[andyg20]

Car's in at the dealer for a service today, the on board computer was saying rear brake pads needing done in 2000 miles when I took the car in, so I was expecting a call.

The dealer sends you an email "health check" report as part of the service, and on that is written "rear pads 1mm from metal".

Now I'm going to get the pads done anyway, but that surprised me. I know the car works the pads based on the wear sensor, but that's as far as my knowledge goes! I had assumed that the on board computer estimate would be very prudent, and even after the number reached zero miles left, there would be some form of safety margin. But if the car is still saying 2000 miles of wear left, and the dealer is saying there is only 1mm of pad left, there is no way that will last a few hundred miles never mind 2000.

Anyone have any better knowledge than me? Thanks in advance.

[a.summers86]

What mileage have you covered in the car?

I was getting 60-70k from my old F21 1 series (based on a lot of motorway driving).

[andyg20]

Car has only done 23,000 miles - mostly town driving, so am not overly concerned about wear rate.

Also have a Mini Clubman Cooper D, again mostly town driving- rear pads do about 24k, fronts 25k between changes. But I get the pads on that changed when there is 500 miles left on the on-board computer and there is still plenty of pad surface left.

[HighlandPete]

Originally Posted by andyg20

But if the car is still saying 2000 miles of wear left, and the dealer is saying there is only 1mm of pad left, there is no way that will last a few hundred miles never mind 2000.

I wonder how 'exact' the report is. BMW suggest 3 - 4mm pad thickness for replacement. My understanding, the wear sensor should have 'triggered' way back, if the pad is physically 1mm to metal.

I'd be asking to see the removed pads.

[a.summers86]

According to my most recent health check (last week) I have 12.2mm on the fronts and 9.5mm on the back. Msport brakes if that makes any difference.

That is with my car showing 9k on the clock.

I'll be well over 50-60k mark when they are due by the looks of it.

I remember on my old BMW it used to say pads needed changing then the garage said there was still plenty of life left - so I wont if its an algorithm as oppose to actually sensing pad wear.

[andyg20]

Just to finish off this thread, rear pads now changed.

One of the rear pads on my car on the driver side was indeed 1mm from metal - the technician showed me it on the car, absolutely nothing left on it! So as has been mentioned, the fact my OBC was saying the car needed rear pads in 2000 miles was irrelevant - If I had tried to leave it 2000 miles I would have wrecked the disc in less than 500. The issue seems to be there are two rear pads on each wheel, but only one wear sensor.

So if you start getting a warning about pad replacement on the OBC, my advice is not to wait too long, and get the brakes checked as soon as you can. Hope this helps.

[HighlandPete]

Originally Posted by andyg20

Just to finish off this thread, rear pads now changed.

One of the rear pads on my car on the driver side was indeed 1mm from metal - the technician showed me it on the car, absolutely nothing left on it! So as has been mentioned, the fact my OBC was saying the car needed rear pads in 2000 miles was irrelevant - If I had tried to leave it 2000 miles I would have wrecked the disc in less than 500. The issue seems to be there are two rear pads on each wheel, but only one wear sensor.

So if you start getting a warning about pad replacement on the OBC, my advice is not to wait too long, and get the brakes checked as soon as you can. Hope this helps.

I'm wondering why the sensor didn't trigger? Or there was so much imbalance across the pads, one was wearing prematurely.

BTW, what braking system? Fixed pot 'sport' option? Draggy calliper on one side?

BMW's floating calliper brakes have the sensor on the pad side that tends to wear fastest. So any sensor trigger, should be for worst case pad wear.

Fixed callipers should wear equally each side, unless one side is dragging for some reason.

[Posh]

2020 320I in for service yesterday. Front brake pads 12mm, rear pads 3mm after 18,600 miles. Questioned service advisor who asked did I use Cruise Control? Only infrequently. Then realised that I do use Speed Limiter very often in 30mph areas. Advisor suggested that is the reason why rear pads are worn. I usually get 80-100k miles from pads and expect fronts to wear faster. At £275 for replacement pads this does noit encourage use of speed limiter or cruise control.

[willougs]

I use adaptive cruise all the time, pretty much every day. My car has done approx 48k miles. Recently had a service (Jan) and end of warranty check (end of Feb), and brake pads not highlighted as an issue.
Apparently 330e is easier on brakes, but 18k seems very low.

[sjb993]

Originally Posted by Posh

2020 320I in for service yesterday. Front brake pads 12mm, rear pads 3mm after 18,600 miles. Questioned service advisor who asked did I use Cruise Control? Only infrequently. Then realised that I do use Speed Limiter very often in 30mph areas. Advisor suggested that is the reason why rear pads are worn. I usually get 80-100k miles from pads and expect fronts to wear faster. At £275 for replacement pads this does noit encourage use of speed limiter or cruise control.

I think the active cruise control does use the brakes, whereas I'm pretty sure the speed limiter does not.

[paulockenden]

Speed limiter definitely doesn’t use brakes. Try it going down hill and you’ll get over-speed warnings. If the advisor told you that the speed limiter is wearing your brakes then I’d be very wary of any other advice they gave you at the same time!

[Assassin]

If your pad friction material is down to 1mm its highly likely that the metal backing of the pad would bind on the unworn rim of the disc and cause a loud scraping noise when braking. That would probably alert you to the issue before the friction material was gone leaving a metal on metal contact and wrecking the disc. That said, always better safe than sorry.

Worth noting that the latest MOT rules require a car to have at least 3mm pad material left or its an automatic fail.

I would think cruise control, speed limiter and the various stability / traction control systems all use the brakes to slow the vehicle (or specific wheel) speed at times where conditions mean that the car is excessively increasing, or cannot safely maintain the desired speed in the relevant circumstances..... e.g. steep downhill or very windy roads at speed. Thats modern car technology for you.

[paulockenden]

Originally Posted by Assassin

I would think cruise control, speed limiter and the various stability / traction control systems all use the brakes to slow the vehicle (or specific wheel) speed at times where conditions mean that the car is excessively increasing, or cannot safely maintain the desired speed in the relevant circumstances..... e.g. steep downhill or very windy roads at speed.

Cruise control does, speed limiter doesn’t. See previous posts.