So why do they replace the CFRP driveshaft with steel ones?From November 2017 onwards, the CFRP driveshaft in the BMW M3 Sedan, BMW M4 Coupe and BMW M4 Convertible will be gradually replaced by an M specific driveshaft made of steel. BMW says this measure will create the necessary technical basis for meeting future statutory emissions requirements. At a later point in time, a petrol particulate filter (PPF) will be incorporated into the existing installation space in these models in major markets.
“The newly developed steel driveshaft has been designed to ensure the superlative performance and handling qualities of the BMW M3/M4 high-performance sports cars remain unaffected,” BMW says in a press release.
For production-related reasons, this pre-enabling needs to be carried out universally for the BMW M3 Sedan, BMW M4 Coupe and BMW M4 Convertible. This measure does not apply to the BMW M4 CS and BMW M4 GTS special-edition models.
"This measure will create the necessary technical basis for meeting future statutory emissions requirements. At a later point in time, a petrol particulate filter (PPF) will be incorporated into the existing installation space in these models in major markets."So why do they replace the CFRP driveshaft with steel ones?
But then why will they leave the CFRP driveshaft for the CS? Maybe it will be out of production when the time for the PPF comes"This measure will create the necessary technical basis for meeting future statutory emissions requirements. At a later point in time, a petrol particulate filter (PPF) will be incorporated into the existing installation space in these models in major markets."
Oh please."This measure will create the necessary technical basis for meeting future statutory emissions requirements. At a later point in time, a petrol particulate filter (PPF) will be incorporated into the existing installation space in these models in major markets."
Maybe the steel one is with smaller diameter, so more space is ensured (just supposing)Oh please.
What does the driveshaft have to do with the emissions?
If anything, the lighter CFRP one helps reduce emissions!
I meant that the CS will be out of production, not the M4The M3 exits next year and the M4 in early 2020. So the M4 is still required to offset emissions regulation.
Yep, lower drivershaft mass, less parasitic losses, less emission. I have no idea what they are talking aboutOh please.
What does the driveshaft have to do with the emissions?
If anything, the lighter CFRP one helps reduce emissions!
What does the driveshaft have to do with the emissions?
I can understand the need for more space.Packaging, or so it seems.
The CFRP shaft is one long straight piece with a uniform diameter. The shaft in a 440i (for example) is a two piece, smaller overall girth in places, and has a UJ in the middle which surely allows for better packaging options. Add to that, that the CFRP driveshaft apparently has additional metal cladding to protect it's weave from road debris, which must take up some additional space.
If they need to fit a PPF in the existing transmission tunnel, I'm sure moving back to a two piece steel shaft gives them more room to play with.
It does appear to be an odd move to make the change without actually having the PPF installed though - it seems they've decided the ability to offer a relatively quick and easy PPF retrofit is perhaps quite important.
That is a big hit, hope the passengers survived.Be careful out on the streets. It's unfortunate that these often end up in the hands of uncapable drivers.
In the NYC area, lots of wealthy kids get M3s/M4s as their first car... and they tend to drive like they're possessed, which means a high amount of M3/M4 accidents.
![]()
![]()
We use essential cookies to make this site work, and optional cookies to enhance your experience.