GBMUD Posted May 24, 2012 Share Posted May 24, 2012 As per the topic title. The one in my VW van rattles a lot, what will the one in my Td5 110 do when it goes south? Chris Quote Link to comment Share on other sites More sharing options...
landy andy. Posted May 24, 2012 Share Posted May 24, 2012 Will rattle and cause vibration when you take up drive. Andy Quote Link to comment Share on other sites More sharing options...
Stevie D Posted May 24, 2012 Share Posted May 24, 2012 Can't comment on the TD5 one but the VW variant will start to litterally 'throw it out of balance', you'll think your driving a van with an old single cylinder lister dump truck engine in the front. Steve Quote Link to comment Share on other sites More sharing options...
pat_pending Posted May 24, 2012 Share Posted May 24, 2012 I think they all do something slightly different, Toyota diesels judder like mad on clutch take up and Transits chuck bits of shrapnel into the starter motor ! They don't seem to be the most reliable of things on any car/van considering the cost of replacement. Quote Link to comment Share on other sites More sharing options...
Steve King Posted May 24, 2012 Share Posted May 24, 2012 So is the aftermarket SMF the way to go?? Quote Link to comment Share on other sites More sharing options...
simonr Posted May 24, 2012 Share Posted May 24, 2012 The reason DMFs are fitted is that modern, low emission engines tend to produce high impulse torque as each cylinder fires compared to old oil-burners. This has two implications. One is transmission noise and the other is the peak torque the transmission has to handle is higher even if the mean torque is the same. This can result in premature transmission failures and increased wear. The DMF just evens out the torque a bit and largely solves the problem. The 'unreliability' is simply that they take a hammering. Without it, the hammering is just passed on to your gearbox! Personally I would stick with the DMF. Si Quote Link to comment Share on other sites More sharing options...
pat_pending Posted May 25, 2012 Share Posted May 25, 2012 Personaly I wouldn't buy a vehicle that has one. Simon is right about the reason they're fitted, If they fail direct replacement is realy the only way to go. It's another of those things that modern vehicles have that fail on a regular basis and cost a fortune to replace. Goes against the Land Rover ethos of cheap and easy to fix IMO. Quote Link to comment Share on other sites More sharing options...
landy andy. Posted May 25, 2012 Share Posted May 25, 2012 Most seem to last as long as a clutch, so can't really see the problem with them. It means you can have the power, but not trash the drive system Quote Link to comment Share on other sites More sharing options...
reb78 Posted May 25, 2012 Share Posted May 25, 2012 There seem to be a lot of people that have switched from the DMF to a solid one without problem though and also run them for some time like this without destroying gearboxes. Just a thought. Quote Link to comment Share on other sites More sharing options...
GBMUD Posted May 25, 2012 Author Share Posted May 25, 2012 Thanks guys. I understand the reason why DMFs are fitted, and on that basis I will replace like for like when the time comes. What I did not know was what symptom I will see/feel when the DMF does expire. I am getting a fairly abrupt take-up of clutch which can give a slight lurch when setting off, I wondered if it might be DMF or just the clutch. I guess that in the event that I end up replacing the clutch I should consider going the extra mile and doing the DMF too. Chris Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted May 25, 2012 Share Posted May 25, 2012 I guess in your case Chris this isn't your only vehicle and the job of replacing the clutch or the DMF is mostly the same. So maybe strip it apart then buy the bits when you know what's wrong? Budget for the worst and then treat yourself to some new toys if it's just the clutch Then you can let us all know what the symptoms of a failed DMF are, unless of course you just have a dodgy clutch, in which case you can tell us what toys you have bought Quote Link to comment Share on other sites More sharing options...
simonr Posted May 25, 2012 Share Posted May 25, 2012 There seem to be a lot of people that have switched from the DMF to a solid one without problem though and also run them for some time like this without destroying gearboxes. Just a thought. The trouble is that 'some time' may not be long enough to determine if the transmission is being damaged. I imagine Land Rover looked at it from a statistical point of view. In the warranty period they will get a certain number of failures. The number of anticipated failures without a DMF in that period must have been high enough that fitting one was cost effective. Also, 'a lot of people'. Is that a representative sample and is the sample big enough compared to the total ownership to be statistically significant? Individual people saying that they have run one for a while without a problem is just not statistically significant and thus does not evidence that it's a good idea. Just as you get people who have been heavy smokers their whole life without a problem, does not mean it's safe for everyone. Is it worth gambling that you are going to be one of the lucky ones? Si Quote Link to comment Share on other sites More sharing options...
reb78 Posted May 25, 2012 Share Posted May 25, 2012 The trouble is that 'some time' may not be long enough to determine if the transmission is being damaged. I imagine Land Rover looked at it from a statistical point of view. In the warranty period they will get a certain number of failures. The number of anticipated failures without a DMF in that period must have been high enough that fitting one was cost effective. Also, 'a lot of people'. Is that a representative sample and is the sample big enough compared to the total ownership to be statistically significant? Individual people saying that they have run one for a while without a problem is just not statistically significant and thus does not evidence that it's a good idea. Just as you get people who have been heavy smokers their whole life without a problem, does not mean it's safe for everyone. Is it worth gambling that you are going to be one of the lucky ones? Si I agree Si. I thought that after i had posted it. It depends on driving style and plenty of other factors too. I was just pointing it out as another option that 'some' consider to be fine. I'd be torn on what to do if it were mine. Take a TD5 though - is an R380 really going to grumble at having the power shoved through it without the DMF when the same box might have taken a fair old hammering behind a 300tdi that never had a DMF? Quote Link to comment Share on other sites More sharing options...
Daan Posted May 25, 2012 Share Posted May 25, 2012 Isn't the solid flywheel a lot heavier, and damps the vibrations purely because of this? As mentioned, I bet a tdi will give the gearbox a much harder time due to vibrations. Daan Quote Link to comment Share on other sites More sharing options...
simonr Posted May 25, 2012 Share Posted May 25, 2012 It's not the vibrations as much as the torque out of the engine. As each cylinder fires you get a sudden ramp up in torque causing the speed of the crank to increase. Diring the gap between two combustions it slows down again. You are familiar with the way suspension works - you have a mass (the vehicle) a spring and a damper (shock absorber). If these are tuned correctly, you can drive over a rippled surface with the body staying level & smooth - known as 'critical damping'. A traditional flywheel just uses mass (momentum & inertia) to smooth out the ripples. A DMF has springs and dampers built in - as well as the mass of the flywheel. This allows it to provide a much smoother output with much less mass. I suspect that to provide the same level of damping on the output, wou would need an impossibly large flywheel. However, like the springs & shocks in your suspension, they have a finite life. Using a SMF is analogous to getting rid of your springs & shocks and driving on bumpy ground. It's not going to be comfortable - and that's what your transmission will be experiencing. With an older Tdi, the output is actually much smoother as the combustion takes place over a longer period leaving shorter gaps between the combustions. Si Quote Link to comment Share on other sites More sharing options...
mmgemini Posted May 25, 2012 Share Posted May 25, 2012 Isn't the solid flywheel a lot heavier, and damps the vibrations purely because of this? As mentioned, I bet a tdi will give the gearbox a much harder time due to vibrations. Daan I don't know what you mean a lot heavier but I couldn't lift one off a table at the Indoor Show. Quote Link to comment Share on other sites More sharing options...
Off Road Toad Posted May 25, 2012 Share Posted May 25, 2012 We fitted a SMF to our 130" because the clutch was slipping and we thought we'd do it all at the same time. BIG mistake. It now feels like your on a washing machine at tickover (fine at higher revs) and the gearbox is now whining and graunching after just 20,000 miles of life with the SMF. (total mileage is only 70k) my comp car is fine with the DMF, 35" tyres and hybrid turbo etc so I'll stick to one of these when the time comes. Steve (the SMF is a Rakeway one NOT &£itpart either) Quote Link to comment Share on other sites More sharing options...
simonr Posted May 25, 2012 Share Posted May 25, 2012 I don't know what you mean a lot heavier but I couldn't lift one off a table at the Indoor Show. Sanatogen? Thanks Steve - that's pretty much what I expected! Although even the DMF is about twice the weight of a Tdi Flywheel, someone told me it would have to be close to 500kg to give similar torque ripple to a Tdi - which is clearly impractical! Apart from any other constraints, you would loose all responsivelness in the engine! The TD5 is such a fantastic engine - the DMF seems a small price to pay for the performance & power it delivers! Si Quote Link to comment Share on other sites More sharing options...
M&S Posted May 26, 2012 Share Posted May 26, 2012 The reason DMFs are fitted is that modern, low emission engines tend to produce high impulse torque as each cylinder fires compared to old oil-burners. This has two implications. One is transmission noise and the other is the peak torque the transmission has to handle is higher even if the mean torque is the same. This can result in premature transmission failures and increased wear. The DMF just evens out the torque a bit and largely solves the problem. The 'unreliability' is simply that they take a hammering. Without it, the hammering is just passed on to your gearbox! Personally I would stick with the DMF. Si That is what I'm doing. My DMF has finally given up (I suspect) and I'm replacing it with another. Done a lot of reading/research and figure that LR fitted it for a reason and whislt a SMF may do the job and not give much noticeable difference in noise or vibration, the gearbox and rest of teh transmission might not be thinking so. Also wonder how the crankshaft/bearings would take it? Mine has done 155,000 miles so that's not so bad. The clutch is showing no signs or problems (no slipping or gearchange problems etc) but the flywheel is making a chattering and I can feel this through the pedal if I rest my foot lightly on it. You can also hear it outside the vehicle when driving. I have spares/AA card at the ready! As well as that I suspect that teh continual stalling when laning last weekend might be down to teh flywheel failing as well? Never considered it at the time but did think it was odd it was stalling a lot. Later in that day the chjattering got very loud and stayed that way in low and high box. Unfortunately I can't do it myself otherwise I would, but looks like I'll have to grin and bear the garage labour costs for the first time in 2 years! Quote Link to comment Share on other sites More sharing options...
reb78 Posted May 26, 2012 Share Posted May 26, 2012 I had a look at prices and they arent that expensive in the grand scheme of things coming in around £300 (less than a gearbox at any rate). So i guess replacement is sensible. Quote Link to comment Share on other sites More sharing options...
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