M40i brakes - design flaw uncovered

ori said:
Jim S said:
McHaggis69 said:
For info

I had my car in at BMW for its MoT within the last two weeks and raised the matter with them.

"Its not something we've heard of and there are no recalls..."

I should have pointed them to this thread.
I've owned dozens of cars and this Z4 is the only one I've ever experienced stones getting trapped and its happened twice!
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They know very well about the problem. It happened to me 5 times in the first 1,270 miles of ownership in 2019. I even wrote directly to Mr Grieve, UK MD, and reported each occasion to my dealer who passed on photographs of the problem to their Technical Department in Germany HO. :headbang:

Poor show from BMW. :thumbsdown:
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How did you write to me grieve? Can you pm me the email address? I wish to do something similar.
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I sent an email to:
[email protected]
 
Thanks Jim, I have just emailed that address along with what I think is the new guys email address. ;)
 
ori said:
Thanks Jim, I have just emailed that address along with what I think is the new guys email address. ;)
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Good luck. Hopefully you will receive a positive response. Let us know how you get on. :driving:
 
hairyfrogowl said:
Has any kind of fix been found for this? Considering a Z and I have a shingle drive way!!
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I have shingle drive also, but not had this problem with the 2 G29's that I've owned.

Mind you, both of mine were/are 2.0 versions so maybe that has some bearing.
 
Had this issue twice and everybody in the street just stops and stares - you can tell theyre thinking 'that BMW is brand new and its broke already' lol. Soooooooo embarrassing - only fix I found is getting on the motorway sharpish and floor it until you hear it ping out
 
Just wondering if BMW has finally upgraded the heat shields on the M Sport front brakes? Are any new G29 M40i owners willing to post a recent photo of their brakes and compare it to the one that I posted on Page 3 of this thread. See link below.

https://z4-forum.com/forum/viewtopic.php?p=1657203#p1657203
 
Well, after 7k (joyous) miles in the M40i, today the dreaded stone in brakes demon struck!

Due to some roadworks I took a detour down some admittedly crappy roads and after a while noticed a weird noise. At first I wasn't sure whether it was just some debris stuck under the wheel arch - it wasn't that loud but after a few miles the dreaded squeal set in.

I learned a few things from this
- when you really need to do some stamping on the brakes in a quiet place every man and his dog turn up to prevent you doing so!
- my ABS work well

So yeah, some heavy braking got rid of it thankfully but not a pleasant experience. It will certainly make me think twice about "off-roading" again any time soon, at least whilst the roads are so muddy/crappy.

Car is due a service soon so will mention it to BMW to see if they have any thoughts about solutions/whether the rumours of a fix are true.

May your miles be stone free :)
 
I got caught out a couple of weeks ago with it, took the other half up to the stables and it sounded like the heat shield being torn off coming out the car park! All the rubbish on the roads, loose stones etc. after a heavy storm.
 
To save me going back over 19 pages, is this issue just on the M40s or all G29s with the sport brakes?
 
Nanu said:
To save me going back over 19 pages, is this issue just on the M40s or all G29s with the sport brakes?
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I imagine to a lesser or greater extent it affects most modern BMWs ..they’ve changed the design logic on the dust shield….almost all now act as an air scoop rather than just as a dust shield..
 
I had it on my 30i. Picked up a stone in company car park. Tried for days to dislodge it to no avail, evenyually it was wheel off.
 
Nanu said:
To save me going back over 19 pages, is this issue just on the M40s or all G29s with the sport brakes?
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My niece had the same problem on her 5 series
 
Scubaregs said:
I had it on my 30i. Picked up a stone in company car park. Tried for days to dislodge it to no avail, evenyually it was wheel off.
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Cheers. So far so good then
 
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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