DMF Flywheels Sleeping Policemen (France)

[filmtech]

My Ford Focus is at the moment in a ford garage having the DMF flywheel fitted. So I started to wonder about my driving technique as to the cause of the problem, my car is a 2003 focus tdi 110 diesel with only 85,400 kls on the clock not excessive mileage and I don't speed, but I do uses the gears when slowing down, that could be a factor, my brake pads have never been changed and still have an amazing amount of pad left, thats the way I drive.
So after shopping two days ago I returned home on my usual root the road has a brand new surface with brand new Sleeping Policemen, its a month old the road is two kilometers long with 9 Sleeping Police humps, and it was at the end of this road (only 200 mtrs from my house) that this problem happened, almighty noise, and vibration on the clutch pedal. This clutch is supposed to even out torque, I have often wondered what the effect of these bumps would have on the cars and thought that the engine mounts would suffer maybe thats the case I don't know about that. but there is a lot of torque when hitting these humps. I am convinced this had a severe effect on the clutch,I use this road about three times a week, not any more.
If you have an opinion I would like to hear it.

PS Sleeping policeman humps are new in France they haven't got it right yet.

Filmtech

[BritishRacinGrin]

DMFs have gotten quite a bit better since 2003 so my advice would be just to not worry about little details. If you're worried about the sleeping policemen specifically you could always dip the clutch as the front axle goes over them. Otherwise just drive normally avoiding laboring the engine below 1,500rpm.

[nawarne]

To OP!

Gears for GO....Brakes for SLOW.

See that so many times - easier and cheaper to replace a set of brake pads rather than a new clutch..even if it's just the friction plate.
Nick

[750turbo]

nawarne said:

To OP!

Gears for GO....Brakes for SLOW.

....

Really!

[ging84]

I have heard that keeping the clutch down while idling can be a big factor in how long a dmf will last. When they have no pressure on them is when they are able to move about the most which is what causes them to wear out. With the clutch plate pressing against the fly wheel everything holds together nicely but the dampening effect is still there

[DrDoofenshmirtz]

nawarne said:

To OP!

Gears for GO....Brakes for SLOW.

See that so many times - easier and cheaper to replace a set of brake pads rather than a new clutch..even if it's just the friction plate.
Nick

Yep - using the clutch and gears to slow the car is not good driving (from a mechanically sympathetic point of view).

[filmtech]

nawarne said:

To OP!

Gears for GO....Brakes for SLOW.

See that so many times - easier and cheaper to replace a set of brake pads rather than a new clutch..even if it's just the friction plate.
Nick

Hi nawarne
Thanks for your imput,you think you are doing all the right thing only to find there is an other way. Driving for 67 years and still learning, great quote.
Bill.

[mwstewart]

It's not your usage of the drivetrain to slow you down that's causing premature failure; it's your inept clutch control: the engine and gearbox can be great friends but only if they have a mutual acquaintance at the party.

[ferrariF50lover]

You say you don't speed. Do you think your flywheel is aware of the prevailing speed limit for the roads on which you drive? Do you think that, somehow, your flywheel would be upset if you exceeded that limit and would destroy itself as some bizarre dirty protest?

Do you also imagine that your refrigerator keeps tabs on your tax affairs and refuses periodically to chill your Brie on the basis of some cash-in-hand labouring?

Simon.

[mybrainhurts]

[quote=filmtechPS Sleeping policeman humps are new in France they haven't got it right yet.
[/quote]

Got it right..?

They're NEVER right.

Pointless and damaging and draw the driver's attention, that should be scanning around for hazards.

[405dogvan]

DMFs - esp of that era - often last a LOT less time than yours - I'd not worry too much.

I agree 101% with the brakes for slow thing tho - do NOT slow your car with the gearbox unless there's no other means available for lots and lots of reasons (more expensive to fix, no brake lights shown etc. etc.)

[mybrainhurts]

Letting the engine labour in a high gear will screw the DMF.

I assume yours is diesel. Slowing through the gears is ineffective anyway, little engine braking with a diesel.

[SLCZ3]

Gears and brakes should be used together to slow down, in this day and age of 5+gears for forward it is even more essential to be in the "right gear" for the situation in a manual gearbox, an automatic is, as it says automatically in the right gear (supposedly).
Who approaches a roundabout or halt/stop/redlight situation in top gear and stops completely on their brakes, I pity your clutch/gearbox/and drive train.

[motco]

IMHO you should not use the gears TO slow down, but AS you slow down or you'll find yourself in a flat-footed vehicle in the incorrect gear when the traffic situation develops ahead, and/or grinding to a shuddering halt still in fifth or sixth and the anti-stall struggling to maintain idle revs. Or you coast...

[McFarnsworth]

DrDoofenshmirtz said:

nawarne said:

To OP!

Gears for GO....Brakes for SLOW.

See that so many times - easier and cheaper to replace a set of brake pads rather than a new clutch..even if it's just the friction plate.
Nick

Yep - using the clutch and gears to slow the car is not good driving (from a mechanically sympathetic point of view).

Doesn't anyone revmatch while downshifting anymore? Can't say I've ever needed to replace a clutch on any of my cars, some of which went well beyond 250k km (~150k miles?)

[Howard-]

McFarnsworth said:

Doesn't anyone revmatch while downshifting anymore? Can't say I've ever needed to replace a clutch on any of my cars, some of which went well beyond 250k km (~150k miles?)

Indeed. Shifting down a gear or two in order to increase engine braking is not going to hurt the clutch or gearbox if you rev-match appropriately.

[pherlopolus]

mybrainhurts said:

I assume yours is diesel. Slowing through the gears is ineffective anyway, little engine braking with a diesel.

I always thought more engine braking on diesel due to the higher compression ratio and the butterfly in the throttle body to restrict air flow?

[motco]

McFarnsworth said:

DrDoofenshmirtz said:

nawarne said:

To OP!

Gears for GO....Brakes for SLOW.

See that so many times - easier and cheaper to replace a set of brake pads rather than a new clutch..even if it's just the friction plate.
Nick

Yep - using the clutch and gears to slow the car is not good driving (from a mechanically sympathetic point of view).

Doesn't anyone revmatch while downshifting anymore? Can't say I've ever needed to replace a clutch on any of my cars, some of which went well beyond 250k km (~150k miles?)

Indeed so, like you I have never worn out a clutch and I have only ever replaced one when the diaphragm spring broke up through fatigue (Triumph Herald), and when a carbon release bearing fell apart (MG Midget). This over a million miles of driving and more than 200,000 miles on one car on original clutch. Heel and toe helps gentle braking and rev-matching to smooth progress. Double de-clutching is unnecessary, though, in modern baulk-ring synchro gearboxes.

[motco]

pherlopolus said:

I always thought more engine braking on diesel due to the higher compression ratio and the butterfly in the throttle body to restrict air flow?

High compression, yes, but no throttle body nor butterfly IFAIK. Power is controlled exclusively by metering the fuel supply.

[The Wookie]

OP, I'll have a guess and say you either left it in gear and ran the engine at very low revs for the hump (which then probably put a spike of torque through the driveline as you hit it), or after going over it you declutched in 2nd or 3rd at low speed and laboured the engine.

Either of those would have finished it off, and lugging at low revs regularly is what will kill a DMF in less than 50k