406 HDi DMF asessment

[Farmcit]

Our 406 HDi RHZ has its gearbox out at the moment chasing gear select problems (see other thread).

How do I test the DMF to see if it is worn out? It does not make any noises, the clutch is OK but I am replacing it while I have the gearbox out. Should I replace the DMF as well?
It has done 220k km of mostly open road driving.

What I see now is about 12mm ('arf' inch) of free rotation movement (slop) then about 25mm (an inch) of total movement including the damped bit. Is this OK?

Should I use a solid flywheel or another DMF?

Thanks,

Farmcit

[Farmcit]

Any comments?

[Peter.N.]

I have never yet had one fail, my first 406 had done 245k miles when the damp got at the electronics and as far as I know the clutch and DMF were still original, the one I have now has done over 200k. It depends a lot on the way it has been driven, how badly worn is the clutch? if its pretty thin then I would think changing the DMF would be a good idea.

What happens to it is the inner and outer parts become loose, check and see if there is any movement between them. If it is faulty the symptoms would probably be vibration and a rattling noise.

Peter

[sparksie]

I'm a bit reluctant to advise on this.
I include a replacement DMF in the cost of replacing a worn out clutch, but in truth, I've not known one to fail on a PSA HDI engine.
However, when they fail on Fords, they don't give much notice before they eat the starter motor.
The decision will have to be based on your specific situation. Will the budget stand it? Would it be a disaster to take the 'box out again next year? The BoL will give measurements for what's acceptable slop... Is yours within tolerance?
Good luck, whichever way you go

[Farmcit]

Peter.n.
Loose as described....

Sparksie
What is the "BoL" you refer to? it sounds exactly what I'm after- a description of how to measure the wear and acceptance limit on the DMF....

I see you have a Xantia, do you happen to have a manual? Would you be willing to share it? I just bought one but do not yet have a manual.

Thanks,

Farmcit

[Hell Razor5543]

The "Haynes" series of books are known as BoL (Book of Lies), as there can be numerous mistakes in them. For example, they copied and pasted the information on how to change the front fog lightbulbs and the instrument panel bulbs from the Xantia Mk1 to Mk2 manual, despite the fact that (for example) you have to take off the steering wheel to change the instrument light bulbs on the Mk1, but you do not have to for the Mk2. Not knowing this, I took off the steering wheel when I had to replace them on my Mk2.

[Peter.N.]

My 206 manual refers you to section 7 on on 'how to access the rear indicators on the SW. It goes from 5 to 8 some error somewhere?

Peter

[Lighty]

I will give you my stance on this for what it’s worth.
We NEVER change a clutch, without changing the DMF. Admittedly the occasional one still looks ok, but the extra strength of the new clutch will soon make it fail.
As for “never seeing one worn out “ well, you should do my job, they are 99% of the time out of spec, and there is absolutely no way that a DMF with 240000km on it is going to be ok.
I find that the biggest cause of failure is wether the flywheel surface remains consistently flat at all times. If you push on the edge of the surface on opposite sides, there is almost always “play”caused by the central bearing being worn.
If this movement plane is not 100%bflat at all times, you will get gear selection issues.

[Oldpug]

The gearbox is out,your replacing the clutch,of course replace the DMF,its staring you in the face. I think you would be very foolish not to . Lets face it at 220km you have had your monies worth,even if its still operating OK.

[Farmcit]

I don't know what happened there, I replied a few days ago but it never appeared in the thread.....

I understand as a repairer you are obliged to do everything in your control to ensure a long lasting job (and offer a warranty).

My situation is different as I'm sure it is with most owner repairers. I do not need to offer warranty but in saying that I do not want it to give problems in the near future. How near? this is the $264,000 question* (143,963.41 pounds).
Hence my question to the forum.... what is the spec on the DMF?

Cheers,

Farmcit


* this is actually a common expression but alas it does not roll of the tongue when converted to pounds

[sparksie]

Sorry
We got burgled and my laptop taken since my last post in this thread.
All my BoLs are in storage and not readily accessible, so I can't easily look it up for you, but I'm sure somebody will.
As I said before, how big a problem would you consider it, if you had to take the box out again next year? Perhaps before the snow's gone?
If you feel prepared to take that risk, then party on...

[aneesh84]

Sorry
We got burgled and my laptop taken since my last post in this thread.
All my BoLs are in storage and not readily accessible, so I can't easily look it up for you, but I'm sure somebody will.
As I said before, how big a problem would you consider it, if you had to take the box out again next year? Perhaps before the snow's gone?
If you feel prepared to take that risk, then party on...

Why dont you get a Valeo Rigid Mass Kit. The cost is just a little over 100 pound more than clutch kit. And no flywheel issues ever in future.

[white exec]

A new DMF will have near-zero rotational slop/freeplay/backlash between the two halves of the device - one half is coupled to the other with a system of springs. As the springs compress, in normal driving, they eventually get tired, and the DMF acquires backlash. This gives poor clutch control - particularly hill-starts, which can require high engine revs - and additional wear on the (unsprung) clutch plate.

During driving, eg pulling away, there can be up to 45deg of rotation between the two flywheel halves - gives you some idea of the amount of compression the internal springs are undergoing.

My own advice is that, if you've got the 'box off and are doing the clutch, then you should renew the DMF, and for two reasons
(a) it won't last for ever, so do it now (and avoid another workshop session)
(b) earlier than expected wear of the friction plate is a sign that the DMF mechanism is failing; really sloppy DMFs can shred and break up a clutch plate completely.

SMF is a cheaper option. Whether you fit one depends on budget constraints, and how long-lived the existing DMF has been. They are, I'm afraid, something of a 'consumable item', and sometimes don't seem to reward even gentle gear changing.