My rear brake fiasco (dealership, I know)

Joined
Jan 17, 2021
Messages
72
Good evening - it's been a while since I've posted on here. Good to be back, I guess! I just wanted to share my rear brake job fiasco, and maybe get some further insight from the pros here. Kind of long but want to give the whole bit of context.

So, I have a 2017 Mazda CX-5 sport, 71K. Bought it used in 2020; in that time I've replaced the front pads and rotors twice, and my rears made it to a whopping 3mm at 70K. I was pretty impressed, until they started making some serious grinding and squeaking noises from the driver side. Until recently, I've brought my car in for routine maintenance at a trusted independent shop, but it's far from my new house and his prices started to rise. I saw an oil change special for my local dealer where I bought the car (literally a 4 minute drive) that was competitive and thought "ah, what the hell!". Had great service. WiFI, coffee, nice...Such a great experience I even decided to get an overpriced front brake job done by them (November, 2023). No issues to speak of, and everything was dandy. About a month later, the rear grinding was unbearable. Decided to take it in. This is where everything went south.

They slapped new pads and rotors on and sent me on my way. I had thought it was a little odd that they didn't mention anything to me about the rotor with the grinding, that it had a noticeable gouge/score mark that the passenger side didn't. Maybe a faulty pad after 70,00 miles, what do I know. I noticed that the brakes smelled a little, but it wasn't too different than the "normal" material burning smell you get with new brakes. Until Friday, when I got out of the car and saw my entire rotor glowing bright red. They maybe had 25 miles on them at this point. Brought it back the next day; many-a-mechanic on Reddit told me it must be the caliper seized or a collapsed flex hose, so I mentioned that to them. They did in fact determine the caliper was seized; I had to insist on them replacing the hoses because "they weren't leaking, so they're fine" (knowing that they can fail inside out).

The dealer was kind enough to replace the rotor, pads, and caliper, and parking brake mother on that wheel at no charge, only I had to fork out the cash for a brake flush and new hoses (I did both sides to be safe). I felt that this was a good compromise, even though I was annoyed that maybe they should have investigated the issue prior to giving me new pads and rotors. When I picked my car up today, before I went in the shop I investigated the new parts...hoses, caliper, all clearly new. Except the rotor...looked a little grooved. All of the other brand new rotors on my car, you can still clearly see most of the cross hatching and there is no grooving. So it raised some alarm bells. I politely brought it up to them, until I wasn't so polite because I couldn't believe that a brand new rotor with only a mile or two on them could already have groove marks on them. So, they put another brand new rotor on in front of me (I hate being this kind of customer, seriously, but I felt it was warranted). Sure as hell, as soon as I get home, there's groove marks on it again. The brakes don't make any unusual sounds, don't smell, and don't appear to be hotter on touch than the other rear rotor. I do feel like the car pulls to the left at coasting a little bit; RPMs all seem to be normal, I rolled fine from drive into neutral, and it doesn't pull when I brake, so nothing seems out of the ordinary. Am I overthinking the almost immediate grooving on the rotor; is it possible they left the old burnt pad on (which they insist is new?). Little impatient at the whole situation, to be honest.

Thanks!

Photos in order;
1) New rotor groove
2) New caliper
3) New flex hose
4) Inferno
5) Rear driver rotor before replacement
6) New rotor groove (2)
7) Rear passenger nice and smooth
 

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How deep is the grove? Did you bed the brakes in?
I have done tons of brakes, I don't think I have seen any wear in like that.
I have owned some 250,000 miles cars and have never had to replace a brake line.
 
A bad fitment of brake pads might do this - or using non oem pads that aren’t a 100% fit to an oem rotor.

If not that then some grit or other foreign body between the pads and rotor - but in a newly fitted pad and rotor set?
 
After its sat for a couple hours and is perfectly cold - run your finger nail across it. If its smooth your fine. Might have got some grease from the caliper pins or something on it? If its smooth you should bed your brakes.

If its grooved already than it shouldn't be. Not sure where you go from there.
 
How deep is the grove? Did you bed the brakes in?
I have done tons of brakes, I don't think I have seen any wear in like that.
I have owned some 250,000 miles cars and have never had to replace a brake line.

Thought it was flush/smooth, but was using my actual finger to check. Just used my fingernail and it definitely caught in the groover, but it's almost unnoticeable to touch. I didn't bed the brakes in, just do what I always do...get in and drive with smooth braking for the first couple hundred. I, too, have never had anything like this happen before. I've had ****ty ceramic pads groove but we're talking thousands of miles in, not 4.

The pads and rotor are OEM. I really think they kept the scorched pad on. The thought of bringing this back to the dealer...yikes. I kind of want to just keep driving it and see if it "resolves", and if there are no other major issues just have a mechanic inspect it at my next oil change. I don't know...
 
I’ve only ever seen brake rotors glowing that way in race cars… your car isn’t a racer and that glowing red hot rotor may have affected other parts including a bearing.

Not sure why that corner is grooving out so much unless the line is damaged a bit further up the way. Hard to know just from a glance and someone needs to get a better look.

At this point I’d visit another dealer, or a good independent shop to get another opinion.

My estimation of dealer service has declined recently given my experience with both Chrysler and Mini after checking their work. Maybe your prior mechanic, despite distance and pricing, is the go-to for this. 😎
 
I’ve only ever seen brake rotors glowing that way in race cars… your car isn’t a racer and that glowing red hot rotor may have affected other parts including a bearing.

Not sure why that corner is grooving out so much unless the line is damaged a bit further up the way. Hard to know just from a glance and someone needs to get a better look.

At this point I’d visit another dealer, or a good independent shop to get another opinion.

My estimation of dealer service has declined recently given my experience with both Chrysler and Mini after checking their work. Maybe your prior mechanic, despite distance and pricing, is the go-to for this. 😎
Yeah, man. My five year old daughter was fascinated by the color haha. So the thing must have been incredibly clamped on or the hose had 0 fluid pushing through.

This sealed the deal on dealerships with me, I just can't shake the feeling that they never fully diagnosed it before all of this happened. Had a bad experience with warranty work on my Tacoma a few years back, too. Anyway - I agree, an independent shop is the way to go. I think right now I'm going to play wait and see before investing more time in it, which I've lost a lot of already. Not my main commuter, thankfully. If braking performance degrades in any way or the rotor is getting gouged out to an extreme degree, I'll take it in sooner. Everything that could have been the problem was replaced (or was it!?); wheel bearing is definitely going to fail over time as the grease is probably gone, but they said the wheel spun fine...don't know.

Cars, eh?
 
How does the park brake energize (cable activating rear calipers & pads). If so could there be something binding that’s partially holding enough pressure to cause the caliper & pads to have too much pressure on that rotor? Just thoughts at random…
 
How does the park brake energize (cable activating rear calipers & pads). If so could there be something binding that’s partially holding enough pressure to cause the caliper & pads to have too much pressure on that rotor? Just thoughts at random…
It's an electronic parking brake. I tested it out and it seems to engage and disengage fine. They also replaced the motor for it. But just because it engages and disengages doesn't mean that it's not fully disengaged. Good thought, good thought...
 
If I were doing that job the first thing I would do is pressure test the caliper. You put the block in with no or one pad depending on the caliper, apply the brake and see how much pressure it is making. Have an assistant press the brake and watch the gauge to see if it returns to zero and how fast it returns, it should be almost instantaneous.
Apply and retract the park brake and watch what it does. I have had one for some years and it really proves its worth finding sticking calipers, bad lines and proportioning valves, MC, etc. A good made in the USA tool. The dealer or any mechanic worth is wrenches should be able to do this, if not find someone who can or buy the tool and DIY.


 
If I were doing that job the first thing I would do is pressure test the caliper. You put the block in with no or one pad depending on the caliper, apply the brake and see how much pressure it is making. Have an assistant press the brake and watch the gauge to see if it returns to zero and how fast it returns, it should be almost instantaneous.
Apply and retract the park brake and watch what it does. I have had one for some years and it really proves its worth finding sticking calipers, bad lines and proportioning valves, MC, etc. A good made in the USA tool. The dealer or any mechanic worth is wrenches should be able to do this, if not find someone who can or buy the tool and DIY.


Hm do you think the caliper has too much pressure going into it? Yeah, to me, if I’m complaining that the rotor doesn’t look new with like 3 miles on it further testing should be done. I can tell they weren’t taking me seriously anymore, or were losing too much labor money on me, which is frustrating.
 
Hm do you think the caliper has too much pressure going into it? Yeah, to me, if I’m complaining that the rotor doesn’t look new with like 3 miles on it further testing should be done. I can tell they weren’t taking me seriously anymore, or were losing too much labor money on me, which is frustrating.
No but I think it may not be relieving pressure for some reason, it could be the electric park brake has a fault, a sticking valve in the system before the caliper. Going by your pictures something is not right. I would start by retracting the parking brake into service mode with a scan tool to see if there is a difference. You have to expose the root cause not throw parts at it.
 
No but I think it may not be relieving pressure for some reason, it could be the electric park brake has a fault, a sticking valve in the system before the caliper. Going by your pictures something is not right. I would start by retracting the parking brake into service mode with a scan tool to see if there is a difference. You have to expose the root cause not throw parts at it.
That's why I brought it to a shop, so they could diagnose it and not throw parts at it. They did the opposite, clearly, lol. Dealer messaged me asking how my experience was, sent them a photo of the rotor and said I'm annoyed...they called me and said "trust me, that's normal on all rotors". No it ain't.

Appreciate the info, I'll look into that.
 
Since this is dealer, I’m sure they warranty their work and materials. I would drive few hundred miles to get the grooves even deeper and then go back.
Get them to re-do that side as many times as it takes to get it right.
That was also my other line of thinking. When I had my Tacoma, there was an issue that the dealer couldn't fix after 3 attempts. It wasn't really their fault, but they didn't do an axle repair that had a TSB. Because I had gone to the dealer multiple times, it was incredibly easy to get Corporate involved and they sent a field tech out like right away, who did a really thorough job diagnosing the issue. The whole vehicle was till under warranty though.

So, for this, I have a pretty steep paper trail right now, including my text to the dealer saying that I was annoyed. And, at this point, since they replaced almost every "known" component that could be causing this issue and claim to have done a diagnosis, I feel like I shouldn't be on the hook for anything within the next year (warranty period).
 
That's why I brought it to a shop, so they could diagnose it and not throw parts at it. They did the opposite, clearly, lol. Dealer messaged me asking how my experience was, sent them a photo of the rotor and said I'm annoyed...they called me and said "trust me, that's normal on all rotors". No it ain't.

Appreciate the info, I'll look into that.
This rear rotor on my BMW looks better. You see orange color? That is bcs. it spent around 270mls on track, and I actually managed to put pads on fire.
The rotor was removed after 30,000 miles. During the life of that rotor, I switched between race pads (hard) on track and regular pads after track time. It was a Pagid rotor, and the cost was, I think, $34 per piece.

Rear rotor burned .jpg
 
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