DMF -driving styles

[HopeImRight]

Are DMFs damaged by driving styles?

If so what harms them and what style helps them give 200k miles:confused:

Please.

[_ZS_]

Yes, DMF will be damaged by harsh or agressive driving. Urban driving will wear them quicker too.

200k, you're probably looking at the "taking the bus" driving style. They're a consumable item, and you've to replace them when replacing the clutch. If you can get 200k out of a clutch then you sohuld get that out of the DMF as well.

[HopeImRight]

Thanks.

Harsh and aggressive I understand. But urban driving??!!? How? why? in what way?:confused:

More info please.

[PumpeDuse]

things like being in too higher a gear and then boost from low revs destroys them.

[psycholist]

things like being in too higher a gear and then boost from low revs destroys them.

Since I have no idea how a DMF works, just familiar with a normal clutch/flywheel arrangement, I'm very curious as to what is going on to damage it when accelerating at low revs. I can understand how the engine will suffer on doing this, but provided the clutch remains connected all the time the flywheel shouldn't see a sudden speed change or more torque than it's designed for.

[HopeImRight]

Many thanks for replies. I think I'm getting the idea.

Lugging in a high gear is not funny or clever. Screaming its nuts off in too low a gear is **** head look at me territory or an old granny in a car park with 6000 revs on and a lovely smell.

So HopeImRight in thinking that the message is simply don't jolt it or jerk it and keep it spinning sweetly in the dead right gear at all times. Well--like drive it properly then.

Is there any other trick to save your DMF? or have I missed anything.

[cjb]

Since I have no idea how a DMF works, just familiar with a normal clutch/flywheel arrangement, I'm very curious as to what is going on to damage it when accelerating at low revs. I can understand how the engine will suffer on doing this, but provided the clutch remains connected all the time the flywheel shouldn't see a sudden speed change or more torque than it's designed for.

A DMF is in two parts with a spring and damper in between- So the two halves can rotate relative to one another. This absorbs some of the vibration in the driveline.

If you slog the engine hard in too low a gear it creates too much vibration and stresses the DMF.

[cjb]

Many thanks for replies. I think I'm getting the idea.

Lugging in a high gear is not funny or clever. Screaming its nuts off in too low a gear is **** head look at me territory or an old granny in a car park with 6000 revs on and a lovely smell.

So HopeImRight in thinking that the message is simply don't jolt it or jerk it and keep it spinning sweetly in the dead right gear at all times. Well--like drive it properly then.

Is there any other trick to save your DMF? or have I missed anything.

No. just drive the car with a bit of care and it will be fine.

[skippy41]

Or if it goes get the dealer to fit the old system its only £230 fitted

[spaniels fr]

Ok, well if you want a response, then i thought id try to inform you, bearing in mind i work for sachs as a warranty inspector, i think i could potentially help out the most

Ok, so here goes...... DMF's have been installed onto almost every new diesel engined car on the market over the past 5-10 yrs. Due to the performance these newer diesels give they produce much higher engine harmonics due to the stronger power pulses when the fuel is compressed and ignited.

How to destroy a dmf is simple, and this can be caused through numerous different things, alot of which have already been said but just to confirm

*Driving in too high a gear at low engine rpm, this will cause the dmf to work to its maximum designed tolerances, making it bounce from one travel stop to the other.... this will also screw up the torsion damper on the driven plate ( kind of the same principle a dmf has which is to dampen out the power pulses produced from the engine)

*Doing agressive launches, when i had my hybrid'd ibiza fr tdi, this still ran the dmf, i knew from working for sachs that unless the car was going to be a track day toy then the dmf needed to stay. If you take away all that damping the dmf does, and replace it for a SMF where is all the vibration going to go? gearbox maybe? and you can guarantee that a fu*ked gearbox will cost more than a DMF. Anyways, hard launches are not advisable, i did it and it was fine up until i wrote it off at 25k miles, this included at least 20 launches at santa pod, inc 1x 2nd gear launch.

* Heat is another thing that can kill these DMF's. If you cook the clutch, and completely burn it out, then the chances are that the DMF will be fooked too. Heat dessipation that is transferred into the dmf from the clutch could potentially cook the grease inside the dmf. I did a claim yesterday on a merc sprinter 311cdi, this had been in 3 weeks, done under 1k miles and the thing was scrap. The whole unit had been exposed to extreame heat from the clutch slipping.

*If the internal parts in the dmf break up, then they could and will punch a whole in the rear of the dmf, sending all this nice black tar like grease spewing all around the bell housing of the gear box.

For those of you who are curious as to how the dmf works, see this link here

If any one has any more questions they need answering please dont hesitate to ask.

Regards

Daniel

[Kitts]

I've heard a lot about the DMF but am not really mechanically minded. (I'm a girl, what can I say hehe)

Does the DSG also have this and if so, how do you know if its wearing?

[spaniels fr]

I've heard a lot about the DMF but am not really mechanically minded. (I'm a girl, what can I say hehe)

Does the DSG also have this and if so, how do you know if its wearing?

Yes the DSG does also have a dmf, but unlike a normal manual there is no clutch is mounted to the unit due to the gearbox having the 2 clutches already in the car.

[HopeImRight]

Thanks everyone.

I'm getting a much better idea.

Drag racing is a no-no.

Lugging it around in too high a gear is a NO-no.

ESPECIALLY accelerating from a high gear low speed lug.

Now a fairly detailed question please.

I have a habit it getting into a high gear as fast as I can when the engine is doing very little work. AND I don't ask it to accelerate without a down shift.

Near where I live is a long dead straight incline -not a hill--when you walk up it you would just about notice it was not flat. It makes cyclist puff a bit going UP because it so long.

The engine is just spinning and being spun by the front wheels (instead of the wheels being spun by the engine) and the fuel use indicator shows zero. There is no sound or feeling of any strain at all because 45 mph or a bit more is ok for 5 th gear.

Is this producing harmful harmonics I'm not aware of?

Can't see how but can you comment?

Please/thanks.

[psycholist]

If the mpg indicator gives you '---' then as far as I know no fuel is being burned at all and the momentum of the car is keeping the engine turning. I'm guessing this won't do a thing to the DMF because the drive from the wheels to the engine is inherently very smooth, so there should be no vibration for the DMF to deal with.

I try to keep my car between 1500 and 2000 rpm for cruising but when accelerating I start from 2000 rpm where more power is available. Hopefully this is the way a DMF drivetrain should be treated.

I did discover that my car would pull all the way to 4th gear at idle on a flat road if I was gentle with the clutch - I drove petrol cars before I got the diesel, so that sort of low end torque had serious novelty. That presumably is not a nice thing to do to a DMF (And probably the engine too) though - nice way to impress people used to petrol engines though...

[Wardy]

You might find this interesting/useful/helpful:

HowStuffWorks "Fly Wheels, Clutch Plates and Friction"

Steve