981 with PDK still need DMFW

[sb01box]

Originally Posted by stephen wilson

LWFW's have been discussed a ton here, some experts like JFP says it's a very bad idea, but others have run them for years with no issues. Do a search, read up, and make your decision. The PDK solution does not apply.

I am not trying to be argumentative. I have looked up DMFW and in Luk's web site, there is fair amount of engineering articles on DMFW.
my question is this. two different, but basically manual transmission. one, the clutch is controlled by the driver uses DMFW, the other is computer controlled.does not appear to have such resonance isolator.
the same fundamental engine and transmission resonances exists.
so WHY "the PDK solution does not apply"? just asking a technical question.

[stephen wilson]

The PDK does not have a traditional flywheel like the 986. From what I've read, the DMFW dampens crankshaft harmonics, like old V8's have a harmonic balancer on the front. I honestly don't know what they use to counter harmonics on the PDK, or the Tiptronic for that matter. You may want to add a dampened underdrive pulley in addition to the LWFW. I'll be the first to admit I don't have all the answers.

[Cloudsurfer]

Originally Posted by sb01box

I am not trying to be argumentative. I have looked up DMFW and in Luk's web site, there is fair amount of engineering articles on DMFW.
my question is this. two different, but basically manual transmission. one, the clutch is controlled by the driver uses DMFW, the other is computer controlled.does not appear to have such resonance isolator.
the same fundamental engine and transmission resonances exists.
so WHY "the PDK solution does not apply"? just asking a technical question.

The DMFW is there to both dampen harmonics of the crank (the same way that many engines use a harmonic damper on the front crank pulley, while all but the M97 do not) AND to provide some "squish" from driveline shock getting transmitted to the crank (the alternative here being a sprung clutch friction disk).

The latter part of this is why the PDK cars do not need a DMFW. Due to the nature of being computer controlled (i.e. smooth, perfectly rev matched shifts EVERY time) and the fact that there are two clutches, one between the engine and gearbox/ one between the gearbox to the halfshafts, the "squish" factor is not needed.

Now, I'm not sure if the DFI motors are running a harmonic damper on the front crank pulley or not (haven't gotten to play with one of these yet), but I imagine they have to be damping harmonics somewhere.

[sb01box]

Originally Posted by Cloudsurfer

The DMFW is there to both dampen harmonics of the crank (the same way that many engines use a harmonic damper on the front crank pulley, while all but the M97 do not) AND to provide some "squish" from driveline shock getting transmitted to the crank (the alternative here being a sprung clutch friction disk).

The latter part of this is why the PDK cars do not need a DMFW. Due to the nature of being computer controlled (i.e. smooth, perfectly rev matched shifts EVERY time) and the fact that there are two clutches, one between the engine and gearbox/ one between the gearbox to the halfshafts, the "squish" factor is not needed.

Now, I'm not sure if the DFI motors are running a harmonic damper on the front crank pulley or not (haven't gotten to play with one of these yet), but I imagine they have to be damping harmonics somewhere.

thanks - yes, my question is the same as your last sentence. "what mechanism, if any does the pdk equipped cars have for engine/trans harmonic dampening; aka DMFW?

[Cloudsurfer]

Originally Posted by sb01box

thanks - yes, my question is the same as your last sentence. "what mechanism, if any does the pdk equipped cars have for engine/trans harmonic dampening; aka DMFW?

My guess is a harmonic damper on the front crank pulley.