I have no side in this but I have installed the MFortory V1 drive shaft 5 yrs ago and 53k miles later now, I have no problem. I am pretty sensitive to change in NVH and I have driven up to 120mph with no issue at all. At least no VH, the sound is different from the chassis with the carbon shaft but I think that's just normal.
Not to
but what I have noticed/recall during installation are the following:
- The oem 2-piece factory drive shaft has a sliding piece in the middle with 2 cv/pivoting joints in the ends that makes installation and removal a piece of cake (besides the weight). The 1-piece carbon drive shaft do not fit in the open space as is cause it doesn't have the sliding piece. I recall having to lower the transmission mount and the front of the diff mount for the shaft to slip in the space and move both the transmission and diff end up slowly for the carbon shaft to 'get in'.
- The ends of the carbon shaft do not line up with the flanges on either side of the transmission and the diff perpendicularly. If one draw a straight line from the transmission flange to the diff flange, the 2 flange faces are not 100% perpendicular to this imaginary line. This is an issue the oem 2-piece factory shaft doesn't have. The oem shaft ensure the shaft entry/contact point on both ends are perpendicular with the bend controlled by the extra mount/bearing in the middle to the chassis. In order to tighten the carbon shaft, I had to rotate the shaft and tighten the bolts on both ends little by little until the surfaces made full contact before final tightening.
I think both of the above are simply due to the difference of 1-piece vs 2 piece shaft. Not saying it's the case here, but I can imagine if a mechanic did something improper during installation, they can damage the joints in the carbon shaft and it will not work right.
Just to reiterate, I am not saying who is right or who is wrong but just giving a little bit my humble opinion/experience on the matter that might be helpful to others.
