Dual Mass or Single Mass Flywheel

[jbfrancis3]

Most people here go with DMF due to NVH. How much NVH are we talking? In reading jbfrancis3 thoughts on Rogue Engineering's SMF conversion and associated clutch kit (steel 14lb flywheel), that's my strong lean. But is this the same level of NVH introduced by say... solid diff bushings? Or Supersprint Race exhaust? Or is this more of an annoyance / rattle at idle?

Let's separate the N from the V from the H...

The N is there in the form of a rattle at idle. You will hear it outside the car up to, say, a 20 ft radius (pulled that out of dark place but you get the idea). There is no V, nor is there any H. That means there is no chatter on initial engagement; the engagement is perfect. I'm speaking to my experience with the RE SMF that uses the 14 lb steel flywheel and their clutch kit. I also like their braided SS clutch line (sold separately) - one of 3 I purchased that was actually sufficiently long enough.

[strummr]

heck, the noise/NVH of a SMF can't be as bad as sitting in traffic with a race-prepped Ducati 999 with the unnaturally loud clacking of a dry clutch with an open, carbon cover - and race headers/pipes to open baffled carbon cans... or full 90mm titanium exhaust system going from catless dps > to titanium quad mid pipes > to quad 102mm tips, with another variation of unnatural clacking/whizzing/robot sounds coming from an all billet geared, ShepTrans built transaxle (R35 alpha 12+ GTR). Back to the thread topic though, I also want to get an idea of how much noise from a SMF... yes, it will be louder DMF, but can someone with recent experience quantify the difference? (every bike and car I've owned beyond the trucks/dailys have had major mods... so noise is relative) My Dinan M3 is getting close to clutch replacement time... and it already has all kinds of wacky noises (uneven idle, dual pipe SS and Dinan exhaust, squeaks coming from the KWs...etc.).

[Syfon]

If you're really that concerned with NVH levels, stick with the stock DMF and (maybe) an aftermarket clutch if you do tend to give it a hard time.

If the NVH component doesn't really bother you (and let's be honest, do you really sit idling clutch out for extended periods?), then go with an SMF and sprung hub clutch disc,

Recently during a hot evening (35c+) I took mine through a McDonald's drivethru. The rattle was loud enough to make everyone else close their windows hahaha. It kinda bothered me but not enough for me to care ahaha.

IMHO the benefits an SMF adds vastly outweigh the extra NVH.

[fourmula1]

DMF unless you are tracking it most of the time and/or need the performance gain from an aftermarket light weight flywheel & clutch assembly. The lightweight-single will make noise/chatter.

That said I do have a Clutchmasters FX350 assembly for sale...installed but like brand new. It will chatter a bit.

[maupineda]

DMF outperforms SMF from an NVH standpoint, even GT3 Porsches have it as an option for a reason. Clutch wear is very dependant on driving habits, I have had manual cars that lasted me 200K km (125K miles), one I recall was my Clio 172 sport, which was cammed and I tracked a couple of times and when we took the clutch out it was still fine, I would say it would last another 50-70k kms. Most people DO NOT know how to drive and abuse the clutch much, just go with OE and as long as you know how to drive a manual transmission it will outlast many other things on the car. In fact, I think the throwout bearing would wear sooner.

[Casa de Mesa]

So not quite the oil debate or air pressure debate or SMG vs. ... you get the idea. But rehashing this debate: DMF vs. SMF.

Took my motor out this weekend, then detached the tranny (that's the easiest way to change the clutch, right?). My dual mass flywheel / DMF is toast - it rotates easily by hand side-to-side along the rotational direction of the crankshaft, as well as having some slop fore and aft. As a result, my clutch is super toast. I will upload photos from my phone as soon as I post this from my laptop.

Most people here go with DMF due to NVH. How much NVH are we talking? In reading jbfrancis3 thoughts on Rogue Engineering's SMF conversion and associated clutch kit (steel 14lb flywheel), that's my strong lean. But is this the same level of NVH introduced by say... solid diff bushings? Or Supersprint Race exhaust? Or is this more of an annoyance / rattle at idle?

Some NVH doesn't bother me and I actually prefer it within limitations. By the same token, this DMF last 74k miles. First owner of the car sold the car due to a hip replacement, so I can't help but wonder if the clutch suffered along with that owner. But 74k miles is pitiful for a flywheel.

I'm not greedy. I'm good with one mass rather than two.

-Casa

Pics:

[Syfon]

In reply to what clutch to pair with JB Racing Aluminium Lightweight Flyhweel - Phill @ Bimmerworld recommended the Clutchmasters FX100 (Sprung Hub). This is what I'll be installing.

[Syfon]

OP FWIW I'll be installing a JB Racing Aluminium Lightweight Flyhweel with a Clutchmasters FX100 (Sprung Hub). I'm currently assembling my motor and awaiting a few parts, so I won't get to drive it for a few months with the new setup (also includes AutoSolutions 20% kit, and csl airbox and cams haha).

I few people have the same setup and said it chatters, however they don't mind. My M3 is a weekend toy so I don't really mind the extra noise. Besides, the exhaust is very loud lol.

It will be interesting to see how the engine characteristics change with the lightweight flywheel.

As for mounts, engine/trans/diff are brand new oe components & subframe is solid aluminium.

[Ob917]

I have the 14lb steel SMF sprung clutch and a raised idle. I think if you need a quite idle you will need a flywheel with about the same mass as the stock DMF. There should be a marginal performance gain in feel if you could find a SMF that has the same mass but probably not worth it. But man the lighter weight setup works great when you want to drive it hard.

[rcarson25]

I think the 14lbs flywheels are considered the middle
ground as the aluminum ones are closer to 10 or 11lbs. I was hoping people had good experiences with the 14lbs steel flywheel and a sprung clutch plate to provide a more stockish feel with the reduced weight and cost of the single mass flywheel.

I agree, it seems there would be good demand for a kit that works well for non racers that want a little bit more performance and a smooth ride.

[digger]

fancy oil or llnkages aint gonna stop the transmission rattle at idle with really light weight stuff.

I dont see why there isnt a moderate weight OE cast iron SMF (somethign from the big six or something) and sprung clutch that would work acceptably well with raised idle

[Rich022]

Your best bet sounds as though a 'heavy' steel flywheel + sprung clutch/close to stock + increase your idle rpm's gives you the best chance of no chatter. Bimmerworld website under clutches has some good links that explain what's going on/causes chatter etc..i have SMG and don't want any potential issues/chatter etc. so went the safe route and ordered the LUX DMF and stock clutch. Lots of parts arriving for plans of tranny swap (experiencing 4th gear synchro grind)... keeping the SMG..

[SteelGreyM]

What clutch would work with my JB racing lightweight aluminum flywheel?

It’s designed and advertised to work with the stock clutch and pressure plate however I’ve learned twice now that it just doesn’t work due to the lack of vibration absorption of the setup.

So essentially who knows what sprung hub after market clutch would bolt up to my JB Racing flywheel? What do I look for to get as close to OEM feel?

And to answer your question op: I ran the above mentioned flywheel for about 15k miles when I learned about my situation on my second broken pressure plate. I opted to try the OEM flywheel setup for a change and it was quite the difference. My flywheel was exceptionally light and it would almost let the engine die on idle sometimes because it didn’t have enough mass to keep the engine spinning. It was embarrassingly loud at stoplights. It honestly took the car to a new level though. The shifting is an absolute blast with a lightweight flywheel. The chatter does really get to you though. So I wouldn’t run it on a daily.

[Amalgam]

I'm running the full face ACT clutch and flywheel package and I love it.

-In gear acceleration for 1st/2nd quicker. The car really comes alive above 3k and pulls hard until redline.
-The exhaust sounds a tiny bit different as it moves through the range quicker.
- Downshifting, the revs come up a little faster, but not a super dramatic change.
-The clutch pedal is firmer, and I do like the increased feel.
-The engagement is not choppy or harsh, and feels similar to the stock clutch.


There was a rattle in neutral, but I've bumped my idle to 950 and it sounds like stock inside the car now.

[T.J.]

Everybody has a different tolerance for noises. And as said above, other mods like mounts and shifter upgrades play a large role as well.