Dual mass flywheel?

[Tight fart]

Can someone explain to me what they do?

what advantages do they have as they seem to fail quite a bit

 

A7 RDP pics here

 

Edited by - Tight fart on 17 Oct 2009 15:15:55

[jingars]

Currently I am having DMF / clutch issues with my Ford Galaxy. I found The Citroen C4 owners forum to have a helpful overview.

[MADMALC]

I too have some issues and looked on a manufacturers web site and was amased to find that they are considered a 'service' item. Life expectancy of 80,000 miles then hey presto another 'profit' opportunity for the dealer to go along with timing belts and brake discs.

 

S7MAD

[geko]

Hi,

 

something to read:

here

 

 

Best regards

Gerhard

 

Caterham CSR 200

MAZDA MX-5, NB, 1840ccm

[SLR No.77]

We have a Mercedes Vito van - dual mass flywheel/clutch broke up at 47000 miles 😳 £1000 repair job Strangely, since being repaired it runs better and smoother than it's ever done!

 

Stu.

 

---

Joint Area Representative MAD Sevens (Merseyside And District)

www.superse7ens.co.uk..........the rebuild 😬

 

 

[I.Mupferit]

You should ask Crudders what he thinks of the DMF's he has had replaced on his 18 month old SEAT if you want an honest opinion. *eek*

 

 

[AMMO]

Horrible things. I've stuck loads of Duratec ones in the skip. They weigh something like 14 kilos. They have bits of plastic in them that look like they are looking for an excuse to break.

 

We had a big Toyota 4x4 at work that had lunched its DMF. It was cheaper to make a steel flywheel in the workshop (not particularly cheap) than it was to buy a new flywheel from Toyota.

 

The car ran smoothly on the new steel flywheel, the customer was very happy in the knowledge he had saved money and it would not happen again.

 

 

 

 

 

Ammo

Raceco.com

[Crudders]

You should ask Crudders what he thinks of the DMF's he has had replaced on his 18 month old SEAT if you want an honest opinion.

 

I fear my honest opinion put into print would look similar to one of Brent's more colourful rants - more asterisks than words

 

To summarise a very long, tedious and will-to-live sapping story, between 3,000 and 9,000 miles I was banging my head against a brick wall trying to get the dealer to admit there was a problem, by 16,500 miles DMF number 3 had gone in, 17,000 miles to date we're back to square one with me in possession of a car that is torture to drive and the dealer coming out with the usual "NWWT", "TADTS" etc. male bovine feeshus 😔

 

To answer TF's original question, the DMF is essentially two flywheels separated by springs, providing a cushion between the engine and transmission. What it actually does is introduce a hideously complex and expensive consumable component into the drivetrain which has totally p1ssed off untold car owners and cost manufacturers millions in warranty claims. My experience of multiple low mileage failures appears to be far from unique.

 

@ AMMO - ISTR that the unit fitted by Ford is the same LUK unit fitted to Seats, and have to agree with you that they are about as much use as a chocolate fireguard. The DMFs made by Sachs are apparently better made, but a pointless piece of engineering is a pointless piece of engineering no matter how well it is put together.

 

Anyone know of a reasonably powerful modern car that doesn't run one of these hideous dual mass flywheels?

 

Cruds

[Stationary M25 Traveller]

Aren't they mainly used with diesel engines ('to provide a smoother power take-up) ?

 

 

[Crudders]

My Leon is a 200PS 2 litre turbo petrol.

 

I suspect high torque is the deciding factor, which is a feature of diesels and forced induction petrol engines.

 

Crudders

[AMMO]

I suppose the obsession to make the engine feel ultra smooth has led manufacturers up the path of dual mass flywheels.

 

Engines will have periods of vibration. The dual mass flywheel doesn't eliminate the vibration, it eliminates the transmission of the vibration down the drive train.

 

However the vibration periods are not severe enough that they cannot be lived with like we've done for the past 100 years or so.

 

I had a Peugeot 205 GTI 1.6 with a skimpy factory flywheel. I can't remember it not being smooth. The same goes for the little Citroen ZX I have been zapping around in for the last few years. In fact I don't think I've owned a car with a DMF.

 

I did have a VW Passat turbo diesel on loan for six months once. Maybe that had one. A German engineer friend told me that VW had lots of problems making this engine feel smooth. Lots of money was spent on developing engine mounts with special rubber to stop vibrations being transmitted to the chassis.

 

I suppose bigger engines with longer strokes and higher torque, especially diesels that don't rev as high, will cruise in the engine's vibration period.

 

I'm not an engine balancing specialist but I do know a little bit about crank balance, crank counterbalancing and balance factors having worked with V-Twins and V8s. I have also commissioned cranks to be designed to my own specifications, perticularly balance factors. I have spent a lot of time (and money) varying the balance factors on cranks to get them to run smoothly. Although not for comfort but for high rpm and racing so they didn't sap power or destroy themselves.

 

Seems to me that nowadays the cranks are not properly conterbalanced and engineers are relying on DMFs to stop the torsional vibrations being transmitted.

 

They have decided to go down this route for a reason. I'm not sure what this is. Maybe someone who does know can tell us.

 

A Duratec ST150 Fiesta engine I purchased recently had a solid flywheel. So why do the same engines fitted to other vehicles have DMFs? Maybe it has to do with the chassis or the way the designers think the vehicle will be driven. Revved through the gears as opposed to pootling along a lowish fixed rpm.

 

DMFs that have failed and have been replaced with solid flywheels to no real detriment makes me think that they are generally un-neccessary and should be avoided at all costs until someone makes one that can last 200,000 miles.

 

Unless you like forking out for a new flywheel and clutch on a regular basis.

 

 

 

Ammo

Raceco.com

[7 Sevens]

Just replaced a DMF on my Focus. Thankfully it had reached 120k miles (50k in my hands) before it failed. When it happened I was about to run from the car from the vibration/clatter/noise/shake Replacement at a private garage set me back £600.

 

I was chatting to the owner who is a friend and he said he had changed one on a Nissan XTrail £1,100 and a new Megane £1,800 !!Those cars like Crudders had done very little in the way of mileage.

[I.Mupferit]

And if you knew Crudders, you would be aware he isn't hard on his cars either, so it really is unforgiveable the way the dealers/manufacturer have pissed him about by not accepting total responsibility for the problem. 3 new flywheels (and needing a 4th) in only 17000 miles is just outrageous.

 

If I was him, I would be setting fire to the SEAT UK Chairmans house by now!

 

 

[Hanns Per]

just started to disintegrate the car for winter activities.

today removed the bellhousing from the engine.

seeing the flywheel I wonder if this is a DMF?

CSR 200 EU4.

any opinions?

thks.

Hanns Per

 

 

my CSR 200 with Cosworth roller barrell

blatting the alps in a CSR 200 now 220

 

[Martin J]

I'm sure there is one fitted in my 2005 TDCI mondeo & we tow a fair sized caravan. The car has covered a little over 50K miles. Am I on borrowed time? Apart from a diesel leak that left us stranded the car has been brilliant but I intend to keep it for sometime yet but may have to budget for DMF failure at some point.

I'll tell Mrs.J to stop pulling away in second!

 

Edited by - Martin Jeffrey on 30 Oct 2009 19:31:50

[oilyhands]

Have already repaled the one on the M5.. (don't ask how much).

 

Oily