JD flywheels

[aumick10]

I stripped the motor in my 29JD as it didn't look right. I found JD cases, 74" flywheels, 61" pistons and barrels with compression plates and some case bolts and some case studs. I have everything to rebuild it back as a proper JD, but have a question on the flywheels. They are 150-24A castings. The wheels i have have been lightened and chamfered on the outside edge. Is this something the factory did, or some racer back in the day.
20230826_164803.jpg Cheers

[Tommo]

Aumick
I've never seen factory flywheels that looked like those so my guess would be that they were modified by a tuner at some time in the past.
I've photographed a set of J flywheels and a set of JD ones sitting side by side and hopefully you can see the different placement of the big end holes that gives the JD its longer stroke.
the JD wheels are thicker than J ones and the second photo shows that difference.
The JD wheels have 150-20D casting numbers.
The third photo shows the earlier spoked flywheels alongside the other two.
The 28 FHAC 500 motor that I used to own had steel flywheels and my 1931 OHV single 31CA503 has steel flywheels as well
In both motors they are polished but are not modified in any way to look like the ones you have.
Hope this helps DSCF4561.JPG DSCF4564.JPG DSCF4565.JPG

[aumick10]

Thanks Tommo,
I have three different flywheels here as shown.. They are top to bottom, cut down 74", std 61", std 74". The two 74" wheels have 150-24A Castings and the 61: wheels have 150-24 casting.
If you look at the locating holes in the wheels, the cut down 74: and the 61" holes are in the same location. The std 74: holes are much wider. The holes on the cutdown wheels have been drilled into a OEM casting, not filled and moved at some time.
Looks like an anomaly we may never know why it was done.




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