The merits of YFCM carbon driveshaft technologies.

The merits of YFCM carbon driveshaft technologies.

"I previously debunked the various misconceptions on carbon driveshafts.

This journal entry focuses on my latest E46 M3 documentation and photography.

It is applicable to all BMW M carbon driveshafts that I curate on EuroConnex in collaboration by YFCM Technologies.

The specifics of each application are available on their individual product listings"
-Matt

It's a lot more rigid than OEM:
3x as much. 

The YFCM carbon tube is is winded from pre-preg carbon fiber sourced in Japan from Toray Industries. It was engineered by YFCM to sustains forces and further tested on a proprietary torsional stress machine to over 5500nm of twisting force. 

The 1 piece design eliminates the need for a center support bearing (CSB). This bearing introduces flex in the drivetrain and commonly fails on E46 M3s with higher mileage. 

It improves the connected feel with the rear end. Needless to say, the E46 M3 is known to be wobbly in factory form. 

 

It's a lot lighter:
6.8 lbs less. 

The reduced weight helps lower the initial moment of inertia, providing improved throttle response and noticeably easier clutch operations. 

On the E46 M3, the OEM 2 piece steel driveshaft weights 8.5kg / 18.7 lbs, while the Carbon Driveshaft weights 5.4kg / 11.9 lbs. 

The YFCM transmission flange is carefully machined to reduce weight in key areas, notably the outmost sections of the flange to further reduce weight on the outer radius on the flange. 

This is engineered to further reduce the initial moment of inertia, a key component to improving throttle response. 

The transmission flange rubber guide is made to YFCM's specifications and can be replaced as a maintenance item. 

It remains vibration free.

The 1 piece design retains the use of the flex disc on the transmission output shaft, a critical component to retaining street friendly, vibration free behaviours of the S54 drivetrain. 

It will not unglue. 

M. Lee holds multiple published patents for his innovative transmission flange in various countries, most importantly Germany and the US

The patented flange is a self-locking design: it is engineered to fit a smaller diameter carbon tube within the flange that is further sealed. 

It eliminates the chance of the tube from spinning free of the flange - a common issue experienced with other manufacturers. 

As a result of superior flange engineering and carbon tube construction, the YFCM tubes do not have any glued on balancing weights. 

It works on the SMG too!

The patented flange was redesigned for the E46 M3 specifically versus the design on the E9X M3, 1M and E6X M5/6. 

The SMG in the E46 M3 is sort of unique in the sense it keeps the OEM 6speed transmission: BMW M bolted hydraulics and shifter linkage actuators to make it the SMGII we love and hate.  

The actuators take up a bit more space in the transmission tunnel by the shifter linkage. 

YFCM extended their patented flange design to clear the actuators and ensure a problem free operation. The length of the original driveshafts are the same between SMG and MT.

YFCM kept that simplified design to fit both the SMG and MT applications. 

QC Results per driveshaft

M. Lee also owns and operate an industrial automation company. He used his knowledge to develop proprietary stress testing equipment specific to automotive carbon tube applications. 

Each driveshaft is individually tested before being shipped out: they are spun to over 8000rpm as a complete assembly on a proprietary balancing machine. 

"Out of close to 100x driveshafts I personally sourced from YFCM, only 3x had vibration fees and were quickly replaced."
-Matt

Blue is the vibration value measured at the CV flange. Green is the vibration value measured at the Transmission output flange.

 

For reference, most OEM 2 piece steel driveshafts have 2 to 3x times the measured vibrations compared to the YFCM. A lot of it is dampened by the center support bearing. 

I am currently discussing with YFCM to publish these results per order along with data on the OEM driveshaft.

To back this up, YFCM backs the driveshaft with a 1 year warranty. 

 

Up Next: 

Reviewing the powertrain bushings & mounts, recommended hardware and installing it!


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