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.
