[amancuso]

Had the oil changed on my '18 430i and I was told the rear brakes were worn under spec at 4mm. The mileage counter says I'm still about 10,000 miles away from needing service there. Did someone prematurely reset that service indicator? They don't squeal or anything yet. Approximately how many miles do I have left on these?


TIA.

[MidtownMike]

That's funny. My rear brakes are also at 4 mm, but my car thinks they still have 90K(!) km left on them. It's a CPO, so all maintenance was done by official BMW dealer.
Conclusion: iDrive indicator for brakes is unreliable AF.

[Gen13 F36]

Usually you take of the wheel and inspect it. Most of the time I have to do that on my previous JDM car. But on this F3x cars they are so easy to look at with just a flash light....you can see the outside pads. Usually I don't totally wait till it's completed out.

I change pads around 20%....I know it still plenty but the pedal feel not the same.

[leathers]

When they look worn to you (conservative approach), or when the light comes on (final indication).

[chowser51]

When the sensor trips or at 2mm. That's when I usually replace pads.

My F33 saga (430i xdrive)
Rear pads and rotors at 48176 miles.
Front pads and rotors at 64954 miles.

pads and rotors bought at fcp euro.
sold car before it hit 80k.

f39 m35i edition, front pads at 26334 miles.
last oil change at 43812 miles, the front pads were at 5mm and rear pads at 4mm. I might make it through winter before needing pads again.

every oil change (9000 miles) or tire rotation (6000 miles), I will look at all the pads. Inner and outer. the basic bmw brakes are the easiest I have ever worked on.

[Billfitz]

The sensors are next to useless, as there are only two sensors, while there are eight pads. The iDrive guesstimate is no better. The only way to be sure they're OK is to visually inspect them, all of them, especially the inner pads, which tend to wear out faster than the outer pads.

[WDE82]

Originally Posted by Billfitz

The sensors are next to useless, as there are only two sensors, while there are eight pads. The iDrive guesstimate is no better. The only way to be sure they're OK is to visually inspect them, all of them, especially the inner pads, which tend to wear out faster than the outer pads.

I don't agree the sensors are useless. The pads should wear fairly evenly per axle and per wheel (inboard and outboard pads). once the sensor trips you have something on the order 1000 miles remaining.

Also don't agree on the inboard vs outboard pad wear difference. I've never observed a difference on mine and based on how either the 2 piston rears or the sliding single pistons work mechanically I don't see how that would happen without something else being a pretty big problem (seized piston or slide).

Totally agreed with "just look at them bruh!" and that cuts through all the BS. Brakes are easy to inspect.

[Billfitz]

My own experience says otherwise. I had to do my first pad change at only 11k miles. The inner pads both front and rear had worn to 2mm, while the outer pads were at 6mm front, 5mm rear. Visual inspection of just the outer pads didn't show it. The sensors didn't trip, because they're on the outer pads. Yes, this was unusual, probably due to inadequate lubrication of the pad to carrier interfaces at the factory, but it did happen. If I'd relied on the sensors, or the iDrive that said they were good for another 30k miles, the only warning I'd have received was when the inner pads were down to nothing and I heard metal on metal, trashing my rotors.

[amancuso]

Originally Posted by chowser51

When the sensor trips or at 2mm. That's when I usually replace pads.

My F33 saga (430i xdrive)
Rear pads and rotors at 48176 miles.
Front pads and rotors at 64954 miles.

pads and rotors bought at fcp euro.
sold car before it hit 80k.

f39 m35i edition, front pads at 26334 miles.
last oil change at 43812 miles, the front pads were at 5mm and rear pads at 4mm. I might make it through winter before needing pads again.

every oil change (9000 miles) or tire rotation (6000 miles), I will look at all the pads. Inner and outer. the basic bmw brakes are the easiest I have ever worked on.

Thanks for sharing, my F33 M Sport car doesn't have the upgraded brakes, just the standard ones. Currently at 60,xxx miles. Hoping I can make it another few months (Only because I'm being lazy and don't fancy doing the job in the heat). I wasn't aware there was an actual sensor on the pad like in the earlier cars as well. I'm fine with waiting until the sensor is tripped and just replace it when I change the brakes.

[Wires]

Originally Posted by Billfitz

My own experience says otherwise. I had to do my first pad change at only 11k miles. The inner pads both front and rear had worn to 2mm, while the outer pads were at 6mm front, 5mm rear. Visual inspection of just the outer pads didn't show it. The sensors didn't trip, because they're on the outer pads. Yes, this was unusual, probably due to inadequate lubrication of the pad to carrier interfaces at the factory, but it did happen. If I'd relied on the sensors, or the iDrive that said they were good for another 30k miles, the only warning I'd have received was when the inner pads were down to nothing and I heard metal on metal, trashing my rotors.

Probably due to them not lubing mating surfaces of the pads in the factory. Mine were like that, and within 1000 miles they squealed so bad it drove me nuts. Hated the dust, and when I was swapping out my "new oem" pads, noticed that there was ZERO lube on the contact points.

Installed the new ones with the supplied copper lube, and they have been quiet and have worn evenly.

[johnung]

IDrive remaining miles estimate for brake pads is totally meaningless. It’s not using any physical sensor data from the car as many people just assume. It’s just a computer generated algorithm that’s usually totally wrong.

In fact the brake pad sensors are not intelligent at all! There’s only one sensor on one of the four front brake pads, and one sensor on one of the four rear brake pads.

The sensor is as dumb as they come. It simply triggers a dash message about replacing the front or rear pads when the pad hits a certain number of millimeters of material remaining. The sensor is single use so if it triggers it needs to be thrown out and replaced.

No reason to panic if you get a front or rear pad replacement message on the dash. There’s usually months worth of driving remaining with pad material that’s left. If you get a brake message that references mileage, just ignore it. That’s the ridiculous algorithm.

[tturedraider]

Originally Posted by Billfitz

My own experience says otherwise. I had to do my first pad change at only 11k miles. The inner pads both front and rear had worn to 2mm, while the outer pads were at 6mm front, 5mm rear. Visual inspection of just the outer pads didn't show it. The sensors didn't trip, because they're on the outer pads. Yes, this was unusual, probably due to inadequate lubrication of the pad to carrier interfaces at the factory, but it did happen. If I'd relied on the sensors, or the iDrive that said they were good for another 30k miles, the only warning I'd have received was when the inner pads were down to nothing and I heard metal on metal, trashing my rotors.

Are you by chance a left foot braker?

[amancuso]

Originally Posted by johnung

IDrive remaining miles estimate for brake pads is totally meaningless. It’s not using any physical sensor data from the car as many people just assume. It’s just a computer generated algorithm that’s usually totally wrong.

In fact the brake pad sensors are not intelligent at all! There’s only one sensor on one of the four front brake pads, and one sensor on one of the four rear brake pads.

The sensor is as dumb as they come. It simply triggers a dash message about replacing the front or rear pads when the pad hits a certain number of millimeters of material remaining. The sensor is single use so if it triggers it needs to be thrown out and replaced.

No reason to panic if you get a front or rear pad replacement message on the dash. There’s usually months worth of driving remaining with pad material that’s left. If you get a brake message that references mileage, just ignore it. That’s the ridiculous algorithm.

So the same as my e36 and e46 then. Thanks!

[HighlandPete]

Originally Posted by Billfitz

My own experience says otherwise. I had to do my first pad change at only 11k miles. The inner pads both front and rear had worn to 2mm, while the outer pads were at 6mm front, 5mm rear. Visual inspection of just the outer pads didn't show it. The sensors didn't trip, because they're on the outer pads. Yes, this was unusual, probably due to inadequate lubrication of the pad to carrier interfaces at the factory, but it did happen. If I'd relied on the sensors, or the iDrive that said they were good for another 30k miles, the only warning I'd have received was when the inner pads were down to nothing and I heard metal on metal, trashing my rotors.

Floating callipers normally have more pad wear on the piston side. More friction and drag across the components to the outer pad. Light braking likely makes the wear on the inner pads even worse.

BTW, that's why the sensor is fitted to the INNER pad (piston side), as it will trigger on the first pad to wear down.

Unless there are severe braking imbalances, one sensor per axle is sufficient.