[subliminalaudio]

Please explain if the M3 M4 issues translates to our beloved m2 ?
Isn't the same part?

[Anthony1s]

I'm not aware of the m3/m4 issue. Please elaborate. And if I recall correctly, M2 doesn't use a carbon shaft like the m3/m4 does.

[///M TOWN]

Originally Posted by Anthony1s

I'm not aware of the m3/m4 issue. Please elaborate. And if I recall correctly, M2 doesn't use a carbon shaft like the m3/m4 does.

Correct I does not.

I'm not aware of an issue with the M4'S drive shaft but do know it's no longer made in CFRP.

[subliminalaudio]

Originally Posted by Anthony1s

I'm not aware of the m3/m4 issue. Please elaborate. And if I recall correctly, M2 doesn't use a carbon shaft like the m3/m4 does.

https://jalopnik.com/2016-and-2017-b...-dr-1830134197

[///M TOWN]

Originally Posted by subliminalaudio

https://jalopnik.com/2016-and-2017-b...-dr-1830134197

Oh snap.

I guess that's why they stopped making the CF version.

[dtmurf]

It does not seem to be a CF issue but how the shaft is matted (bonded?) to the flange. I wonder if the replacement drive shaft will be CF. Assuming not, what would the weight difference be between a CF and steel (?) drive shaft? Would there be an impact on performance?

[delhang]

Woah this really sucks for those owners, hope no one injuries have come from this recall. Also hoping this doesn't carry over to the F87 platform.

[Msmall143]

its the non cf shaft thats being recalled. cf was in 2015. 16 & 17 m4's didnt have cf shaft

[Cavpilot2k]

Coincidentally, just the other day I was watching a video of a high-powered twin-turbo mustang with a CF driveshaft. On the second launch the CF driveshaft literally disintegrates.
It doesn't just break - it comes apart into a pile of dust and fiber stretched out behind the vehicle for 15 feet.

I guess CF driveshafts are not really suited for high-torque applications.

[Poochie]

Carbon fiber is an extremely strong and light combo, its what they trust to use for aircraft components..

I am pretty sure this batch of defective driveshafts are just related to the adjoining flanges and not the quality of the carbon fiber material..

[Cavpilot2k]

Originally Posted by Poochie

Carbon fiber is an extremely strong and light combo, its what they trust to use for aircraft components..

True, but aircraft applications are not high-torque applications.
In almost all aviation applications, torque is a limiting factor on structural and drive components (i.e. you must restrict torque below x-value - exceedance may cause failure).

This makes sense to me. CF, being a non-homogenous mass, would not be ideal for applications applying extreme stresses on multiple axes simultaneously.

[Msmall143]

Originally Posted by Poochie

Carbon fiber is an extremely strong and light combo, its what they trust to use for aircraft components..

I am pretty sure this batch of defective driveshafts are just related to the adjoining flanges and not the quality of the carbon fiber material..

this recall is non cf drive shafts.

[Cavpilot2k]

I had a CF driveshaft on my old Mazda RX-8, but even modified, that was a high-revving HP car, not a torque-producer.

[Msmall143]

Originally Posted by Cavpilot2k

True, but aircraft applications are not high-torque applications.
In almost all aviation applications, torque is a limiting factor on structural and drive components (i.e. you must restrict torque below x-value - exceedance may cause failure).

This makes sense to me. CF, being a non-homogenous mass, would not be ideal for applications applying extreme stresses on multiple axes simultaneously.

this is regular drive shafts, not cf. only 15 m4 is cf which isnt included in the recall.

[Cavpilot2k]

Originally Posted by Msmall143

this is regular drive shafts, not cf. only 15 m4 is cf which isnt included in the recall.

True, but the reason they are discontinuing the CF ones is that in order to handle the power demands placed upon them in the future, a CF DS would have to increase in diameter to maintain enough structural strength.
That increase in size won't fit.

So, they have to go back to a material that can handle the stresses and still fit in the space available (IIRC, the reason for the space limitation has something to do with the new particulate filters).

[Msmall143]

Originally Posted by Cavpilot2k

True, but the reason they are discontinuing the CF ones is that in order to handle the power demands placed upon them in the future, a CF DS would have to increase in diameter to maintain enough structural strength.
That increase in size won't fit.

So, they have to go back to a material that can handle the stresses and still fit in the space available (IIRC, the reason for the space limitation has something to do with the new particulate filters).

Where did you get that from? I think its more probable they moved away from CF to cut cost vs an actual integrity concern. BMW claimed its do to emmisions. Race cars have preferred carbon fiber drive shafts over steel for years.

[Cavpilot2k]

Originally Posted by Msmall143

Where did you get that from? I think its more probable they moved away from CF to cut cost vs an actual integrity concern. BMW claimed its do to emmisions. Race cars have preferred carbon fiber drive shafts over steel for years.

https://carbuzz.com/news/bmw-to-phas...-the-m3-and-m4

It's possible I'm wrong, but this isn't the only place I heard that.
And yes, it's due to emissions because the new emissions hardware (particulate filters) give less room for a driveshaft, so a thinner DS is needed than can be built from CF (CF may have better strength-to-weight ratio than steel, but given equal dimensions, steel is stronger).

I'm not saying CF isn't a good option if you can make it big enough, but in this case, it seems space constraints won't allow them to use a CF DS because it would have to be too large for the space in which they have to work.

[akkando]

Originally Posted by Msmall143

its the non cf shaft thats being recalled. cf was in 2015. 16 & 17 m4's didnt have cf shaft

I'm 99 percent sure the 16 and 17 f80 f82 had cf drive shaft and the steel was used only very very recently.

New owners claimed to get cf drive shaft up until sometime this year! let alone 16-17.

[GoneIn4Secs]

I think they stopped the cr driveshaft for '18s

[doug_999]

CF shaft in the M3/M4 till late 18 in the NA. (Nobody has actually proved we got steel, but my 18 has CF)

EU particulate filter (needed and used only in EU for new emissions laws and not here in NA) is big and only place to put us next to driveshaft. So driveshaft moves to steel.

M3 and M4 have different wheel bases and enigine than OG M2 and OG M2 doesn't use CF driveshaft. So not same part - even the steel one. (Didn't look up in real oem, Someone else can)

https://f80.bimmerpost.com/forums/sh....php?t=1411862

[GoneIn4Secs]

Originally Posted by doug_999

CF shaft in the M3/M4 till late 18 in the NA. (Nobody has actually proved we got steel, but my 18 has CF)

EU particulate filter (needed and used only in EU for new emissions laws and not here in NA) is big and only place to put us next to driveshaft. So driveshaft moves to steel.

M3 and M4 have different wheel bases and enigine than OG M2 and OG M2 doesn't use CF driveshaft. So not same part - even the steel one. (Didn't look up in real oem, Someone else can)

https://f80.bimmerpost.com/forums/sh....php?t=1411862

The wheelbase is same for m2 and m2c

[doug_999]

Originally Posted by GoneIn4Secs

The wheelbase is same for m2 and m2c

Correct, but that is a different forum and I bet the driveshaft part is different there too