[Fugly M3]

Originally Posted by Boss330

I'm pretty sure the seratiom is axial not radial. In case of a head on collision the driveshaft can collapse instead of becoming a spear...

Originally Posted by kyleb350

That thought crossed my mind, but I'm sure it's strictly designed to give under impact force vs. rotational force.

I considered that, but a serration is a serration and I can still see it happening...perhaps not to all cars...but tuned RWD I could theoretically see it.

[Sedan_Clan]

Originally Posted by Boss330

Rule # 1 when the public perception of a technical downgrade is negative is to explain what caused this. Especially when it's a change that has been forced on you by external circumstances.

What is said in this video is basically; "We at BMW M would have loved to give you the CFRP driveshaft, but unfortunately regulation changes has made that practically Impossible. We evaluated every possible solution to achieve this, but in the end it came out with no advantages over the steel shaft".

Exactly this!

[adc]

The single use adhesive capsule is very interesting... I wonder if this method could be used for other fittings in the car...

The CF driveshaft discussion awakened my curiosity. I have an end of production F80, built in June or July 2018 at a time when BMW was allegedly fitting steel driveshafts in all the M3 and M4s. I have an alignment coming this Monday, I should able to confirm the material.

The CF unit definitely has the “cool” factor. Although I seriously doubt anyone could tell the difference in a side by side driving test.

[Fugly M3]

Originally Posted by adc

The single use adhesive capsule is very interesting... I wonder if this method could be used for other fittings in the car...

The CF driveshaft discussion awakened my curiosity. I have an end of production F80, built in June or July 2018 at a time when BMW was allegedly fitting steel driveshafts in all the M3 and M4s. I have an alignment coming this Monday, I should able to confirm the material.

The CF unit definitely has the “cool” factor. Although I seriously doubt anyone could tell the difference in a side by side driving test.

Pretty sure the CFRP driveshaft utilization ended in November of 2017. Can't recall, but that seems to ring a bell. Edit...appears 03/2018 was the switch per the realoem.com site.

[Boss330]

Originally Posted by F8SEVEN

I considered that, but a serration is a serration and I can still see it happening...perhaps not to all cars...but tuned RWD I could theoretically see it.

Yes, of course there is a possibility. But since there are also serrated shafts in the transmission and diff, the serrated driveshaft need not be the weakest link... (but it would be preferrable from a cost of repair viewpoint that the driveshaft snaps rather then the gearbox or diff).

[NISFAN]

Originally Posted by Boss330

Rule # 1 when the public perception of a technical downgrade is negative is to explain what caused this. Especially when it's a change that has been forced on you by external circumstances.

What is said in this video is basically; "We at BMW M would have loved to give you the CFRP driveshaft, but unfortunately regulation changes has made that practically Impossible. We evaluated every possible solution to achieve this, but in the end it came out with no advantages over the steel shaft".

Except it's not forced by external circumstances. If it was really important to M they would have found a compromise to package the filters and retain the CF DS.
But even with the filters it's only the front section that is restricted, they could have made a full 90mm OD rear CFRP section. They didn't.

But in any case, there isn't a single thread in G80 forum crying about CFRP drive shaft omission. Everyone moved on after F82 lost CFRP. So this marketing video only serves to drag up an old topic. In a negative way. We also find out that it's even worse. The DS is now only 50mm diameter, and is so thick wall sectioned to keep the stiffness that it needs a collision sleeve in it to prevent it spearing the cabin. What a marketing triumph that was to come clean on.

[Poochie]

Originally Posted by NISFAN

Except it's not forced by external circumstances. If it was really important to M they would have found a compromise to package the filters and retain the CF DS.
But even with the filters it's only the front section that is restricted, they could have made a full 90mm OD rear CFRP section. They didn't.

But in any case, there isn't a single thread in G80 forum crying about CFRP drive shaft omission. Everyone moved on after F82 lost CFRP. So this marketing video only serves to drag up an old topic. In a negative way. We also find out that it's even worse. The DS is now only 50mm diameter, and is so thick wall sectioned to keep the stiffness that it needs a collision sleeve in it to prevent it spearing the cabin. What a marketing triumph that was to come clean on.

I agree, it's total bullcrap reasoning on why it couldn't be done..

If they wanted to, they could of fitted a carbon fiber driveshaft, with an OPF filter and find some work-around but you know, that's just more added cost that they can't up-charge you for in some optional $4,000 "performance" package, so why bother when they can just increase the boost pressure to compensate for the potential lost of unsprung weight reduction.

[zamboni]

Originally Posted by adc

The single use adhesive capsule is very interesting... I wonder if this method could be used for other fittings in the car...

The CF driveshaft discussion awakened my curiosity. I have an end of production F80, built in June or July 2018 at a time when BMW was allegedly fitting steel driveshafts in all the M3 and M4s. I have an alignment coming this Monday, I should able to confirm the material.

The CF unit definitely has the “cool” factor. Although I seriously doubt anyone could tell the difference in a side by side driving test.

I had a Jun 18 production would be interested to find out whether mine had the CF or steel version. Keep us posted.

[CanAutM3]

Originally Posted by F8SEVEN

Forget the CFRP part...the "crash" serration bit is interesting...I have a suspicion that the level of force required to trigger that chain reaction might just also happen when the car is tuned and there's a ton of torque heading down the driveshaft...crank hub 2.0?

Not the same type of applied force. Torsional vs axial...

[CanAutM3]

Originally Posted by adc

The single use adhesive capsule is very interesting... I wonder if this method could be used for other fittings in the car...

The CF driveshaft discussion awakened my curiosity. I have an end of production F80, built in June or July 2018 at a time when BMW was allegedly fitting steel driveshafts in all the M3 and M4s. I have an alignment coming this Monday, I should able to confirm the material.

The CF unit definitely has the “cool” factor. Although I seriously doubt anyone could tell the difference in a side by side driving test.

The CF driveshaft is not only about lighter weight, but also about drivetrain rigidity.

[CanAutM3]

Originally Posted by NISFAN

Except it's not forced by external circumstances. If it was really important to M they would have found a compromise to package the filters and retain the CF DS.
But even with the filters it's only the front section that is restricted, they could have made a full 90mm OD rear CFRP section. They didn't.

But in any case, there isn't a single thread in G80 forum crying about CFRP drive shaft omission. Everyone moved on after F82 lost CFRP. So this marketing video only serves to drag up an old topic. In a negative way. We also find out that it's even worse. The DS is now only 50mm diameter, and is so thick wall sectioned to keep the stiffness that it needs a collision sleeve in it to prevent it spearing the cabin. What a marketing triumph that was to come clean on.

Indeed, a smaller diameter means significantly thicker walls to maintain load bearing capability. It will be interesting to see the weight of the G8X driveshaft vs the F8X steel one.

[CanAutM3]

Originally Posted by Poochie

I agree, it's total bullcrap reasoning on why it couldn't be done..

If they wanted to, they could of fitted a carbon fiber driveshaft, with an OPF filter and find some work-around but you know, that's just more added cost that they can't up-charge you for in some optional $4,000 "performance" package, so why bother when they can just increase the boost pressure to compensate for the potential lost of unsprung weight reduction.

They have to work within a given chassis’ constraints. If there isn’t enough room in the exhaust/transmission tunnel, their options are limited.

[Sedan_Clan]

Originally Posted by CanAutM3

Indeed, a smaller diameter means significantly thicker walls to maintain load bearing capability. It will be interesting to see the weight of the G8X driveshaft vs the F8X steel one.

Originally Posted by CanAutM3

Not the same type of applied force. Torsional vs axial...

Originally Posted by CanAutM3

Torque is tangential, not radial

Originally Posted by CanAutM3

The CF driveshaft is not only about lighter weight, but also about drivetrain rigidity.

Originally Posted by CanAutM3

They have to work within a given chassis' constraints. If there isn't enough room in the exhaust/transmission tunnel, their options are limited.

+5

[Poochie]

Originally Posted by CanAutM3

They have to work within a given chassis' constraints. If there isn't enough room in the exhaust/transmission tunnel, their options are limited.

Humor me please and watch this video below on the strength of compressed carbon fiber, then come back and tell me with a strait face that the BMW dude is not full of shit and it can't be engineered to fit, especially when they where designing a car from scratch, fully aware of the OPF regulations...

[CanAutM3]

Originally Posted by Poochie

Humor me please and watch this video below on the strength of compressed carbon fiber, then come back and tell me with a strait face that the BMW dude is not full of shit and it can't be built to fit, especially when they where designing a car from scratch.

Composites are very strong per unit weight, but require much more volume for a given load bearing capability. There are very few materials that favourably compare to steel regarding load bearing density.

[Poochie]

Originally Posted by CanAutM3

Composites are very strong per unit weight, but require much more volume for a given load bearing capability. There are very few materials that favourably compare to steel regarding load bearing density.

Ok bro, we going to have to agree to disagree on this one..

I'm sure it has absolutely nothing to do with the cost..


.

[MasterP]

Well good news to anyone in here wanting a CFRP driveshaft I have one for sale. Lol

[Ibiza]

Originally Posted by Poochie

Humor me please and watch this video below on the strength of compressed carbon fiber, then come back and tell me with a strait face that the BMW dude is not full of shit and it can't be built to fit, especially when they where designing a car from scratch.

As F8SEVEN pointed out, this is prelude to SCH 2.0. I assume it's cheaper to replace a steel drive shaft compared to retiming the crack hub.

[Poochie]

Originally Posted by Ibiza

As F8SEVEN pointed out, this is prelude to SCH 2.0. I assume it's cheaper to replace a steel drive shaft compared to retiming the crack hub.

Yikes, say it ain't so, I plan to own one of these things some day and beating the crap out of it..

I'm going to reserve judgment until an official technical training manual or equivalent is leaked, with more intricate details; so I can make a more logical conclusion on its efficacy or - lack thereof.

However, I must say, I don't like the sound of breakaway driveshafts and never heard of a driveshaft becoming projectiles in an accident or it being failure-prone, so if it ain't broken.. But I still have faith in BMW, so we'll see how it goes..

[Sedan_Clan]

Originally Posted by Ibiza

As F8SEVEN pointed out, this is prelude to SCH 2.0. I assume it's cheaper to replace a steel drive shaft compared to retiming the crack hub.

Didn't they already change the design altogether to deal with that? It was in the transmission video and I think they explicitly mentioned fixing that issue.

[ashtaron14]

Certainly that regulations and cost might just be some of the issues, but the adhesive & balancing issues with a CF driveshaft should also be considered.

For the E9x M3 aftermarket, CF driveshaft from DSS/Fall-Line/MFactory all had some sort of issues whether it's from bonding or from balancing or from heat issues such that additional heat resistant material is to be installed around the CF driveshaft.

[JustChris]

Originally Posted by kyleb350

So THAT was the cause of the driveshaft recall on my F82? ...in the U.S.?

Couldn't the filter just be relocated/reshaped instead of having to reengineer the whole drive shaft?

I know right. 2020s cars .... what's more important driveshaft or a filter.

Yep we will re engineer the car based around the filter :