F8X M3/M4 CF Drive shaft mod

[EthanolTurbo]

Here's my impressions and notes now having driven the converted shaft.

First, the good: it does indeed tighten everything up, makes the car feel more powerful, and makes shifting better. It further reduces M Clunk, and is overall very beneficial for drivetrain feeling and connectedness.

Now, for the bad: past 80 mph it vibrates like crazy through the whole chassis and gets worse as speeds increase. I'm very sensitive to NVH so this is completely unacceptable to me.

I guess the next question is WHY? It was balanced by the driveshaft shop and they said it balanced fine. Is the CF driveshaft itself causing vibration? Wouldn't a vibration this bad turn up on the balancing test?

I'm frustrated because this is a great mod that helps tighten up the clunky stock drivetrain and it's relatively cheap. Unfortunately I can't recommend it at this time because it's a dice roll: is the shaft bad already? Does the conversion potentially cause vibration? I wouldn't want anyone else to feel this frustration and disappointment. Plus it's annoying to have to swap back and forth.

For me personally, I don't have the time, patience, or money to take it back, have it rebalanced and try it again. I guess if I had to do it over again, I would grab one of Matt@Euroconnex's YMCA CF shafts and put it on a credit card for peace of mind in case it's a POS.

Sorry guys. I wanted this to be a great mod for the community. If someone else wants to step up to the plate and try it themselves, YMMV but there is potential. If someone else tries it and it works, maybe I can take mine to get fixed.

[Obioban]

I grew up in Glenside, PA...the home of Beaver College. Which was a woman's liberal art college. They've since changed the name to Altria or something.

Intercourse, PA is next to Blue Ball, PA... and not far from Hand Place, PA.

None of the above is made up.

We should probably get back to talking about shafts.

[ugaexploder]

...

There's a town called cumming?

I thought Intercourse, PA was bad.


If I didn't already have one, I'd pay the extra for a BNIB one for $750.

It’s definitely something you never get used to! 🤣🤣🤣

[bigjae46]

...

There's a town called cumming?

I thought Intercourse, PA was bad.


If I didn't already have one, I'd pay the extra for a BNIB one for $750.

I grew up in Glenside, PA...the home of Beaver College. Which was a woman's liberal art college. They've since changed the name to Altria or something.

[Obioban]

...

There's a town called cumming?

I thought Intercourse, PA was bad.


If I didn't already have one, I'd pay the extra for a BNIB one for $750.

[ugaexploder]

Oh then that's a bargain.

thinking about picking one up
unsure about this mod though, waiting for the brave souls to try this out first!

[0-60motorsports]

In all fairness, they are brand new

Oh then that's a bargain.

[ugaexploder]

Nice rip off deal. They weren't more than $300 on eBay. What's a shame.

In all fairness, they are brand new

[0-60motorsports]

For the ATL guys, there is a guy in ATLBIMMERS with (12) new f8x driveshafts for sale in Cumming. 750 obo

Nice rip off deal. They weren't more than $300 on eBay. What a shame.

[ugaexploder]

For the ATL guys, there is a guy in ATLBIMMERS with (12) new f8x driveshafts for sale in Cumming. 750 obo

[TheElite///M3]

My stock driveshaft is coming out tomorrow to confirm measurements against the sheet vs stock length/extended baseline. After that I must do the diff bushings etc so maybe another 2 weeks but hoping before Easter break.

get on eBay and snag ya driveshafts now boys!

[0-60motorsports]

It's in. Driving impressions later tonight.

Yes! Thanks buddy.

[EthanolTurbo]

It's in. Driving impressions later tonight.

[EthanolTurbo]

Carbon driveshaft should be installed tomorrow. I wasn't able to use the lift I normally have access to, so that's why it took a long time. Will have a full driving impression by the end of tomorrow with luck.

[simonnim]

Which shop? I’m in NorCal too and about to submit the parts sheet and measurements from the picture here to JRL Machine & Driveline in Petaluma. Would love to hear some results as well.

You mean the sheet that said 53.875 total length and 3.250 from one flange point to the other?


Oh I just realized it has the part numbers for the parts used too. Shoot I'll just bring it there on Monday and see what they say.

I'll let you know the shop if they said they can do it.