driveshaft

[e92zero]

I am interested in this too but sorry for the OP to go through this much trouble and still not working. It's interesting that the F80 carbon shaft retains the factory torque disc while this one do away with it. Wonder if there are some weight difference/benefit doing it one way or the other.

Good luck to the OP.

[whats77inaname]

Originally Posted by pbonsalb

Depends on whether new m3 shaft is longer or shorter. The 700 rwhp guys drag racing are not breaking stock shafts. Why change?

For me it isn't about the strength, it's a matter of rotational mass saved. If there's a significant amount of rotational mass saved it might be worth looking into, but like I said, it's have to be quite a bit of weight. Saving 2 lbs? Meh, not worth it to me. Saving 6lbs? That's another discussion.

[Hujan]

Edit: Looks like the weight savings of this shaft are negligible leaving only the other potential benefits:

The fact that this is a one-piece design, unlike the factory shaft which is a two-piece design with a coupler in the middle. I gotta believe that the one-piece design will, similar to firmer differential and transmission mounts, result in more direct transfer of power from transmission to rear wheels.

Then there are also the potential benefits of sound damping for those of us who are running solid subframe and differential mounts and therefore have some noise from the drivetrain that we'd like to muffle.

[whats77inaname]

Originally Posted by Hujan

Let's be clear here: I believe it was stated earlier in the thread that the stock shaft weighs 30 lbs. while the CF shaft weights 20 lbs. If the CF shaft was weighed without the 2lb.-adaptor plate, that is still an 8 lb. difference in rotating weight on the driveline.

Let's be clear indeed

Originally Posted by squartus

I weighed both the drive shafts for you guys wanting to know.
I was surprised on the weight:
OEM + guibo 24.6 LBS
DSS + Adapter plate 22.2 LBS
Checked it a couple times to make sure was right, kept getting same result.

http://www.m3post.com/forums/showpos...&postcount=104

And I have the Delrin/alum diff/subframe bushing setup, as well.

[thekurgan]

Originally Posted by italyix

Damn, really disappointed this did not work out, as my 2015 plans included the CF shaft for weight savings...guess I'm staying stock and use the money to upgrade the diff (mine is basically blown).

Btw, lb to lb for bang for buck, CF roof (10lbs) is the same price and sheds (if you have moonroof) around 45lbs (45lbs of glass + 10lb of steel from roof) off the top. Better rotational savings are achieved by swapping wheels and tires....or for 2 lbs don't for two days

The glass doesn't weigh 45 pounds. I removed mine and my past E90 to replace the gasket, and you can toss it around like a frisbee. Maybe the underlying cable, cartridges and motors add to the weight, but not the glass alone.

[Hujan]

Originally Posted by whats77inaname

Let's be clear indeed


http://www.m3post.com/forums/showpos...&postcount=104

And I have the Delrin/alum diff/subframe bushing setup, as well.

Wow, my sincere apologies. I completely missed that post. I wrongly assumed everyone was focusing on the weight of the adapter plate. My bad. Thanks for setting my straight. I will edit my post.

I can't believe there is only a 2 lbs. difference between them. The OEM design must be really good or their shaft is not actually CF.

[whats77inaname]

Originally Posted by Hujan

Wow, my sincere apologies. I completely missed that post. I wrongly assumed everyone was focusing on the weight of the adapter plate. My bad. Thanks for setting my straight. I will edit my post.

It's cool, my man

Originally Posted by Hujan

Then there are also the potential benefits of sound damping for those of us who are running solid subframe and differential mounts and therefore have some noise from the drivetrain that we'd like to muffle.

Just curious, running that Akra you have, how much diff noise can you actually hear?

[Hujan]

Originally Posted by whats77inaname

Just curious, running that Akra you have, how much diff noise can you actually hear?

Unfortunately, quite a bit, actually. The diff whine does not bother me around town when you're frequently accelerating and decelerating. The only time it's a bit of a pain is steady-state cruising on the highway. At 3250 RPM the Akra is pretty quiet and the diff whine is at its loudest with no change in pitch.

BTW, I used to complain quite a bit about my Akra Evo. I found it very loud and bassy at low RPMs. I could never understand those who said it was too tame, almost OEM-like. As it turns out, it was not installed correctly, resulting in some unwanted resonance and noise from, among other things, a small leak at the headers. I had my second Akra Evo installed by MRF and it is completely different experience. I am very pleased with the Akra Evo now.

[squartus]

Yea im supercharged with AA signature exhaust and test pipes, pretty grunty and loud. Can hear the diff whine over exhaust, supercharger whine and radio depending on the rpm.
Which is the main reason im trying the CF driveshaft.

[italyix]

Originally Posted by thekurgan

The glass doesn't weigh 45 pounds. I removed mine and my past E90 to replace the gasket, and you can toss it around like a frisbee. Maybe the underlying cable, cartridges and motors add to the weight, but not the glass alone.

I meant to say the whole moonroof assembly including rails and such, yes if the glass weighed 45 lbs, I'd be worried.

There was thread on another owner who did the CF conversion, that's where I got the 45lb number.

[squartus]

Alright got my new bolts in today 50mm bolts is whats needed for the e90 m3 adapter plate.
Everything went in super smooth, the double CVS make it much easier to mount and work with vs the old driveshaft. Just letting the RTV silicone cure (needed to seal the diff to the driveshaft as does not have a plate on it like the oem shaft) before taking it out and seeing how it feels and sounds.

Small bolts are 60lbs torque, 3 large trans flange bolts are 74lbs torque incase anyone needs to know.

Few pics of it installed:

[M33too]

Looking good! Let us know how it feels.

[e92zero]

Looks great!!!! Interested in the need of the RTV sealant. Shouldn't they have an integrated gasket/seal of some sort on the adapter plate for the diff side?

[ashtaron14]

So after getting the correct adapter plates, the correct length for bolts, and RTV silicone cure (not provided I guess), it's finally done!

Lets hope the diff whine goes away.

[Hujan]

Looks great! Must be a relief to have that thing in finally.

Eager to hear what, if anything, it does for the diff whine.

[pbonsalb]

Originally Posted by e92zero

Looks great!!!! Interested in the need of the RTV sealant. Shouldn't they have an integrated gasket/seal of some sort on the adapter plate for the diff side?

I have used a couple of DSS DS on other BMWs and they came with siliconed endcaps for the CV joint. My guess is either DSS forgot it, it fell off in the packaging and the owner missed it, DSS has not gotten around to stamping out a cap yet because it is uncertain what the diff input flange looks like, of the E90M3 diff input flange for some reason does not fit a cap. I would rather have a cap so I can remove the DS without making a mess and so the CV is not at risk of contamination if temporarily off the car.

[squartus]

When I asked them about it I was told the way it was made that it did not have room for an end cap, they are the ones that said it needed the RTV silicone for a proper seal.
Not sure if that was true or not but is what they told me over the phone.

[e92zero]

Originally Posted by pbonsalb

I have used a couple of DSS DS on other BMWs and they came with siliconed endcaps for the CV joint. My guess is either DSS forgot it, it fell off in the packaging and the owner missed it, DSS has not gotten around to stamping out a cap yet because it is uncertain what the diff input flange looks like, of the E90M3 diff input flange for some reason does not fit a cap. I would rather have a cap so I can remove the DS without making a mess and so the CV is not at risk of contamination if temporarily off the car.

I agree and that's my point. An endcap or some sort would seem more fitting and cleaner. I can't tell clearly in the picture but are those plastic zip ties on the 2 ends of the driveshaft?

Originally Posted by squartus

When I asked them about it I was told the way it was made that it did not have room for an end cap, they are the ones that said it needed the RTV silicone for a proper seal.
Not sure if that was true or not but is what they told me over the phone.

I don't know and I never saw this product in person but having to use RTV just seem so 'patch-up' and afterthought. If they designed the driveshaft from the ground up for the E92 M3, they should allow for enough room for an end cap, right? Given the ordeal that you went through, it just seem that they threw what they have on their bench together and let you be the genuine pig. Maybe I am completely off base but it just seems wrong on their part. Hopefully the driving experience will offset these 'detail'.

[pbonsalb]

I agree. There is room for an endcap with either a shorter DS or a thinner adapter. The only reason not to have one would be if the diff input flange somehow did not allow one. I have not studied the E90M3 diff, but I have used DSS DS on BMW 188mm 4 bolt input diffs and 210mm 6 bolt input diffs and both those DS had stamped sheetmetal endcaps for the end of the CV at the diff end (both those DS had a CV only at the diff end and used a u-joint at the trans end).

[squartus]

Here is a pic of the backing plate on the OEM driveshaft. Think to story is more like they did not want to go through the trouble of stamping it out since it looks like it would take a bit of time to get right. OEM backing plate locks into the diff like a socket, actually had to yank the shit out of it to remove it because it was seated in so well.

[e92zero]

Originally Posted by squartus

Here is a pic of the backing plate on the OEM driveshaft. Think to story is more like they did not want to go through the trouble of stamping it out since it looks like it would take a bit of time to get right. OEM backing plate locks into the diff like a socket, actually had to yank the shit out of it to remove it because it was seated in so well.

Hmm, I agree they didn't want to take the time/trouble to do it right. But then, it means this new driveshaft will be completely relying on the 6 bolts where as the oem one relies on the actual backing plate for the torsional/twisting force. Will be interesting to see how it will hold up long term. Do you have a chance to take it out for a spin yet? Must have been a long wait with all the trouble you have to go through.

[squartus]

Not to worried about just the bolts holding it, only 3 bolts hold it to the trans so 5 should do the trick.
Finally got to take her out for a nice drive, after needing to turn right back around because the heat shielding by the rear diff was rubbing on the driveshaft "horrible noise btw" but was quickly fixed with some tin snips.

Now first impressions, drive train slop is TOTALLY gone we are talking no more clunk or lashing at all. Feels like a rubber band, same with rev match downshifts or letting off the gas and engine breaking kicking in. Before was always bit of a clunk or lurch not anymore. I would of bought the one piece driveshaft for that alone.
Shifts are much smoother as well, I assume this is from less things moving around kind of like new solid trans mounts but much better.
Now I always hear that these types of drive shafts give better traction so one of the first things I did was roll out of 1st and slam 2nd "M dynamic mode on" now what usually happens is traction control kicks in like crazy then it kills engine power and you end up going nowhere. Not only did it not kill power but the traction control light never even flashed!!
I tried this a few times with the same result, now keep in mind im running a ESS 625 kit as well.

Was getting dark so I did not try out any hard launches with DSC off but I will tommrow. Usually if I just punch it ill break traction in 1st ass throws out, 2nd melt rubber with ass thrown out whole time and 3rd ass comes in with a bit of wheel spin then straightens out.

Now... for the bad news... Does nothing for rear diff whine from having solid rear diff mounts. It may actually make it a bit louder until 70mph so if you looking at this for any kind of sound deadening effects its a total bust.