J-Fiber Carbon Fiber driveshaft.

[dfwashere]

I have the J-fiber drive shaft for a 6 speed car that I got as part of the group by last year's. Taken it up to 130 and don't have any vibration's at all. Have solid subframe mounts as well purp powerflex diff bushings and no problems on my end.

[peter de la mare]

Originally Posted by dfwashere

I have the J-fiber drive shaft for a 6 speed car that I got as part of the group by last year's. Taken it up to 130 and don't have any vibration's at all. Have solid subframe mounts as well purp powerflex diff bushings and no problems on my end.

That speed on a 6MT with standard final drive will be nowhere near the 6400 rpm limit of the J-Fiber driveshaft.

[AC/DC]

I have one the early MFactory CF driveshaft as well and I've definitely been in the speed ranges mentioned throughout this thread (6MT) and haven't had any issues. In fact, I am glad I swapped seeing how the stock ones eventually get U-joint problems and start clunking. I sold my stock DS literally to a guy with a bad U-joint in his. Outside of avoiding that issue, you're literally losing weight in the best possible place on the vehicle with the CF DS. Sorry you're having issues. Maybe buy the new MFactory version? Best of luck!

[stosh1]

Originally Posted by Redd

Ah that explains it. J-Fiber may have supplied the CF shafts but YCW made the flanges and they claimed that was where the complexity was. If tolerances on the flanges were off, the shaft would vibrate. As part of their business arrangement, J-Fiber would supply CF shafts to YCW, and YCW supplied a batch of flanges to J-Fiber. So the early batch of J-Fiber driveshafts were identical to Gen1 MFactory driveshafts.

After their falling out, your new one probably no longer has the YCW flanges and that's why it vibrates.

I originally started the GB thread over on M3F for these d/s's, and was also the original beta tester...the above info is correct according to how it was initially explained to me by Michael over at MFactory/YCW. I had almost 50 ppl signed up for the d/s, but YCW had a falling out w/J-Fiber over the particulars, and so...the original GB was cancelled. (I think that J-Fiber wasn't happy w/the profit margins.) Somebody else on the forum picked it back up, and started another GB directly through J-Fiber (albeit at a higher price than the original GB), and I believe they sold around 20-25 units.

Sooo, if this is indeed true, it could be that J-Fiber was only able to source a limited number of the known 'good' flanges before their stockpile was exhausted? FWIW, I've had my car up to about 165mph w/zero NVH issues.

I was trying to organize another GB directly through YCW w/their own in-house Gen II cf d/s, but sadly we weren't able to secure enough buyers to move forward w/the GB.

[Redd]

From what I've been reading here and other forums, YCW/MFactory are the only one piece driveshafts for E9x M3 that are consistent and do not give problems.

[wyatth]

I’m in for the next YCW/MF DS GB if it happens!

[AC/DC]

Originally Posted by Redd

From what I've been reading here and other forums, YCW/MFactory are the only one piece driveshafts for E9x M3 that are consistent and do not give problems.

100 percent agree!

[peter de la mare]

Originally Posted by wyatth

I’m in for the next YCW/MF DS GB if it happens!

Same here

[stosh1]

Anyone interested can try contacting Michael directly by e-mailing him @ myip@teammfactory.com. I would be more than willing to sponsor another GB for the E46 platform, but someone else would need to jump in to handle the E9X crowd.

[statik]

Assuming the one I just received this week is the gen 2? shipping to NY was exceptionally quick!

Originally Posted by MFactory

We have the E90/92 MT/DCT driveshafts (Gen.2) in stock and ready to ship. The new batch of 1M fitments will be ready in 2-3 weeks time. No need for a GB, as we sell out of each batch within weeks of them becoming available. Details on the revised design (and how it differs from the Gen. 1) in the 1st post here: https://www.e90post.com/forums/showthread.php?t=1573938

[peter de la mare]

Nightmare continues. I shipped it back and they have been avoiding me. I finally got to speak to Jessy and she still maintains there’s nothing wrong, which I guess there isn’t, just that their product is no good for track cars with short final drive ratios.

Apparently it takes 2 months to organise a $1,000 refund. This is also ridiculous. I never want to hear the name J-Fiber again. It’s cost me another $400+ in shipping and import duties over the original purchase price.

[rhyary]

I am on 3.62 DCT with mfactory gen-1 and at 135-138mph (end of LRP straight) no vibration and 132mph end of NYST straight no vibration

[pbonsalb]

And I’ve done 150 on the jfiber bootleg version of the mfactory V1, and driven it in -20F and 100F. It’s looking like jfiber is inconsistent in making its own shaft independently and should be avoided.

[peter de la mare]

Originally Posted by rhyary

I am on 3.62 DCT with mfactory gen-1 and at 135-138mph (end of LRP straight) no vibration and 132mph end of NYST straight no vibration

Is that GPS speed or what the car’s dial is saying?

[rhyary]

Originally Posted by peter de la mare

Is that GPS speed or what the car’s dial is saying?

AiM gps

[peter de la mare]

If that is the same shaft as I had, then you’re pushing it right to its max safe rpm I think. It’s possible different tires are giving you slightly lower revs at that speed.

[rhyary]

Originally Posted by peter de la mare

If that is the same shaft as I had, then you're pushing it right to its max safe rpm I think. It's possible different tires are giving you slightly lower revs at that speed.

May be, until I get to WGI, I don't see myself getting to a higher speeds.

I am typically on 295/30/19

I do have one set of 295/25/19 to experiment with, that will get the shaft rotating faster. i will be watching for the vibration you have noticed.

[M3SQRD]

I most be missing something because I don’t see how changing the final drive in the diff changes the angular velocity of the driveshaft. The DS connects to the trans output shaft and to the diff input shaft. The DS speed depends on engine rpm and trans gearing whereas the diff output drive axle angular velocity is affected by engine rpm, diff FD (2nd single-gear trans) and trans gearing. Diff FD does not change the input shaft speed to the diff. That only happens during a money shift.

[rhyary]

Originally Posted by M3SQRD

I most be missing something because I don’t see how changing the final drive in the diff changes the angular velocity of the driveshaft. The DS connects to the trans output shaft and to the diff input shaft. The DS speed depends on engine rpm and trans gearing whereas the diff output drive axle angular velocity is affected by engine rpm, diff FD (2nd single-gear trans) and trans gearing. Diff FD does not change the input shaft speed to the diff. That only happens during a money shift.

At a given speed, say 140mph, a driveshaft will be rotating faster using a 3.62 diff than a 3.85 diff.

On a 3.62 diff, it is easier to get the DS to rotate at speed that gets vibration.

[peter de la mare]

Originally Posted by rhyary

At a given speed, say 140mph, a driveshaft will be rotating faster using a 3.62 diff than a 3.85 diff.

On a 3.62 diff, it is easier to get the DS to rotate at speed that gets vibration.

Close. The DCT’s original 3.154 FD, changing this to 3.62 makes the shaft spin faster. You’re spinning the engine faster for the same speed. It’s handy for demonstration purposes that 7th gear is 1:1, at some tracks the engine revs in 7th are way over the 6,400 rpm limit of the J-Fiber shaft.

[M3SQRD]

Originally Posted by peter de la mare

Close. The DCT’s original 3.154 FD, changing this to 3.62 makes the shaft spin faster. You’re spinning the engine faster for the same speed. It’s handy for demonstration purposes that 7th gear is 1:1, at some tracks the engine revs in 7th are way over the 6,400 rpm limit of the J-Fiber shaft.

Correct. A shorter FD will require the engine to turn at a higher rpm to achieve the same road speed vs. a taller FD; however, the relationship between engine rpm to DS speed doesn’t change when the FD in the diff is changed. I guess I misread your original statement - we’re saying the same thing.

[peter de la mare]

We’re saying the same thing lol.