See Why the M3 M4 Carbon Fiber driveshaft is so cool (video on CFRP drive shafts)

[NYAWE60]

Originally Posted by elitex

cool, My RX8 had a CF drive shaft also.

The 350Z had a carbon fiber driveshaft in 2002. . . why is this so amazing. I have no doubt the M3/M4 will be world class performance vehicles and once again raise the bar, but this is no way is ground breaking or as special as a bespoke engine like the S52/S65

[IMLH]

thanks for posting - couldn't believe it till I saw it

[Jockey]

Originally Posted by Mr.Metak2you

Impressive. I don't think you could get as high as 4500nm with the CF if the drive shaft was operating at higher temperatures, pretty sure it would be less but still greater than the steel. Where the steel performance would remain relatively unchanged at higher temps.

Huh? Steel begins to become quite soft around 1000 degrees F. Steel is not exactly known for it's ability to withstand high temps.

[OverDriven]

There is a trade off here. Carbon fiber is strong, but it's also hard. Steel is somewhat weaker, but it's also softer. Harder materials are more likely to shatter when they are subjected to shock (basically they're brittle).

CF looks pretty good when you slowly apply force like you see in this video. Try rapidly applying force (like you might get if you dump the clutch) and the numbers will look much different. I'm not saying CF driveshafts are bad, but this video is far removed from what you would see in the real world. The sample here withstands around 4500 newton meters, which converts to around 3300 ft/lbs of torque. We all know that no car puts down that kind of power, yet plenty people have shattered CF driveshafts with normal cars. Like I said...real world vs test bench. Also FWIW, small dents in a CF driveshaft can critically weaken it.

Aluminum driveshafts are actually preferable to CF.

[GregW / Oregon]

Originally Posted by OverDriven

Aluminum driveshafts are actually preferable to CF.

I know aluminum driveshafts are used for many custom muscle car applications, but I think it's because they are relatively easy to fabricate compared to carbon fiber and still have much of the low mass advantage. If they were indeed preferable for this application why wouldn't BMW go that direction? Can you name a production car with an aluminum shaft?

[NISFAN]

CF shaft........brilliant on a transaxle gearbox car like a GTR......M'eh on an M3.

Better than a steel option, until it snaps $$$$ Someone mentioned temperature, age is more of a problem, however I am sure a RWD won't manage enough tyre grip to snap one. A modified M3 with drag radials might.....

[PhoenixRising]

What I'm curious about is how do they adhere the CFRP to the steel end pieces? I thought that would have been the failure point due to two different materials being mated together. Cool stuff!

[JustChris]

Originally Posted by PhoenixRising

What I'm curious about is how do they adhere the CFRP to the steel end pieces? I thought that would have been the failure point due to two different materials being mated together. Cool stuff!

I was thinking that, some impressive bonding used, it was not the failure point so is rated >4500Nm that broke the shaft, my word!

[pwr hungry]

Originally Posted by gee-m-w

I'd love to see a static load test on all of the "lightweight" wheels people buy.

It's not a static load test you should be concerned with, but an impact test...unless you want a static load test from a lateral angle.

[mPlasticDesign]

Originally Posted by Jockey

Huh? Steel begins to become quite soft around 1000 degrees F. Steel is not exactly known for it's ability to withstand high temps.

1000deg? I was referring to temps closer to actual operating temperatures. Above 180-200deg F, carbon fiber strength is compromised as apposed to steel that does remain relatively the same. Like I said, it's probably still way strong than steel just not as strong as was demonstrated in that test.

[Jockey]

Originally Posted by Mr.Metak2you

1000deg? I was referring to temps closer to actual operating temperatures. Above 180-200deg F, carbon fiber strength is compromised as apposed to steel that does remain relatively the same. Like I said, it's probably still way strong than steel just not as strong as was demonstrated in that test.

That's true if BMW used the same resin that is used in CF bicycles. I'm assuming the resin used in the driveshaft is of a higher quality. Aerospace quality resin performs over 400+ F with no issues.

[Kayani_1]

+1........ while it is nice this should have been something that should have been offered a while back starting with lci M3, 1M, the newer fat pigs called M5 and M6.

Oh well better late then never....

Originally Posted by swamp2

Excellent video. You can have significantly lighter and significantly stronger in a single part. That is the "magic" of composites. The slightly disappointing story is that Nissan have put these on relatively pedestrian passenger vehicles for close to a decade. BMW is not leading the way here with a bleeding edge technology. I know you did not claim they were, but I think it is still relevant.

[GreeKon]

WOW

[BPMSport]

Awesome video!

[Desert_Fox]

I surprised no one mentioned the fact that the host is Richard Hammond from Top Gear!

[b-thumper]

Originally Posted by Desert_Fox

I surprised no one mentioned the fact that the host is Richard Hammond from Top Gear!

No one mentioned that it is also a video!












Do we need to point out the obvious?

[IMG]

That was an awesome stress test,never seen anything like that before !

[Desert_Fox]

Originally Posted by b-thumper

No one mentioned that it is also a video!












Do we need to point out the obvious?

+1 Useful contribution! Just noticing something interesting that other car enthusiasts might notice too. Not sure what you're spending time for on an automotive enthusiast group otherwise...

[nonagon]

Originally Posted by Desert_Fox

+1 Useful contribution! Just noticing something interesting that other car enthusiasts might notice too. Not sure what you're spending time for on an automotive enthusiast group otherwise...

Richard Hammond is, like, really famous. No need to point him out. If you were to bring him up, something more useful would be to make fun of his shirt and hair, which looked a bit odd in that segment.

[Theonem3]

German engineering. Nothing like it.
I think there is a lot a value in the Price of our BMW's.
Way to go you german technology driven Freaks.

[ASAP]

Originally Posted by OverDriven

There is a trade off here. Carbon fiber is strong, but it's also hard. Steel is somewhat weaker, but it's also softer. Harder materials are more likely to shatter when they are subjected to shock (basically they're brittle).

CF looks pretty good when you slowly apply force like you see in this video. Try rapidly applying force (like you might get if you dump the clutch) and the numbers will look much different. I'm not saying CF driveshafts are bad, but this video is far removed from what you would see in the real world. The sample here withstands around 4500 newton meters, which converts to around 3300 ft/lbs of torque. We all know that no car puts down that kind of power, yet plenty people have shattered CF driveshafts with normal cars. Like I said...real world vs test bench. Also FWIW, small dents in a CF driveshaft can critically weaken it.

Aluminum driveshafts are actually preferable to CF.

Excellent comment...

[RingMeister01]

Originally Posted by Theonem3

German engineering. Nothing like it.
I think there is a lot a value in the Price of our BMW's.
Way to go you german technology driven Freaks.

+1