When we first got the 3rd gen 3, the rear brakes looked obviously like it was able to fit something larger from a different Mazda. The parts catalog showed that the brake shield is off a CX-5, so that was a clue. My hunch was right, but people on another popular Mazda3 forum discovered long before I did that the CX-5 brakes did indeed fit. They also discovered the 3rd gen 6 brakes also fits, but are slightly smaller/lighter than the CX-5's but nevertheless a small but significant upgrade over the 3's. They also discovered that the CX-9 front brakes also fits, and eventually the CX-5 turbo used similar brake calipers and same size rotors from the CX-9.
On a freeway panic stop over the summer, the "big" stock 2.5l brakes got cooked. Rotors got "warped" and no amount of hard stops afterwards could undo the uneven pad transfer on them. The lug nuts have always been torqued evenly by hand too. Seeing as the brake pads were down to less than 6mm left, I decided it's time to replace and upgrade the brakes to CX-5 ones.
Anyway, let's break this down in rotor sizes:
The brake calipers and pads are also obviously different. The biggest difference I discovered is that the 3 has "rust proof" and "heat resistant" phenolic front caliper pistons. Great in theory, until they get too hot.
The brake pads are a lot bigger in the CX-5:
The caliper piston sizes are also bigger:
I decided to get the non-turbo CX-5 front calipers rather than the dual pistons turbo ones because they're cheaper, lighter weight, and better matching with the master cylinder size on the car since I'm not upgrading the master cylinder. The CX-5 turbo has a bigger master cylinder than the non-turbo ones. Getting the turbo calipers will get the "ultimate stopping power", but the much heavier unsprung weight will hurt handling a lot more than the small impact it already has with the larger/heavier than stock non-turbo CX-5 brakes. Fitment won't be an issue with the stock 18" wheels, however.
You might have noticed that the CX-5 (and even 6) front brakes are only 2mm larger than the stock 2.5l ones. But the true upgrade lies in bigger pads, steel pistons that won't distort/crack and seize compared to the stock plastic resin ones, and 3mm thicker rotors that have much better ventilation design. The gives much higher thermal capacity that makes it more reliable without a big impact on unsprung weight. I haven't heard of any stories about caliper piston issues yet on the 2 and 3, but on other brands of cars with phenolic caliper pistons, the plastic resin eventually distort or crack, causing major issues. That's not acceptable to me on a long term safety standpoint.
Not only that, the CX-9 rear brakes are not bolt on. Fabrication is needed for it to fit. In addition, our car has a traditional cable parking brake, not EPB. This limits the rear upgrade options to either the early 3rd gen 6 or the early CX-5. On that other forum, most people upgraded to either 3rd gen 6 brakes, or later CX-5 ones with the EPB as the ones who do care and posted there have a later 3rd gen 3.
Also to note: the stock calipers are made in China, whereas the ones on the 6 and CX-5 are made in Japan. Just another fact about cost cutting measures Mazda did to the 3 to keep the car affordable lol
The master cylinder bore sizes:
100% brand new parts from Mazda is crazy expensive these days, so I opted for used ones from the junk yard. New/reman aftermarket ones don't all seem to have the Mazda logo/branding on them, so I'm a little picky about having them. So, I settled for used ones as that guarantees I get "genuine" parts.
They came functionally in good condition with half worn brake pads, but cosmetically, they were pretty bad. Surface rust all over, lots of grime. Typical junk yard junk lol
I ended up cleaning and painting them, which was a day's work:
Next, I had a hell of a time finding Advics high carbon 2019-2025 CX-5 rotors. These are certified high carbon, and the 2019-2025 rotors have vented hubs which the earlier years don't have. Must be a supply chain issue or something because they sold out quickly once they came back in stock for me to order them from Rock Auto. Other places were pretty much sold out during the summer. These are cheaper than OEM ones and probably a lot better too. They're also fully coated for rust protection.
Then, I had to get a "matching" unvented rear rotor too:
As for brake pads, I used to be a fan of OEM brake pads, but the stock brake pads on the 3rd gen 3 left a lot to be desired. Mediocre initial bite, mediocre pedal feel, lackluster high speed/high heat performance.
So, I was going to get Endless SSS brake pads as they're known to be low noise, low dust, and Endless pads (the racing versions) are used by official Mazda racing teams in Japan, so that seems pretty "kosher" to me. But reviewing the specs, they weren't that great compared to the Project Mu Type-PS which I already have on my Protege. But good timing has it, the Project Mu Type-PS HW (HW for heavy weight) just came out in June for very select vehicles. The CX-5 is one of them. So, that is what I got:
They're advertised to still have the same behavior as the regular Type-PS: decent initial bite, decent pedal feel, decent modulation control, very good high heat stopping power. As you can see in the pics, they're rated for 500 degrees celsius (932 degrees fahrenheit) with no warm up necessary. Although on my Protege, I've found that heating the pads up do make a huge difference in performance. The coefficient of friction is a very good 0.38mu cold and excellent 0.50mu hot. For a low noise, low dust street pad with these well rounded characteristics that's unoffensive like stock, it's pretty rare.
It was a good thing I got them before the tariffs hit. For the price of 2 sets of OEM pads from the dealer (with discount), I got these Project Mus to my door straight from Japan. No stupid performance shop markups here.
I bought new OEM shim kits from eBay for much less than what the dealer would charge, and scavenged the wear squealer clips from the used CX-5 pads. The rear pads have squealers on both sides and they sit towards the ground once installed on the car. The front one goes in the inner pad towards the top of the car.
For the first time ever, I used the OEM slider pin and pad guide grease I bought from Japan. I didn't buy the OEM grease for the shims and used the Wurth one from my old job which works good.
The shim kits also came with a pack of copper "Molykote" 7439 antiseize that goes on the mounting tabs of the brake pads. All of the prep work/assembly took much longer than expected, but everything is assembled almost like factory condition.
Special attention also must be paid attention to the front guide plates. I didn't pay attention that the top and bottom ones are different when taking the used ones off to paint the calipers. The shop manual is confusing, but after reviewing other people's pics/how-to guides, the guide that doesn't sit flush with the caliper bracket goes to the top end of the caliper, while the one that clips all the way flush sits in the bottom side.
And then stupid me for not noticing that Mazda changed the rear caliper bracket bolt size from M10x1.25 bolts to M12x1.25 bolts in 2015. So, this meant I had to drill out the smaller caliper mounting holes in the rear spindles to fit the bigger bolts. This was a nightmare on a late weekend night with worn drill bits, but perseverance paid off in the end. For no fuss 100% bolt on, get 2013-2014 CX-5 rear calipers if you have a early 3rd gen. Otherwise, you're still stuck having to drill the holes on a later 3rd gen, and also needing to change out the EPB motor connector to the CX-5's or 6's
The other nightmare is taking the parking brake cable off. It seems there's no way to unclip it from the caliper without loosening the cable adjustment at the hand brake lever. The Protege is so easy to take off the cable by comparison.
So finally, the "before" and "after" pics:
Finally, I flushed out the Castrol GTLMA DOT4 brake fluid with Endless FP-6 DOT5.1 Class 6 low viscosity, then went for a test drive. Of course new brakes always works great, but the biggest difference I now feel is that the brake bias is a lot more balanced. The car doesn't nose dive as much under any braking anymore, which makes it more similar to the Protege. The nose diving, which is pretty normal on most cars, bothered me a lot when we first got this 3rd gen 3 as it was very un-Mazda like. So, now it's fixed.
On a freeway panic stop over the summer, the "big" stock 2.5l brakes got cooked. Rotors got "warped" and no amount of hard stops afterwards could undo the uneven pad transfer on them. The lug nuts have always been torqued evenly by hand too. Seeing as the brake pads were down to less than 6mm left, I decided it's time to replace and upgrade the brakes to CX-5 ones.
Anyway, let's break this down in rotor sizes:
| Model | Front Rotor Diameter & Thickness | Rear Rotor Diameter & Thickness |
| 3rd gen 3 1.5l/1.6l/US 2.0l Engine | 11.0" x 0.98" (280 x 25mm) | 10.4" x 0.35" (265 x 9.0mm) |
| 3rd gen 3 2.5l Engine (2.0l Engine non-US/Canada, Diesel worldwide) | 11.6" x 0.98" (295 x 25mm) | 10.4" x 0.35" (265 x 9.0mm) |
| 3rd gen 3 Hybrid | 11.7" x 1.1" (297 x 28mm) | 10.9" x 0.39" (278 x 10mm) |
| 3rd gen 6 | Gasoline / 2013-2021 Diesel: 11.7" x 1.1" (297 x 28mm) 2022-2025 Diesel: 12.6" x 1.1" (320 x 28mm) | 10.9" x 0.39" (278 x 10mm) |
| CX-5 | 11.7" x 1.1" (297 x 28mm) | 11.9" x 0.39" (303 x 10mm) |
| CX-5 Turbo | 12.6" x 1.1" (320 x 28mm) | 11.9" x 0.39" (303 x 10mm) |
| CX-9 | 12.6" x 1.1" (320 x 28mm) | 12.8" x 0.43" (325 x 11mm) |
The brake calipers and pads are also obviously different. The biggest difference I discovered is that the 3 has "rust proof" and "heat resistant" phenolic front caliper pistons. Great in theory, until they get too hot.
The brake pads are a lot bigger in the CX-5:
| Model | Front Pad Area & Thickness | Rear Pad Area & Thickness |
| 3rd gen 3 1.5l/1.6l/US 2.0l Engine | 8.293sq in x 0.39" (5350mm² x 10mm) | Cable Parking Brake: 4.108sq in x 0.35" (2650mm² x 9mm) EPB: 4.737sq in x 0.35" (3056mm² x 9mm) |
| 3rd gen 3 2.5l Engine (2.0l Engine non-US/Canada, Diesel worldwide) | 8.293sq in x 0.39" (5350mm² x 10mm) | Cable Parking Brake: 4.108sq in x 0.35" (2650mm² x 9mm) EPB: 4.737sq in x 0.35" (3056mm² x 9mm) |
| 3rd gen 3 Hybrid | 8.432sq in x 0.39" (5440mm² x 10mm) | Cable Parking Brake: 4.51sq in x 0.31" (2810mm² x 8mm) EPB: 4.991sq in x 0.35" (3220mm² x 9mm) |
| 3rd gen 6 | 8.432sq in x 0.39" (5440mm² x 10mm) | Cable Parking Brake: 4.51sq in x 0.31" (2810mm² x 8mm) EPB: 4.991sq in x 0.35" (3220mm² x 9mm) |
| CX-5 | 9.300sq in x 0.39" (6000mm² x 10mm) | Cable Parking Brake: 4.340sq in x 0.33" (2800 x 8.5mm) EPB: 4.340sq in x 0.35" (2800mm² x 9mm) |
| CX-5 Turbo | 9.517sq in x 0.47" (6140mm² x 12mm) | 4.340sq in x 0.35" (2800mm² x 9mm) |
| 2nd gen CX-9 | 9.517sq in x 0.47" (6140mm² x 12mm) | 5.689sq in x 0.4" (3670mm² x 9mm) |
The caliper piston sizes are also bigger:
| Model | Front Caliper Cylinder Bore | Rear Caliper Cylinder Bore |
| 3rd gen 3 1.5l/1.6l/US 2.0l Engine | 2.1" (54mm) | 1.4" (36mm) |
| 3rd gen 3 2.5l Engine (2.0l Engine non-US/Canada, Diesel worldwide) | 2.1" (54mm) | 1.4" (36mm) |
| 3rd gen 3 Hybrid | 2.25" (57.2mm) | 1.5" (38mm) |
| 3rd gen 6 | 2.25" (57.2mm) | 1.5" (38mm) |
| CX-5 | 2.37" (60.3mm) | 1.5" (38.2mm) |
| CX-5 Turbo | Dual Pistons: 1.79" (45.4mm) | 1.5" (38.2mm) |
| 2nd gen CX-9 | Dual Pistons: 1.79" (45.4mm) | 1.687" (42.85mm) |
I decided to get the non-turbo CX-5 front calipers rather than the dual pistons turbo ones because they're cheaper, lighter weight, and better matching with the master cylinder size on the car since I'm not upgrading the master cylinder. The CX-5 turbo has a bigger master cylinder than the non-turbo ones. Getting the turbo calipers will get the "ultimate stopping power", but the much heavier unsprung weight will hurt handling a lot more than the small impact it already has with the larger/heavier than stock non-turbo CX-5 brakes. Fitment won't be an issue with the stock 18" wheels, however.
You might have noticed that the CX-5 (and even 6) front brakes are only 2mm larger than the stock 2.5l ones. But the true upgrade lies in bigger pads, steel pistons that won't distort/crack and seize compared to the stock plastic resin ones, and 3mm thicker rotors that have much better ventilation design. The gives much higher thermal capacity that makes it more reliable without a big impact on unsprung weight. I haven't heard of any stories about caliper piston issues yet on the 2 and 3, but on other brands of cars with phenolic caliper pistons, the plastic resin eventually distort or crack, causing major issues. That's not acceptable to me on a long term safety standpoint.
Not only that, the CX-9 rear brakes are not bolt on. Fabrication is needed for it to fit. In addition, our car has a traditional cable parking brake, not EPB. This limits the rear upgrade options to either the early 3rd gen 6 or the early CX-5. On that other forum, most people upgraded to either 3rd gen 6 brakes, or later CX-5 ones with the EPB as the ones who do care and posted there have a later 3rd gen 3.
Also to note: the stock calipers are made in China, whereas the ones on the 6 and CX-5 are made in Japan. Just another fact about cost cutting measures Mazda did to the 3 to keep the car affordable lol
The master cylinder bore sizes:
| Model | Master Cylinder Bore Diameter |
| 3rd gen 3 1.5l/1.6l/US 2.0l Engine | 0.8126" (20.64mm) |
| 3rd gen 3 2.5l Engine (2.0l Engine non-US/Canada, Diesel worldwide) | 0.8126" (20.64mm) |
| 3rd gen 6 | Cable Parking Brake: 0.8126" (20.64mm) EPB: 0.8748" (22.22mm) |
| CX-5 | 0.8126" (20.64mm) |
| CX-5 Turbo | 0.874" (22.2mm) |
| 2nd gen CX-9 | 0.8748" (22.22mm) |
100% brand new parts from Mazda is crazy expensive these days, so I opted for used ones from the junk yard. New/reman aftermarket ones don't all seem to have the Mazda logo/branding on them, so I'm a little picky about having them. So, I settled for used ones as that guarantees I get "genuine" parts.
They came functionally in good condition with half worn brake pads, but cosmetically, they were pretty bad. Surface rust all over, lots of grime. Typical junk yard junk lol
I ended up cleaning and painting them, which was a day's work:
Next, I had a hell of a time finding Advics high carbon 2019-2025 CX-5 rotors. These are certified high carbon, and the 2019-2025 rotors have vented hubs which the earlier years don't have. Must be a supply chain issue or something because they sold out quickly once they came back in stock for me to order them from Rock Auto. Other places were pretty much sold out during the summer. These are cheaper than OEM ones and probably a lot better too. They're also fully coated for rust protection.
Then, I had to get a "matching" unvented rear rotor too:
As for brake pads, I used to be a fan of OEM brake pads, but the stock brake pads on the 3rd gen 3 left a lot to be desired. Mediocre initial bite, mediocre pedal feel, lackluster high speed/high heat performance.
So, I was going to get Endless SSS brake pads as they're known to be low noise, low dust, and Endless pads (the racing versions) are used by official Mazda racing teams in Japan, so that seems pretty "kosher" to me. But reviewing the specs, they weren't that great compared to the Project Mu Type-PS which I already have on my Protege. But good timing has it, the Project Mu Type-PS HW (HW for heavy weight) just came out in June for very select vehicles. The CX-5 is one of them. So, that is what I got:
They're advertised to still have the same behavior as the regular Type-PS: decent initial bite, decent pedal feel, decent modulation control, very good high heat stopping power. As you can see in the pics, they're rated for 500 degrees celsius (932 degrees fahrenheit) with no warm up necessary. Although on my Protege, I've found that heating the pads up do make a huge difference in performance. The coefficient of friction is a very good 0.38mu cold and excellent 0.50mu hot. For a low noise, low dust street pad with these well rounded characteristics that's unoffensive like stock, it's pretty rare.
It was a good thing I got them before the tariffs hit. For the price of 2 sets of OEM pads from the dealer (with discount), I got these Project Mus to my door straight from Japan. No stupid performance shop markups here.
I bought new OEM shim kits from eBay for much less than what the dealer would charge, and scavenged the wear squealer clips from the used CX-5 pads. The rear pads have squealers on both sides and they sit towards the ground once installed on the car. The front one goes in the inner pad towards the top of the car.
For the first time ever, I used the OEM slider pin and pad guide grease I bought from Japan. I didn't buy the OEM grease for the shims and used the Wurth one from my old job which works good.
The shim kits also came with a pack of copper "Molykote" 7439 antiseize that goes on the mounting tabs of the brake pads. All of the prep work/assembly took much longer than expected, but everything is assembled almost like factory condition.
Special attention also must be paid attention to the front guide plates. I didn't pay attention that the top and bottom ones are different when taking the used ones off to paint the calipers. The shop manual is confusing, but after reviewing other people's pics/how-to guides, the guide that doesn't sit flush with the caliper bracket goes to the top end of the caliper, while the one that clips all the way flush sits in the bottom side.
And then stupid me for not noticing that Mazda changed the rear caliper bracket bolt size from M10x1.25 bolts to M12x1.25 bolts in 2015. So, this meant I had to drill out the smaller caliper mounting holes in the rear spindles to fit the bigger bolts. This was a nightmare on a late weekend night with worn drill bits, but perseverance paid off in the end. For no fuss 100% bolt on, get 2013-2014 CX-5 rear calipers if you have a early 3rd gen. Otherwise, you're still stuck having to drill the holes on a later 3rd gen, and also needing to change out the EPB motor connector to the CX-5's or 6's
The other nightmare is taking the parking brake cable off. It seems there's no way to unclip it from the caliper without loosening the cable adjustment at the hand brake lever. The Protege is so easy to take off the cable by comparison.
So finally, the "before" and "after" pics:
Finally, I flushed out the Castrol GTLMA DOT4 brake fluid with Endless FP-6 DOT5.1 Class 6 low viscosity, then went for a test drive. Of course new brakes always works great, but the biggest difference I now feel is that the brake bias is a lot more balanced. The car doesn't nose dive as much under any braking anymore, which makes it more similar to the Protege. The nose diving, which is pretty normal on most cars, bothered me a lot when we first got this 3rd gen 3 as it was very un-Mazda like. So, now it's fixed.
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