

Thanks.

Offline Deeps

  • Sr. Member
  • ****
  • Posts: 395
  • Located 20mins NW of Stuttgart, Germany
  • Body: SUV
  • Colour: Crystal White Pearlescent
  • Engine: 2.2L 150ps
  • Fuel: Diesel
  • Model Grade: SE-Lux
  • Transmission: Automatic
  • Year: 2015
Re: Rear brake discs rusted/heavily scored
« Reply #10 on: May 30, 2018, 11:21:27 am »
The photograph shown in the above post(s) were taken by me only for reference purposes and to post here. The dealer subsequently took photographs of their own which were then submitted to Mazda, I played no part in that.

Your dealer is unable to replace the discs/pads unless authorisation is received from Mazda so I would suggest you revisit the dealer and insist that they take photographs of their own or forward the ones you took directly to Mazda. If your discs look anything like mine then no, this is not acceptable.
Mazda CX-5 Exclusive Line 2.2D (150PS) 6AT AWD tugging a 2016 Hymer Eriba Troll 542 Caravan (1300kg).

Offline HighlanderUK

  • Newbie
  • *
  • Posts: 19
  • Body: SUV
  • Colour: Machine Gray
  • Engine: 2.0L 165ps
  • Fuel: Petrol
  • Model Grade: Sport Nav
  • Transmission: Manual
  • Year: 2018
Re: Rear brake discs rusted/heavily scored
« Reply #11 on: July 16, 2018, 08:03:46 pm »
good to know and appreciate the feedback. 

i have some thin bands on my rears just now, having got the car earlier this year during the snow i thought rock salt stuck too, but now with very hot weather, I still have a few marks.

Mazda CX-5 Forums

Re: Rear brake discs rusted/heavily scored
« Reply #11 on: July 16, 2018, 08:03:46 pm »