[boostninja]

Its the giving season right? I encourage everyone to share information instead of keeping good info secret, this helps progress the platform. I could of very well kept this to myself and gone faster and no one would of been the wiser. Happy Holidays!

The Idea:

I have been working on David Rooney's 135i DCT swap for awhile now. I am very familiar with the look of and weight of the n54 DCT flywheel. While reading about a clutch upgrade on a f80/82 I noticed a picture of the flywheel in the m3/m4 and it looked much different and much lighter. I was curious and used realoem to inspect weights of the two. The difference was huge. The m4 part rang in at 8.1kg and the stock 335is unit was a whopping 12.92kg! I verified they both used the same bolts, same bolt pattern, thread pitch, and same clutch pack. On paper everything looked great. Located a used m4 dct flywheel from a junk yard and the project was on.

The Swap:

When the m4 unit arrived I could immediately tell it was a much lighter unit. I verified the splines on the clutch pack were the same and test fitted it onto the crank of a n54 I happened to have in the garage. Everything looked as expected.

I pulled the trans out of my 335is and removed the DCT flywheel. The side by side shot says it all. The 335is flywheel is a typical bmw dual mass flywheel and the m4 unit while still listed as a dual mass did not have any noticeable play in it or even look like it was dual mass. It could be dampened internally but I could not be certain.

As you can see in the photos the weight difference huge 10.5lbs between the two. The flywheel bolted right up. I used new flywheel bolts and torqued to the m4 specifications. The two cars share the same bolts.

The Results:

I took before and after free revving videos at roughly the same operating temp and the difference is noticeable.

https://youtu.be/2gjf0byD6zQ

The car felt quicker after the upgrade, no more or less than expected. Worth the 300 dollars to me. I am hoping it will help my launches at the drag strip because I've been leaving too hard with the stock flywheel and 5k launch. I am also hoping this is easier on the rest of my driveline.

[Dave @ BMS/Fuel-It!]

Awesome write up!

[Newguy123]

Oh wow that's a good catch! Wonder if the n55 135i's are the same way?

[boostninja]

I would think so but you'll have to do your own research.

www.realoem.com is your friend

[007335i]

Need to get an "is" now.

[hustler71]

super
is this the bmw part nr 21212283829 ??
lean

[katsooba]

Originally Posted by Newguy123

Oh wow that's a good catch! Wonder if the n55 135i's are the same way?

i dont see why it wouldnt fit the N55 engine DCT if it is on the M2 DCT

now just to find one cheap and hope it would resolve the DCT slipping issues

[rhm135]

Nice! I would like to do this when I upgrade my clutch packs.

[A418t81]

Really slick idea! I hope to see more development and high HP 335ISs out there. While not great from a stop in current configuration, the DCT makes the 335 a roll-on monster.

[phil1320]

As mentioned on FB, thanks for the tip Terry!

I am pursuing the quest of building a high HP DCT 335is. Currently has Doc Race ST 6266 (may switch to 6466), ADE "1000 HP" intercooler, Fuel It Stage 3 Pump, ADE PI kit, Stett Stage 2 oil cooler, dif lockdown brace, TFT charge pipe, and HPF 3.5" exhaust. On order is MFactory LSD, MFactory axles, and custom MFactory D/S. Lastly, when I recoup from this debt, (planning for around March '17) M4 DCT flywheel and SSP clutch packs. Shooting for at least 800 hp

[katsooba]

What about the guys who dont have fb? ;-)

[phil1320]

That's why he posted his findings here

[thenewrick]

Interesting find. The question is does it make the drivability worse? I have put lightweight flywheels in manual transmission cars before and it made the car much worse to drive.

Have you noticed any difference in the feeling of how it drives or any issues?

As an aside, the clutch from the IS models fit on the regular 335i and work great. Very smooth and hold better than stock 335i clutch.

[phil1320]

Originally Posted by thenewrick

Interesting find. The question is does it make the drivability worse? I have put lightweight flywheels in manual transmission cars before and it made the car much worse to drive.

Have you noticed any difference in the feeling of how it drives or any issues?

As an aside, the clutch from the IS models fit on the regular 335i and work great. Very smooth and hold better than stock 335i clutch.

Drive ability should only be improved as the engine is able to rev up quicker and with less stress (easier). I've put a lightweight alum flywheel in my drag mustang that is a 6 speed and the only thing I could see that would make some people 50/50 on the swap is that the pedal is way too touchy. I'm used to it but at first it was difficult to get a hang of. Now keep in mind we are also talking the DCT trans in this topic. So this flywheel is not for the 6 spd and would also make it even easier to drive since there is no foot clutch. This also applies to the 335is clutch swap people do. That is from the 6 spd and not DCT clutch packs

[thenewrick]

Things are engineered for a reason. I'm curious how the drivability has changed and if any issues have arisen from the OP who's done the swap in their car.

[Newguy123]

Originally Posted by thenewrick

Things are engineered for a reason. I'm curious how the drivability has changed and if any issues have arisen from the OP who's done the swap in their car.

I can't wait to do this to my 135i. 11lbs is a TON of rotational weight to save!

[CharliesN54]

I would absolutely love to do this mod. And for the price you paid its an absolute steal. However in my effort to attempt to duplicate what you've done, the cheapest I can find the M4 DCT Flywheel is $1050.

[phil1320]

Originally Posted by CharliesN54

I would absolutely love to do this mod. And for the price you paid its an absolute steal. However in my effort to attempt to duplicate what you've done, the cheapest I can find the M4 DCT Flywheel is $1050.

You just have to keep your eyes open and look for people parting out wrecked M4 or try and find a junkyard that has one. It will be tough but it would be worth the find.

Like previously mentioned, 11 lbs of ROTATIONAL mass is a HUGE difference. Pair this up with a lightweight CF D/S and you will reduce quite a bit of stress on your drivetrain as well as freeing up some HP. (NO, neither mod will MAKE more power, it just reduces the amount of power the engine loses through the drivetrain. Please don't confuse this and flame me)

[katsooba]

Maybe Stephen from MFactory can chime in and give us a reasonable priced flywheel for the dct system?
Seeing they already make M/T lightweight flywheels for E8x E9x transmission
Maybe they can make some for our DCT transmission that are not bmw taxed

http://store.ycwengineering.com/cata...acing-flywheel

500$?
I am in!

[JGmerchant]

how much is a dct swap? I feel like it would be very costly

[andym3100k]

Originally Posted by ***sooba

Maybe Stephen from MFactory can chime in and give us a reasonable priced flywheel for the dct system?
Seeing they already make M/T lightweight flywheels for E8x E9x transmission
Maybe they can make some for our DCT transmission that are not bmw taxed

http://store.ycwengineering.com/cata...acing-flywheel

500$?
I am in!

I'm in too, let's get the ball rolling & if there are 10 or more people keen on it I think MFactory will for sure make 1 for us 👍.

Many benefits on the DCT flywheel, for those that are running Stage 2 turbo or high whp that has misfiring issues at or towards 6500rpm may all have their problem solved maybe. Being able to pull to redline is already a big plus point to all the hybrid or ST guy's!

[MFactory]

andym3100k has offered to send us his oem DCT flywheel for measurements.

If we can get at least 10 people on board (i.e confirmed with a 50% deposit), we can make our SMFW's for the DCT (will be same price as our MT SMFW's). Lead time around 2-3 months.

6-Bolt:
1) phil1320
2) Newguy123
3) ***sooba
4) Kish2604
5) Andy_N
6) artsoasis
7) Pure Turbos

8-Bolt:
1/2/3) andym3100k
4) Jeffrey (10/08 build date. To Confirm)
5) saddart (10/08 build date. To Confirm)

[katsooba]

well than let's get it going.

i am seeing on realoem that the e92 dct N54 and the 135i N55 flywheels are the same.

once you have the flywheel and samples, and have the the process confirms i might as well start the list

1. ***sooba
2.

[MFactory]

Will do

If you guys could help spread the word on the other forums/fb etc, hopefully we can get the 10 required!

[katsooba]

already spread the word on the other forum

lets get it going!