M40i brakes - design flaw uncovered

bleatoid said:
Yep - we had this happen today and I reckon Jim's theory is correct re the centrifugal force - hissing / squealing started just after slowing down at a roundabout and the racket was horrendous though strangely intermittent after that. Fortunately we were 3 miles from home - called BMW roadside assist and the guy knew immediately what the issue was.

I've got the M performance brakes on my 4 series and never had an issue in 3 1/2 years - the M40i we've only had for 3 months.....at least we know what it is and how to fix it next time - or would, if we had a jack...
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Yes, the noise is horrendous. Thought BMW might have come up with a fix by now. 6 years since it first happened to me. :thumbsdown:
I bought a cheap scissor jack and extended wheel nut wrench and socket in the boot of my car so that I could remove the wheel and stone if I needed to. Used it one time, the other times I either managed to “drive” it out or called in BMW. :headbang:
 
Jim S said:
bleatoid said:
Yep - we had this happen today and I reckon Jim's theory is correct re the centrifugal force - hissing / squealing started just after slowing down at a roundabout and the racket was horrendous though strangely intermittent after that. Fortunately we were 3 miles from home - called BMW roadside assist and the guy knew immediately what the issue was.

I've got the M performance brakes on my 4 series and never had an issue in 3 1/2 years - the M40i we've only had for 3 months.....at least we know what it is and how to fix it next time - or would, if we had a jack...
Click to expand...

Yes, the noise is horrendous. Thought BMW might have come up with a fix by now. 6 years since it first happened to me. :thumbsdown:
I bought a cheap scissor jack and extended wheel nut wrench and socket and kept it in the boot of my car so that I could remove the wheel and stone if I needed to. Used it one time, the other times I either managed to “drive” it out or called in BMW. :headbang:
Click to expand...
 
Jim S said:
bleatoid said:
Yep - we had this happen today and I reckon Jim's theory is correct re the centrifugal force - hissing / squealing started just after slowing down at a roundabout and the racket was horrendous though strangely intermittent after that. Fortunately we were 3 miles from home - called BMW roadside assist and the guy knew immediately what the issue was.

I've got the M performance brakes on my 4 series and never had an issue in 3 1/2 years - the M40i we've only had for 3 months.....at least we know what it is and how to fix it next time - or would, if we had a jack...
Click to expand...

Yes, the noise is horrendous. Thought BMW might have come up with a fix by now. 6 years since it first happened to me. :thumbsdown:
I bought a cheap scissor jack and extended wheel nut wrench and socket and kept it in the boot of my car so that I could remove the wheel and stone if I needed to. Used it one time, the other times I either managed to “drive” it out or called in BMW. :headbang:
Click to expand...
 
So it happened to me today, did not have any issues for the first three years and now twice in the space of six months. Solved by reversing and braking hard and repeat.

It really is the worst sound in the world :cry:
 
I was one of the first owners of the Z4 M40i in the UK when I took delivery of the car in April 2019.

The very first time I took the car out it happened to me.
During the first 700 miles it had occurred 4 times and then once more at 1,200 miles.

Happened again at around 4,000 miles but that was the last time during my 5 years and 7,500 miles ownership.

It appears to me that as the Michelin Super Sport tyres wear a bit and they get less “sticky” and start to attract less stones.

Hope this gives current owners some insight into what to expect regarding this problem. It might be different for others, but this was my experience during the 5 years that I had the car.
 
sars said:
So it happened to me today, did not have any issues for the first three years and now twice in the space of six months. Solved by reversing and braking hard and repeat.

It really is the worst sound in the world :cry:
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I would get rid of that car as soon as possible now it’s happened, and replace it with a newer one :rofl: :rofl:
 
Nanu said:
I would get rid of that car as soon as possible now it’s happened, and replace it with a newer one :rofl: :rofl:
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Good idea :thumbsup:
The only downside is going back to MPSS and not the outstanding GYEF1A6, which are almost brand new as I've had winters fitted until April. Also why did you bother changing your tyres :headbang:
 
sars said:
Nanu said:
I would get rid of that car as soon as possible now it’s happened, and replace it with a newer one :rofl: :rofl:
Click to expand...

Good idea :thumbsup:
The only downside is going back to MPSS and not the outstanding GYEF1A6, which are almost brand new as I've had winters fitted until April. Also why did you bother changing your tyres :headbang:
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When I changed them the one I have now wasn't for sale and I didn't have STMBO permission :lol:
The dealer did take the new tyres into consideration and put a new set of boots on this one when I pointed this out.
 
Exactly the same has happened to my M40i. Done just under 4,000 miles and happened twice.
It's dangerous, as I've had to pull over quickly on busy roads. I hope BMW recognise the issue and design a fix.
Thanks,
 
Harrib said:
Exactly the same has happened to my M40i. Done just under 4,000 miles and happened twice.
It's dangerous, as I've had to pull over quickly on busy roads. I hope BMW recognise the issue and design a fix.
Thanks,
Click to expand...

I’m surprised that this still an issue with the Z4 M Sport brakes as it was April 2019 when I first reported this issue to BMW and opened up this thread shortly afterwards. BMW have had plenty of time to offer up a solution, particularly on the newer cars. :thumbsdown:

I sold my Z4 M40i a few months ago and replaced it with the new X2 M35i, which I understand has the same M Sport Brakes. I have not had any issues with the brakes on the X2 so far, but have only done just over 1,000 miles. I will be keeping my fingers crossed.
:driving:
 
Just had another stone incident in 2024 z4 m40i. Called dealer, they said it wasn't a known issue, but acknowledged they didn't see many z4s. They advised to call BMW assist and if they couldn't sort it, they'd put it on a truck and rake it to the dealer, (ArnoldClark Irvine.)
Even before I'd done this, they were telling me they'd need to charge to remove the wheel. 30 mins mechanics time..
BMW dealerships are really awful.
 
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