G-series M440 brakes eating themselves

[highway]

Following a happy 12 months with a 2017 LCI 440 coupe, I fancied another convertible. Really wanted a 991 cab but the back seats aren’t really dog friendly and I was always going to daily it.
Found a nice low miles 2021 M440 cab. Car specced with all options and although I don’t much like Dravit Grey, I bought it.
Seller was reluctant to allow a test drive as I wasn’t fully comp on his car. Respectable seeming chap of a particular age, nice house, nice part of the world. He drives- seems fine and I’m reassured that the car was under warranty.
Off to the bank, funds transferred and I drive back. As soon as I touch the brake pedal I can feel the car juddering under braking. Almost like the discs were warped. Called BMW assist. Car goes into dealer.
They conclude that, as result of ‘atmospheric conditions’ the faces on the front discs (both sides) had corroded. This, they claim, caused the juddering. Not a manufacturing defect and so not covered under warranty.
Discs true under DTI. No visible corrosion on the front discs. They weren’t lipped. Pads present as new.
Having complained, BMW made a goodwill contribution towards cost of replacement front discs and pads which has cured the problem.
I still feel aggrieved that this can happen on a car with 8k miles just because, apparently, it hadn’t been used much.
I’ve read some owners mention that braking issues with pads leaving deposits on the discs, isn’t uncommon. I would add, hard braking wouldn’t cure the issue. Posted as a cautionary tale.
Thankfully, the car is excellent now this issue has been resolved.

[Pica-Pica]

It’s lack of use (and in my case, salt gritters). I replaced my front discs and pads (as they were low) at 43k. Judder still there, so replaced rear discs, and pads. Judder went.
This is from the (on line) handbook:-

[curvature]

The above makes interesting reading as my 640d has an intermittent judder.

New aftermarket pads all round at 69k miles last year (the first the car had had!) and the judder started several thousand miles later.

I then changed the front discs and pads for genuine items and it went away for a while.

My commute is only 6 miles each way and driving sensibly I can get away with minimal brake usage and I get no juddering.

I also undertake one or two long journeys each week for work that can be anything form 150 - 300 miles and I tend to sit their at 65-70mph keeping myself out of everyones way so again minimal braking. However if I brake from higher speed this is when I now get the judder and as a passenger in the rear my wife said she could feel it so maybe it is the rear discs/pads that need changing now.

[d_a_n1979]

It's stuff like this that makes me recommend giving the car an Italian tune up once every 2 weeks if you can... Keeps things moving/working as they should and gives the car/engine/brakes/suspension a good shakedown too IMO

My F31 sits on the drive all week; gets used at the weekends

So, every so often when I'm out using the car; I'll go the longer way round on purpose & when its safe to do so (motorway stretch, bypasses etc) I'll run the car hard in a higher gear and be a bit harder on the brakes etc

Keeps everything sweet

[Pica-Pica]

d_a_n1979 said:

It's stuff like this that makes me recommend giving the car an Italian tune up once every 2 weeks if you can... Keeps things moving/working as they should and gives the car/engine/brakes/suspension a good shakedown too IMO

My F31 sits on the drive all week; gets used at the weekends

So, every so often when I'm out using the car; I'll go the longer way round on purpose & when its safe to do so (motorway stretch, bypasses etc) I'll run the car hard in a higher gear and be a bit harder on the brakes etc

Keeps everything sweet

But once the judder has set in, heavy braking won’t restore things, it’s too late.
I used to be a light braker. This has changed my mind since I had to replace every disc and pad to get rid of the judder. Now I make sure I do regular braking - nothing remotely severe at all, just a regular ‘sweep’ of the discs each journey.