C Crosser, Dual Mass or Solid Flywheel

[Bigjohn]

This question came up at the weekend between myself and a mechanic friend, Dual Mass which due to the way they are designed are not all that suitable for towing, a solid old fashioned flywheel works so why has everyone started fitting a dual mass? all they have done is moved the dampening springs from the clutch plate to a complicated chocolate Flywheel?? so the question was asked is there a flywheel from another PSA engined car that would fit where you could source a Centerplate, and cover,which for years with the incorporated springs have done the job a lot better than a floppy dual Mass? He has a Diesel Focus where he sourced a Solid flywheel from an early Citroen C8, achieved by wandering round a scrap yard with his dual mass on a trolley whilst comparing the rear end of removed engines!!

The only fly in the ointment is we're not sure what the 6 speed gearbox was sourced from, and are we going to suffer from a Citroen Mitsubishi headache? We know the same 2.2 HDi was also used in the Land Rover Freelander and I believe the Jaguar? They all appear to be dual mass.

Has anyone been involved with a similar situation and what was the outcome?

Before anyone says why change a dual mass is ok, I'm from an engineering back ground, the first time I saw a dual mass I thought some one was having a laugh.

Thought it would promote some discussion and may answer my question?

[white exec]

I'll just throw in that "SMF" (single-mass flywheel) kits are available to replace troublesome DMFs, and from reputable manufacturers like Valeo, Blueprint, Borg+Beck.

Our RAV4 D4D has one (a Blueprint 4-part kit: flywheel + traditional sprung 3-part clutch), after two Toyota DMFs broke up (one at 60k miles, the next at 20k). Penalty on this vehicle is slightly more vibration, but the perfectly controllable steep hill starts (even in the high-geared reverse) you'd expect from a traditional clutch. Current mileage is c150k and AOK.

Controversy surrounds SMF conversions, and I'll be advised by others on yours.

[Bigjohn]

I'll just throw in that "SMF" (single-mass flywheel) kits are available to replace troublesome DMFs, and from reputable manufacturers like Valeo, Blueprint, Borg+Beck.

Our RAV4 D4D has one (a Blueprint 4-part kit: flywheel + traditional sprung 3-part clutch), after two Toyota DMFs broke up (one at 60k miles, the next at 20k). Penalty on this vehicle is slightly more vibration, but the perfectly controllable steep hill starts (even in the high-geared reverse) you'd expect from a traditional clutch. Current mileage is c150k and AOK.

Controversy surrounds SMF conversions, and I'll be advised by others on yours.

Hello Chris, thank you for your reply, I use an excellent Motor Factor in Southampton and they cant locate a kit, the parts chap is old school and knows his parts like an encyclopedia, excellent for wanting old truck parts along with the Cars of the time, not saying there is not one, just they cannot locate. Likewise a trawl of the net come back with nothing, there is going to be one considering the problems with the rear main oil seal and warranty claims, I reckon if I find proof of what gearbox is used I may be able to find a fitment for another car, I am a little concerned the gearbox is a Mitsubishi part, and was matched to their 2.0 Diesel, as mine is a 2007 model.

[GiveMeABreak]

Newer engines -> more power -> more torque at lower engine revs -> more vibration and torsional stress -> more damping needed. Get rid of the DMF and where do you think that torsional stress is going to go? It has to go somewhere, so is transferred to the drivetrain / transmission. A solid flywheel just won't cut the mustard on all applications of vehicle.

A simple explanation for those reading the topic from LUK:

[Edit: Video No longer Hosted]

And here's Eric & Ernie explaining why it's not a good idea to convert (dubbing is a bit awful, but hey...)

[Edit: Video No longer Hosted]

[Bigjohn]

I've seen the video, and all the selling bumpf, not impressed, all they have done is reinvented getting the power to the drive train, all manual race people use solid flywheels, the old way of doing things I think is the best, the load dampening springs have been moved from the clutch plate to the flywheel, in my opinion a severe step backwards,. Why do so many DMF fail under stress of towing? And heavy driving?

[GiveMeABreak]

I’m not suggesting they are ideal, but they are necessary. Racing cars are designed to be hammered though and they have the budget to replace things as soon as they fail - longevity is not their goal, only performance for the here and now.

Love them or hate them they are here for the foreseeable. I agree with you about towing, the added strain of towing is not suited to a DMF as I can attest from the previous owner of my X7. I had to have the clutch and shattered DMF replaced at 40k. I don’t tow anything and am very gentle with take offs to keep it as long as I can, but would never swap it for a solid flywheel.

As they have said, why bother with the expense of a DMF if they could use a SMF? It would reduce production costs of a new car, so makes no sense except that it’s simply needed to handle the torsional stress generated.

[doctle]

A few years ago I had a 2001 Octavia 1.9 diesel. The clutch went and it had a DMF. I looked into it a little and discovered that the DMF had been fitted to cars in the second half of 2001 in the first half it was a traditional clutch. I got a used G60 flywheel for I think £20 on eBay put in the old type clutch and it was still fine a year later. The price difference was about €600 it would have been double that in a dealers. You hear of DMF's failing with low mileage all the time nice for dealers not so nice for the motorist

[GiveMeABreak]

They may have increased the engine power and therefore fitted a DMF as a result. It’s not uncommon for them to tweak the same engine throughout its life.

[Paul-R]

Could be. The VAG engines increased in power when they went from a rotary pump in the VE/VP engines to the Lucas UIS injectors in the PD engines starting in around 2000.

[white exec]

DMF came about not long after many engine manufacturers went diesel Direct Injection, and then Common Rail. Compared to the previous IDI (Indirect Diesel Injection) engines - such as we have in Citroen BX, CX, XM, ZX, and some Xantia - many of these DI and CR engines are relatively harsh, especially at low revs. Something was needed to smooth out inherent crankshaft vibration.

Another argument that was advanced in favour of DMF was that it would enable the manufacturers to reduce the mass of some downstream transmission components (gearboxes, transfer boxes, differentials), because the clutch would provide a smoother output.

What wasn't mentioned was that the energy produced by the increased engine vibrations has to be absorbed somewhere - and that was in the circumferential springing inside the DM flywheel. Under pull-away and hill-start torque, these long springs can "wind up" (compress) by a huge amount, with the two parts of the DMF rotating relative to each other by anything up to 45°. This doesn't make for good hill-starts or pull-aways (especially when towing or carrying a heavy load), because of the non-positive clutch action, with energy stored in the long springs. When the clutch finally bites fully, this stored energy becomes released, and what would have been a smooth hill-start/pull-away with an SMF becomes something of a catapult action, resulting in poor control. One way to overcome this is to use much higher engine revs, in an attempt to stop the clutch snatch.

Many of the animated marketing videos of DMF showed this internal springing happily absorbing the low-excursion vibrations of engines under steady load. What they did not show was the "wind up" of the springing under heavy load or hill-start, nor the consequencies of it.

Toyota caught a bad cold with DMF (around the year 2000 and after), and thousands of 2.0 D4D Avensis taxis worldwide ended up being converted by their owners to SMF. Our D4D went through two DMFs - the unsprung clutches were literally shredded by the flywheel break-up - before I called it a day, and fitted a Blueprint SMF kit, which has been trouble-free. I was lucky in that Toyota had not changed any of the transmission components (eg fitting lighter ones) along with the move to DMF, so there was no inherent risk of overstressing the drivetrain, which had previously been with a conventional flywheel and clutch.

The DMFs promoted by LUK and others caused mayhem at this time, and many had to be replaced under warranty. VW and others caught a similar cold. I'm sure that the DMF system has been refined over recent years, and complaints are certainly fewer these days. From an engineering point of view, it leaves a lot to be desired, and has resulted in car manufacturers now having to class flywheels as "consumable items".

The DMF belongs in Bin 101, along with so many of the bolt-on devices that plague and strangle the modern ICE, including DPF, EGR, and now EGS. It is ironic that today's small and powerful engines will end up seeing out their days shackled by these devices, in the praiseworthy attempt to clean up the environment. It just makes the shift to all-electric all the more sensible.

[Mandrake]

Sounds like a good argument for a motor design that doesn't require any sort of clutch...

If it's not there it can't wear out or go wrong, or shudder, or snatch...

[EDC5]

This is why I got a X7 with a torque converter auto. The DMF doesn't sit well with me, plus the fact that PSA cars tend to have sloppy gear sticks/linkages I don't think I'm missing out on much.

As to the C-Crosser, I'm sure I read somewhere it uses a Getrag gearbox. I can't find the source now though.

[Mandrake]

Ah but an auto box is full of hydraulically operated clutches that wear out after a while (including the worst of them all - the torque converter lockup clutch, which is under a lot of strain) and in doing so dump metal particles into the oil that eventually cause problems with the control block and/or complete failure...

I was of course alluding to an electric motor, which doesn't require any clutches of any sort.

[EDC5]

Ah but an auto box is full of hydraulically operated clutches that wear out after a while (including the worst of them all - the torque converter lockup clutch, which is under a lot of strain) and in doing so dump metal particles into the oil that eventually cause problems with the control block and/or complete failure...

Very true, and despite all this the reliability for the AM6 seems better than the manual clutch / flywheel combo fitted to the X7 At least when you consider the maintenance cost. A few litres of oil and a few hours labour to change the ATF compared to £1500 for a new flywheel and clutch that could be buggered in another 70k miles....

I do of course recognise that there have been many horrendous automatic gearboxes in the past, but when it came to the X7 I thought I'd take my chances with the AM6 over the DMF and clutch setup. Time will tell i suppose.

[Bigjohn]

So glad this subject was taken on board and sensibly debated, I was going well with one post until electric vehicles were mentioned, just my personal view but I much prefer Diesel, just wish all the rubbish was taken off them that stops them breathing properly, I drive long distances, with the stops required for the average electric car it would make the trip very long, they have a far higher carbon footprint, and no matter what fuels the national grid they still have to plug into it, they use lithium batteries which is mined under appalling conditions, just so people can dream they are green!!

I cannot find out the make of the 6 speed gearbox in the c crosser, and I know the hp was lowered due to the DMF not being able to take the strain, (Its a good job I no longer tow a Caravan) now if this is due to the gearbox being an original mitsubishi unit? or a small clutch plate I have no idea, but the same engines are fitted to Transit, Jaguar, Land Rover, all the HP figures are around 170, except the c crosser which is 156hp