If so, how much longer can I drive on it?

Steve

Sounds like the DMF to me - had just the same thing on my old A3 (about 2 months before part exing against my Vrs - Grrrrr), and from first noticing the clunks I reckon I got about 1200 miles - but I would say get it seen to before it goes, as when mine went I got stranded at a busy intersection and it is fair to say that my fellow road users were not very understanding, which cheered me up no end in addition to the 2 hour wait for the RAC and the £900 bill.

Hope it works out OK for you.

TC

Sounds like the DMF to me -

had just the same thing on my old A3

(about 2 months before part exing against my Vrs - Grrrrr), and from first noticing the clunks I reckon I got about 1200 miles - but I would say get it seen to before it goes, as when mine went I got stranded at a busy intersection and it is fair to say that my fellow road users were not very understanding, which cheered me up no end in addition to the 2 hour wait for the RAC and the £900 bill.

Hope it works out OK for you.

TC

You could have got a single flywheel and clutch fully fitted for £230 all in

You could have got a single flywheel and clutch fully fitted for £230 all in

So, are there any decent descriptions anywhere about how well or badly a SMF works in comparison to the DMF? I've seen recent mentions here, but only from one or two people.

When I, and the dealer, thought that the DMF was the problem on mine, he advised strongly against changing to a SMF, saying that they had done this for some taxis and that they had all returned within a few months to have dmf's refitted. My feeling is that to get these modern diesels to feel lively and quiet, the flywheel has been made with less mass. Is this right? Does the smf have more mass than the dmf?

SMF is definetly NOT an option. Too much vibration transmitted , and flexing of the crank shaft

Odd that skoda offer the smf to taxi drivers due to the issues with the dmf.

Didn't re-occur during a 160mile round trip to Elvington Airfield (used an MX5, not the Tavia).

Then reversed into the drive and clunk-bang-wallop!

Steve

Mine used to give trouble in reverse.Used to judder and clunk and shake the engine.

Eversince i had mine converted to SMF at 33K miles (1.9TDi) mine has gone very quiet and 100% no vibration at all from anywhere.The gearchange is ultra smooth now and the drive picks up very smoothly with no cold start juddering.

And "Flexing of the crankshaft" thats a good one.Did all the crankshafts break in the early pre-DMF days?

Study of crankshaft torsional deformation under steady-state and transient operation of turbocharged diesel engines

The modelling of transient operation of turbocharged diesel engines appeared in the early 1970s, and continues to be in the focal point of research due to the importance of transient response in the everyday operating conditions of engines. The majority of studies have focused so far on thermodynamics, as this directly affects heat release predictions and consequently performance and pollutants emissions. On the other hand, issues concerning the dynamics of engine operation are often disregarded or over-simplified. In the present work, an experimentally validated diesel engine simulation code is used to study and evaluate the importance of a notable engine dynamic issue, i.e. the crankshaft torsional (angular) deformations during turbocharged diesel engine operation owing to the difference between instantaneous engine and load (resistance) torques. The analysis aims ultimately in studying the phenomena under the very demanding, and often critical, transient operating conditions. Detailed crankshaft angular momentum equilibrium is formulated that takes into account instantaneous gas, inertia, friction, load as well as stiffness, and damping torque contributions. Details are provided concerning the underlying mechanism of the crankshaft torsional deformations during steady-state and transient operation. This deformation can assume significant values depending on the engine-load configuration (load change, flywheel, crankshaft stiffness, kind of aspiration of the engine), and as such it is of great importance for safe engine operation.

Wait till you put big torque through a Lighter SMF on a PD TDI. On a 2.0 Tdi that has been chipped, the high torque peak (which is that sudden burst of power followed by a flat spot) really puts the crank under pressure, as the lighter SMF has a lower moment of inertia and will rotate easier than a DMF.

A PD 150 Golf Van in Ire Puttin out over 230 on a Sachs SMF conversion, sheared the four bolts of the SMF . Are you tellin me that in order for that to have happened, there was no torsional stress transmitted back through the crank.

I have the torque band on mine lowered to prevent that sudden burst, but it has been widened, so that i can use that torque through a wider rev range, giving me a smoother delivery.

Who said you had to use a lightened SMF?

You still need the mass and some vibrational dampers but what you don't need is the overly complex way it's been done in a DMF.

Who said you had to use a lightened SMF?

You still need the mass and some vibrational dampers but what you don't need is the overly complex way it's been done in a DMF.

Agree with that.All i have is the PD105 thats been converted to SMF as told by SUK to do so as they are recieving high volumes of warranty claims on DMF,s so are recommending this conversion (1.9 TDi).Mine isn,t a taxi either and i have no plans of re-mapping and ridiculous amounts of torque and isn,t raced so no damage or so called flexing of the crankshaft ( ) will happen with just 105bhp

Agree with that.All i have is the PD105 thats been converted to SMF as told by SUK to do so as they are recieving high volumes of warranty claims on DMF,s so are recommending this conversion (1.9 TDi).Mine isn,t a taxi either and i have no plans of re-mapping and ridiculous amounts of torque and isn,t raced so no damage or so called flexing of the crankshaft ( ) will happen with just 105bhp

Torsional Stress Map Of A Crankshaft

Edited 19 February, 201016 yr by tom1362

What the hell is that illustrating!?

I have no idea at all either and 8 cylinders

Looks like SUK will have to pay out for all us SMF converted owners as we will all need new crankshafts.LOL

All iam doing is replying to what the dealers have done with car as recommended by SUK giving owners information ******************************* .

Edited 21 February, 201016 yr by DGW
Comment not relevant to this topic deleted.

Im being serious though, i want to understand the diagrams. But finding it a little hard to, even though i understand vaguely whats happening. The diagrams are a little complicated to understand.

Im being serious though, i want to understand the diagrams. But finding it a little hard to, even though i understand vaguely whats happening. The diagrams are a little complicated to understand.

Looking at the first yellow illustration, there are 7 indiviual structures.

1 Crank

4 Con-rods

1 Timing pulley

1 Flywheel

While these are mounted to gether to act as 1, when testing for torsion (flexure or any other deformation) or be it a modal analysis as i illustrated in the second diagram, these components each have their own idividual torsional, acoustic, modal, vibrational properties.

E.g resonance frequency of con-rod 1 will be different to resonance frequency of con rod 2, same for inertia. A good example of this is the individual balancing of a cranks counterweight to that of its partner con-rod.

My original proposition, was that if you dramaticaly alter one of these components, i.e flywheel (be it SMF. Lightening SMF or other) , this will have an effect on the other compnents overall mechanical functin as a mechanism.

If i was to pull off very quickly from a standing start on a dry day with a good road, with a set of 225/40/18's on the driven wheels, I would place a lot of strain on the drives, gbox, clutch and flywheel assembly, and what is bolted onto this... crank).

Not only am i doing this, but i am trying to transmit high levels of torque through each.

This was my initial point.

A DMF has multiple degress of freedom as it is manufactured from multiple components, each with their own vibrational characteristic. Most likely at this lower RPM range and while we are transmitting considerable torque through it , it reaches its resonance frequency or a close harmonic of it, giving the spring damping mechanism more energy. A repetitive cycling of this would be a good candidate for the DMF's shortcomming.

A you can then imagine, a SMF being of one solid component, will have 1 degree of freedom, making it easier to predict and controll.

I wouldn't necessarily take what SUK or a VAG dealer has to say as gospel, just because the cheapest way of overcomming the global problem of failing DMF's was to revert back to a SMF.

(Which BTW will most definetly transmit extra vibration while idling and pulling off )

Edited 20 February, 201016 yr by tom1362

I have done 47,000 miles ( now on 115,000) since I had mine converted last year to a single system with no problems its really quiet and the gear changes are smooth