Corrosion of the Rear Brake Disc

[Ortsmatt]

As my vehicle approached its second anniversary, I scheduled a service appointment at my local Mazda shop. The vehicle had accumulated just 10,700 miles. I reluctantly scheduled the appointment due to my previous difficulties with this dealership; but, I received two years of complimentary service at no additional cost when I purchased the vehicle, prompting me to go.

The service was satisfactory, although it was marred by persistent communication challenges similar to those seen before; the service department was almost inaccessible by phone, sometimes resulting in calls ringing out before Reception intervened to take a message for information relay or a callback request. Later in the afternoon, I received a call informing me that the automobile was ready for collection. Upon my arrival, I was informed that the vehicle was prepared for departure; but, an issue related to the rear brakes was identified during the EVHC (electronic vehicle health check), and the findings were advisory. The report was not yet accessible, but they assured me it will be sent subsequently. In my haste, I seized the keys and departed without more enquiries. The health check revealed that the rear discs were rusted, necessitating replacement, along with the brake pads, as per standard practice. They provided estimates for the replacements using either authentic Mazda components or parts obtained from other sources. Initially, I felt astonishment since the automobile was under two years old and had accumulated little mileage, despite never being kept idle for extended periods without being driven. Surprise transformed into frustration when the situation became clear, although I spent many days to contemplate before taking action. I also had the opportunity to inspect the rear discs myself, and there seems to be some rust present. The adequacy for necessitating replacement is a separate inquiry (I am not a technician). My frustration stems from the fact that, although I acknowledge that brake discs are subject to wear and regarded as consumables, I would anticipate this occurring over a somewhat extended timeframe and/or greater miles. Acceptable deterioration, if you like. Given the car's low mileage and youth, I find it difficult to categorise the replacement of the rear brake discs as a result of "fair wear and tear." In my opinion, brake discs should have a far longer lifespan than this. I believe the fundamental issue is the usage of inferior components.

Today, I returned to the dealership, since I find telephonic communication too cumbersome. I was informed that brake discs and pads are not covered under warranty, and they have never replaced any under warranty. I articulated the aforementioned rationale and my perspective that it need to be addressed as a warranty replacement matter. They dismissed my concerns and instructed me to communicate directly with Mazda. I did not go without obtaining a phone number for Mazda. Upon returning home, I contacted Mazda UK and did not receive the same information provided by the dealer. The representative acknowledged that the necessity for brake disc replacement appeared premature; however, she lacked expertise in the matter. She assured me that she would escalate the issue to the relevant department, and someone would respond within a week. I will await their reaction.

My vehicle operates well, and the parking brake seems to engage and disengage without complications. The hill hold function works well, and the overall braking performance is satisfactory and progressive.

The forum discussion below does not clarify if the maintenance was performed under warranty or whether the member incurred costs for the service, and the mileage is almost double that of my vehicle.

[Ortsmatt]

I would have assumed that 20,000 miles is quite premature for a rear disc to need replacement, but I am uncertain if this was due to disc wear or corrosion.

I will provide updates on the process and would welcome opinions about the reasonableness of a warranty replacement in my situation, as well as any comparable experiences people may have with the rear brakes.

[Darrellll]

What is the extent of the corrosion? Merely superficial matters? whether so, I would do many abrupt stops from speeds over 60 mph to see whether it improves their condition.

[Ortsmatt]

Significantly pitted, with a noticeable reduction in the shining region where the brake pads make contact, particularly on the rear left side. I have been using the brakes more forcefully in recent days, however there is no discernible improvement in my vision.

It is possible that Mazda may want the dealer to provide photographs of the discs if they are contemplating a warranty replacement. If the dealer has correctly characterised the problem and confirmed the need for disc replacement, the procedure should ideally go efficiently and expeditiously. If the dealer has not correctly represented the condition of the brake discs, then is a separate matter.

[keithmerc220]

I own the same issue on the back of my Mazda. The rings no longer contact the rotor surface.

I purchased new rotors, EBC green pads, and Corksport stainless steel brake lines.

I subsequently coated all the rotors with high-temperature paint and will install them once the pads are available in stock. This should prevent the recurrence of the rusting problem.

The brakes exhibit considerable weakness on the highway when the vehicle is occupied by several passengers. This is the reason I chose to update the pads and lines for assistance.

[MrGreedy]

After three years, I received comparable MOT recommendations, although there were no stipulations to repair the rear discs or pads. Corrosion is likely to occur more rapidly in coastal locations of the UK than inland. The contributing factors include limited mileage and the duration of driving with an inadequately loaded vehicle. When just you and a front seat passenger are present, with no cargo in the trunk, the front brakes bear the braking strain, resulting in surface rust on the rear brakes. My vehicle is parked outside year-round, which exacerbates the rust problem.

[Mistral]

I own an older Subaru and a new CX-30. I have observed that when the Subaru is left unused for a week or two while I am travelling, the disc brakes emit a faint grinding noise until the vehicle is used for a while. As OldFart indicates, I relate this phenomenon to a superficial layer of rust that dissipates rapidly with use.

[Ortsmatt]

Thank you everybody for your responses. Mazda UK responded and essentially indicated that they were disassociating themselves from the matter. Not covered by warranty, suggesting it was due to normal wear and use.

I have had three VW Golfs before to the Mazda and two Seats before that, and I have never seen any difficulties with brake rust within the first two years. Comparable yearly mileage as well. My current and former residences are not in proximity to the sea, and while I do not accumulate a significant number of yearly miles, I use my vehicle often and with much enthusiasm when road conditions allow.

I will take the vehicle for an extensive drive on many familiar winding routes and thoroughly test the brakes by progressively increasing the braking force to see the effects. Thus far, I have determined that executing forceful braking in a straight trajectory is steady and progressive, and the brakes seem to be as robust as they have ever been. It is possible that the corrosion may resolve; we will see.

I must express my disappointment with Mazda's answer, which I will include into my decision when selecting my next vehicle, likely next year.