Checking DMF play with the gearbox in place

[Mike Noc]

When trying to sort my drive clunk yesterday with the car jacked up and in gear I'm sure I could hear the DMF springs taking up the play when rocking the wheels.

Thinking about it this could be a good way to check the play in the DMF. With the car in 5th gear and just the passenger front wheel off the ground the play when rocking the wheel will be in direct relation to the amount of play in the DMF.

The gearing is a factor of course, and the differential will be operating.

So if anyone is changing their clutch can I ask a favour - do the above check before you start work and measure the amount of movement on the outside of the tyre. Then measure the play in the DMF once the box is off and we can compare the two figures.

With a few readings we should be able to come up with an acceptable limit of wheel play before the DMF is suspect.

[Bolin]

Wouldn't there be a bit of play from the CV joints too, even when they are not 'worn out'?

[Mike Noc]

Yes there could be a bit of play here and there but it should give a reasonable ball park figure to show if the DMF is nearing its wear limit..

[FrenchMike]

Good idea Mike ,

Worth having a try

Knowing the behaviour of the DMF play is springy opposite to others :}

How much do you get on yours ?

Mike

[T-Cut]

It's an interesting idea, but I wonder if the road wheel play would be consistant enough to enable a general 'DMF Rule' to be formulated. There is a variable backlash in every joint and gear in the drive train between the wheel and the crankshaft/DMF. I suspect - but it obviously needs investigation - that the permitted slop at the wheel will be too great to enable a reliable correlation to the DMF slop. Another factor is the sensitivity of the test. Will the wheel give a good feel of when the DMF springs are just at the contact point? It needs testing on lots of cars to formulate a rule but is certainly worth the experiment.

TC

[Mike Noc]

Good idea Mike ,

Worth having a try

Knowing the behaviour of the DMF play is springy opposite to others :}

How much do you get on yours ?

Mike

With the box off last time around at 299k miles 2 years ago it was just under 28mm, so pretty near the limit, but I didn't replace it.

I didn't go as far as measuring the play on the outside of the tyre, but can give it a go when I get a spare moment.

The interesting thing would be to compare the two readings when taken together though.

[beinet1]

Are you able to "see" the DMF play when the starter is removed??

[FrenchMike]

With the box off last time around at 299k miles 2 years ago it was just under 28mm, so pretty near the limit, but I didn't replace it.

I didn't go as far as measuring the play on the outside of the tyre, but can give it a go when I get a spare moment.

The interesting thing would be to compare the two readings when taken together though.

On mine at 100.000 km (110.000km now) i have mesured ,like you
about 30 mm.

I 'll have a look soon and tell the result

Mike

[FrenchMike]

Are you able to "see" the DMF play when the starter is removed??

Good question ,i think so

[johnny t]

There's always seems to be a lot of worry about the dmf, has anyone had one actually fail or is it just a expensive part that we fear.
What are the symptoms of dmf problems

[FrenchMike]

Hi Mike ,done:

http://rovermg1.free.fr/rovermg/thumbnails/kwK4GtMa3Djo6Mm53qwu.jpg (http://rovermg1.free.fr/rovermg/images/kwK4GtMa3Djo6Mm53qwu.jpg)

i get 40 mm in each direction ....

Mike

[Mike Noc]

Thanks Mike that was quick. :bowdown:

Working on Mrs Noc's Rover 25 at the moment - only a slight leak at the heater valve but best nip it in the bud.

Will check mine when I get a chance.

[FrenchMike]

However,i Wonder if it includes the plate springs compression ???:shrug:

[T-Cut]

However,i Wonder if it includes the plate springs compression ???:shrug:

Hence my query about the sensitivity. Is it possible to differentiate between the point the springs make contact and when the springs are compressing? It needs more tests on different cars.

I wouldn't expect the inner and outer masses to both be visible by removing the starter motor, but I've never actually done it.

TC

[FrenchMike]

Something like this i guess ?

http://rovermg1.free.fr/rovermg/thumbnails/ZsSZJIzrRPTT1uCpJ270.jpg (http://rovermg1.free.fr/rovermg/images/ZsSZJIzrRPTT1uCpJ270.jpg)

[Mike Noc]

Well just checked mine and sadly it looks like I'm into an early lead at 62mm. :(

That is feeling the free play only. Valid point about sensitivity TC, as if you push hard enough on the wheel edge you can even turn the crank.

[FrenchMike]

Well just checked mine and sadly it looks like I'm into an early lead at 62mm. :(

That is feeling the free play only. Valid point about sensitivity TC, as if you push hard enough on the wheel edge you can even turn the crank.

Mike,i have not measured the torque ;And the spanner was only 1 foot long !

[Mike Noc]

Oh dear...... I could be further in the lead than I thought. :getmecoat:

[Mike Noc]

There's always seems to be a lot of worry about the dmf, has anyone had one actually fail or is it just a expensive part that we fear.
What are the symptoms of dmf problems

Yes they do fail and yes they are expensive. Symptoms can be anything from a bit of juddering on taking up the drive to complete failure where you get no drive at all.

Compared with some cars our DMF's do seem to last well. Some garages will change them anyway though which is why it would be handy to have an easy way to measure the free play.

I did contact a scrapper about a used one he had on ebay to check how much play it had. The answer was no play at all so I didn't bother buying it.

Have driven my car from new but it was originally a company car, and I only have a log of what was changed and when after I bought it at 118k miles.

It had a new slave just before I bought it - this was the second time it had been in the garage to sort out clutch problems. Just under a year later the clutch went again and as luck would have it it was done under warranty.

They said they had changed everything but I don't know if that included the DMF - probably not given the cost of them.

So the DMF in my car has either done around 190k or 336k miles. :shrug:

[johnny t]

I only ask as everyone these days is worried about them in particular my friends with vw's. I've put 118 k on mine with the usual slave and master cylinders but can't say I've ever worried about the dmf. I often read people giving advice about changing it when having clutch work done, but have never seen a post about total failure

[Mike Noc]

I only ask as everyone these days is worried about them in particular my friends with vw's. I've put 118 k on mine with the usual slave and master cylinders but can't say I've ever worried about the dmf. I often read people giving advice about changing it when having clutch work done, but have never seen a post about total failure

Mondeos are well known for DMF failure as well. :getmecoat:

It is rare for them to fail totally, but here you go:

http://forums.mg-rover.org/showthread.php?t=423503&highlight=dmf+total+failure

[johnny t]

Thanks for that I can start worrying now

[Billy1mate]

There's always seems to be a lot of worry about the dmf, has anyone had one actually fail or is it just a expensive part that we fear.
What are the symptoms of dmf problems

A work mate of mine has his DMF fail on his Seat Altea, it needed a clutch, DMF and gearbox as the DMF had chewed into the gearbox bell housing. £2500 bill.