# Why switching to a single mass clutch causes chatter?



## Arnolds64 (Nov 13, 2009)

What's deal with switching out the Dual Mass Clutch and people saying it will chatter on our cars? I would imagine the older 1.8t's VW's had the regular Flywheel and it worked fine. So why do we hear this? Just wondering so I can decide what to do in the future. I did search and could not find much.


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## untitled (Jun 9, 2006)

i dont have the answer... it does chatter. It's livable though IMO


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## jbrehm (May 16, 2006)

The 'chatter' is actually gear lash – the small amount of 'play' in the gears rattling. The DMFW damps the power pulses from the engine, effectively 'smoothing' out the energy transmitted to the drivetrain. Several people report that a Fluidampr nearly eliminates the gear lash.


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## Arnolds64 (Nov 13, 2009)

*Chatter.*

Could it be the type of disk these guys are buying? I know the ferric Ceramic are horrible to try to use on the street no matter if you have the flywheel surface prepped. Tried one once 6 puck and it sucked. In or out it seemed. Could not slip it or the car would sound like it was going to shake apart. 

I wonder if most people that are changing over just are going overboard with race type clutches. I have always only gone like one step up. Maybe a slightly stronger pressure plate and a stock style disk. We have a low torque engine that does not need a huge clutch. So is it more in the selection? I did plug in some keywords different an found some better threads. One guy said he was not having an issue using Southbend.


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## Arnolds64 (Nov 13, 2009)

*Gear lash*



jbrehm said:


> The 'chatter' is actually gear lash – the small amount of 'play' in the gears rattling. The DMFW damps the power pulses from the engine, effectively 'smoothing' out the energy transmitted to the drivetrain. Several people report that a Fluidampr nearly eliminates the gear lash.


Here is a good article from a BMW point of view. http://www.uucmotorwerks.com/flywheel/gear_rattle.htm
In summary it speak about the fact that most gear rattle is from using solid disk like the original disk with a Regular solid flywheel. Anyone will tell you not to do this with any experience for a street car. Spring center will dampen the gear lash and especially with a lightened flywheel. So to compromise I think I will go with a heavier single mass flywheel and a spring hub. 

I have an old air cooled bug using a solid Kennedy disk, plate and 12lb flywheel. Different car but 30+ year old technology mated with late model and no chatter.


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## murTTer (Jun 27, 2009)

i actually had a 14lb flywheel and sachs clutch on my 180 and had no chatter at all. fwiw.


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## beetlevdubn (Apr 25, 2005)

murTTer said:


> i actually had a 14lb flywheel and sachs clutch on my 180 and had no chatter at all. fwiw.


That was because your 180 had a 5speed (unless there were some 180's that came with 5 speeds, but I didn't think so) this is only an issue with the 6speed 02M transmission. My 6speed S4 trans had a tiny bit of this as well. The worst was my 337 with a LWFW and LSD, but R32's, GLI Jetta's and TT's all suffer from the noise if a single mass FW is used, and is due to the gear lash as mentioned above.

Also, I have had the noise when running a sprung disc, and also with a rigid disc. There was no difference that I noticed between the two. The issue comes from the torque pulse dampening that the dual mass FW provides.


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## jbrehm (May 16, 2006)

Arnolds64 said:


> Here is a good article from a BMW point of view. http://www.uucmotorwerks.com/flywheel/gear_rattle.htm
> In summary it speak about the fact that most gear rattle is from using solid disk like the original disk with a Regular solid flywheel. Anyone will tell you not to do this with any experience for a street car. Spring center will dampen the gear lash and especially with a lightened flywheel. So to compromise I think I will go with a heavier single mass flywheel and a spring hub.
> 
> I have an old air cooled bug using a solid Kennedy disk, plate and 12lb flywheel. Different car but 30+ year old technology mated with late model and no chatter.



Sprung vs. unsprung hub is not necessarily akin to the DMFW vs. SMFW. A sprung hub clutch disc and a SMFW will_ not_ result in _no_ gear lash on a 1.8T. I've only heard of a handful of people that don't have chatter after they go SMFW, regardless of the clutch disc type. Playing with fluids and idle RPM can alleviate the condition somewhat, but you're not going to be able to eliminate it altogether. 





beetlevdubn said:


> That was because your 180 had a 5speed (unless there were some 180's that came with 5 speeds, but I didn't think so) this is only an issue with the 6speed 02M transmission. My 6speed S4 trans had a tiny bit of this as well. The worst was my 337 with a LWFW and LSD, but R32's, GLI Jetta's and TT's all suffer from the noise if a single mass FW is used, and is due to the gear lash as mentioned above.


FWIW, it's also an issue in many of the VAG 5-speeds.


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## murTTer (Jun 27, 2009)

beetlevdubn said:


> That was because your 180 had a 5speed (unless there were some 180's that came with 5 speeds, but I didn't think so) this is only an issue with the 6speed 02M transmission. My 6speed S4 trans had a tiny bit of this as well. The worst was my 337 with a LWFW and LSD, but R32's, GLI Jetta's and TT's all suffer from the noise if a single mass FW is used, and is due to the gear lash as mentioned above.
> 
> Also, I have had the noise when running a sprung disc, and also with a rigid disc. There was no difference that I noticed between the two. The issue comes from the torque pulse dampening that the dual mass FW provides.


I agree that it is due to back lash and agree that a dmfw is technically more for luxury, assuring that there is the least amount of noise made during shift. One less thing for the avg TT driver to complain about, bc lets be honest 90% of TT owners do not modify their cars nor to they care to hear the car changing gears of feeling torque pulastions through the tranny. I figured it was an 02m thing, but just having the 225QR for 2 months now and having not experienced this myself bc clutch was done w oem, I was just stating that chatter wasnt an issue in other applications or in my case atleast. This is good to know though for when a clutch upgrade is in order for the Roadster. 

Has anyone found anything that is better than the other? Preferably somewhere in the realm of stg2?


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## Neb (Jan 25, 2005)

I have a heavy single mass in my 180 5-speed. It chatters. I hate it. I opted to go with a stage 1 clutch kit from fourseasonstuning. I believes it's a 21lb flywheel too.


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## beetlevdubn (Apr 25, 2005)

Neb said:


> I have a heavy single mass in my 180 5-speed. It chatters. I hate it. I opted to go with a stage 1 clutch kit from fourseasonstuning. I believes it's a 21lb flywheel too.


When you say it chatters, are you saying it chatters upon engagement when driving, or it chatters when sitting at idle?


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## Neb (Jan 25, 2005)

chatters at idle.


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## beetlevdubn (Apr 25, 2005)

Wow, I have never heard a 5spd with SMFW chatter at idle, and I have been around a bunch. Have you checked your trans fluid? Maybe someone put really lightweight fluid inside, or its original.


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## jbrehm (May 16, 2006)

beetlevdubn said:


> Wow, I have never heard a 5spd with SMFW chatter at idle, and I have been around a bunch. Have you checked your trans fluid? Maybe someone put really lightweight fluid inside, or its original.


I dunno where you're hanging out; I've heard plenty (and owned a few)


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## beetlevdubn (Apr 25, 2005)

jbrehm said:


> I dunno where you're hanging out; I've heard plenty (and owned a few)


Maybe its the canadian 5speeds 

You learn something everyday, and I guess it makes sense since the 5 speed cars have DMFW's just like the 6 speed cars.


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## Neb (Jan 25, 2005)

Too bad the car is a US car that was imported


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## speed51133! (Aug 5, 2002)

I'm not sure you know what chatter is....
Are you talking it chatters while the car is out of gear and the motor is at idle?

i dont think that is really chatter. chatter is when you are in the process of engaging the clutch and it skips on the flywheel surface casing vibrations and chattering.

if it makes noise out of gear, it is NOT CHATTER, thats just loose tolerances.


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## ejg3855 (Sep 23, 2004)

FWIW the 5speed in the Quattro cars is 02M based. It has a few idlers and plastic space holders that keep it from being a six speed.

_This is my TT world pet peeve, everyone automatically thinks an 5speed means its a FWD car. They did make 180Q with 5spds_

The FWD cars have an 02J variant. 

I have a 7lb flywheel and a sprung 4 puck in my S362 car and it chatters but its not unbearable, get some good gear oil. Run a fluid damper and enjoy some quick revs.


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## Neb (Jan 25, 2005)

speed51133! said:


> I'm not sure you know what chatter is....
> Are you talking it chatters while the car is out of gear and the motor is at idle?
> 
> i dont think that is really chatter. chatter is when you are in the process of engaging the clutch and it skips on the flywheel surface casing vibrations and chattering.
> ...


I dunno, that's the only definition of chatter I've ever read about (being at idle)


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## speed51133! (Aug 5, 2002)

http://www.edmunds.com/car-technology/when-fact-meets-friction-the-basics-of-clutch-operation.html

Clutch "chatter" is often caused by an overheated clutch (normally from "slipping" the clutch when starting on an incline) or from oil on the clutch disk. 

or....

http://www.turbomagazine.com/tech/0407tur_clutch_tech_basics/index.html

Troubleshooting
T: What causes clutch chatter?
S: A high coefficient of friction, bad motor mounts, an incorrectly machined flywheel or faulty pressure plate, spring-centered race disc (aggravates chatter), and contamination (oil, grease, or rust).

Chatter is basically the engine winding up in the mounts as the clutch is engaging and then bouncing off the mounts, disengaging the clutch for a brief moment before engaging again and winding up again. No matter how aggressive a clutch is that would normally chatter severely on a normal street car, it generally won't chatter at all on a car with solid mounts and a rigid disc because there is no wind-up effect.



Read more: http://www.turbomagazine.com/tech/0407tur_clutch_tech_basics/index.html#ixzz1XNjBwaeL


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## jbrehm (May 16, 2006)

I explained what the SMFW 'chatter' is in my first post in the thread. Although, I do really think we should clear up the nomenclature, and start calling it what it really is – gear lash.


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## AudiMick (Sep 1, 2010)

Some of what you hear is chatter.

The other reason for the DMF is for Noise Vibration Harshess (NVH).

The DMF acts as variable speed noise damper for the motor, when the manufacturer specs a DMF he is trying to tame vibrations in both the drivetrain and inside the cabin. 

Now on a ten year old car, you might not worry about your "Big Gulp" sloshing around because of vibration. If the occasional fastener works loose it's probably OK.

If you looking at $40K + cars you might care.

The science of NVH is a big deal, manufacturers spend a lot of time on it.


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## R1_2fast4u (Sep 15, 2011)

I havE the same problem, but I don't know what to do with it. I I was planning on ordering a stock clutch with the flywheel.


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