Let's talk about dual mass flywheel failures

[Lex]

All of our cars come with an OEM dual mass flywheel (DMF) and all our cars are noisy around the transmission area.

The purpose of the DMF is to dampen vibrations from the engine going into the transmission and chassis. It also lessens loads on the transmission itself and reduces synchro wear. All good things so far.

The downside is that the springs get soft over time and sometimes fail altogether. I've had a noisy (what I thought was) throwout bearing since new and recently it's becomes worse. When disengaging a gear quickly under load such as pushing in the clutch when backing out of the driveway or after doing a slight burnout at the track, there is a distinct rattling from either the throwout or the DMF that dies out after a second or 2.

We keep on blaming the throwout bearings in these cars for rattles but the DMF might also be to blame for the rattles and noises in the transmission area. As they age, we will see more failures and it would be a good idea to list some of the symptoms of failure and failure modes so that people know what to look for.

Our flywheels are made by LuK.

For those of you that have swapped clutches, was the DMF failed? Was it seized? Was it loose?

LuK —|—Products —|—Dual Mass Flywheel (DMF)

3D animation of dual mass flywheel - YouTube

3D animation of dual mass flywheel - YouTube

[silvapain]

My dual-mass flywheel was fine when I pulled it out at ~70K miles. Loose, maybe, but every one I've pulled has felt loose, so I don't know if that's due to wear or that's how they are new.

[Lex]

Originally Posted by silvapain My dual-mass flywheel was fine when I pulled it out at ~70K miles. Loose, maybe, but every one I've pulled has felt loose, so I don't know if that's due to wear or that's how they are new.

Was your transmission noisy when engaging and disengaging the clutch? How was the throwout?

[El_Diablo]

My neighbor works for LUK (he's an engineer). Any data that you might need that I may be able to get?

[silvapain]

Originally Posted by Lex Was your transmission noisy when engaging and disengaging the clutch? How was the throwout?

No noise to speak of, and the throw out bearing functioned fine. The throw out bearing was a bit worn though if I remember correctly. I replaced it only because the clutch was slipping.

I still have my OE clutch, so if there are any pictures or videos you like me to take of it let me know.

[kritz]

So along this line of thinking a single mass fw might be accountable accelerated synchro wear.

Sent from fastest Ko4 Pu.

[silvapain]

I'm not sure how a DM or SM flywheel would impact synchro wear, because when the synchros are doing their job (shifting gears) the clutch is disengaged and the flywheel is not acting on the transmission.
@Lex; what are your thoughts?

[Lex]

Originally Posted by El_Diablo My neighbor works for LUK (he's an engineer). Any data that you might need that I may be able to get?

I would be interested if they rate the flywheels for torque load and longevity. Since it has a spring and moving parts there is a wear as well as a load factor. Ask him if this is the case. They probably have an internals part number for our FW, let me know if you need the Mazda specific one.

[Ziggo]

@Smelson;

I had no issues with the stock clutch, besides it's ability to hold torque once things got hot. But I can confirm the regular act lightweight flywheel makes plenty of noise with the clutch out in neutral. Sounds almost like a ducati

Zigatapatalka

[Lex]

Originally Posted by silvapain I'm not sure how a DM or SM flywheel would impact synchro wear, because when the synchros are doing their job (shifting gears) the clutch is disengaged and the flywheel is not acting on the transmission. @Lex; what are your thoughts?

This is simply based on the fact that there is less coupled mass to be "synchronized" if the clutch is made without dampening springs. Our clutch has dampening springs.
Has anyone used an aftermarket clutch with the OEM DMF?

[8.5MS3]

the springs in mine were shot

a local shop rebuilt it with better springs, it requires special tooling but it can be done

[El_Diablo]

Originally Posted by Lex I would be interested if they rate the flywheels for torque load and longevity. Since it has a spring and moving parts there is a wear as well as a load factor. Ask him if this is the case. They probably have an internals part number for our FW, let me know if you need the Mazda specific one.

I'll ask him next time I see him (probably not tonight).

[Tenchix]

When I did mine in my ms6 @ 92k miles it was shot to hell, If I can find it I have a video of it just clunking around when we moved it by hand. A black disk fell out of it in tiny piece and there was a lot of black dust, not just from the clutch. And it felt like there was no springs in it. When it went bad the signs where, grinding of gears, it was really hard on 2nd gear. And in about one week you could not drive it, to save your life.

[Tenchix]

And I remember every time I put the clutch in you could hear it chattering away.

[skiptowncat]

Originally Posted by Lex This is simply based on the fact that there is less coupled mass to be "synchronized" The transmission is coupled to only half a flywheel so there is less coupled mass and thus inertia when changing gears. Has anyone used an aftermarket clutch with the OEM DMF?

Using an organic compound clutch I bought from eagle motorsports before they got banned from here. I'm on 75k now, about 20k with the em clutch. All feels well at the minute.

[silvapain]

Originally Posted by Lex This is simply based on the fact that there is less coupled mass to be "synchronized" The transmission is coupled to only half a flywheel so there is less coupled mass and thus inertia when changing gears. Has anyone used an aftermarket clutch with the OEM DMF?

When the clutch pedal is pressed, the flywheel and pressure plate rotate with the engine and only the friction disc rotates with the transmission.

[Lex]

Originally Posted by silvapain When the clutch pedal is pressed, the flywheel and pressure plate rotate with the engine and only the friction disc rotates with the transmission.

You're absolutely correct - not sure what I was imagining when I wrote that.

The lighter assembly is the clutch itself. Ideally by moving the dampening springs to the flywheel the clutch disc can be made either without the springs or with much smaller ones since it doesn't have to dampen nearly as much of the torque shock.

Our clutch does have springs - not sure if it would be lighter should the flywheel be solid.

[Bobforapples]

I actually have my old clutch, pp, and DMF from the recent swap. I'll get the Canon out tomorrow to take pics.

The disk and flywheel are actually in pretty good shape. Still noticeable grooves on the disc, no heat spots. My rear main however was toast and there was oil all over the inside of the bell housing.

and @Lex; good call on the recommendation. Loving it so far, but still in break in mode.

[Lex]

Originally Posted by Bobforapples I actually have my old clutch, pp, and DMF from the recent swap. I'll get the Canon out tomorrow to take pics. The disk and flywheel are actually in pretty good shape. Still noticeable grooves on the disc, no heat spots. My rear main however was toast and there was oil all over the inside of the bell housing. and @Lex; good call on the recommendation. Loving it so far, but still in break in mode.

Keep an eye on the slave cylinder with the new clutch. They do tend to go so if starts to feel soft look for leaks.

[sidekick]

I've always wondered if my clutch feel/shifting issues are related to my dual mass flywheel, but obviously that involves taking it out to diagnose. Lol. A service advisor at Mazda told me that there are rubber parts in the dual mass flywheel that actually melt/fail. Is there any truth to that? I've never seen pictures of our OEM flywheel.

[Bobforapples]

Originally Posted by Lex Keep an eye on the slave cylinder with the new clutch. They do tend to go so if starts to feel soft look for leaks.

Yep that actually died before we could even test drive. Ended up having to wait another 4 days to get the red boot one, and then almost had to wait again because of the seal on the hard line.

[Design]

So what's the consensus of this board when it comes to the DMF? Are we finding it's generally worn to the point it needs springs or a full replacement? Or are some of you just swapping the PP/disc with decent results?

I think we all agree it's going to vary by user/environment. Just trying to get an idea of what the typical results have been to date.

[Lex]

I think I would go by mileage and how worn the friction surface is. That and how willing are you to do the job twice.

[Nliiitend1]

I do sort of wonder how good of an indicator the condition of the friction surface is for the purpose of assessing DM flywheel wear (when it comes to the springs and internal mechanism at play)...

I'm not quite sure what I'm going to do when the time comes to replace my clutch... Like most folks, I don't really want to spend ~$1200 on a new OEM flywheel, but I'm also not sure I'd like a Fidanza and I don't know that I'd reuse the original once it's approaching 100K miles of hard use...

[Design]

My experience with BMW tells me it's hit or miss. As a general rule, anything with 100K or more should get replaced. But at nearly 1K, risking another 6 hrs/$500 in labor makes it "almost" worth it.

And to the above point, there really is no suitable heavyweight replacement for our cars.

[sidekick]

There should be some specs in the shop manual for the the amount of play in the springs, to indicate reuse/replace. However, if I end up doing my clutch, I will not even consider reusing mine or purchasing a new OEM DMF. ACT Streetlite is steel and only a few pounds lighter than stock, so you won't end up with as much chatter as going with a lighter/aluminum flywheel. There will be some chatter and possibly more vibration, but it's kind of a moot point when a lot of us are fully mounted anyways. DMFs really only matter if you're going for as little NVH as possible, which is why OEMs use them. With all of the people running aftermarket flywheels on here, I'd think we would see more transmission issues if it was really significantly reducing drivetrain stress. In fact, a bad DMF will probably be even worse than an aftermarket SMF.

[Design]

The lack of damping on the SMF is enough to steer me away. The clutch face on these cars is non-linear enough without introducing further rigidity. And the extra 10% in weight makes a world of difference when calculating inertia at 1K RPMs or more. I imagine slightly higher RPMs would get around many of the issues. But for a typical DD they are often more headache than they're worth.

[sidekick]

Originally Posted by Design The lack of damping on the SMF is enough to steer me away. The clutch face on these cars is non-linear enough without introducing further rigidity. And the extra 10% in weight makes a world of difference when calculating inertia at 1K RPMs or more. I imagine slightly higher RPMs would get around many of the issues. But for a typical DD they are often more headache than they're worth.

This is why I recommended a steel SMF. Steel is much less rigid than aluminum, so will still give you some vibration dampening. A 5lb difference should not affect driveability very much. I'm not sure what you mean by "non-linear" in terms of the clutch face. There are still dampening springs in the clutch hub as well.

I used a SMF to replace the OEM DMF in my old GTI, it was about half the weight and aluminum. It was noticeable when leaving a dead stop, but other than that, it wasn't noticeable. It just meant feathering/slipping the clutch a little more. I can't imagine a 5lb drop is going to make a significant difference. Especially considering these engines make about 3x as much torque as my GTI did.

[Lex]

On older Porsches replacing the DMF with a SMF caused some crank failures due to the lack of dampening but I haven't seen that here.

[sidekick]

Originally Posted by Lex On older Porsches replacing the DMF with a SMF caused some crank failures due to the lack of dampening but I haven't seen that here.

It's definitely possible, I just think we would have seen some failures by now with all of the people running super light flywheels and beating the shit out of their cars. Lol.

[Design]

Originally Posted by sidekick This is why I recommended a steel SMF. Steel is much less rigid than aluminum, so will still give you some vibration dampening. A 5lb difference should not affect driveability very much. I'm not sure what you mean by "non-linear" in terms of the clutch face. There are still dampening springs in the clutch hub as well. I used a SMF to replace the OEM DMF in my old GTI, it was about half the weight and aluminum. It was noticeable when leaving a dead stop, but other than that, it wasn't noticeable. It just meant feathering/slipping the clutch a little more. I can't imagine a 5lb drop is going to make a significant difference. Especially considering these engines make about 3x as much torque as my GTI did.

I'm not sure how the engagement is with other flywheels, but my experience with driving the Prolite on an MS6 suggests there is much less forgiveness. But I'm not sure how much of that is attributed to the accumulative wear in my own clutch/flywheel. As far as weight, yes I'm referring solely to engagement from a stop. And I do a lot of stop & go here in So Cal. A 10% delta can be significant as torque is only around 60 lbs from a stop in normal driving, IMO.

The writeup in this thread mimics my own conversations with fellow 3 series owners (though a bit more technical). Most agree if you can afford it, get the DMF for a DD:
OEM Dual Mass Flywheel Or Exedy Single Mass Flywheel - MINI Cooper Forum


To your point, I completely agree that a steel SMF is a MUCH better option over aluminum.

[sidekick]

Originally Posted by Design I'm not sure how the engagement is with other flywheels, but my experience with driving the Prolite on an MS6 suggests there is much less forgiveness. But I'm not sure how much of that is attributed to the accumulative wear in my own clutch/flywheel. As far as weight, yes I'm referring solely to engagement from a stop. And I do a lot of stop & go here in So Cal. A 10% delta can be significant as torque is only around 60 lbs from a stop in normal driving, IMO. The writeup in this thread mimics my own conversations with fellow 3 series owners (though a bit more technical). Most agree if you can afford it, get the DMF for a DD: OEM Dual Mass Flywheel Or Exedy Single Mass Flywheel - MINI Cooper Forum To your point, I completely agree that a steel SMF is a MUCH better option over aluminum.

Prolite: 15.7lbs
Streetlite: 21.4lbs

The prolite is over 10lbs lighter than stock, IIRC the stock DMF is somewhere between 26-30lbs. "Forgiveness" in a clutch setup is generally related to how aggressive the clutch material is and the clamping force of the pressure plate.

[Design]

Yeah I'm aware of the weight difference but wasn't aware it was a whole 10 lbs lol. OEM Flywheel is just over 26 lbs (opposed to 30). And for some reason I thought streetlight was more like 23-24. Guess not?

I still think any difference - however small - is going to impact driveability in stop & go. On the Civic EM1, many of my peers went with the Exedy HF01 flywheel while I stuck with Exedy OEM (Daikin). It was only a 15-20% delta. But matched with low end torque from the B16, it was tough to engage from a stop without chatter.

Our cars aren't much better outside boost. We need the inertia, IMHO.

[Bobforapples]

FWIW, with @Lex; recommendation for the ACT Street kit and street lite flywheel, I've been very impressed. It was noticeably stiffer the first 100miles, but now @ 500mi the pressure, release point, and engagement feel near to stock. Now my leg could be used to it, but it engages and slips exactly like OEM to me.

There is chatter, but it's only noticeable when engine braking. I don't hear it cruising w/o music. Only a 88a RMM atm.

[toadatx]

I had mine fail at 70k. The symptoms were huge vibration (imagine vibration bad enough that you couldn't see clearly in any of the mirrors/dash moving up and down ~1") It was startling. I had the clutch replaced at the same time but it was in relatively good condition. I Autox'd the car very frequently and wonder if the extended high rpm/bouncing redline activities led to the failure.

[sidekick]

Originally Posted by toadatx I had mine fail at 70k. The symptoms were huge vibration (imagine vibration bad enough that you couldn't see clearly in any of the mirrors/dash moving up and down ~1") It was startling. I had the clutch replaced at the same time but it was in relatively good condition. I Autox'd the car very frequently and wonder if the extended high rpm/bouncing redline activities led to the failure.

Hmmm, were the vibrations felt in the clutch pedal at all? Makes me think my issue really is related to my flywheel.

[smr87]

I have the ACT Street Disk and Prolite Flywheel. My driving style has changed but it isn't like driving a triple disk or anything. You lose revs between shifts much quicker and it doesn't care for reverse with the clutch fully engaged. But otherwise it is perfectly steetable.

The car sounds like a mix between a tractor and a dry clutch Ducati at idle with the clutch out, because racecar.

I have all my stock setup, Ill take a look at the stock flywheel and see if anything is amiss.

[toadatx]

Originally Posted by sidekick Hmmm, were the vibrations felt in the clutch pedal at all? Makes me think my issue really is related to my flywheel.

I had. JBR 88 side mounts and the chromoly rear. The vibes could be felt from 3 cars away. When we removed the flywheel the outter plate was askew from the rear disk. I'm surprised the motor lasted another ~15k after the fix (I drove the car to nationals in Lincoln, from Austin, raced it and drove back with it acting like this. No time to fix it )

[Absolut1l]

Not sure how much this will help but... The day after I bought my MS6 with 72k miles, the clutch went out. I never got a chance to look at the DMF.. But I saw the PP and it was literally broken/cracked. The dealer replaced it for free, so they got to choose what clutch to put in it. They chose a Clutchmasters FX100 kit that came with a lightweight aluminum flywheel. 10,000 miles later, my car is in the shop getting a new transmission and clutch. Before I took it to the shop, the car was hopping around and making an awful loud racket coming right out of the transmission/bell housing. Maybe it was me constantly shifting like a noob due to the absurdly heavy clutch pedal, or maybe the setup just wasn't ideal. But I've been through hell so far and will soon have a 3rd clutch in my car in barely over a year.. I purchased a South Bend Stage 2 clutch kit that will go in next week. I also didn't want to pay $1200 just for a new stock flywheel. And I didn't want to keep that ridiculously loud flywheel or ridiculously heavy clutch pedal either. The SB kit has a custom Steel flywheel. So in a month or so I'll be able to chime in on all 3 types of flywheels on this car. I'm really hoping the steel SMF is a good compromise between the DMF and light weight SMF. I can say that the stock DMF was far quieter than the SMF I had. Oh, and I am on all stock motor mounts. (for now)

[Jeff23spl]

mine just went out 2 weeks ago...73k miles. The oem clutch wasn't slipping at all even when i spin the tires

the TOB noise was there since 1-2 years right after stiffer mount install. I wasn't concerned that much because 88duro bring some noise but 2 weeks ago, after few WOT in 4-5 gears, a heavy vibration and rumbling noise appeared. I drove back slowly to home and was sure something expensive went out!!!
i checked axles, tranny oil and decided to remove the tranny and check it believing main bearing inside tranny was shot.
Tranny removed, i touchecd the FW and was afraid it fall out without removing the bolts...! The PP + halft the FW was loose on the crank like if the crank bolt was 3-4 turns loose. The PP forks are worn not evenly, the disc is worn but the slipping surface isn't blue or uneven. Jus the FW have so much play in all ways that i believe it was almost going to have the second part to ''fly'' away from the other if i kept driving it!!!

I can move it up and down of about 3/8'' but the play in the rotation movement isn't that much, just 5-6 teeths.

My pilot bearing is completly destroyed, the tranny input shaft was no longer supported.

I just don't know if the pilot bearing broke first and make the FW to go loose or if the FW broke the bearing by vibrating that much...

Anyway i need to put something new and i don't know yet is i want 1 piece or DM???