M40i brakes - design flaw uncovered

Flyingfifer · Post by **Flyingfifer** » Mon Jun 03, 2019 5:47 pm

Nictrix wrote: ↑Mon Jun 03, 2019 3:48 pm
Jim S wrote: ↑Mon Jun 03, 2019 2:48 pm
Nictrix wrote: ↑Mon Jun 03, 2019 2:45 pm Off the top of my head the only car I have had that the shield covers the disc is the E89 rear brakes.
The front disc shield on the E89 doesn't cover the disc.
It is just the gap that the shield covers, not the whole disc.
Yeah thats what I mean. Most are either flat or curve slightly away from the disc except the rear of the E89 which slightly covers the outer edge.

Looking at the E86 one it curves towards the disc as well
https://cdn11.bigcommerce.com/s-dals72e ... 00.JPG?c=2
https://cdn4.pelicanparts.com/techartic ... /pic01.jpg

Nictrix · Post by **Nictrix** » Mon Jun 03, 2019 7:10 pm

Flyingfifer wrote: ↑Mon Jun 03, 2019 5:47 pm
Nictrix wrote: ↑Mon Jun 03, 2019 3:48 pm
Jim S wrote: ↑Mon Jun 03, 2019 2:48 pm

It is just the gap that the shield covers, not the whole disc.
Yeah thats what I mean. Most are either flat or curve slightly away from the disc except the rear of the E89 which slightly covers the outer edge.
Looking at the E86 one it curves towards the disc as well
https://cdn11.bigcommerce.com/s-dals72e ... 00.JPG?c=2
https://cdn4.pelicanparts.com/techartic ... /pic01.jpg

Yeah that's pretty much the same as the rears on the E89. Both those pics are rears also.

flybobbie · Post by **flybobbie** » Mon Jun 03, 2019 8:24 pm

Probably designed by someone that did realise what the lip was for on the original design.
I always call it reinventing the kettle spout.

Bit like the caravan i owned, the version i bought they moved the water heater the furthest they could from the shower and sink, so the water froze in the pipes in winter.
Previous versions the heater was next to the shower and sink.
2 years in that van i think i could design caravans better than the company making them for 50 years.

Jim S · Post by **Jim S** » Wed Jun 05, 2019 10:48 am

My dealer sent me the latest response received from BMW UK regarding the problem with stones getting into the M Sport brakes on my M40i. I am taking the car in for the requested inspection tomorrow.

"BMW UK Technical have replied to the further information we sent them this morning. To paraphrase, as the vehicle is a new model, there will be some feedback generated to AG, however they do not expect a solution introduced to prevent stones from being picked up by the wheels. They would like us to confirm the brake components fitted to the car are correct and to check the brake shields, even though they believe they cannot be fitted incorrectly. Is there a possibility the car could be made available for us to check the parts fitted are correct and we can reply to the Technical case? This will give us an opportunity to take some images and measurements that they requested in their initial reply.

it is worth pointing out there have been no other issues of this nature reported to BMW UK, other than your own. We copied and pasted your entire email to the technical case, so they are aware of all your comments."

Flyingfifer · Post by **Flyingfifer** » Wed Jun 05, 2019 11:35 am

Jim S wrote: ↑Wed Jun 05, 2019 10:48 am ...

Id ask about returning the car

Jim S · Post by **Jim S** » Wed Jun 05, 2019 12:17 pm

Flyingfifer wrote: ↑Wed Jun 05, 2019 11:35 am
Jim S wrote: ↑Wed Jun 05, 2019 10:48 am ...
Id ask about returning the car

I do like the car otherwise if they could fix the problem with the brakes I would be happy. In any case it would cost me a lot of money to take it back.

Jim S · Post by **Jim S** » Thu Jun 06, 2019 12:57 pm

This photo of the front M Sport brake assembly clearly shows what the problem is. The wide open top is a magnet for catching stones and the bottom of the shield bends in towards the disc closing the gap and trapping the stone. The bottom of the shield can't be bent outwards because of the track rod end which is right up against the shield.

: image.jpeg (321.29 KiB) Viewed 2176 times

Jim S · Post by **Jim S** » Fri Jun 07, 2019 11:00 am

And here's the rear brake assembly. Better than the front but not great. Needs the top of the shield to bend over to close the gap between the shield and the disc rotor.

: image.jpeg (313.2 KiB) Viewed 2142 times

flybobbie · Post by **flybobbie** » Fri Jun 07, 2019 6:49 pm

I wonder if a edging rubber with a lip could be fitted.
This sort of rubber.
https://www.ebay.co.uk/itm/Leaf-Fin-Sea ... Swj4dbmVlR
https://www.ebay.co.uk/itm/Large-Vertic ... 0005.m1851
https://www.ebay.co.uk/itm/Large-Expose ... 0008.m2219

Ewazix · Post by **Ewazix** » Fri Jun 07, 2019 7:54 pm

Has some top things you need to know as an M driver including about stones in the dust shield

Looks like the FX8 ones curve over as normal.
https://youtu.be/rgVLBT0HWWE?t=57

Jim S · Post by **Jim S** » Fri Jun 07, 2019 9:05 pm

flybobbie wrote: ↑Fri Jun 07, 2019 6:49 pm I wonder if a edging rubber with a lip could be fitted.
This sort of rubber.
https://www.ebay.co.uk/itm/Leaf-Fin-Sea ... Swj4dbmVlR
https://www.ebay.co.uk/itm/Large-Vertic ... 0005.m1851
https://www.ebay.co.uk/itm/Large-Expose ... 0008.m2219

Yes, that may work on the rear brakes if it stays in place. Might be worth a try. Thanks for offering this solution flybobbie.

Jim S · Post by **Jim S** » Fri Jun 07, 2019 9:11 pm

Ewazix wrote: ↑Fri Jun 07, 2019 7:54 pm Has some top things you need to know as an M driver including about stones in the dust shield

Looks like the FX8 ones curve over as normal.
https://youtu.be/rgVLBT0HWWE?t=57

Thanks for sharing Ewazix

NickDE · Post by **NickDE** » Fri Jun 07, 2019 9:28 pm

Most cars can get a stone stuck in the gap occasionally. I've found that reversing for a few yards is usually effective at getting it back out.

Flyingfifer · Post by **Flyingfifer** » Fri Jun 07, 2019 10:08 pm

Jim S wrote: ↑Thu Jun 06, 2019 12:57 pm This photo of the front M Sport brake assembly clearly shows what the problem is. The wide open top is a magnet for catching stones and the bottom of the shield bends in towards the disc closing the gap and trapping the stone. The bottom of the shield can't be bent outwards because of the track rod end which is right up against the shield.
image.jpeg

............... WTF is that design!?!

Jim S · Post by **Jim S** » Fri Jun 07, 2019 10:25 pm

Flyingfifer wrote: ↑Fri Jun 07, 2019 10:08 pm
Jim S wrote: ↑Thu Jun 06, 2019 12:57 pm This photo of the front M Sport brake assembly clearly shows what the problem is. The wide open top is a magnet for catching stones and the bottom of the shield bends in towards the disc closing the gap and trapping the stone. The bottom of the shield can't be bent outwards because of the track rod end which is right up against the shield.
image.jpeg
............... WTF is that design!?!

Shocking, not fit for purpose. BMW should be ashamed of it.

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