Dual mass flywheels - signs of failure?

[pugwash4x4]

fitted a solid flywheel to my st170- got it chattered in idle after that. Got so bad that i took the solid flywheel out and put a brand new DMF from LUK back in- ahh much nicer.

would hvea stuck with a solid for a track car, but as an everyday car i was happy with neither the sounds nor the potential wear on the gearbox.

[red21]

Aftermarket have just done a article on DMF's. Go to pages 9-12
http://www.browse-and-read.co.uk/aftermarket/2011-...

[mybrainhurts]

red21 said:

Aftermarket have just done a article on DMF's. Go to pages 9-12
http://www.browse-and-read.co.uk/aftermarket/2011-...

Blimey...

[Old Merc]

Old Merc said:

I`ve always been anti DMF and suggested here fitting solid flywheel/clutch kits , BUT...Since talking to a very knowledgeable motor engineer this may be not a good idea?? apparently there have been a number of cases,(Skoda snapping a crankshaft and a VW cracking a gearbox)blamed on converting from DMF to solid!! saying these engines are designed around a DMF. Any comments on this guys??

My friend must have seen this article?Consider me re-educated? and I`m now sure its not a good idea to replace a DMF with the "solid kits".its just a shame that they give trouble early and are so expensive to replace.

[anonymous-user]

So when a bloke who actually designs and develops engines for a living says "DMF's - you really want to leave 'em on" no one blinks and eyelid, but once some ropy trade magazine has a 1 pager on the subject then suddenly everyones converted...... lol!

[buggalugs]

The article helped me to understand a bit better what they do vs. a sprung clutch plate - when you've got a modern turbo diesel 4-pot making some crazy amount of torque at 1500RPM, each pot firing is a fair old kick in the nuts for the gearbox and a plain sprung clutch doesn't have the range to smooth that out. But a DMF has a lot more range and puts the flywheel on the other side of the springing too so I can see how that helps to deliver a smooth line of torque to the gearbox, vs. a solid one where the gearbox gets a kick in the nuts every time a pot fires at low revs. Hence people complaining about gearboxes starting to make strange noises when DMF's are deleted.

But if that's right, do V8's and V12's still need or get fitted with DMF's? As the torque output will be a lot smoother?

[Slinky]

Max_Torque said:

So when a bloke who actually designs and develops engines for a living says "DMF's - you really want to leave 'em on" no one blinks and eyelid, but once some ropy trade magazine has a 1 pager on the subject then suddenly everyones converted...... lol!

Welcome to the internet...

[red21]

Max_Torque said:

So when a bloke who actually designs and develops engines for a living says "DMF's - you really want to leave 'em on" no one blinks and eyelid, but once some ropy trade magazine has a 1 pager on the subject then suddenly everyones converted...... lol!

I am with you regards DMF's
We just reap the rewards when things start breaking due to a lot of mis-information.

[stevieturbo]

Max_Torque said:

So when a bloke who actually designs and develops engines for a living says "DMF's - you really want to leave 'em on" no one blinks and eyelid, but once some ropy trade magazine has a 1 pager on the subject then suddenly everyones converted...... lol!

So these flywheels appear to be important for diesel engines designed to need them.

What setup does a DSG VW use ? Does it have a DMF ?

[les3002]

I run the solid M20 flywheel on my E36 328i, no chatter at all, drives much nicer than with the DMF, although I've never driven it with a brand new DMF so who knows.

I would definitely recommended it, I always found taking off and the change from 1st to 2nd difficult to do smoothly in my car but it's much better now.

Edited by les3002 on Friday 18th February 12:58

[Mark34bn]

les3002 said:

I run the solid M20 flywheel on my E36 328i, no chatter at all, drives much nicer than with the DMF, definitely recommended.

Can you give us a quick rundown on which components are used, and which are different to std. What clutch etc?

Cheers
Mark

[buggalugs]

Mark34bn said:

les3002 said:

I run the solid M20 flywheel on my E36 328i, no chatter at all, drives much nicer than with the DMF, definitely recommended.

Can you give us a quick rundown on which components are used, and which are different to std. What clutch etc?

Cheers
Mark

It's a common swap on M5x engines. M20 2.0 or 2.5 flywheel & bolts, M20 starter, M20 2.5 clutch. You might need to either mod the clutch release fork, use an e30 323 release bearing, or mod the slave cylinder depending what gearbox & clutch slave combo you've got. You will also need to either have some material removed from the back face of the flywheel or take a grinder to take a few mm one of the protrusions on the back of the block where one of the sump bolts comes home. It only takes a sec, when you try and bolt it up you'll feel where it hits and can keep shaving it and trying again, no biggie.

It makes the engine a bit quicker to gain & loose revs, and you might pick up a tenth or so in acceleration in 1st. Downsides I found are that the clutch action doesn't seem as nice, it takes a little while to get smooth with the gearchanges again, and my box makes a slight gravely noise accelerating below about 1300rpm only audible from outside the car. That could just be my box though, I did only pay 30 quid for it.

[les3002]

Tbh I found the clutch action better.... maybe my dmf was knackered beforehand. Performance wise I can't really tell any difference, not to say there isn't any though.

Here's the parts I used:

M20 Flywheel
M20 Clutch and release bearing
M20 Flywheel and clutch bolts
M20 Starter motor

All the guides on the net say to use an e21 release bearing but I just used the one that came with the clutch and it's spot on. The guides also say it's possible to mod the e36 starter to use the e30 ring gear but I tried that and it doesn't work.

Other than that as mentioned above I had to grind a few webs slightly on the back of the block.

[great2cyou]

Just had a VW T5 in with a "seized engine"

Locked solid. Could not move it rocking the car in gear. But if you pushed the clutch, van would roll.

Sump off, nothing obvious. Cam not moving either. Decided the belt must have jumped. Head off. Valves ok.

Still solid. Took the engine out leaving the gearbox behind. Did not want to split, but when we did get it apart we found that the DMF had 'exploded' through it's outer edge, gouged out the bell housing until it jammed solid!

Bugger. One to remember! Will have to wait and see in anything else was damaged, crank etc, although no way of knowing except putting it back together and road testing it I guess.

[mcford]

It must have looked something like this:





That came out of a not very high mileage 5 year old Skoda diesel.

[stevieturbo]

Surely that's warranty territory regardless of age or mileage ?

That sort of failure isnt just dangerous, it could be lethal !!

They might need to be fitting SFI approved steel bellhousings next !

[neiljohnson]

stevieturbo said:

Surely that's warranty territory regardless of age or mileage ?

That sort of failure isnt just dangerous, it could be lethal !!

They might need to be fitting SFI approved steel bellhousings next !

Its a thought i pulled the carpet out of an Bmw a while back looking for a water leak & found part of a dual mass lodged in the floor (not the cause of the leak) from a failure when we looked undernaeath there was a fair bit of damage to the cars floor so it must have destoyed the gearbax bellhousing!!

[AcidReflux]

stevieturbo said:

Surely that's warranty territory regardless of age or mileage ?

"Oh, they all do that, sir."

[leerees]

My Audi A4 (B6) makes a slight warbling noise as you pull away. After reading all these horror stories I immediately assumed it must be the DMF.

Took it to one garage, he said clutch / DMF could be on it's way out (despite no clutch slippage). Took it to quick fit, they said nothing wrong with it. Took it to a 3rd garage and he said it doesn't sound like DMF failure and that I should carry on driving and bring it back if the problem gets worse.

It's like a slight warbling sound, it does it on idle, it's not mega loud but if you listen carefully it's there.

I'm wondering what to do now, I don't want to spend £600 on a new DMF + clutch only to find the fault is still there. Both garages have quoted £600 including parts, which isn't too bad (for an Audi), quick fit quoted £700.

Edited by leerees on Thursday 10th October 14:31

Edited by leerees on Thursday 10th October 14:33

[Mikey G]

leerees said:

My Audi A4 (B6) makes a slight warbling noise as you pull away. After reading all these horror stories I immediately assumed it must be the DMF.

Took it to one garage, he said clutch / DMF could be on it's way out (despite no clutch slippage). Took it to quick fit, they said nothing wrong with it. Took it to a 3rd garage and he said it doesn't sound like DMF failure and that I should carry on driving and bring it back if the problem gets worse.

It's like a slight warbling sound, it does it on idle, it's not mega loud but if you listen carefully it's there.

I'm wondering what to do now, I don't want to spend £600 on a new DMF + clutch only to find the fault is still there. Both garages have quoted £600 including parts, which isn't too bad (for an Audi), quick fit quoted £700.

Edited by leerees on Thursday 10th October 14:31

Edited by leerees on Thursday 10th October 14:33

Last A4 I diagnosed with DMF failure the customer was complaining of a small rattle in 2/3rd gear when he was lightly accelerating or at a cruise in that gear. When out of gear at idle it was silent, but if you picked the revs up there was a clanging sound as if someone was hitting the bellhousing with a hammer. Removing the little inspection panel underneath revealed metal particles assumingly from the DMF clanging around...