jensenracing77

i was wondering what you can tell me about these flywheels. the first one is like all the ones i seen before. the second one has less holes and the center recessed area is smaller. the first one is 5 7/8 the other is 5 1/8. they both fit 350/455.

100_4988-1.jpg?t=1321216039

100_4989-1.jpg?t=1321216097

dc2x4drvr

Are both flywheels the same thickness?

jensenracing77

i think so but i will have to check. the dirty one was surfaced 2 times so i am not sure what the correct thickness is.

2blu442

OK, here's my guess on the extra holes drilled through the flywheel. The bottom one has only the two sets of clutch pressure plate holes, for the 10" or 11" clutch. The top one has the same plus extra holes to be used in balancing the flywheel. The reason I say that is I have a flywheel in the garage with pins in two of the extra holes. I've also got one flywheel with 1/2 the amount of extra holes as your top picture. I don't know if this is an early or late production thing, or maybe the manufacturing plant they were purchased from. No idea on the center diameter difference. John

aliensatemybuick

I have also seen "balancing" pins. But shouldn't that be a 10.5" and 11" clutch? I am NOT offering this correction in any other spirit other than to make sure correct info. is provided (and I suspect you for one won't take it any other way).

Of course, if I'm wrong...

joesw31

It could be a 1967 or earlier flywheel, bu it looks more like a pontiac flywheel

2blu442

Thank you for your thoughts. You may be right, I know the larger one is an 11" but am not sure the smaller size.

Joe, I don't think any other GM flywheel will fit on the Olds cranks. But I'm not an expert on this topic. It will be interesting to see what other ideas are posted to the thread. John

Run to Rund

The second one might be aftermarket. Show us pictures of the reverse sides.

jensenracing77

here are a couple pics of the back and some numbers i found on the clean one.

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100_5031-1.jpg?t=1321316408
100_5034.jpg?t=1321316442

100_5041.jpg?t=1321316474

Run to Rund

Stock Olds wheels have a cast in rectangular recess for balancing, like the top, rusty wheel. The other wheel with drilled holes is aftermarket.

jensenracing77

thanks, would there be a way to look up the numbers and see who made it? i tried google but didn't see anything.

507OLDS

The holes in the aftermarket flywheel might have also been drilled to balance to the engine's rotating assembly,depending on how the engine was balanced,internally,or externally.

wmachine

As a post script here on OEM Olds flywheels, I believe *almost* all early V8 ('64-'67) and all late V8 ('68-'73) ones came drilled for both the 10-1/2" and the 11" clutches.