[Dave / Franklin MA]

I think another reason for the heavy flywheel was due to the very poor roads at the time. Many rural roads were not much improved from the frontier trails they followed, and could be very rough going. When a car bounces along a road like that, as it hits the various holes, ruts, and rocks there are shocks and stresses that are transferred back along the drive shaft that can stall the engine.

I believe a heavy flywheel has a very high rotational inertia that prevents rapid speed changes, and effectively absorbs and dampens these forces so the engine is much less likely to stall under these conditions. That same rotational inertia also helps get the car over the small bumps without losing much speed.

Of course, with the nice smooth roads we have now, that is no longer a consideration and it does make sense to lighten it.