What Do You Make of This???

[Joe C.]

This is a GM 3791021/22 replacement flywheel, cast 12/12/67, made of nodular iron:


See here for more information:
https://www.forums.ncrs.org/showthre...64684&uid=4340

[Mike M.]

Re: What Do You Make of This???

Maybe I'm a little touchy when it come to this and other safety issues.
However, I think this is a great conversation piece that is better left out of the car. It does demonstrate some of the effects of slippage.
I don't believe in the present condition that it would even take any high revving to eventually turn this into a grenade.
My aluminum flywheels used to get these heat cracks, but, never that bad.
I trust you all have seen the pre-and post scattershield era photos showing what happens to the floor, dash and driver's feet when one these assemblies lets go.
While watching a late model stock car race from the grandstand when a clutch blew in one of the contestants cars, a friend took a flying fragment in the frontal lobe, obviously and sadly, he has never been his prior self since.
HaND and count your blessings.

[Donald S.]

Re: What Do You Make of This???

i have seen this lots over the years . in the past i would have had the fly wheel surfaced then magnafluxed and checked for cracks .. i have resurfaced many over the years and have never seen the heat checking cracks go all the way through . just my thoughts Don ...

[Duke W.]

Re: What Do You Make of This???

That flywheel has seen a lot of abuse. IMO it's a boat anchor.

Blue "hard spots" and maybe short (no more than about one-half inch) cracks indicate normal use.

It's tough to see from the photos how deep the cracks are, but I expect they are too deep to eliminate with a small surface cut.

Duke