DMF vs. Solid.

atrixblue.-MFR-.

Retrogamer wrote: »

Is this the case?
I thought the majority of crankshafts were made from molten metal (cast) rather than machined from a solid billet.
Hence all the roughness on parts not machined down to be smooth.

The only car i know off the top of my head that doesn't like SMF is the 4x4 Octavia TDi. As the engine is the same as other TDI models with no SMF / Crank issues it's likely the extra vibration from the 4x4 transmission is what causes the crank to fail

I know of vw golf 4 motion TDI that has the SMF conversion, its done over 100k miles since fitment with no issues from the engine at all (its a taxi).








DMF was created simply for comfort and experience and to limit torque reaction to transmissions from first to second mainly for prolonged life that a SMF application product would otherwise last, not that the vibration caused disastrous fatal engine issues it was purely to give noise and feel a bit more of a comfort to the driver whilst extending transmission (inc clutch) life.

EdGasket

Engines and gearboxes never used to need DMF's so why do they suddenly all need them now?

A cheapskate fix for a busted DMF is just to weld it up (must be really well or the welds break) and thus create a solid flywheel. But if you are paying for the job to be done, then it probably is better value to replace the DMF or fit a proper solid conversion.

iolanthe07

Buy an automatic, then you don't have to worry about any of this.

Retrogamer

EdGasket wrote: »

Engines and gearboxes never used to need DMF's so why do they suddenly all need them now?

Seems to be a combination of refinement and longer gear ratios.

Longer gear ratios cause the engine to labour more often. On older diesels the vibrations from the labouring engine were transmitted into the cabin but the DMF absorbs them


Funny enough i had a very slight wobble at idle sometimes from my DMF when i got my car at 97k so was on it's way out.
It's 114k now and even with some hard launches it's still holding up.
Replacement just shortly though as the vibration / noise is getting too much

Gloomendoom

iolanthe07 wrote: »

Buy an automatic, then you don't have to worry about any of this.

Unless it is one of the new fangled torque converterless autos.

patman99

There is a specialist company in Ipswich that machines SMFs out of aluminium. They are made for racing and are designed for that make/model of vehicle.

If these kits could cause damage to the engine or gearbox, then I doubt they would make then.

Gloomendoom

I wouldn't bank on it. Racing engines are often rebuilt between races.

patman99

A great deal of his customers buy them to fit on road cars.