Hi


I'm a Dmax/ZF'r and I'm wondering if someone can tell me what a "dual mass" flywheel is or does that's different from and ordinary flywheel? Why would GM spec a " dual mass " flywheel for the ZF.


Dinger

it is, simply stated, a two piece flywheel with springs used to reduce or absorb torque at the lower rpm levels. the two pieces are riveted together. It is a thick and heavy flywheel. It is also a piece of $^&%. CPMac is working on a replacement and a clutch since the OEM clutch system will not hold to any significant loads, speeds, big tires, or power chips . . .

A dual-mass flywheel is basically a two-flywheel sandwich with spings in between, allowing the two halves to turn, within limits, relative to each other. The front 1/2 is bolted to the engine crankshaft and the rear half, through the clutch, connects to the tranny input. It's purpose in life is to prevent the spikey tourque reversals that a diesels creates at low RPM (generally lower than idle RPM) from pounding the tranny to bits, or at least causing objectionable gear rattle. A single-mass flywheel would have to be much heavier to accomplish the same goals, and might in the process increase forces within the crankshaft to unacceptable levels. (Cummins takes that route, with a much heavier crankshaft and a single-mass flywheel).


As observed above the rivets that hold the sandwich together on the DMF are a weak point. I haven't broken mine, but I run stock power. Many have had failures with increased power and some with stock power and heavy use. A few apparently have broken springs without abusing anything . . . the springs are expected to absorb a lot of energy during start-up and shut down as the engine passes though a resonant RPM. The good news is that the flywheel is specifically included in the 5yr/100,000 mile D-max engine warranty.

excellent post - thanks Colorado


Dinger

CPMac has two clutch setups available for the ZF one piece billet flywheel and your choice of dual disc or single disc clutch. I am saving my $$ for mine later on this summer.