C5 clutch dual mass or single plate?

[falling-out-with-my-car]

well if you've got 50,000 Dual Mass flywheel kits in stock your not going to
chuck them all out just to change back to single mass units and especially not of it costs the consumer more money to replace them.
do you realy believe ordering 10,000 units equates to more money per kit for the manufacturer?
the producers will have to have made ordering DMF kits cost effective for the factories.

No I do not believe it is all a conspiracy to make money from consumers.
somebody has cut a corner here, its like the catalytic converter story.

The government had to cut emissions, the fuel refineries knew how to make less polluting fuel
but they would have had to basically re-tool the refinery at a massive cost to them eating into their profits.
along comes a scientist have you heard about the catalytic converter? we can pass the costs to the consumer.

Valeo seems to be the only clutch kit producing company that have made an effort to absorb the damping qualities of the
single mass clutch in the 4P single mass kit they now produce.

I have to ask why if single mass clutch conversions such as this are deemed useless as conversions in dual mass flywheel vehicles
originally assembled with a dual mas flywheel, why Valeo are even bothering to make them?

https://www.valeoservice.co.uk/en/node/5459

https://www.valeoservice.co.uk/en/servi ... vehicle=pc

regards.

Nigel

[elma]

well if you've got 50,000 Dual Mass flywheel kits in stock your not going to chuck them all out just to change back to single mass units and especially not of it costs the consumer more money to replace them.

Car manufacture doesn't work like that. They use a "just in time" system. Parts for production of new cars are delivered to the factory just before they are needed. Most factories work with enough parts for 3 to 6 hours production. This saves them carrying such stock levels and allows changes to spec at the drop of a hat.
Cost will be a factor, but to themselves rather than the consumer. I think it more likely that Valeo are not yet able to offer the 4p in large enough numbers for producers and haven't made it available to them yet.

[flying clutchman]

Not being a structural engineer I'm not really sure why changing the flywheel should break crankshafts. I think the dmf is the easiest way of achieving a smooth drivetrain, however their use has increased the sales of aftermarket products from Sachs, LUK, and Valeo dramatically. Let me explain; previously if the clutch needed changing the customer bought a new clutch kit. Typical cost £100 (very often a patterned part, so no ££ for the original manufacturers). Now with dmf, the customer buys clutch kit + dmf cost £400 and the sales are generated by the original supplier. So apart from technical considerations it all adds up to a healthy aftermarket sales boom for the big three manufacturers. On Ford diesels the flywheel is usually the first thing to go, even before the clutch wears out. Most rear wheel drive transits more than 6 or 7 years old are running on solid conversions because the owners are fed up with flywheel failures. DMFs are here to stay though (until diesels disappear) so we have to live with them

[Paul-R]

DMFs are here to stay though (until diesels disappear) so we have to live with them

Does that mean that petrol engines don't have DMFs?

[flying clutchman]

some petrol engines have dmfs (mk3 Mondeo, bmw etc) but they go on forever

[Paul-R]

Presumably because the power band is shifted upwards and there's less low speed stress. Which is a pity for diesel drivers as I for one like being able to pull away from ridiculously low revs.

[falling-out-with-my-car]

This has a lot to do with the power to weight ratio
of any given engine we still have 2.0l engines but they are pushing 150BHP
instead of the 90bhp of say twenty years ago. so there is an argument for
a DMF on that basis. Valeo have said their SMF 4P Kit flywheels have a 1 million mile guarantee.
I seriously doubt I will ever do 1 million miles in one car unless I leave home and move into it full time.

James, this is what I was weighing up costs: a DMF £400 plus a clutch kit £275.00 plus fitting £500.00

if the gearbox goes somewhere down the road because of a single mass 4P kit conversion costing £275 initially plus £500.00 to install it
a gearbox on a palate delivered is around £60.00 to £80.00 and fitting is about £300.00
The repair process having a second gearbox fitted is cheaper in the long run than paying out £1075.00 for a new DMF clutch by around £400.00.
for my Mk2 C5 exclusive. ok its a little annoying but Pleiades has a free courtesy car.

you would think that all the DMF failures have given the Manufacturers a bad name especially in diesel models.
so why are the manufacturers not chasing up companies like Valeo to increase production of their 4P kits?
Do the Manufacturers still believe that the DMF is the only way? or is it more about shunning any responsibility above the guarantee period of say 36K?
or three years? when the premature wearing out of the DMF becomes apparent.
if I were a Manufacturer I would want longevity from my vehicles and the chance to prove that my vehicles last a long time.

it seems true that many dealers are the same they will sell you a vehicle and then when you go back and say I would like to add
a gadget, they reply it cant be done, it should have been added at the factory, yet it is possible to buy the items online and fit them yourself
so why the anti customer service attitude from the dealerships? I think the DMF's will continue to fail because of this attitude from the manufacturers and the dealerships
and nothing will change because they don't really care that they are building vehicles that have clutches that will fail prematurely.

[GiveMeABreak]

...you would think that all the DMF failures have given the Manufacturers a bad name especially in diesel models.

A DMF is a service item, like a clutch - it is designed to wear. How quickly it wears is often down to the driving style and whether you tow.

so why are the manufacturers not chasing up companies like Valeo to increase production of their 4P kits?

Why should they? Their engines were designed to incorporate a DMF by design; to reduce the damaging vibration levels that would otherwise weaken and destroy the metal shafts and transmission components as already said. A standard solid flywheel is not designed to provide the same levels of protection or dampening. There may now be some kits like the KIT4P that have subsequently been developed - but as can be seen from their own brochure, they are not a one size fits all solution and it is highly unlikely that the majority of car manufacturers will retrospectively start fitting and endorsing these.
Like I said - a personal choice and risk for each owner to make.

[elma]

I think there is some confusion.

DMFs we all know about.

A lot of people swap the DMF for a SMF and a conventional clutch, potentially putting undue strain on the drivetrain and engine which is where the horror stories seem to come from.

The 4P is seemingly Valeos reaction to that, giving the option to still have the damping but in (what seems to me to be) a more sensible place that allows the flywheel to no longer be a consumable part. I am unaware off any complaints of damage occurring from a SMF with a 4P.

I'm purely speculating about why the 4P is not chosen as oem equipment, it is just as likely it could be and manufacturers like profiting from changing DMFs or are totally unaware the kit even exists. I have no idea it's just my thoughts and Marcs comment above makes perfect sense.

If I had a DMF car I would probably fit the 4P when the DMF gave up. I think it is a better engineering solution. Of course I think that the car should be up to taking the power of the engine in the first place and won't buy a DMF car primarily for that reason.

[RichardW]

My unsubstantiated opinions...

DMFs fitted to reduce vibration and bottom end stress, which allows a thinner oil to be used, which gives an edge in the official consumption tests.
Driving style kills DMFs - I think that heat kills them, and therefore holding it on the clutch, or slipping it too much at start off is a (very) bad idea. They also dislike being lugged, so not using enough revs at low speed means they are having to work hard to damp out the torque peaks from the engine (a victim of their own success?).

My 307 on its original DMF and clutch (AFAIK) at 127k - although only 45k of that is me. The C4 had to have a new clutch at 90k - but that was because the release bearing exploded (*). The clutch itself was not that worn, and the DMF looked OK, but it was replaced - mechanic reckoned they work best as matched sets, and often judder or slip if new clutch is mated to used DMF.

* Tip 2 - don't sit with your foot on the clutch in a modern car. Release bearings are often built down to a price, which means they can't stand prolonged running under load.

[falling-out-with-my-car]

Marc,

old single mass fly wheeled cars had clutches that lasted nearly 100k or more whether towing or not
many modern DMF's fall very short of that figure some going as soon as 31K apparently.
I agree with your statement that its often down to driving style but at 31k I'm not so sure.

Honest John did a write up about the 31k problems here: http://www.honestjohn.co.uk/faq/dual-mass-flywheels/

[GiveMeABreak]

I realise all that Nigel, but a DMF is a wear item as I said and as such will vary according to the model, design, power, torque and driving habits. As a Solid flywheel is just that it should last. My Mark 1 C5 110 had a DMF and I never had it or the clutch changed in over 150k miles! The X7 on the other hand had the DMF replaced with clutch at about 46k miles and the DMF was in a bad state. This probably had to do with the fact that the previous owner towed a caravan plus this car is a lot more powerful. I had the towbar removed, so I will expect a lot less mileage before it needs doing again. We will see!

[falling-out-with-my-car]

I'm Sorry Marc but if you are fearful of using a tow bar on a 2litre engine car because of the DMF
then there is something very lacking in the trust you have upon the DMF to actually last.

a Citroen family car should be able to tow frequently and the clutch should at least see 80K or more.
my xantia clutch was replaced at 89k and I towed heavy four wheeled trailers every few months
with xantia's Bx's and my 2cv on them over the space of about five years.

I know I know what you will say it depends upon driving style, but there also seems to be something lacking
in the design of these DMF's to force someone to have to remove their tow bar because they fear the DMF might wear out.

I have noticed that quite a few of the write ups about DMFs say don't reverse uphill or tow with a DMF.
ive never owned a diesel without a tow bar and can't imagine having to give up towing because of unreliable components.
hence my like of the 4P kit.

I respect your decision and I wouldn't try to change that one bit. but if it came to that for me I'd be looking for a decent tow car
and get rid of the dam thing or send that enquiry to Valeo customer services even if it means not having it done right away.

regards.

Nigel.

[GiveMeABreak]

I had the tow bar removed from a personal choice as I had no use for it. Aside from that, it's a fact that towing with any car will put an additional strain on a clutch and if you have a DMF that too. That is a likely contributing factor why it failed at 46k.

I'm sure you'll be happy with your Solid Flywheel conversion Nigel, but after undertaking much research myself, I have made a personal choice to stick with a DMF as the manufacturer intended.

[elma]

It's reversing a braked trailer that seems to hurt the DMF, they really don't like it at all. I wouldn't worry about a small trailer but a braked trailer mated to a DMF vehicle isn't something I'd do. Been there, seen the damage.