now like I said, I don't know much about them. Explain to me what the benefit is please
Like everything else, removing the two center counter weights was a cost cutting measure. At the time, engines were ridiculously under square and were run at very low RPM. The pencil pushers, always looking for ways to bleed a turnip for all it’s worth decided the two center counterweights could be removed.
Does it work? Yeah. A bagillion plus miles have been put on 6 counter weight cranks. But they flex more, are harder on bearings and a 6 CW crank isn’t nearly as smooth as an 8 CW crank is and never can be.
Those counterweights offset the weight of the piston assembly, connecting rod, rod bearing and rod pin. There should be center counter weights to off set the weight of the center pistons.
Think of it this way. When you externally balance a crank, its because the counterweights aren’t heavy enough (not enough mass) to offset the weight of the above assemblies. So you add weight to the damper and flywheel OUTSIDE of the crank case. Regardless of how many miles and years guys put on their externally balanced cranks, adding weight to the ends of the crank adds in bending moments to the crank. It’s a cheap assed way to make a crank that doesn’t have enough mass to be used.
Its the same principle when you remove the center counterweight. You are asking 6 counterweights to do the work of 8. And the center of the crank is weaker because there are no counterweights there.
Long strokes (relatively), high RPM and/or both bend the hell out of the crank at the center main bearing and you can see it in the bearings. I dealt with it for a long time. A good damper helps a bit, but it can’t fix missing counter weights.
The cost of CCW cranks would drop by a fair margin IF they quit making 6 counterweigh cranks. Of course, you have the marketing issue because it’s hard to convince someone that what they haven’t had for ever is worth the extra money.
