2017~2025 CX-5 Original Front Brakes, Outside Pads No Wear, Inside Finished?

[Davidiot]

I first noticed a cyclic rubbing/dragging sound seemingly coming from one or the other of my front wheels while driving with the radio off one day. The rub seemed to be consistent with each revolution of a wheel (the frequency of the rubbing sound quickly increasing with the vehicle’s speed). This was soon followed by some aggressive steering-wheel shaking during braking, making the culprit much more certain. Only 24,000 miles since I bought my CX-5 brand-new, I wasn’t expecting to need brakes yet, much less new rotors .

Since the first 6,000 miles, though, my car’s really only seen town miles, almost exclusively stop & go, so I had to consider that perhaps this mileage could be normal, given my circumstances? Not sure how I managed to warp (at least one of the) rotors without ever hearing any warning sounds from brake wear indicators; but might that be because Mazda doesn’t install them?

I went ahead and bought new front rotors and a set of brake pads for all 4 wheels, and borrowed a pair of jack stands and a couple of torque wrenches so I could get started on doing the work myself. Having only two jack stands and the scissor jack from my trunk, I haven’t been able to take a look at the rear brakes yet; but I did pull off the fronts earlier today.

I am in SHOCK at what I found. Wtf, Mazda?

The inside pads on both the front left and front right wheels are worn down completely; while the outside pads are still almost as fat as the brand new replacements I just bought. How could this have happened with factory-installed brakes? What other parts am I now looking at having to replace to make sure the same thing doesn’t happen again to my new rotors and pads?

 

[HyFlyer]

... I am in SHOCK at what I found. Wtf, Mazda? ...

I don't have time to type much at the moment, but to be honest, this isn't a "WTF Mazda" problem rather it's a lack of brake maintenance in a highly corrosive environment. If you do your own maintenance, I can tell you what to do in the future to prevent that from happening. If you're paying someone to do your maintenance, however, you should find a new shop! (Unless you turned down suggested brake maintenance)

 

[leeharvey418]

You know in the manual when it says to lubricate your caliper pins? This is why it says that.

 

[stickerbush]

Wow that sure is a lot of corrosion for a 5yr old car, you must be driving roads that are salted in the winter. The uneven wear is likely due to lack of lubrication on the caliper pins, at this point they may be corroded too. Depending on the extent of the corrosion you will need new calipers or best case, a thorough cleaning and lubrication of the pins.

 

[sm1ke]

Wow, this is certainly the worst case of uneven pad wear I've seen. I had a 2018 CX-9 with a small amount of uneven pad wear on one side, and indeed, it was due to a lack of remaining lube on the slide pin on that side, which resulted in some corrosion starting to form on the pin itself.

In your case, if the pins have corroded, I would replace them or at least grind the corrosion off, then make sure they are lubricated before you reinstall them. Also double check the slide pin rubber boots to make sure they aren't damaged - replace them if they are. Hopefully that resolves the issue.

 

[N7turbo]

That is really bad.

Not sure if it's relevant, but my 2023 had one of the rear pad retaining clips installed incorrectly. Wouldn't have noticed if I didn't do my pad swap.

 

[RedBaron]

Interesting... there's a TSB out for the CX-50's for this same type of issue (though the cause may be different)...

https://static.nhtsa.gov/odi/tsbs/2025/MC-11014796-0001.pdf

 

[Mazdiod2]

Since the first 6,000 miles, though, my car’s really only seen town miles, almost exclusively stop & go, so I had to consider that perhaps this mileage could be normal, given my circumstances? Not sure how I managed to warp (at least one of the) rotors without ever hearing any warning sounds from brake wear indicators; but might that be because Mazda doesn’t install them?

I haven’t been able to take a look at the rear brakes yet; but I did pull off the fronts earlier today.

Did you measure any runout or out of round on the rotors? They look rusty. I bet replacing parts is a good idea considering the obvious rust. Plus the sticky calipers and guide pins. I lubed mine because of sticking a few years back and I haven't noticed any problems.
I found if I loosened both bolts that hold the caliper but only remove one of them I can rotate the caliper enough to remove the pins and clean them.

Be sure and follow the directions carefully to disable the Electric Parking Brake before servicing (don't wait til you have it apart_)> They are a big problem, and according to what I've read here the rear brakes usually have more wear than the fronts.

Your 2020 only has 25000 miles, but the years take their toll. Brake fluid gets contaminated, too. so consider if it's been changed recently.

 

[Jmaz]

+1 on the brake fluid flush/change as recommended above. Let me add a few more random comments:
With the apparently corrosive environment and amount of rust, be sure to clean/scrape/file all contact points where caliper and pads meet. There are caliper files made for this purpose ( or just a coarse one works along with a scraper like an old wood chisel and a wire brush). And after cleaning apply caliper grease to the area underneath the stainless steel pad guides to prevent "rust jacking" where rust expands and forces the pad guide tightly against the pad ears and binds up pad movement within the caliper slot.

Be sure to use an approved caliper grease that is rubber friendly. One of the pins has a small rubber ring near the tip and wrong grease could swell it causing a bind in it's bore.
The pins can be reused if not worn even if just discolored. New pins (2) are only ~$10 at Autozone. Might want to replace the little rubber accordion boots if dried out from road chemicals/environment. Only ~$5 for 2 and should include new small rubber ring but be careful because I've come across where that little ring is too thick and makes for tight fit so I just reused the original ring, so don't cut or tear it if removing, you may need to reuse it.

Once lubed the pins have a tendency to not stay in but pop back out because trapped air acts like a spring so it needs to be "burped" by lifting the edge of the rubber accordion boot and pushing the pin in to force the trapped air out. Otherwise that trapped air acting like a spring can force the caliper(and pads) against the rotor.

Thinking back years ago when doing the rear for the first time I remember remarking at the small amount of grease on the pins when removed. Felt like Mazda could have added a little more.

Be careful when tightening the small bolts that retain the pins. I twisted one off in the pin and had to buy new pins (they should come with bolts) in lieu of trying to extract the bolt shank that broke off flush with the pin. It has a low torque spec, around 23 ft-lb IIRC.

I don't know if you know/follow all of this already in which case it may just be a reminder if you haven't done brakes in a while.

P.S. If you elect to not change brake fluid maybe at least open the bleeder when compressing the piston to force old dirty fluid out instead of forcing it back up the line. It also helps to be loosened because in another 5 years it may be corroded in place from never being loosened and twist off when trying to open. Good luck.

 

[N7turbo]

Be sure to use an approved caliper grease that is rubber friendly.

That would be the Sil-Glyde packets I picked up from the auto parts store. I am trying to avoid collecting too many bottles of things in the cabinet