New '17 CX-9 vibration through brake pedal

holmes6

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2017 CX-9 Sport
So I got a new CX9 about a month ago. Pretty much right after the test drive noticed that the engine would vibrate the gas pedal under certain loads, like higher RPM downhill.
Brought to dealer who machined my brand new rotors, which helped in most situations, but under the right conditions the pedal still vibrates pretty severely.
Does anyone else have any hint of that? Looks like I'm going to a second trip to the dealer for this.
 
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If you are experiencing the vibration still then there is no substitute for new rotors. My Mazda back in 2012 came off the lot with a vibration that only new rotors cured. Seems Mazda may still have an issue undersizing the brakes for this vehicle? PS - if you do get new rotors, and you should, it would be best to bed them in properly and take it easy as you can on them for the first 500 miles or so.
 
my suggestion is for you to make the dealer change the rotors, to machine then will only work for a small period of time.
as Rowlands57 just said, the bedding of the breaks is of most importance so you don't bend the rotors again .
 
If you are experiencing the vibration still then there is no substitute for new rotors. My Mazda back in 2012 came off the lot with a vibration that only new rotors cured. Seems Mazda may still have an issue undersizing the brakes for this vehicle? PS - if you do get new rotors, and you should, it would be best to bed them in properly and take it easy as you can on them for the first 500 miles or so.

- bedding your brakes is only for high performance braking systems and only AFTER you break them in with normal use for about 500 miles.

- rather small rotors does have something to do with it, but the rotors are simply weak and not very resistant to warping

- if your 2012 Mazda had warped rotors "from the factory" that means someone took it out for a test drive before you managed to get your hands on it and drove it like a dumbass.

resurfacing your rotors will help, but you are correct it is best to simply buy new brakes. the OEM pads seem to be okay, but I would get better rotors like EBC or Centric.
 
my suggestion is for you to make the dealer change the rotors, to machine then will only work for a small period of time.
as Rowlands57 just said, the bedding of the breaks is of most importance so you don't bend the rotors again .

FWIW the dealer reported the brakes were spotted, most likely from sitting around too long without being driven before I bought it. I don't know what to believe really, it doesn't make sense to me that a problem with the rotors would only occur at certain RPM's. I wonder if this isn't 2 separate problems, spotted rotors and a bad mount or something else that is allowing engine vibration where it doesn't belong.
 
FWIW the dealer reported the brakes were spotted, most likely from sitting around too long without being driven before I bought it. I don't know what to believe really, it doesn't make sense to me that a problem with the rotors would only occur at certain RPM's. I wonder if this isn't 2 separate problems, spotted rotors and a bad mount or something else that is allowing engine vibration where it doesn't belong.

Do the brakes vibrate the car while braking from a high speed (eg. Getting off the highway?) and you said you feel it in the brake pedal? What mileage are you at?

Have the dealer replace your brakes or at least resurface them and see if that fixes the problem. I would also have your brakes inspected by a reputable mechanic (aka not the dealership) and make sure everything is in good working order. That doesnt sound very normal to me.
 
Do the brakes vibrate the car while braking from a high speed (eg. Getting off the highway?) and you said you feel it in the brake pedal? What mileage are you at?

Have the dealer replace your brakes or at least resurface them and see if that fixes the problem. I would also have your brakes inspected by a reputable mechanic (aka not the dealership) and make sure everything is in good working order. That doesn’t sound very normal to me.

The brakes feel very smooth and effective when the engine is not revving much. It's vibrating the brake pedal before my foot even touches the brakes when I'm engine braking though. My plan right now is another trip to the dealer, try to go on a ride with the tech to make sure they dupe the problem, then go from there. It definitely isn't normal, never felt this in 25 years of driving a wide range of cars. The weird thing is I can't really find any people reporting the same problem on any vehicle. Makes me wonder if I am having some kind of trouble describing or searching for it, but I'm usually pretty good with that stuff.
 
The brakes feel very smooth and effective when the engine is not revving much. It's vibrating the brake pedal before my foot even touches the brakes when I'm engine braking though. My plan right now is another trip to the dealer, try to go on a ride with the tech to make sure they dupe the problem, then go from there. It definitely isn't normal, never felt this in 25 years of driving a wide range of cars. The weird thing is I can't really find any people reporting the same problem on any vehicle. Makes me wonder if I am having some kind of trouble describing or searching for it, but I'm usually pretty good with that stuff.

Thats not normal. I would get the engine and all the pulleys/belts inspected along with the rest of the car. Sounds abnormal, Im not surprised you havent found anyone with the same issue.

Keep us posted and best of luck
 
I agree with GJ. This sounds like something other than a brake problem. Things get shaken, and you feel it on the brake pedal, but the brakes aren't the cause of the shake. Stick with it, and please let us all know when the solution is found.

Brake discs do not warp. They've cast iron, and even if they warped, they'd get cupped, not create run out. What happens is when the operation creates heat greater than the pad friction compound is made to handle. Extremely thin layers of the brake compound get deposited on the discs in uneven spots. When the brakes are next applied, the pads stick-slip-stick-slip, judder is felt, and warping is blamed. The discs are cleaned by turning them on a lathe or grinding, but even just sandpapering the surface and washing with brake solvent will correct this problem. The judder problem will return if the brakes are similarly overheated again, so a better grade of pad may be needed by drivers who experience this.
http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths
 
Small update. Haven't been to the dealer yet, but just took a good barefoot test drive. Turns out the vibration occurs even with the car in park, so the rotors are definitely not the problem. It's worst in the 3000-3500 range and obvious 500 additional RPM on each side of that.
 
Well, dealer was able to dupe the issue, but won't fix. Says that he tried another brand new cx9 and it had the same behavior.
I may test out another one myself to confirm that.
 
I've experienced a vibration on the brake pedal on my previous Volvo XC60 since I had that brand new and there was no fix for it due to its design, the vibration was caused by the Aux fan whenever it turned on...could this be a possibility with the CX9?
 
Small update. Haven't been to the dealer yet, but just took a good barefoot test drive. Turns out the vibration occurs even with the car in park, so the rotors are definitely not the problem. It's worst in the 3000-3500 range and obvious 500 additional RPM on each side of that.

that's weird.......even in park? so definitely not a rotor or brake issue, maybe a loose motor mount ? only thing that would cause vibration in park would be the engine shaking back and forth on a loose mount ......
 
Is something rubbing up against the brake booster or the lines? Something like this happened on a VW Golf I had.
 
Well, dealer was able to dupe the issue, but won't fix. Says that he tried another brand new cx9 and it had the same behavior.
I may test out another one myself to confirm that.

That is a totally unacceptable answer from them. Two of our vehicles have the same defect therefore it's not a defect???? Unbelievable! Of course a vehicle sitting on the lot may have the same issue as having not being driven much they will have all kinds of surface corrosion on the rotors and the brakes have not been broken in. I would take this issue up with Mazda corporate as it appears you have either an incompetent or lazy service rep on your hands.
 
that's weird.......even in park? so definitely not a rotor or brake issue, maybe a loose motor mount ? only thing that would cause vibration in park would be the engine shaking back and forth on a loose mount ......

totally agree on batmancx suggestion, I have had this problem in a golf gti years ago. the engine mount was broken and the engine was moving from its place, as a consequence there was a weird vibration in the car at different moments.
 
Hey came upon this thread through Google. I have a 2017 CX-9 purchased in September and I seem to have the same brake pedal vibration issue as well (less than 7k miles on the car and issue started happening a while back). Will be taking it into the dealer to see if it is warped rotors.
 
Hey came upon this thread through Google. I have a 2017 CX-9 purchased in September and I seem to have the same brake pedal vibration issue as well (less than 7k miles on the car and issue started happening a while back). Will be taking it into the dealer to see if it is warped rotors.
Hi, did you figure out what it was? I know it's an old post. My 2020 cx9 was bought with 3500 miles, and i started feeling the vibration of the brake pedal pretty much after starting to drive it. Did anybody take it to the dealer/mechanic and figured out what the issue was?thanks
 

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