1974 Ford 4000 SOS

[RickB]

I changed the ring gear on my 1971 3 cylinder 4000 from gas to diesel when I dropped the Diesel engine in. I have zero reason to think you could not do the same with the 3910 flywheel. There is no doubt the flywheels will have different part numbers. But dimensionally they are interchangeable.

 

[strum456]

I had 2 different tractor salvage guys tell me that they won't interchange. The one guy's explanation was that the part where the ring gear presses on is wider on a diesel than on the gas flywheel. The other guy didn't give an explanation. He wants $1000 for the trans and rear axle. The tractor had turf tires and was some kind of special purpose deal. It was modified and painted gray by some company that used to set up these tractors for highway use, road sweepers and such. I'm wondering if the rear axle ratio is going to be high for the 30 inch rubber I have. If you're sure about the flywheel interchanging, maybe I'll try to get it thrown in with the deal. I have made a lot of calls and have had zero luck finding a "diesel flywheel".

 

[strum456]

1985 Ford 3910 LP gas tractor

The trans donor is similar to this one. American Lincoln

 

[RickB]

Calculate the offset between the crankshaft mounting boss on the flywheels and one edge of the ring gear. I will bet they are the same, the flywheel thickness may not be. Then measure the gas and diesel starters from the mount flange to the extended pinion gear. I will bet they are the same. I cannot guarantee you a thing because you are talking about a different model than I worked with but I am certain you can swap ring gears and bolt everything up and it will work.

 

[RickB]

Get the model code off the salvage donor and decode it. Then check the parts catalog to see what R&P it has.