Brake Grinding Noise

[Jimct]

I will respectfully disagree that it is "normal". I've been driving many years (over 40 years) and while I've heard my share of brake noises as well as done brake jobs on just about every common car, this is different.
Rust Noise - Not this time.
Vibration - Not this time.
Quietness of the car and normal noise? - maybe.
Could I possibly be hearing the result of the pad and the rotor just coming to a stop? - maybe.
Could it be an interaction between the motor regen and the brake system? - maybe

But again, this isn't something I've ever heard on any other vehicle before, therefore, I asked the question. And, for the record, this isn't a "squeal" but, we agree, it does seem to be a noise generated by the contact between 2 surfaces, and in this case, we believe these surfaces are the rotor and the pad. This action occurs on EVERY motorized vehicle, but why am I hearing it on this one, and only at the slowest of speeds (like 1 MPH) when I do?

As mentioned - I will respectfully disagree with your theory, but will certainly keep trying to figure it out, and if it comes back as nothing, then I will report back. Not looking to get into a debate on this.

My Kona EV does exactly the same thing, especially after a rain and dry-out. Taking it off regen and using the brakes helps, but the grinding is certainly noticeable in reverse and slow speed. My friends on the Kona forum all agree it's completely normal.

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[My GT E]

Yes, 100%. Unlike a Tesla, the MME has a blended braking system. That means that every time you press the brake pedal, the car will try to use as much regenerative braking as possible before engaging the friction brakes. If you slam the pedal, it will engage the friction brakes much sooner, but in every day driving the friction brakes are used very little. Regen is usually enough to bring the car close to a stop, and then the friction brakes kick in at the very end and stay engaged to hold the car at a stop.

Seriously, feel the rotors after a drive and you'll see that they're cold.

Great information, of which, I didn't know. This does help explain this situation. I will check the brake rotors after I drive. Seems like the actual rotors and pads should last a very long time, unless the driver is constantly slamming on the brakes!

 

[generaltso]

Great information, of which, I didn't know. This does help explain this situation. I will check the brake rotors after I drive. Seems like the actual rotors and pads should last a very long time, unless the driver is constantly slamming on the brakes!

Yes, pads and rotors should wear much slower in an EV. But rust can become an issue due to lack of use.

 

[nicholaspe]

Grinding noise at low speed only. I usually drive in one pedal driving so only notice it when actually engaging the brake. I’m at 3200 miles and my front brakes are clean silver but the rears look ground and rusty!! Is any of this normal?

 

[generaltso]

Is any of this normal?

Yup, sure is.

 

[HuntingPudel]

My mid-October production GT-PE makes a low frequency rumbling noise when I back out of the driveway in the morning. It does not make this noise when I back out of the space at work. It does not make the noise once I have gotten going. After backing out of the driveway and shifting into forward motion it does not make the noise when traveling at the same speed. I theorize that it has to do with the slope of my driveway, the velocity I am traveling, the amount of brake force I am using. This probably has nothing to do with the OP’s problem, but posting this just so that we all see a little different spin on a brake noise. ?‍??

 

[RMoore]

Yes, 100%. Unlike a Tesla, the MME has a blended braking system. That means that every time you press the brake pedal, the car will try to use as much regenerative braking as possible before engaging the friction brakes. If you slam the pedal, it will engage the friction brakes much sooner, but in every day driving the friction brakes are used very little. Regen is usually enough to bring the car close to a stop, and then the friction brakes kick in at the very end and stay engaged to hold the car at a stop.

Seriously, feel the rotors after a drive and you'll see that they're cold.

Great information, of which, I didn't know. This does help explain this situation. I will check the brake rotors after I drive. Seems like the actual rotors and pads should last a very long time, unless the driver is constantly slamming on the brakes!

There is a nice analysis by @phidauex in this long thread about this topic--worth taking a look at. Confirms what @generaltso has said.

 

[My GT E]

Thanks.

For the record, I did try shifting into neutral before coming to a stop and the noise was there. Due to this, I fully believe the grinding noise I am hearing in that last few feet is the friction brakes and rust on the rotors, as several have said.
Thanks everyone for jumping into this conversation.

 

[Quick Sliver]

For the record, I did try shifting into neutral before coming to a stop and the noise was there. Due to this, I fully believe the grinding noise I am hearing in that last few feet is the friction brakes and rust on the rotors, as several have said.
Thanks everyone for jumping into this conversation.

I had a thought (a rare occurrence some might say) based on this thread.

I noticed the other day that my rear rotors weren't nearly as smooth as the fronts. Both had....not gouges per se but if you ran a fingernail across them you'd definitely feel record-like grooves. The front's OTOH are still mirror smooth. Since the rear brakes tend to "balance" (eliminate nosedive) rather than do the heavy duty braking work like the front's, I wonder if what you're hearing is rear-brake specific? Different rotors, different pads, different use profile?

 

[My GT E]

I had a thought (a rare occurrence some might say) based on this thread.

I noticed the other day that my rear rotors weren't nearly as smooth as the fronts. Both had....not gouges per se but if you ran a fingernail across them you'd definitely feel record-like grooves. The front's OTOH are still mirror smooth. Since the rear brakes tend to "balance" (eliminate nosedive) rather than do the heavy duty braking work like the front's, I wonder if what you're hearing is rear-brake specific? Different rotors, different pads, different use profile?

My noise is absolutely coming from the rear. I also have the same rear rotor feel as you have described. My front rotors aren't a whole lot better because when I do most of my drives, they are longer distances and mostly highway. Bottom line is, I'm no longer going to worry about it.

 

[Rugbyjay1]

I reported this to my dealer when the car was taken in for warranty work (roof and software updates). In the end, they made the decision to order new pads which are on backorder. Hopefully they will come in soon. Been around three weeks.

 

[Scooby24]

I reported this to my dealer when the car was taken in for warranty work (roof and software updates). In the end, they made the decision to order new pads which are on backorder. Hopefully they will come in soon. Been around three weeks.

This will be an exercise in futility unless you have another issue with the pads like them being stuck to the rotors.

 

[bellyer]

So, about 12,500 miles in and I have just started noticing the brake noise being mentioned above. Has anyone been able to get their issue with the brake noise resolved at this point and can you let me know what it took to fix it? I was thinking it was due to snow/ice build up now that Chicago's roads are covered in muck all the time...

 

[Benny’66]

When the pad material is a semi-metallic, the material on the rotor will rust over more than organic or ceramic/carbon pads.

My M40i was terrible with the stock pads. Soon as I switched to ceramic pads it stopped. The initial bite and cold performance also suffered so for an EV, you definitely want that cold bite.

Just look at all that rust ruining my photo!

That’s rust? Looks like a titanium rotor.

 

[My GT E]

So, about 12,500 miles in and I have just started noticing the brake noise being mentioned above. Has anyone been able to get their issue with the brake noise resolved at this point and can you let me know what it took to fix it? I was thinking it was due to snow/ice build up now that Chicago's roads are covered in muck all the time...

I chalked it up to the brakes not being used much and rusty rotors, as just about everyone has said. I did notice that in reverse, the rusty grinding noise is more prevalent. I'm not going to worry about it.

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