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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Fri, Jan-11-2019, 05:51:49 PM   #21
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

I think you are right that drivetrain loss does not double when you double the horsepower. With a supercharger, drivetrain loss does increase with power because the blower is dragging on the crank and it drags more when it is pulley’d to spin faster to make more power. But I don’t think the driveshaft is doing more work when the car makes 900 rwhp than when it makes 300 rwhp so I would not expect 22 rwhp gain.
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Old Fri, Jan-11-2019, 06:01:47 PM   #22
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

These carbon shafts are generally a larger diameter that more than offsets the weight loss, causing a loss in horsepower.
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Old Fri, Jan-11-2019, 06:11:59 PM   #23
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

Anyone measured the OD on this shaft?
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Old Fri, Jan-11-2019, 06:18:44 PM   #24
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

Quote:
Originally Posted by HassanEido View Post
which is actually heavy as fuk to dampen the vibrations. It was actually not designed to be light, it is a steel shaft with carbon fiber reinforcement, as far as I know.
The thing with aftermarket CF shafts is that they are also generally wider, putting the rotating mass at a larger moment arm.
The M3 stock shafts are hollow, at 18 pounds, so 11.5 to 12 pounds is saving you 6 pounds, but doing so with a larger diameter (again correct me here), but even so, as mentioned above the diameter change would be small, and the overall effect would be minimal? Just speculating here, would love to see Dyno numbers. I know Stan picked up a few ponies due to the drive shaft so it's an automatic win there.
My only concern with a CF DS would be if it comes in contact with the heat-shielding at some point, would it unravel back to strands or damage it enough to go out of balance? Other than that, it would be nice to see what difference it makes on the dyno
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Originally Posted by m3 hal View Post
These carbon shafts are generally a larger diameter that more than offsets the weight loss, causing a loss in horsepower.
As I stated in my previous d/s thread, I'm not sure what the science works out to in terms of d/s dia vs. rotational mass vs the gravity on the moon...but there is MOST def a noticeable increase in engine response/rpm's vs a factory d/s. It's def not placebo! I'm sure that forum member Wubai can also attest to the effect.
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Old Fri, Jan-11-2019, 06:46:52 PM   #25
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

Quote:
Originally Posted by Obioban View Post
I'm not sure that logic follows.

As in, my intuition says it takes a certain (absolute) amount to spin up a given weight a given speed. So while a light weight flywheel might give 2% less drive train loss at 333hp, what it's really doing is using 6.66 hp to spin it up. I can't intuit a reason it would take more hp to spin it up on an engine with more hp on offer.

But, this is based on nothing other than pondering.

Edit: unless it's because a faster engine spins up faster, and therefore needs more hp to spin it up at that faster rate
Let me just explain a few things 'not to u specifically ' but so ppl know how the physics of this works.
So a few things to know:
-rotating mass such as flywheel and driveshafts, wheels etc.. Store and release energy into the system. With marginal losses to friction(bearings, tire drag.. etc), so the power not released as mechanical energy is released as heat energy.
-spinning up a rotating mass to accelerate it takes power, usually a typical 30 pound shaft stores about 0.25 of a horsepower(eg. Mustang driveshaft). Most of that will be released back into the system as soon as the system stops accelerating.
-increasing the radius exponentially increases the power loss. Stored energy goes up by the square of the radius. The radius here is the weight distance from the center line.
The weight of the ds here, really, is the least important factor here. Since if you double the weight of the shaft, u will only double the power stored in the shaft(keeping the same diameter). Whereas if u double the radius of ds u will quadruple the power stored. That is a 4x loss at only twice the radius increase. Again this is assuming all the weight is at the outer line of a hollow cylindrical shaft. That will be a whopping 1hp loss
-similarly if you reduce the diameter in half, u will lose 4x less of the power lost while accelerating and therefore 4x less power stored in the system.
The best investment while managing rotating assembly weight is to change the distribution of the weight, bringing most of the weight inward while keeping the weight down.
A quick calculation from the given input so far, the weight loss in this driveshaft is ~30%. Which means a reduction of 30% in lost energy while accelerating.
If the diameter (assuming weight is at the outer edge of the moment arm) is increased by only 7-8% that will negate any advantage that weight reduction has made.
Knowing how driveshafts are made from cf,the weight is distributed uniformly across the radius of the cylinder. Which means that most of that weight is moved inward of the original rotating mass's location from the center line. This in addition to the lighter weight will have a net positive yield to the power output. Having said that, the net positive will be mostly observed on a calculator as the shaft doesn't store much energy at all. Most of drivetrain loss is due to spinning up(accelerating, in this order) :large tires, wheels, flywheel, break disks,transmission gears, diff gears, axles, last and least is the driveshaft.
Regarding the 0.25hp number, this is assuming a long period of acceleration, as you would observe in a 3rd or 4th gear pull. The longer the period overwhich it accelerates the less the power is lost due to the rotation mass. The stored energy is the same, since it takes more time to input the speed into the system but it eventually is there when it stops accelerating. The shorter the period( higher acceleration) the more u use power to accelerate the rotating mass. That why u will notice benefits in shorter gears 1st and second for example, while in longer gears its a wash.
Best investment would be tires and wheels. If you're gonna upgrade to a cf ds, u should be doing it for extra damping, durablility for higher horsepower builds, and bling.
A flywheel change can have 40x more the effect of ds, assuming it starts accelerating from 0 rpms, and takes a second or two to accelerate to max rpm.
I hate the nuances the flywheel adds, so to me light wheels are the way to go always. Oh and tires are more important since they are at the very edge of the rotating assembly.
Hassan out
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-Custom CF airbox
-SSV2 catless headers(with a modified collector extention), Custom 2.5" dual sec1, Custom sec2 2.5" dual with e9xM X pipe, SuperSprint Race inspired custom section 3..
-Cat Cams 280 272.
-Custom dyno tune
-Tms pulleys and electric fan conversion
385.7 whp 288 wtq

Custom exhaust thread and dyno http://m3forum.net/m3forum/showthread.php?t=569086
Cams thread and dyno http://m3forum.net/m3forum/showthread.php?t=554439
Custom cf airbox thread http://m3forum.net/m3forum/showthread.php?t=595180
Why not to use after market bearings with surfacetreatments and /or increased clearance
http://www.m3forum.net/m3forum/showp...4&postcount=10

Last edited by HassanEido; Fri, Jan-11-2019 at 06:56:04 PM.
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Old Fri, Jan-11-2019, 06:56:54 PM   #26
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

Quote:
Originally Posted by stash1 View Post
As I stated in my previous d/s thread, I'm not sure what the science works out to in terms of d/s dia vs. rotational mass vs the gravity on the moon...but there is MOST def a noticeable increase in engine response/rpm's vs a factory d/s. It's def not placebo! I'm sure that forum member Wubai can also attest to the effect.
Your car is at the top of its game brother
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Mods:
-Custom CF airbox
-SSV2 catless headers(with a modified collector extention), Custom 2.5" dual sec1, Custom sec2 2.5" dual with e9xM X pipe, SuperSprint Race inspired custom section 3..
-Cat Cams 280 272.
-Custom dyno tune
-Tms pulleys and electric fan conversion
385.7 whp 288 wtq

Custom exhaust thread and dyno http://m3forum.net/m3forum/showthread.php?t=569086
Cams thread and dyno http://m3forum.net/m3forum/showthread.php?t=554439
Custom cf airbox thread http://m3forum.net/m3forum/showthread.php?t=595180
Why not to use after market bearings with surfacetreatments and /or increased clearance
http://www.m3forum.net/m3forum/showp...4&postcount=10
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Old Fri, Jan-11-2019, 07:06:09 PM   #27
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

Quote:
Originally Posted by HassanEido View Post
Let me just explain a few things 'not to u specifically ' but so ppl know how the physics of this works.
So a few things to know:
-rotating mass such as flywheel and driveshafts, wheels etc.. Store and release energy into the system. With marginal losses to friction(bearings, tire drag.. etc), so the power not released as mechanical energy is released as heat energy.
-spinning up a rotating mass to accelerate it takes power, usually a typical 30 pound shaft stores about 0.25 of a horsepower(eg. Mustang driveshaft). Most of that will be released back into the system as soon as the system stops accelerating.
-increasing the radius exponentially increases the power loss. Stored energy goes up by the square of the radius. The radius here is the weight distance from the center line.
The weight of the ds here, really, is the least important factor here. Since if you double the weight of the shaft, u will only double the power stored in the shaft(keeping the same diameter). Whereas if u double the radius of ds u will quadruple the power stored. That is a 4x loss at only twice the radius increase. Again this is assuming all the weight is at the outer line of a hollow cylindrical shaft. That will be a whopping 1hp loss
-similarly if you reduce the diameter in half, u will lose 4x less of the power lost while accelerating and therefore 4x less power stored in the system.
The best investment while managing rotating assembly weight is to change the distribution of the weight, bringing most of the weight inward while keeping the weight down.
A quick calculation from the given input so far, the weight loss in this driveshaft is ~30%. Which means a reduction of 30% in lost energy while accelerating.
If the diameter (assuming weight is at the outer edge of the moment arm) is increased by only 7-8% that will negate any advantage that weight reduction has made.
Knowing how driveshafts are made from cf,the weight is distributed uniformly across the radius of the cylinder. Which means that most of that weight is moved inward of the original rotating mass's location from the center line. This in addition to the lighter weight will have a net positive yield to the power output. Having said that, the net positive will be mostly observed on a calculator as the shaft doesn't store much energy at all. Most of drivetrain loss is due to spinning up(accelerating, in this order) :large tires, wheels, flywheel, break disks,transmission gears, diff gears, axles, last and least is the driveshaft.
Regarding the 0.25hp number, this is assuming a long period of acceleration, as you would observe in a 3rd or 4th gear pull. The longer the period overwhich it accelerates the less the power is lost due to the rotation mass. The stored energy is the same, since it takes more time to input the speed into the system but it eventually is there when it stops accelerating. The shorter the period( higher acceleration) the more u use power to accelerate the rotating mass. That why u will notice benefits in shorter gears 1st and second for example, while in longer gears its a wash.
Best investment would be tires and wheels. If you're gonna upgrade to a cf ds, u should be doing it for extra damping, durablility for higher horsepower builds, and bling.
A flywheel change can have 40x more the effect of ds, assuming it starts accelerating from 0 rpms, and takes a second or two to accelerate to max rpm.
I hate the nuances the flywheel adds, so to me light wheels are the way to go always. Oh and tires are more important since they are at the very edge of the rotating assembly.
Hassan out
That's why I specifically said flywheel. Was dodging the power from driveshaft conversation
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Old Fri, Jan-11-2019, 10:31:45 PM   #28
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

Alright, so I'll chime in with my thoughts on the driveshaft.

First, please understand that I don't know the physics behind it and I'm not here to claim to be an expert. I'm not, far from it. The main reason I wanted this shaft to begin with was because it would eliminate the CSB, so one less thing to worry about.

As for my car, it is a TTFS tuned (SMG and DME) NA car. I'm running Euro headers and section 1. Tubi section 2 and Dinan muffler. I'm also running an Eventuri intake. So, a pretty well sorted NA car without being too loud. I also have a fully built LSD with stock gearing from Jim Blanton at performance gearing (amazing piece of kit, btw).

When it comes to driving, what I can say is that I'm extremely sensitive. I'm one of those people that thinks 1 or 2 mm changes in seating position make a 'world' of a difference. For me, the M3 is like a fine wine and I really like to get into it and appreciate it. I also do my own alignments at home and make changes, then go and try them out, come back, make more changes and try them out. I'm not part of any groups, I don't go to meets, I'm just a guy who really enjoys his car and wants to get the 'purest' experience that best fits me, whatever that means.

First, let's get into the cons of this driveshaft before I talk about the drive-ability and what I've felt.

1. It was a pain in the rear to install, period. I had to fully unbolt the entire differential because there is obviously no slack in the driveshaft. Also, when tightening it down I numbered the bolts and went around in a star pattern probably 50 times (no joke) slightly increasing the pressure until I reached full torque on the bolts. This meant moving the wheel with my leg, then going and setting the parking brake, over and over and over again. Probably took me 1 hour just because I wanted to get the 'perfect' seal. Again, I'm OCD and I'm fine with this.

2. You need to be extremely careful with handling carbon fiber. You cannot let it bounce on the ground. You must handle it like a newborn baby. This made installation a little bit more of a challenge, not much, but It made me very careful and paranoid.

3. You can have absolutely NOTHING touching the driveshaft even a little bit once it is installed. I was super paranoid about the headshield touching it. I used a small mirror and flashlight and checked and triple checked to make sure it cleared. I moved the wheels and listened for noise. No rubbing, but again, there is ZERO room for error. If it touches, it will eventually shred, and that's it.

4. If it shreds or you drop it. Well, good luck. I seriously doubt there will be much support, since J-Fiber could say the problem was due to installation issues and not the product. They are a small, but very passionate company. They don't have the infrastructure for dealing with massive returns. This is a risk, so just be mature about it and know what you are getting into. For me, if it shreds then I'm willing to take the hit. Its a gamble, and for me it has paid off. But don't think this is an Apple iPhone where you just walk into a store and they hand you a brand new one in a box and send you on your merry way. This is international. I recently purchased something from TaoBao from China. Was terrified. Luckily it is shipping, but the language barrier and dealing with international shipping if something goes wrong really should be considered. In this case, I was willing to lose the money completely. But again, these are my own personal calculations based on the amount of risk I myself am willing to take, so keep that in mind.

So if you've read this far and I haven't put the fear of GOD in your hearts yet, then lets get into the good stuff.


PROS!

Transmission:

First thing I noticed was the shifting. With my SMG I like to keep things in S4, even with the TTFS tune and I still do my little 'partial lift' technique when shifting to make sure everything is smooth.

Before the TTFS tune, I had to lift a little bit more on upshifts and give a little bit more on downshifts. After the tune, which make things considerably quicker and smoother, I had to make less adjustments, or rather, I had to make finer adjustments in order to be smooth. It took some getting used to, but it was a net increase.

This driveshaft just took things to another level. The shifts are now so fast that I can't even make micro adjustments because by the time I even think about it, its already in gear. In fact, I now drive in S5 because it is smoother than S4 was. It seems to quickly 'slot' in gear. Before with the OEM driveshaft it never 'slammed' in a gear obviously, but you can definitely sense there is less 'mass' impacting the gear changes if that makes sense. It feels light, but strong. But it doesn't feel like there is a spring that is absorbing rotational forces, it actually feels stiffer than the OEM driveshaft, just lighter and tighter.

It made such an improvement, that I can honestly use the A mode and just drive around like normal in A5 and the car is almost like a DCT. But make no mistake, it still feels like an SMG and not a DCT when you are really getting on it. You just don't feel like you are beating up the car as much. For example, if I am in S6 and am flooring it in 3rd and shift to 4th at redline with an OEM driveshaft, I always felt that quick but forceful shift. It felt raw and racecar-like, but it was a guilty pleasure that I didn't like doing often because I felt I was being too rough on the car. Now, since there is less mass involved it doesn't feel like I'm damaging the car at all, it just snicks into gear quickly and more gently. Truly difficult to explain in words now that I'm trying to type everything out.

Okay, so that's all I have on the transmission and shifting part.

Vibrations and driveability:

I was praying and praying that I wouldn't have vibrations in the driveshaft once I installed it. I was so worried that I would, and it would be something I would have to deal with to a certain degree. Boy was I wrong.

Now up to that point I never really considered that the OEM driveshaft would be a source of noise or vibrations, and really it isn't. But something happened once I got the J-Fiber installed. The car was quiet! I could tell a pretty noticeable decrease in noise just through normal driving, which wasn't something I ever expected. Also, it was SMOOTH. I'd say a good 30 percent smoother of a driving experience driving around the neighborhood at 30mph. I called my buddy and told him that it really felt a lot more like a Lexus than an M car all of a sudden. Honestly, it almost was too smooth for me as I was driving around the neighborhood after I first installed it. The car was just quiet and seemed to 'glide' around. This gliding sensation was strange since everything seems so directly and light and quiet and smooth. I even said "Wow, it just feels like I'm gliding on glass." It is a weird sensation in the beginning and a step towards refinement. Less exciting and feelsome at neighborhood speeds, much more adult. But not in a bad way.

Now let's get to the throttle response before talking about the power (spoiler, no gain in power, just less parasitic loss).

Throttle response was the area of most improvement for me. It now felt as if I had a tight wire directly tied between my throttle pedal and the differential. What this means is that when you are mid-corner at close to the limit, you have a direct and telepathic relationship that you've never had before with the rear end of the car. Any tiny micro adjustment with your foot gets translated INSTANTLY with the differential. The entire experience when driving fast through a corner becomes higher resolution, but still in a lighter and smoother way. Which leads me to power delivery...

Power Delivery:

I have a set of four leaf clover exit/on ramps that I had early Sunday mornings at about 4:45AM. These are those ramps where if you never merge onto the highway, will allow you to just keep repeating over and over and over again. Two are uphill and two are downhill. I've named each one of them and know them like the back of my hand. Between the first one (El Jefe) and the second one (Yellow) there is a straight section where you can merge onto the highway if you change lanes, or you can stay in your lane and continue onto Yellow. I'm usually at full throttle coming out of the apex on El Jefe and am right at redline by the time I'm about to brake for Yellow.

With this driveshaft, I was a redline about 70% of the way to Yellow's turn in point. This means that I now have to shift from third to 4th then back to third again to make this turn. This is because this driveshaft just makes your car fly to redline. Now, if I had a lighter flywheel it would do much of the same, however it would also bring with it a slew of daily driving driveability issues that I'm unwilling and unable (SMG) to deal with. This driveshaft improved my daily driving, throttle response, NVH and responsiveness without the drawbacks commonly associated with a flywheel modification.

Because the car moves to redline faster, it 'feels' faster. I would say that people who have normal NA cars like mine with similar mods can best understand this as the difference between normal mode and sports mode. Want to know how much 'power' this driveshaft will give you? Just put it into sports mode. Its pretty much exactly like that. Except, I hate sports mode because it doesn't give me the precision I need to really drive at the limit. This driveshaft lets you keep the car in normal mode with all the precision, plus more, but gives you that sense of 'power.'

Now the final thing I will say about this driveshaft is that It has made me much more careful about how I apply the throttle. The first time I really got on it, the rear end was getting loose. In fact, the rear end would get loose pretty often in the beginning because I wasn't being as precise with the throttle as I needed to be. Now, I'm extremely anal about these things so don't think I'm some ham fisted (ham-footed?) caveman with the throttle pedal application. But this driveshaft made me realize just how much attention and recalibration I needed to give my inputs in order to maintain smooth outputs. Again, its just taking the resolution of the driving experience to another level. It's like a great set of speakers, they sound great but feed them a poor recording that sounded great on your old speakers an they will show EVERYTHING. But feed it an amazing recording and just sit back and enjoy the music.

So I think part of the reason I think this is an absolutely transformative addition to the car is because I'm making OEM+ levels of power with my mods. It's like drinking a fine scotch with water and really getting to taste all the nuances of the experience. Anthony's car is like taking shots of grain alcohol straight with no chasers. Everything is turned to not to 11, but probably 111. It's like asking Arnold in his prime what benching 400lbs feels like compared to 450lbs. Those 50lbs might not feel like a lot to him, but slap them on my bar and believe me I can tell you that its a difference.

So that leads me to my final take on this driveshaft, which is the question of who this product is really for.

Is it for the person who wants to make more power? No, not even close. I've never been that guy anyways. I could have gotten different headers, and entirely different exhaust and gone with a CSL intake if I wanted more power. I know I'm leaving a lot of power on the table with my mods, and I did it all on purpose. I want a car that is OEM+, more refined and more precise than stock and I want it to sound good (as much as our cars can) and deliver the power the way I want it. For me, its an experience car and one that I want to craft into the type of car that best suits me personally. If I wanted a different experience, I would just get another car. So if you are planning to get this to free up HP, then your money would be better spend elsewhere.

This is for the person who has already done everything they want to do, and just want that final cherry on top in terms of driveability and delivery. In Anthony's case, it will give him some extra juice as well, or free it up. But if are an anal SOB who is all about the 'purity of experience' and all that stuff, then you will love it. Don't get me wrong, its not subtle like "Hey, can you taste the difference between this $20 bottle of wine versus a $35 dollar of wine?" No, you don't have to be that anal to decipher its benefits, they are obvious to anybody. Having said that, if you are the type that really likes to savor the entire driving experience from throttle application, sound, smoothness, speed of shifting and faster revving, not to mention the direct relationship your foot will now have with the differential at extremes of traction, then you will certainly love this thing.

Is it worth the risk? For me, hands down. It is amazing, and the driving experience is now exactly where I want it to be.....

Except, now I need a BBK. Then I need some APEX ARC-8s... OH, or maybe some TE:AL! Then it will be perfect. Shoot, no...then I need to get some TCK DA's and make sure I have flat ride. YES, then it will be done. Hmm, but then I'll probably want to upgrade to Ground Control sway bars and really dial them in, and once that's done I'll probably want to.....oh gosh, it never ends. Let's face it.
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Old Sat, Jan-12-2019, 02:56:27 AM   #29
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Default Re: J-Fiber E46 M3 SMG/NON-SMG CF Driveshaft Review

That was a thorough review. Please, collect the money and letís get this party started. Thank you for doing this!


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Old Sun, Jan-13-2019, 08:18:01 PM   #30
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Default Re: J-Fiber E46 M3 CF Driveshaft Review

Quote:
Originally Posted by HassanEido View Post
which is actually heavy as fuk to dampen the vibrations. It was actually not designed to be light, it is a steel shaft with carbon fiber reinforcement, as far as I know.
The thing with aftermarket CF shafts is that they are also generally wider, putting the rotating mass at a larger moment arm.
The M3 stock shafts are hollow, at 18 pounds, so 11.5 to 12 pounds is saving you 6 pounds, but doing so with a larger diameter (again correct me here), but even so, as mentioned above the diameter change would be small, and the overall effect would be minimal? Just speculating here, would love to see Dyno numbers. I know Stan picked up a few ponies due to the drive shaft so it's an automatic win there.
My only concern with a CF DS would be if it comes in contact with the heat-shielding at some point, would it unravel back to strands or damage it enough to go out of balance? Other than that, it would be nice to see what difference it makes on the dyno
Itís carbon composite, not steel covered by cf lol. It was designed for strength sure, but still light
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Discussing J-Fiber E46 M3 CF Driveshaft Review in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)