1.6hdi clutch flywheel or solid ??

[white exec]

It's not the clutch (pressure plate, friction plate, release bearing) that gives up as such, but the break-up of the DMF (it goes sloppy, with increasing amounts of backlash), which in turn often wears and then destroys a perfectly good friction plate. Simply fitting another OE DMF is just "hoping" it won't happen again. I've done just that, and 24k miles later, it all happened again. That's an expensive game.

There's a reason SMF (4p) conversion kits are offered by Valeo, Borg+Beck, Blueprint, and others.

[Romzi]

It's not the clutch (pressure plate, friction plate, release bearing) that gives up as such, but the break-up of the DMF (it goes sloppy, with increasing amounts of backlash), which in turn often wears and then destroys a perfectly good friction plate. Simply fitting another OE DMF is just "hoping" it won't happen again. I've done just that, and 24k miles later, it all happened again. That's an expensive game.

There's a reason SMF (4p) conversion kits are offered by Valeo, Borg+Beck, Blueprint, and others.

But I hardly believe, that after 20.000km, slippage is or was caused by DMF.
Now, at 100.000 km, slipping is just way beyond acceptable limit, but there are no signs of failing DMF yet. No shaking, no strange sounds, nothing.

[Romzi]

I've got some info from the dealers in Slovenia, and mostly opinion is, Valeo 4p for this setup is no-go.
I am more and more sure we will use new OEM DMF plus Sachs Performance Clutch kit (https://www.sachsperformance.com/en/clu ... 00951837-s).
It is quite reliable solution, but quite expensive.
Are there any delaers fro this, or only online buy from above webpage?

What are the reported problems with valeo 4p? I generally had heard of good feedback about them.

Too many cases where customers were complaining because of beyond acceptable vibrations.
I really must find somene with this bloody 4p kit - to see and test it myself.

[Romzi]

I discussed about this with one of the (top 3) official Citroen Dealers/service in Slovenia.
The conclusion is, that they have replaced many clutches on these 100kw 2.0 HDIs, stilll under manufacturers warranty - not because of DMF failures, but because of pressure plate (or friction plate) failure/disfunction, or more posibly - bad design. Many of these replaced clutches (complete, with pressure and friction plate, DMF, bearing) failed again not very long time and kilometres after replacement. The only proven thing that "cures" the issue, is letting the pensioner driving a car. Almost if not the same cluthes are used and working fine in vecihles with the "same" engine with less power and torque (120 HP, 300Nm), like in Peugeot Expert II. Which corresponds to the pensioner's driving. It is common in all (Peugeot an Citroen) 2.0 HDIs with 100kw engines. The issue was never admitted by PSA (or LuK/Valeo/Sachs), and NEVER really cured. Even today, OEM (or same quality) replacement cluthes are peace of s**t.
The theory is, that SAC system (self adjustment clutch) is rather nice design, which allows that max. permitted torque is very precisely calculated and that only necessary material is used, no less, no more.
But it looks like, the calculation is a little bit too optimistic and over time, the pressure (and/or friction) plate loosens some of its characteristic, or "jump" of SAC system is a little bit too late (or never ) to compensate the wear of the friction plate.
With the classic clutch design (non-SAC), the pressure plate must be overdimensioned, if not, the cluth will slip while new.
Later, when wearing of the friction plate occurs, the pressure plate is getting stronger, because of the geometry of the spings in it. So the clutch will even less likely to slip. In fact, the pedal is getting harder to operate.
Nevertheless, the dealer said, when they were replacing those almost new and low-milage cluthes, most of DMFs were completely fine.
So in short , I ordered Sachs Performance clutch, OEM DFM will be provided by the delaer.
It was reported to work without issue, even on remapped cars. It is expensive as pig, but I hope iz will outlast the car.
It will take about a week to be delivered, but since - because of the pandemy - I will work from home for at least two weeks (IT company), In these circumstances, current clutch will work just fine.

BTW:
I also found another supplier of enforced clutches (https://www.performance-kupplung.de/) but was recognized as somehow not being serius - the first price on their webpage for full enforced clutch kit with DMF included was about 500€. When I contacted them about technical details, the price went up to 670€ because of their mistake. The same happend with shipping cost. And again, PayPal payment was not possible, but on www it is one of the payment options. I contacted them again about some discount (the price just rised for almost 200€ for no reason ), there was no reply at all. So I decided to stay away from them.

[GiveMeABreak]

Thanks for the write up - an interesting read.

I'm not a pensioner by any means, but I also treat the clutch very gently - no riding the clutch and no sudden pulling away - and I certainly don't drive in 5th or 6th gear unless necessary to save the DMF life as best I can. I hope this will last for a good while - that is until we are all forced into electric shoe boxes before too long

[white exec]

A really unfortunate sequence: inherently harsh DI engines → an attempt to mask that with a sprung flywheel → requiring adoption of unsprung friction plate → compression and weakening of the flywheel springing → excessive wear of the movement dampers → flywheel backlash → impaired clutch control (eg hillstart difficulty) with need to use higher engine revs → accelerated friction plate wear → eventual loss of drive or friction plate breakup.

If the wear in the DM flywheel itself is purely circumferential (spring compression), this can be overlooked on inspection, and the conclusion that the DMF is ok. (This is likely why the recommendation is to replace the DMF whenever the clutch is replaced.) As the casualty of DMF deterioration is almost always the clutch friction plate, it is easy to blame the friction/pressure plate. This opens up the marketing opportunity described above.

All of these problems are virtually unknown with tried and tested conventional flywheels and sprung friction plates. Traditional clutches can outlast the life of the car, or cover massive mileages, in the hands of drivers who do not abuse them.

To have to avoid low revs on a diesel is just absurd. One of the raisons d'être of diesels is their ability to deliver useful power below and around 2000rpm. This was something that (especially our) IDI engines never had an issue with. OK, there are benefits of DI injection, but harsh running is not one of them. This should have been tackled via revised injection control — and it was, in the case of some engine manufacturers — but simply slapping a springy flywheel (with questionable and short-life friction damping built in, to deter oscillations) into the drive train was just daft, but very heavily promoted by its makers.

I'm sure delivered examples of DMF-equipped test vehicles from LUK and others worked splendidly. When new, they do, but it doesn't always last, as we now know to our cost.

[bobins]

The self adjusting clutch is a problem I've highlighted quite a few times on here. Mine has been slipping on and off for a few years now. It can be not slipping on one journey, then slipping the next time I get in the car. If it gets bad then my 'cure' is to abuse the clutch a bit - red-line the car in 2nd / 3rd and/or do some harsh down changes. That normally sorts it for a while

[Romzi]

The self adjusting clutch is a problem I've highlighted quite a few times on here. Mine has been slipping on and off for a few years now. It can be not slipping on one journey, then slipping the next time I get in the car. If it gets bad then my 'cure' is to abuse the clutch a bit - red-line the car in 2nd / 3rd and/or do some harsh down changes. That normally sorts it for a while

Exactly my point. Mine performed the same from 20.000 when first slipping occured and unil aprox. 100.000 km. Now it's fubar - slipping all the time, except when not runnig at all
How the f***k DMF could cause such behaviour?

[white exec]

Trouble is, destruction of the clutch by DMF wear also occurs on non-self-adjusting set-ups, whether cable or hydraulic.

[bobins]

In theory - would a mildly slipping clutch* help to prolong the life of a DMF as it could cause less backlash on the DMF springs ?

* - Assuming it doesn't slip enough to generate large amounts of heat etc.

[Romzi]

In theory - would a mildly slipping clutch* help to prolong the life of a DMF as it could cause less backlash on the DMF springs ?

* - Assuming it doesn't slip enough to generate large amounts of heat etc.

No. Quite opposite. Slipping clutch in conjuction with DMF can cause juddering or vibration, it's bad for DMF rubber dampers. And I think, these DMF spring are subject ot wear. It's nothing to wear on normal operating spring.
This juddering can be felt, but since DMF is very well isolating such behavior, does not feel very bad.
On the other hand, friction plate is wearing quicker than it would in normal operation.
Also, some people were reporting that driving a car like they stole it, can cure the problem (to (re)activate SAC system).
But such driving style is shortening the life of DMF again. You just can not win.

Yesterday, i got some feedback about 4p and C5 II: a local forum member took a test drive with it. The owner of the car claims "it is the same as driving with DMF", but this forum meber just said it 's terrible to drive, like having the stick in his *****.
So It's just about personal impression, I guess. Some people can't notice anything, even If a front wheel drops off.

[GiveMeABreak]

It's the torsional stress that has to be considered - that additional stress has to go somewhere - if not via the flywheel, where do you think it goes - through the transmission components / gearbox components = additional strain. I'm not surprised there is all that extra vibration as it's not getting damped as intended. It's a risk everyone has to consider themselves - but don't expect Valeo or other makers to cover any peripheral damage if it shortens the life of other components.

The increase in vibration that you can feel has to tell you something.

Here's a good video (turn the volume right up) explaining why not to do it and some of the consequences of fitting a solid flywheel:

DMF SMF Issues and Comparison

Crankshaft failure
Gearbox destruction
Windscreen shaken lose.....

Some good points regarding interaction with the clutch and self-adjustment / slave cylinders too that has been discussed in this topic. In this video they are not trying to sell you anything either which is worth remembering.

[white exec]

I know it's of little use or consolation - we've got what we've got - but the vibration tells you
(a) many of our DI engines now run more harshly than their predecessors, where this was never a problem;
(b) if (and I say if) crank or drivetrain components break, they were either not up to the job, or have been reduced in strength on the back of the availability/marketing/claimed advantages of DMFs;
(c) crankshaft, crankshaft damper, and maybe other engine components are of insufficient mass to absorb the DI shocks.

I remember when we were looking to buy a diesel 4x4 in 2003, in preparation for our move from the UK to mountainous Andalucia. We had run several XUD engined cars before, and were also running our 2.5 XM. These always provided a really smooth diesel driving experience. When we took a brand new RAV4 2.0 D4D out for a test drive with a Sussex Toyota dealer, my immediate impression was of the harshness of the engine. Remarked on this to the dealer salesman, who said "Well, you're not going to get the smooth quietness of a French diesel with this – but they do quieten down." Well, they don't. Almost a quarter of a million km (and two failed DMFs) later, the engine, although decently powerful, is still what I'd call semi-agricultural. It's a more-than-adequate AWD workhorse, but not something we choose for long journeys. Do I regret buying it? Yes. Should I have looked more widely? Yes. Was I aware of the DMF issue in 2003? No. (Toyota only fitted them from around 2001, I believe, and - interestingly - did not sfaik change any of the engine or drivetrain components at the same time.) It remains a real pleasure to drive the XM 2.5, thank goodness. Occasional passengers and other drivers still find it difficult to believe it is actually a four-cylinder diesel.

[GiveMeABreak]

As you say Chris we have what we have - and if the manufacturer's did not consider them necessary in light of these newer diesel engines then they would obviously have saved themselves the added costs of incorporating them - vibration increase aside, do we really think they would fit SMFs and risk having warranty claims for failed transmission components - I think not.

So ultimately it has to be a personal choice and the best general advice is to do the research, and don't listen solely to the marketing hype from the companies providing conversion kits, then make a choice.

[white exec]

Worth noting that the conversion kits are, in the main, being offered by the same manufacturers that produce the DMFs. The latter are around twice the cost, and may well also need replacement down the line, so no great incentive for them to push their lower-priced SMF solution.

Agree, though, it's a personal choice. Too much hearsay and heat around the issue.