The V8 driveshaft procedures.

The V8 driveshaft procedures.

"These build journal entries are part of a Special Series on the E9x M3 V2 carbon fiber driveshaft by YFCM Technologies

I cover the bizarre backstory to uncovering the manufacturer of the renowned and authentic V2 product, its comparaison with the counterfeit unit along with my installations tips and driving impressions. 

In this entry, I cover the installation of the YFCM V2 carbon fiber driveshaft and share tips & tricks to validate to your installation. 

The installation of the YFCM carbon driveshaft was relatively straight forward - yet it has new mission-critical information that we were never made aware until I started chatting with M.Lee at YFCM.

- Matt

Preliminary checks.

Inspect & Replace worn bushings and mounts!

If your bushings and mounts are worn - I highly recommend you change them. 6spd guys should be mindful of wheel hop on hard launches.

I previously fitted solid subframe bushings, PurpleFlex poly diff bushings along with a myriad of stiffened suspension arm bushings. Engine and transmission mounts were kept stock to avoid excessive NVH. 

    Pick the right balancing bolts.

    Your OEM driveshaft is carefully balanced at the factory and has a few versions. 

    BMW uses a colored line on the driveshaft flange to indicate the balancing method used and the specific balancing bolt hole.  


    The colored marking. 

    Prior to September 2009 production date, the balancing was using washers on the marked hole. After 09/09, colored balancing bolts are used. My 2012 M3 uses the original diff from the factory.

    1. The blue marking indicates the black bolt (SKU: 26112284154)
    2. The yellow marketing indicates the green bolt (SKU: 26112284153)
    3. If your differential has white marking, then you're in luck: regular bolt it is. 

    My diff had a blue line: It required the Black balanced bolt. 

    Recommended hardware. 

    • 1x Flexdisc "guibo" (SKU:  26112282573)
    • 1x Balanced CV flange / Diff bolt (SKU: see below)
    • 5x Standard CV flange / Diff bolt (SKU:  26117526322)
    • 3x Self Locking Nut for Guibo / Transmission flange (SKU: 26127536563)
    • 6x Hex Bolt for Guibo / Transmission flange (SKU: 26117527475)

    Installation Steps.

    Get to the driveshaft. 

    You need to remove the center exhaust bracket, disconnect 02 sensors off the exhaust and remove the entire exhaust systems.  

    The OEM steel driveshaft and center support bearing can then be removed.


    It's a tight fit! 

    1. We needed to lift the transmission all the way up with the engine supported.
    2. We also loosened the differential bushings and pried off them to get the YFCM to fit.

    Validation Steps.

    You need to meet these clearances before completing the installation as it may otherwise lead to catastrophic failure of the tube.

    "After having sold 100 + driveshafts, and over 500+ of these being around, I have yet to see a carbon tube ungluing."
    - Matt

    Matching Differential Marking & CV Flange Bolt.

    I chatted before about aligning the balanced CV / diff bolt colored in black with the blue mark on the diff but took a clearer picture this time around.


    Telescopic Flange Measurements

    The CV flange is telescopic and allows for some play for the rubber bushing in the powertrain such as the engine mounts, transmission mounts, diff and subframe bushings.

    As the 1 piece carbon tube design is engineered to flex and move with the drivetrain, YFCM carefully engineered the tube length to match with the CV flange.

    It must have a 64mm / 2.52 inches distance between both points pictured. 

    If you installation does not come within the specifications listed below, you may have worn bushings and/or mounts across the powertrain. It's ideal to have had the car under the load if you changed any bushings. 

    Here's how we took the measurement. The car was still on the lift. 

    Carbon Tube Clearances

    Carbon tubes are larger than steel driveshafts and more susceptible to being damaged by screws and bolts that are at the top of the tunnel.

    Careful attention to clearances and free range of movement of the tube must be validated. There are 2x bolts and 1x screw by the CV flange that are to watch for.

    There should be at least 20mm / 0.8 inches separating the tube from any physical element across the driveshaft valley.  


    Up next: I go on a few drives, and experience the hype. 

    Can you really feel it? I'm about to find out. 

    I will also share David's impressions on his 6spd testing. 

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