Driveshaft and diff

[MoreBoost]

Hi guys,
so I've been running GC turbos for over 2 years. While street driving I normally limit boost to 24 psi. On the drag strip I've gone to 27 psi with more aggressive timing and luckily everything remained intact.
People have said that the connection between the drive shaft and the diff is a weak point. On 335s the driveshaft is connected by a nut. On the E9x M3 its a big CV joint.

335i
https://www.realoem.com/bmw/enUS/showparts?id=3R92-EUR-07-2013-F82-BMW-M4&diagId=26_0276

e9x M3
https://www.realoem.com/bmw/enUS/showparts?id=WD93-USA-09-2006-E92-BMW-M3&diagId=26_0239

However! The latest M3 and M4 also use the nut as a connection, to a different type of diff. The F90 M5 also used a CV joint.

M3/M4
https://www.realoem.com/bmw/enUS/showparts?id=3R92-EUR-07-2013-F82-BMW-M4&diagId=26_0276

M5
https://www.realoem.com/bmw/enUS/showparts?id=FV92-EUR-03-2011-F10-BMW-M5&diagId=26_0239

It seems strange that BMW should give an M4 the nut type connection while the previous M3 with much lower torque had what looks like a stronger connection?

Anyway. My question is, can we 335i owners upgrade this connection. I know going with the e9x M3 driveshaft and diff will replace it, but I have a DCT with a 2.56 final drive ratio.
The M4 diff is 3.46 apparently. How much torque will this nut connection take? I'm also based in England which makes importing upgrades very pricey.

 

[LMB335is]

Hi guys,
so I've been running GC turbos for over 2 years. While street driving I normally limit boost to 24 psi. On the drag strip I've gone to 27 psi with more aggressive timing and luckily everything remained intact.
People have said that the connection between the drive shaft and the diff is a weak point. On 335s the driveshaft is connected by a nut. On the E9x M3 its a big CV joint.

335i
https://www.realoem.com/bmw/enUS/showparts?id=3R92-EUR-07-2013-F82-BMW-M4&diagId=26_0276

e9x M3
https://www.realoem.com/bmw/enUS/showparts?id=WD93-USA-09-2006-E92-BMW-M3&diagId=26_0239

However! The latest M3 and M4 also use the nut as a connection, to a different type of diff. The F90 M5 also used a CV joint.

M3/M4
https://www.realoem.com/bmw/enUS/showparts?id=3R92-EUR-07-2013-F82-BMW-M4&diagId=26_0276

M5
https://www.realoem.com/bmw/enUS/showparts?id=FV92-EUR-03-2011-F10-BMW-M5&diagId=26_0239

It seems strange that BMW should give an M4 the nut type connection while the previous M3 with much lower torque had what looks like a stronger connection?

Anyway. My question is, can we 335i owners upgrade this connection. I know going with the e9x M3 driveshaft and diff will replace it, but I have a DCT with a 2.56 final drive ratio.
The M4 diff is 3.46 apparently. How much torque will this nut connection take? I'm also based in England which makes importing upgrades very pricey.

I honestly can't see how a M4 driveshaft/connection would work with a standard E series diff but stranger things have happened with BMWs.

Since you have a DCT, I'd honestly just do the E9x M3 drivetrain upgrade with the M3 GWS/software upgrade. If the 3.15 is too low for you, which was the case for me, a 2.81 FD from a old E31/38/39 will fit a M3 diff. It works with the M3 software, and is a good compromise between the M3 3.15 and 335i 2.56.

 

[Mikejones1208]

With those turbos and you being auto you probably wont ever see enough power to actually have a problem with that, only people i know shearing the input shaft on their diff's are big power 800+ cars with sticky tires and hard launches.

 

[LMB335is]

With those turbos and you being auto you probably wont ever see enough power to actually have a problem with that, only people i know shearing the input shaft on their diff's are big power 800+ cars with sticky tires and hard launches.

He has a DCT. I've seen stock DCT cars smoke that pinion nut connection with launch control. It's a pretty common failure on non M DCT cars.

 

[MoreBoost]

He has a DCT. I've seen stock DCT cars smoke that pinion nut connection with launch control. It's a pretty common failure on non M DCT cars.

Yes the hard launches seem to have a cumulative effect. So it would be great to strengthen that connection.
I have toyo R888s. They hook hard on regular roads.

I don't know if that nut might gradually round off as well. The gear changes on the DCT at maximum clamping force and 600WHP are brutal.
Thats just the road tune. People have broken at much lower power levels than I'm running.

 

[MoreBoost]

Its amazing actually how many people have had half shafts fail at the CV joint back in the earlier days. 2010, 2012.

One guy had it happen multiple times. Very strange.