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Discussion Starter · #1 ·
Hey guys

My car ( 2018 S60 polestar ) has a bit of a quirk where if i get up to high speeds the apply brakes then let go of the brakes and not press the accelerator it still feels like the brake is being gently pressed.
It seems like its the brakes because when you apply hard brakes you can hear the whirring sound from the slotted front rotors and when you let go of the brakes you can still hear that sound slightly and it does feel like its slowing down with slight brake press still.

I had the TCM update done, and that fixed some other issues ( like bouncing off the limiter and holding low gears too long when off the throttle ) but the brake quirk still seems to be there.

The closest thing i can compare it to is like a manual car holding a too high gear or a car with regenerative braking harvesting power off throttle...though as far as I know these polestar cars dont have regenerative braking ? And since its an auto i dont think its holding a too high gear either ( especially after the TCM update ).

Any idea whats the problem here ? Anything to be concerned about ( eg sticky caliper ) ?
 

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Would this be something to do with the hill descent ? Because I always felt the car is applying the brakes at the lights and I would need to apply a lot of effort on the gas pedal to make it go when the lights turn green. It’s really annoying , I also have 2018 P*


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That doesn't sound right - my '16 doesn't do that. I'd take it back to the dealer to have someone ride along with you to see what you're talking about.
 

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My 2018 P* brakes do not do that; as suggested above, I would have dealer check it out.
However my brakes need a surprisingly firm application of the pedal (will start a separate thread so as not to derail this one).
 

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I have noticed that on my 2017 model the brakes often seem to not want to release quickly as well, as if the pistons are slow to retract. I can only really notice it at stoplights. It is difficult to determine whether this is the case or not because there is no easy way to test another car.

At times you can tell when the hill descent control is on because the brake pedal will not move back up if you release it. When you are on a hill it is obvious, but I have also had it happen a few times where I put the car into reverse on a relatively flat surface and it does not move as the brakes do not disengage, which is irritating.

However, I have never felt that there was any problem at higher speeds.

My only other complaint is what sounds like wheel bearing hum (but is not) only when lightly accelerating between 56-60km/hr, and also somewhere around 90km/hr, again only when lightly applying the accelerator. Not sure if it is the tires or something else. Again, not easy to determine if it is normal because there are no other vehicles available to test.

Otherwise it is a very neat car, just a few hundred pounds too heavy.
 

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Discussion Starter · #6 · (Edited)
My only other complaint is what sounds like wheel bearing hum (but is not) only when lightly accelerating between 56-60km/hr, and also somewhere around 90km/hr, again only when lightly applying the accelerator. Not sure if it is the tires or something else. Again, not easy to determine if it is normal because there are no other vehicles available to test.

Otherwise it is a very neat car, just a few hundred pounds too heavy.
Yeah i get those sounds as well, pretty similar to what you describe but i can hear it when decelerating too.

The car is very heavy, the 2.0L has to work really hard to get these cars to go fast. It really doesnt feel like it has 362HP on tap, you have to really drive it quite hard to get the performance out of it.

Dealers test drove with me, they didnt seem to think it was a problem, they say there might be slight brake binding when the brakes get hot, since its got so little mileage theres a lot of meat on the pads still. I don't know though, its quite a strange thing.
 

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I have noticed that on my 2017 model the brakes often seem to not want to release quickly as well, as if the pistons are slow to retract. I can only really notice it at stoplights. It is difficult to determine whether this is the case or not because there is no easy way to test another car.

At times you can tell when the hill descent control is on because the brake pedal will not move back up if you release it. When you are on a hill it is obvious, but I have also had it happen a few times where I put the car into reverse on a relatively flat surface and it does not move as the brakes do not disengage, which is irritating.

However, I have never felt that there was any problem at higher speeds.

My only other complaint is what sounds like wheel bearing hum (but is not) only when lightly accelerating between 56-60km/hr, and also somewhere around 90km/hr, again only when lightly applying the accelerator. Not sure if it is the tires or something else. Again, not easy to determine if it is normal because there are no other vehicles available to test.

Otherwise it is a very neat car, just a few hundred pounds too heavy.
You explained it better than me , I have the same issue with the brakes releasing slowly. Noticed it from day one but I’ve never had the time to address it with the dealer. I feel like I have to apply the accelerator earlier and time the lights or else I won’t be following the traffic.


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Discussion Starter · #8 ·
I noticed today that you get most of the noise and pedal feedback when the brakes are cold. After a couple of hard stops from freeway speeds the system starts to quiet down. Its strange that they decided to go for such an extreme front brake system setup considering this car isnt really in the performance league of something like an M3 and they didnt bother to improve the rear brakes at all ( the brake balance cant be good ).
Having brakes that need to be constantly kept in their operating range seems an odd choice for a car thats maybe going to see one or two track days a year if that.

Maybe it can be improved for everyday use with a different set of pads and non-slotted rotors. Sure its nice having track oriented brakes but it seems the default pad/disc combo is not a good street setup.
 

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I noticed today that you get most of the noise and pedal feedback when the brakes are cold. After a couple of hard stops from freeway speeds the system starts to quiet down. Its strange that they decided to go for such an extreme front brake system setup considering this car isnt really in the performance league of something like an M3 and they didnt bother to improve the rear brakes at all ( the brake balance cant be good ).
I know what you mean about the rear brake setup. It's bothered me since I bought the car.....not anymore. Just made it like they should have done at the factory and it is way more balanced under sudden and panic stops.
20190616_140249-1a.jpg
 

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Discussion Starter · #10 ·
I know what you mean about the rear brake setup. It's bothered me since I bought the car.....not anymore. Just made it like they should have done at the factory and it is way more balanced under sudden and panic stops.
View attachment 52795
Where did you get those rear calipers from ? And how did you manage to get it to integrate with the cars electronic park brake system ?
 

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Where did you get those rear calipers from ? And how did you manage to get it to integrate with the cars electronic park brake system ?
There are a couple company’s that make rear brake setups, rotora and playground tuning are 2 that comes to mind and the kits come with a new electronic parking brake I believe.


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There are a couple company’s that make rear brake setups, rotora and playground tuning are 2 that comes to mind and the kits come with a new electronic parking brake I believe.
Yes, you are correct. Mine is the Rotora rear BBK, from California. The Playground Tuning kit is from Taiwan, but the Playground Tuning kit is a "bigger setup" (the rear rotor is almost or same as the front and 6 piston rear caliper).
 

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There are a couple company’s that make rear brake setups, rotora and playground tuning are 2 that comes to mind and the kits come with a new electronic parking brake I believe.


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CEIKA in Hong Kong also makes big brakes for the P3 platform with significantly more customization. Especially if you want to go all in, they offer carbon ceramic.
Though I didn't go with them due to higher cost than Playground's kit. I do know their rear kit doesn't need trailing arm cutting unlike the Rotora kit.
 

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CEIKA in Hong Kong also makes big brakes for the P3 platform with significantly more customization. Especially if you want to go all in, they offer carbon ceramic.
Though I didn't go with them due to higher cost than Playground's kit. I do know their rear kit doesn't need trailing arm cutting unlike the Rotora kit.
Haha they are not cheap, $16k for front ceramic brakes lol


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Discussion Starter · #15 ·
Yes, you are correct. Mine is the Rotora rear BBK, from California. The Playground Tuning kit is from Taiwan, but the Playground Tuning kit is a "bigger setup" (the rear rotor is almost or same as the front and 6 piston rear caliper).
Where can I order them and is the fitment straight forward ?

The stock car is very squirrely under braking unless you are in a perfectly straight line. I always worry that the back end is going to step out under hard braking into a corner.
 

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Just to finish up on my previous post, I finally decided to point out the various items I mentioned to the service manager on a test drive. The humming noise at certain speeds is possibly a driveshaft bearing, while all of the brake "problems" are apparently normal, which I am inclined to believe based on the other posts here.

As an aside, I did some travelling last week with the car, and when parking at a Burger King on a perfectly flat surface after about 2 hrs. on the highway I got back into the car, started it up, put it into reverse, and it wouldn't move. Required some gas to unlock the brakes. Irritating. Those Rotora rear calipers look very good.
 

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Discussion Starter · #17 ·
The E brake on my car does hold the car like you describe, but it doesnt bother too much because i dont need much throttle if any to get it moving ( usually i just wait about half a second and it will start rolling ). I think its basically the same as the hill assist on the manual cars, for some reason these auto cars have it as well.
Based on what you describe yours might be holding the brakes a bit too hard.

Regarding the driveshaft actually being the source of the humming, thats interesting it would make sense considering the car does it while coasting, did he say its normal or can be fixed ?
 

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With respect to the driveshaft, it occurs only while applying throttle, and really only at one particular speed where I can always tell it is there. Let off the gas and it disappears. It really is quite faint, and you would think it was tire noise or a wheel bearing if the problem presented itself differently. I think with a couple of years left on warranty I will monitor it and see if/how much louder it gets. It can definitely be fixed.
 
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