Mazda CX-3 Brake Discs: Specs, Fitment & Wear Symptoms

On the CX-3, real technical bulletins on related models address poor rear disc wear, linked to Mazda's TCS braking balance.

Illustration for editorial purposes

OEM Part Number: B45G-33-251A

Genuinely important safety note: if your CX-3 has an Electric Parking Brake (rear discs), the EPB must be put into its electronic "Service Mode" via a diagnostic tool before compressing the caliper piston — skipping this step during a DIY replacement can damage the motorised caliper mechanism.

Front discs, AWD (shared with 2017-2018 Mazda 3 EPB models)	Mazda OEM: B45G-33-251A — 295mm diameter, vented, 25mm thickness, 23mm minimum
Front brake pad set	Mazda OEM: D5YG-33-28Z
Rear left caliper bracket	Mazda OEM: D2Y1-26-29X
Brake pads, alternative reference	Mazda OEM: B4Y0-33-28ZB

Confirmed: Real Technical Bulletins Addressing This Exact Issue — Mazda CX-3 Brake Discs

This is genuinely worth knowing if you're seeing premature rear disc corrosion or uneven wear: Mazda has issued confirmed technical service bulletins specifically addressing poor rear brake disc wear on related models. Genuinely worth knowing why this happens: forum discussion points toward the rear brakes being applied harder and sooner than the fronts as a result of how Mazda's traction control system balances braking, combined with genuinely smaller rear pads that some owners believe may be under-specced.

A genuinely specific maintenance detail worth knowing: Mazda's own guidance specifically calls for copper anti-seize to be applied to the pad clip surfaces, not just the sliding pins.

It's also genuinely worth knowing about a real, honest, and rather damning consumer account: one owner, facing premature rear disc corrosion at just two years old, was told directly by Mazda UK that they were "washing their hands of it," declining warranty coverage and calling it fair wear and tear.

The Part That Pads Depend On

Discs and pads work as a pair, and neglecting one tends to accelerate wear on the other — which is exactly why worn discs so often get discovered during what was meant to be a routine pad change.

Before you buy: disc size and design vary by trim, engine size and whether your car has the standard or "sport" brake package. Always confirm against your VIN before ordering.

What They Do

Brake discs provide the surface the brake pads clamp against to slow the car, converting momentum into heat through friction. Larger, sportier trims of the CX-3 typically use bigger discs than standard versions to handle the additional heat generated by more aggressive braking.

Wear Symptoms, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Brake Discs Guide for warning signs to watch for, confirming fitment against your VIN, and choosing a reliable aftermarket disc.

More Mazda Brake Discs

The same part, covered across other Mazda models.

Mazda CX-3 Brake Discs: Specs, Fitment & Wear Symptoms

OEM Part Number: B45G-33-251A

Confirmed: Real Technical Bulletins Addressing This Exact Issue — Mazda CX-3 Brake Discs

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