F8X M3/M4 CF Drive shaft mod

[Bry5on]

Hah, when did you move to SD? I thought you were in the Bay. I can go grab you a non-telescoping CF driveshaft and take your donor shaft to the drive shaft shop in Garden Grove for the conversion. Or you can test my already converted CF DS.

I’m game to do a test if it installs without dropping the rear end! Alternatively we can take some detailed measurements of the stock shaft against the modified one to verify you got the dimensions sorted out with the last go around. I moved down to SD a few months back, it’s been a long time coming!

[0-60motorsports]

I think grape mint is what he smokes, he probably copied you. Message me on IG so I can start your driveshaft conversion.

Hahahahhahah YES! I can't find you bud. Can you please add me 060motorsports on ig

[EthanolTurbo]

I’m game to do a test if it installs without dropping the rear end! Alternatively we can take some detailed measurements of the stock shaft against the modified one to verify you got the dimensions sorted out with the last go around. I moved down to SD a few months back, it’s been a long time coming!

Awesome yeah, either works. You have to rock the diff backwards to install.

I'll PM you my phone #.

[Bry5on]

Ok, thanks to EthanolTurbo the driveshaft is in my hands. Some info:

Measurements (~ +/-2mm):
Stock driveshaft: 1365mm
Modified F80-e46 carbon driveshaft: 1360mm

Weights, like-for-like naked with rear CV only (bathroom scale, using me as tare weight, repeated 6x each alternating back and forth between driveshafts, ~ +/- 0.1lb):
Stock driveshaft: 17.5lb
Modified F80-e46 carbon driveshaft: 14.1lb

Weight savings: 3.4lb, 19%

Extra measurements:

Diameter, carbon center shaft: 79.8mm
Diameter, carbon steel ends: 88.5mm

Diameter, e46 front: 75.1mm
Diameter, e46 rear: 60.3mm

Length, e46 front section, from flange as in photos: ~635mm
Length, e46 rear section, to solid end of shaft (not CV): ~730mm

Hope this clears some things up. Will try to measure runout and get to a test fit as soon as I get the chance. I'm betting that being 5mm short doesn't end up being an issue because I'm running solid subframe bushings and there's more than 5mm of play in the subframe bushings alone.

Edit: I don't think this has a moment of inertia benefit, so this *shouldn't* feel like a lightweight flywheel in first gear. So we'll see what the difference is with the stiffer shaft and fewer moving joints.

[CrisSilberGrau]

Bry5on please indicate the exact points you measured the length from.

[Bry5on]

Bry5on please indicate the exact points you measured the length from.

I did that above, but reiterating for the sake of clarity:
front: guibo flange surface
rear: solid end of the driveshaft

You do not need a rear CV joint installed to build one of these using the dimensions above. So no nonsense about whether the CV joint is fully or partially extended or anything like that.

[CrisSilberGrau]

Bry5on Thank you I appreciate it, that clears it up.