Wobbly Harmonic Balancer
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Cool video! The Y block in my slick had exactly the same when I got it twenty years ago. A good highway run would cause it to go catawampus (precise technical term) like that.
The inertia weight is designed to absorb crankshaft torsional vibrations. Due to the pulse of the pistons, the loading and unloading etc, the crankshaft under certain conditions can actually twist back and forth up to 2°, the idea is that the heavy steel weight itself sandwiched in elastomeric (rubber) to the damper hub, leads and lags a bit.
When the rubber turns to stone though there's no longer any spring action, and it simply breaks the bond and does whatever it wants. The crankshaft has at least a couple specific RPMs in the band where it will reach resonance and at least one of them is somewhere in there where we drive. It's enough in extreme cases to cause cracks or even break crankshafts. I'd expect more commonly it contributes to rear main seal leaks and beats the hell out of thrust bearings, main bearings, &c.
The inertia weight is designed to absorb crankshaft torsional vibrations. Due to the pulse of the pistons, the loading and unloading etc, the crankshaft under certain conditions can actually twist back and forth up to 2°, the idea is that the heavy steel weight itself sandwiched in elastomeric (rubber) to the damper hub, leads and lags a bit.
When the rubber turns to stone though there's no longer any spring action, and it simply breaks the bond and does whatever it wants. The crankshaft has at least a couple specific RPMs in the band where it will reach resonance and at least one of them is somewhere in there where we drive. It's enough in extreme cases to cause cracks or even break crankshafts. I'd expect more commonly it contributes to rear main seal leaks and beats the hell out of thrust bearings, main bearings, &c.
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