Rear pad wear surprise on a 2017

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2017 CX-9 Signature
I just did brakes on my wife's 2017 CX9....was only monitoring the fronts as the rears are always better than the fronts right? Wife mentioned there was some grinding, one rear pad was down to the plate!

I did a full rotor and pad job, all 4 corners done so all good now but damm....I need to monitor all now I guess.

Car had 95,000 KM's so it was due but fronts were still ok with about 30% left. Mostly highway driving.

Why the rear so early over the front? ....just a bad design?
 
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2010 Mazda 5 Sport
Sticking rear caliper. I would have it replaced.

If it was both rear pads...that would be a design issue or just really bad luck.
 

sm1ke

Work In Progress..
Moderator
Contributor
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Canada
:
'18 CX-9 Signature
The CX-9 has rear brake bias. Rear pads will usually need to be replaced before the front.
 
Brake Wear and Adaptive Cruise

The CX-9 has rear brake bias. Rear pads will usually need to be replaced before the front.
I've seen people mention that, if you use the Adaptive Cruise a lot, when the car needs to slow down, it applies the rear brakes (to minimize nose-dive, vs. applying the fronts), and that can cumulate to a lot of extra rear brake wear.

In fact, while I love the Adaptive Cruise on the open road, I'm using it less now in tight traffic, because I get annoyed by the short quick control-brake applications that I can avoid by managing the throttle 'manually' - it seems I can look ahead and drive smoother than the Adaptive Cruise, in traffic. And not wearing the brakes out prematurely seems like a nice bonus.

Also, on hilly roads, the Cruise will apply the brakes on downhill stretches, when 'manually' I would just let the speed build a few mph to coast up the next grade - the Cruise just isn't able to take the long view and judge the road gradient a few hundred yards ahead. Maybe Mazda can work on that for the next generation of Cruise ;)
 
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Ottawa, Ontario
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17 Mazda 6 GT
If you got 95K out of the rear brakes, you did well.
I've owned a lot of cars over the past 50 years, and rear drum brakes will last forever, while rear discs have always worn out much faster than the fronts.
I've always had to replace my rear brakes before the fronts, regardless of make of vehicle.

My 2017 6, with only 15,000kms on it (just under 10k miles) is already showing wear and grooves on the rear rotors. I can sometimes feel them grinding. The fronts look new.
I mentioned this to the dealer when I had my oil changed last month, and the service advisor pulled out this pre written full page note with all the excuses as to why this is "normal".
Mazda obviously has this problem, and has given the dealer a talking point memo to show the customer when they ask.
Apparently, I don't drive it enough, or far enough, or aggressive enough....blah blah blah.
What a load.
My 17 year old Pathfinder has the original drum brakes still on it. Never been replaced. Still works fine, including the emergency brake. Give me rear drums anytime.
 
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2014 Ford Explorer Sport, 2009 CX9(Wife's)
My wife's CX9 rears lasted about 130K miles. Fronts were changed 2-3x in that span.

My old Speed6 went through rear pads in about 40k miles, original fronts were still 50% @ 65k when I traded it in.

My '14 Explorer when through rear pads in about 70k miles, fronts were at about 50% at that time.

I've heard more stories of rear pads wearing faster than fronts in the recent years.
Might be a mechanical reason for more rear bias. Maybe more rear bias under light (normal braking) as mentioned to prevent nose dive?

Short story long, rear pads wearing before fronts is not abnormal these days.
 
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2017 CX-9 Signature
Short story long, rear pads wearing before fronts is not abnormal these days.
Yea it would seem so, I will be surely inspecting carefully now all pads at oil service moving forward to prevent this. In fact I put a reminder in my maintenance log to have a full front and back replacement set on hand after 60k. My wife is a heavy user of the adaptive cruise so I believe there is merit to the theory of it being a primary factor to all this.

Brakes (when done by yourself) are a pretty cheap maintenance item, I am simply disappointed with myself that I let them get that far.
 
We have a 2017 CX 9 GT also. Had it about 20 months with 25,000 miles on it. At my last oil change the dealer stated I'm down to "yellow" on the rear pads and recommended doing a rear brake job. I asked to look at the pads and they allowed me into the shop and I looked and measured them, they were at 5 mm. I said "no thanks" I'll wait for another few oil changes. 8mm is full, so 5 mm is still 60% left. The fronts still have 6-7 mm left. So, it looks like the rears do wear faster than the fronts. My wife does mostly around town driving.

And yes I go to the dealer for oil changes. They sold me a package of 9 oil changes for $275. That's $30 per oil change. Hard to do it myself for that amount. Plus I get to eat their snacks, drink their coffee and get a free car wash. I do my own cabin filters, air filters and wipers.
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
:
'18 CX-9 Signature
And yes I go to the dealer for oil changes. They sold me a package of 9 oil changes for $275. That's $30 per oil change. Hard to do it myself for that amount. Plus I get to eat their snacks, drink their coffee and get a free car wash. I do my own cabin filters, air filters and wipers.
Make sure you do your own fluid checks after every service, and ensure they are using the correct oil and filter. I've heard way too many dealer horror stories to leave it solely up to them.
 
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Mazda CX-9 Grand Touring 2016
"Make sure you do your own fluid checks after every service,"
Carry a paper towel out when you're ready to take the car home. Pull the dipstick, wipe it off, insert and pull. Lay the dipstick horizontally on the paper towel. Oil that is too clean to see well will show up easily as it is absorbed into the paper. Check both cleanliness and the level of the oil on the dipstick.

You get what you inspect, not what you expect.
 
Make sure you do your own fluid checks after every service, and ensure they are using the correct oil and filter. I've heard way too many dealer horror stories to leave it solely up to them.
Amen to that. Every dealer is different but beware the ones that promise 2 year free mtce. It was an absolute joke with my Tundra. I feel like the dealer just looks at it as free money from the manufacturer if the customer doesnt notice. Not going into it but lets just say that these programs had absolutely no bearing when I was last car shopping. Oh, and I do like the Tundra.
 
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2016 CX-9 Sport AWD
I agree. Traditionally, front pads wear out long before the rears. In my case, the rear brakes on my 2016 Sport wore out well before the fronts as well. I don't have adaptive cruise control, so that wasn't the reason. My guess is that the rear brakes are either undersized, use a faster wearing pad, or biased to provide more braking than the typical vehicle.

Now I keep a closer eye on the rears during tire changes and tire rotations.
 
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Mazda CX-9 Grand Touring 2016
I've seen the rear pads wear first on another car. I owned a Volvo 850 for 200,000 miles. It was great to us, and I saw the rear pads wear out before the fronts every time.
 
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2016 CX-5AWD GT+Tech/ 2018 CX-9AWD GT
This is 100% true. Its so the nose of the car doesn't nose dive during harsh braking so the system is designed to favor the rear.
I*ll agree as well. My CX-5 is the same, we*re still on the original front pads and the rears have been replaced once. I just checked my CX-9 this morning because the brakes were squealing. The rears are pretty worn and the fronts look good. One very odd/interesting thing I found, one (just one) of the rear brake pads was installed backwards (they are all still original). I thought that was the cause of the squealing, so I flipped it the right way, but upon test driving, the sound was even worse. I*m thinking since it bedded in backwards, flipping it forwards created even more issues, so I flipped it back. I added some break grease all around and the squealing is 90% gone. In any case I just ordered new pads for the rear, and I*m only at 21k miles.
 
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CX-9, Mazda6
Just replaced the rear pads on mine at 30,000 miles. Fronts still have ~50% left.

I went with Raybestos EHT's off rockauto.com for only $15 a set! At that price, as long as they perform well enough, I won't mind them wearing out so quickly. I could buy 6 sets of the Raybestos for the price of 1 set of OEM's.
 
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17 CX-9 GT FWD
Just replaced rears on out 2017 @ 38,500 mi. Were down almost to the plates. I consider our driving style to be easy on brakes. Glad I had seen this thread earlier so I was prepaired.
 
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Mazda CX-9 Grand Touring 2016
Mine is at 5 mm remaining on the rears with 41,000 miles of mostly freeway driving. It all depends on driving conditions.
 
2016 mazda CX-9, just did all brakes changed front and back rotors and pads at 117,000 km, about 72,000 miles. My mechanic said that's a lot for those vehicles.
 
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