Ford 3000 Flywheel ring gear

[blehmann]

Can you mark a tooth and slowly wrench the engine over to count the teeth on the flywheel? eBay and some tractor sites call out the same starter for both diesel and gas engines. The New Holland parts site will give you the part number you need for a gas tractor.

I pulled the starter and it is a 3139N. That is the number that pulls up for the diesel engine. Mine is a gas engine so I have the wrong starter. The correct part number for the gas engine is D7NN11001A. Both starters show to have a ten tooth pinion which makes no sense to me. I did trace the tooth pattern on the ring gear and also measured the gear on the starter. The ring gear pitch is about.2" at the bottom of the cut and the pitch on the outside of the pinion is .3". I called my starter rebuilder and he says that he has never seen anything other than a 10 tooth pinion on the old Ford starters. So, logic says that there must be a slight offset on the gas starter frame to move the pinion further away from the gear so that the teeth can mesh.

I can't for the life of me understand why the gas starter doesn't have 12 or 13 teeth on it. I went ahead and ordered a starter from Yesterdays Tractor. I tried to call but after being on hold for a half hour (on my dime) I hung up. If it doesn't work, I'll return it.

 

[RickB]

There isn’t room to mount a 5” diesel starter on a 3 cylinder Ford gas engine. The starter interferes with the carb. The tooth count on the starter drive is immaterial to the discussion. Tooth count and tooth pitch vary with pinion diameter which has not been mentioned. Ring gear diameter whether gas or diesel is a constant so the ring gear tooth count is relevant to the ring gear tooth pitch.

 

[blehmann]

There isn稚 room to mount a 5 diesel starter on a 3 cylinder Ford gas engine. The starter interferes with the carb. The tooth count on the starter drive is immaterial to the discussion. Tooth count and tooth pitch vary with pinion diameter which has not been mentioned. Ring gear diameter whether gas or diesel is a constant so the ring gear tooth count is relevant to the ring gear tooth pitch.

All that I am going off of is that a 3139N shows as a diesel starter on several websites that I visited. When I check compatibility the gas engine does not show up for that starter. I haven't measured it.

I agree that the ring gear diameter is constant and that the tooth count will change(or should) the tooth pitch. I cannot find any information about the pinion diameter on the so called gas starters. I find that rather maddening. Even a guy that has been in the starter and alternator business for forty years is puzzled about what Ford did on this particular tractor. If you have the dimension for the gas starter pinion, I would sure appreciate knowing it.

 

[Ultradog MN]

I have a couple of NOS gas ring gears here.
Would sell one prettty reasonable.

 

[blehmann]

I have a couple of NOS gas ring gears here.
Would sell one prettty reasonable.

Thanks, but that won't be necessary. I flipped the ring gear and the teeth are good now. I just walked in to the house for a cool drink after I installed a new starter that arrived at noon. The thing cranks and starts great now. I'm pretty sure that the old starter, and the new starter a year and a half ago had the wrong pinion in them. I just eyeballed it when I put the new one in today and really could not see that it looked smaller, but it works, so good enough.

 

[City Farmer]

Thanks, but that won't be necessary. I flipped the ring gear and the teeth are good now. I just walked in to the house for a cool drink after I installed a new starter that arrived at noon. The thing cranks and starts great now. I'm pretty sure that the old starter, and the new starter a year and a half ago had the wrong pinion in them. I just eyeballed it when I put the new one in today and really could not see that it looked smaller, but it works, so good enough.

Happy to hear you got it back together and all is well. If the drive gears are the same and the ring gear OD is the same like Rick B said, there has to be a center difference between the diesel and gas starters. There’s no way you’re meshing 2 gears with a different diametral pitch and having them last very long.

Maybe theres a tooth profile change to make it work but there’s a difference somewhere. You cannot add more teeth to the ring gear and keep the same DP without additional material on the OD.

 

[blehmann]

Happy to hear you got it back together and all is well. If the drive gears are the same and the ring gear OD is the same like Rick B said, there has to be a center difference between the diesel and gas starters. Thereç—´ no way youæ±*e meshing 2 gears with a different diametral pitch and having them last very long.

Maybe theres a tooth profile change to make it work but thereç—´ a difference somewhere. You cannot add more teeth to the ring gear and keep the same DP without additional material on the OD.

I think that it has to be the o.d. of the pinion. But I've been wrong before. I would like to see engineering information on the tooth pitch on both the diesel and gas pinions. That is what I was looking for but not finding. I actually found some data for the diesel pinion but not for the gas. It would be nice to know and about the only way I know to do it is pull the new starter and pull the pinion out and then put the micrometer on it. Maybe later. I'm enjoying having a tractor that starts for now!

 

[blehmann]

Just for fun, I was going through my photos this morning and ran across this. All in all, the repair took several hours but was not that difficult. I still have trouble getting the thing to fire and have found that voltage goes to nothing once the starter engages. It is probably something to do with how I have the switch wired in. I just jumper a hot wire to the coil to fire it up, then pull the jumper and go on about my business. I'll find a wiring diagram someday for the switch and get things hooked up right.