Replacement starter

brahman265 · Jul 17, 2016

Hello, I ordered a new gear reduction starter for my Ford 5900 and it has 10 teeth instead of the 9 teeth on the old starter. Does anyone know if this would be a problem? It is the newer gear reduction starter versus the OEM starter. Thanks for any help.

Midniteoyl · Jul 17, 2016

I take it the new starter gear is a little bigger? As long as they match up with the flywheel teeth, I see no problem... Maybe someone else will chime in.

This the one you have? Amazon.com: NEW GEAR REDUCTION STARTER FITS FORD FARM TRACTOR 5 51 52 534 56 561 59: Automotive

Or this one? Ford 5900 Starter, DIESEL engines - D8NN11000CE

They both have 10 teeth and say they'll work.

brahman265 · Jul 17, 2016

Yes that first one is what I have. Hopefully someone else has ran into this before and can confirm the 10 teeth can replace the original 9 teeth. Thanks.

Steave · Jul 17, 2016

As long as the teeth are the same size it won't matter as Midniteoyl said the gear is just bigger. That's a hefty price for a starter when you can get a new starter for $135. Several online sites have them for simular prices. Is there a reason you need the gear reduction starter. Just wondering if I need to start thinking of a little more ump for my old ford. So far so good and it's 50 years old.

jimmysisson · Jul 18, 2016

If the gear is bigger won't it mesh too tight w the ring gear? I'm confused. Or is the od the same, in which case the teeth would be a little small. ?
Jim

flyerdan · Jul 18, 2016

If the gear pitch is the same, it doesn't matter how many teeth are involved. Going to a larger diameter starter gear would require more teeth for the same pitch, and would increase the gear ratio. Since it's a reduction drive starter, the ring gear ratio increase would be offset by the internal reduction.

sd455dan · Jul 18, 2016

flyerdan said:
If the gear pitch is the same, it doesn't matter how many teeth are involved. Going to a larger diameter starter gear would require more teeth for the same pitch, and would increase the gear ratio. Since it's a reduction drive starter, the ring gear ratio increase would be offset by the internal reduction.

I think Jimmy is asking if the starters mounting position is (adjusted) on the pm gear reduction starter to maintain bendix gear teeth to ring gear clearance during engagement.

It would seem that with more teeth- the diameter would be larger on the drive pinion (assuming identical tooth profile) and therefor this would need to be taken into account to maintain some mesh clearance

jimmysisson · Jul 19, 2016

What he said. Center-to-center of the two gears would have to change if one gets bigger.
Jim

Steave · Jul 19, 2016

brahman265 said:
Hello, I ordered a new gear reduction starter for my Ford 5900 and it has 10 teeth instead of the 9 teeth on the old starter. Does anyone know if this would be a problem? It is the newer gear reduction starter versus the OEM starter. Thanks for any help.

I think the starter you took off is the oddball if it has 9 teeth. Ford 5900 came with a 10 tooth starter and the replacements also have 10 teeth. Not sure what kind the 9 tooth is. Hope the one you bought works for you. My brother bought a gear reduction for a Belarus and wow it's a lot stronger. His engine has a compression release for starting but the new starter will spin it without releasing the compression. That thing seems to have enough power to spin the ring gear off.

Steave · Jul 21, 2016

Well I stand corrected. Was talking to a tractor mechanic today and happened to mention the 9 tooth starter and he said he's send them on some fords. I remember ford used 4 1/2" and 5" starters and maybe on the same model tractor. I haven't run across the 9 toother yet and probably won't as I don't work on tractors much anymore. Mostly just old plows now (Hobby) by the way.