Dual Mass Flywheels

[jedi134]

Petrol V6 golfs have DMF's why? I thought it was just diesels?

[Cyker]

Is a bit weird, esp. on a V6... DMF is only really useful on low-rpm engines that deliver a high impulse when a cylinder fires - they need heavy flywheels to balance the power pulses, but that slows down acceleration which is why the DMF was invented as it gives the best of both worlds (Fast spin up of a light flywheel but damping of a heavier one).

Unfortunately, it introduces an oscillating part into a highly stressed part of the drive-train and the springs are constantly rubbing against the inside of the DMF like sand-paper which is why they tend to fail...

Low RPM and hard acceleration causes high wear in most DMFs.

[jedi134]

Yep strange indeed, V6 engines are smooth to start with, Seems there are a lot of petrols with DMF'S fitted, but you don't hear about many failing.

[Cyker]

Well petrols don't generate enough of a pulse to need a heavy flywheel in the first place, plus they run at higher RPM which smooths out the power delivery so the DMF would be under a lot less stress; But then as you say, why fit such a part when a solid flywheel would be cheaper and more reliable and would do almost as good a job?!

I don't know... I must admit I didn't even know petrols had them; This is the first I have heard of it!!

I could maybe understand on a 3-cylinder engine, but not on a V6!!

[anchorman]

Maybe the risk is from stalling. Some engines generate a hell of a kick if they stall.

[shcm]

A while ago I read a technical paper from a certain component supplier that all but admits they got the design calculations wrong for the DMF springs and why therefore they have a relatively short life. Mathematically, it's a relatively heavy paper, but the date of it fits in with production time for things like the 4.2.

It might have some bearing on why we hear of few DMFs failing on 4.3s.

[Cyker]

Maybe the risk is from stalling.  Some engines generate a hell of a kick if they stall.

Oooh, good point, I hadn't even considered it from that angle!

[Paxos Stu]

Hi all

Love this website/forum especially when you live on a small Greek island with only 2 little mechanic repair centres!!

We've got a UK registered Rav 4 2.0 D4D manual 3 door here (Reg no H12 OPR) & we've had it 2-3 yrs without any hiccups (I love it) Its done 128,000 miles

Recently (in past 4-5 months) its developed quite a heavy vibration (mainly when under load going uphill or when you back off the throttle on a motorway) & with that came a slight creaky rattle when the clutch got to biting point, not a jingling but almost like the drive belt needed some WD40 on it. I had a feeling it was either clutch or maybe a driveshaft rubber coupling or something, today I was coming up the hill to our house & it slipped a bit "as in clutch slip", but not like when a clutch normally goes & slips all the time & the revs go up, it just slipped (missed a beat) for a split second & then was ok & the vibration's getting worse.

I have been looking on here & immediately seen these suffer from Dual Mass flywheel issues.

My other issue is I am stuck with regards to getting someone to fix it here, there are a couple of fitters here on the island but they're kind of pads, oil filter, head gasket type boys, I wouldnt trust them when something gets a bit technical, so I need to know if this is very technical or should a normal fitter be able to handle it??

Would anyone know roughly what a workshop would book for this job, as probably the only reliable firm I would have here would be Toyota main agent, obviously I should replace the clutch whilst I'm at it.

I have also read that a lot of people replace with a solid flywheel conversion?? Has anyone done this at all & if so is it fairly straightforward & are there trade offs i.e vibrations etc, I dont really want to turn my lovely Rav into a Land Rover farm vehicle or Massey Ferguson!!

I hope someone can give me some advice as I dont want to give someone an open chequebook to experiment on fixing it.

Wait to hear back

Thanks in advance

Stuart

[anchorman]

I did a SMF conversion for somebody. It is a straight forward job which is more of a heavy maul than highly technical. If they can do a clutch in a big front wheel drive they should be fine. Listening to the prognosis, I think you are safe to order up some parts

[Paxos Stu]

Thanks Anchorman, was hoping I'd get a reply from you.

One more question, any suggestions what make clutch I buy?? LUK??

Stuart

[anchorman]

Most here seem to go for a kit from blueprint. If you can find an LUK kit it will be good quality too.

[Paxos Stu]

Sorry AM, I used to work for Car Giant in London (they process 1000 cars a week through their workshops) The SM there says that they only tried SMF conversion once & they found it threw the engine out of balance & have this always stuck to DMF (although blo*dy expensive) What are your thoughts??

[anchorman]

Well look, I've always been an advocate of staying with a DMF but I have fitted an SMF and so have many others. I bought a japanese one from a motor factor. It was bit dearer but I fealt confident about the engineering. All I can say is, I wouldn't expect any problems with a decent kit.

[Tech01]

Sorry AM, I used to work for Car Giant in London (they process 1000 cars a week through their workshops) The SM there says that they only tried SMF conversion once & they found it threw the engine out of balance & have this always stuck to DMF (although blo*dy expensive) What are your thoughts??

Yes, but whose kit was it? And was it fitted correctly? And is their experience limited to only one?

As Don says, many of us have fitted SMF kits successfully, when other avenues were closed (eg second DMF failures).

The Blueprint kit is a 4-part one: it includes SM flywheel, conventional sprung clutch plate and cover, and the thrust bearing. (So there is no need for additional clutch parts.) Fitting is straightforward - just remember to apply thread-locking fluid to the flywheel bolts, and torque up correctly.

Chris

[Paxos Stu]

I have ordered a LUK conversion system & we're gonna give it a go here in Greece.

Thanks guys for all of your advice, very valuable (as ever!)

[Davrav]

I have ordered a LUK conversion system & we're gonna give it a go here in Greece.

Thanks guys for all of your advice, very valuable (as ever!)

Let us know how you get on Stu. If you get to take any photos that would be helpful too.

Good luck

[Alan Hancox]

Hi all, before I ask my question I would like to say that I have read this long thread. Also my wife's rav4 has failed while I am on the other side of the world and so I am trying to diagnose the failure remotely and before I have to call in the local garage.

The Rav is a 2005 d4d rav4 with 66k on the clock. Owned from new with a full service history. Over the last year it has developed a mild clutch judder, particularly when cold, and a strange metallic noise in gear1 which also manifests itself in any low gear when under heavy load.

I found this thread last year and suspected it might match the symptons of car, but 2 local mechanics thought there was nothing wrong.

Yesterday, the car failed. My wife describes the following symptom.

Able to depress clutch and there is clutch pressure.

Able to select all gears.

On releasing the clutch, with a gear selected, the car attempts to move, but then the engine rpm rise and the car does not move forward.

There is no smell of burrt clutch.

The car was recovered by the RAC to our house, the Rac mechanic was of the opinion that the Transfer gearbox had failed.

I now have the choice of getting the car recovered by a clutch replacement specialist in my area who had already given me a good quote for the replacement of a DMF.

Or I can get the car recovered by a reputable local garage, who would be able to fix either the clutch or the gearbox, but would be a lot more expensive.

My question is, is there any easy way I can get my wife to confirm DMF failure rather than Transfer gearbox failure.?

Also I do not know the symptons of transfer gearbox failure, so if anyone has had this it would be helpful to know the symptons.

Many thanks for any advice.

[Tech01]

Hi Alan,

From what you describe, this sounds like either clutch plate failure (centre sheared/broken up, so that drive is not passed from flywheel to gearbox), OR - and unusual - the DMF has completely disintegrated, so that the two "halves" of it are no longer connected.

I would have thought that transfer box failure was unlikely; it hasn't been (to my knowledge) reported here.

When DMFs get sloppy and begin to run badly, they typically cause premature clutch wear and clutch plate failure.

If you've had a good price for a DMF-and-clutch replacement, by all means go for it. To replace these items, the transfer box has to be removed anyway, which will allow for its inspection.

Having had one DMF fail, and having had its Toyota replacement fail too after just another 20,000 miles, I don't rate these items very highly. I now run a Blueprint SMF (as detailed in above posts) which performs without trouble, and offers far better clutch control. The kit contains flywheel, and a complete conventional clutch.

Chris

[Alan Hancox]

Hi chris, many thanks for your opinion. I suspect that we may have been experiencing some of the DMF failure symptons for over a year, so total failure is possible. Also, some years ago we used the rav to tow a caravan which is also not good for the DMF.

If I was to have Transfer box failure do you know what the symptons would be?

[anchorman]

The transfer box is bombproof and in the unlikely event it did fail I doubt it would attempt to move. DMFs are the weaker link on that model.

[Tech01]

The transfer box is bombproof and in the unlikely event it did fail I doubt it would attempt to move. DMFs are the weaker link on that model.

Agreed.

Chris

[Alan Hancox]

Thanks.

I have instructed the clutch specialist to recover the car, and will keep my fingers crossed.

[Paxos Stu]

Hi all

Wanted to give something back to this forum as its been "Invaluable" to me in diagnosing my DMF fault on my beloved Rav 4.

Alan Hancox you have exactly the same symptoms as me, I would bet my Rav on it that you have DMF failure.

Have just got my 2003 D4D Rav back from Corfu mechanic & its running great (touch wood) on the SMF (LUK system) bought from Nationwide Clutch Distributors on eBay, fantastic firm & very knowledgeable (couldnt recommend them enough) £299.99 complete LUK conversion kit + postage to Greece (4yr guarantee on clutch & lifetime on flywheel!)

Anyway, my symptoms (looking back on it) were:

Early stages: morning clutch judder from cold, metallic tinkling sound at biting point of clutch & under load & heavy vibration through car when backing off throttle on motorway & under load. (Suspected worn UJ or rubber coupling to begin with)

Middle stages: Gambled & took the car to Italy for short trip, as I got off the ferry in Brindisi it became very hard to get into gear, sometimes having to switch it off to get into gear, then one day a loud clattering sound from Gearbox vicinity, then that stopped.

Final stages: Got increasingly difficult to get into gear & then when the mechanic took it off the ferry in Corfu, it drove 2km & then lost all drive & had to be towed to the garage, so I was very lucky.

So far so good with SMF, just a little freeplay in the clutch pedal which wasn't evident when I got car back, mechanic said maybe the clutch needs bleeding. Cant find the fluid reservoir for clutch for the life of me!!! Anyone assist with this?? Can find brake one!!

Thanks again all for your help, would have been totally lost without you all

Stuart

[anchorman]

The clutch gets its fluid from the brake reservoir (you will see a little pipe to the master cylinder).

There is no harm bleding it but also check the push rod at the top of the pedal. There should be enough slack that the push rod isn't under any kind of pressure. If after that there is 15-20mm free movement before you start to get any back pressure then don't worry, the clutch is working fine. If you can get it into reverse without it cruching gears, that is OK.