Ford 8N Flywheel / Ring Gear Question

Jeff Calder

New User
Hello fellow tractor enthusiasts! I have recently cracked my 1952 8N because the ring gear had become completely separated from the flywheel. I had suspected it was a prior issue, which was confirmed when noticed six spot welds that had been holding the old ring gear in place.

We removed the old ring gear but I have one question:

I noticed that there is a groove in the flywheel where the ring gear sat originally. We can't tell if it is supposed to there or not. Can anyone confirm if this is normal? I have a friend who is a diesel mechanic who is good enough to heat and install the new ring gear, but we are questioning if the flywheel is compromised as well. He thinks that with the groove there that the flywheel is too small and the ring gear won't adequately shrink into place as it cools. He is suggesting that we spot weld again, but with a little more gusto then the previous owner's attempt. Any insights into this would be fantastic. As always, thanks for your help tractorteers!
 
I agree with your mechanic. But I think the flywheel is made of cast iron. If you're going to weld it, better get some nickle rod.
 
The groove is supposed to be there, sorry I don't have a "spec" for it's exact depth or the original OD of the casting in that area.

As to tack welding the steel ring gear to the cast iron flywheel successfully, I wouldn't count on it, as what you had happen is a typical result in my humble experience.

Others report great success, and your actual results probably will depend on how much wear there is in that area of the casting.

If there's little or no wear and you go ahead and tack it you will see great success (but it probably would have held from "shrink in place" anyhow).

If lots of wear/fits loose you MAY get by with tacking it, but I wouldn't hold my breath over it holding up over the long haul.
 
I just did the flywheel on my 9n a few years ago. The groove was in the original flywheel just like you said. I also doubted the ability of the ring gear to be tight so I spotwelded mine in about 4 spots around the diameter. It was easy as pie. I think they have a steel flywheel. It has been used and abused a million times since I did it and it's been fine. Weld the sucker!
 
Regardless of our differing opinions on welding it, rest assured the flywheel IS cast iron and the ring gear is steel.
 
That cast iron steel flywheel on my 9n sure did weld up nice to the ring gear when I did it with a regular Lincoln buzz box and 6013 rod. Looked like factory welds.
 
Most people heat a starter ring gear too hot. Before you heat it see if it will almost slip on. If it slips on cold it will never shrink enough.
 

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