Ford 860 12 volt conversion question

I recently had an issue with the starter on my 55 Ford 860 failing to release from the ring gear. I was able to free it with some difficulty. After removal I noticed some damage to a section of the ring gear. I found a past post that stated this could be caused by using a 6 volt starter on a 12 volt system. My tractor was converted to 12 volt but still uses a 6 volt starter and solenoid. I'm not overly mechanical so I'm asking for an explanation of why this set up is incorrect. It appears I should be replacing both with 12 volt?

Starter ring gears are a "wear" item, and as such, eventually wear out.

A four cylinder engine, due to pistons coming up on compression, will 'most always come to a stop at one or the other of two crankshaft positions.

So when the starter is engaged there's two areas on the ring gear that get almost all the wear of the teeth mashing into engagement.

Some (cheap) guys knock the ring gear off the flywheel and install it 90? or 180? "off" from where it was, so the starter engages on a "new" area of the gear.

All that being said, there's many many formerly 6 Volt tractors that have been converted to 12 Volt and have never had the starter or solenoid changed to 12 Volt.
Common ring gears aren't terribly expensive, for all the work involved in splitting the tractor I prefer to replace them.

Alford, you ask "I'm asking for an explanation of why this set up is incorrect."

While its NOT ideal and perfect I guess it could be considered "incorrect" due to the stronger initial engagement (harder faster kick in) between starter drive and flywheel ring gear and extra wear and tear when 12 volts is applied to a 6 volt starter.

HOWEVER myself (past farmer and used tractor dealer) and many others have done it successfully for years and never had a problem. Even if the correct starter is used years and years of starting eventually takes its toll on ring gears and/or starter drive mechanisms.

One "fix" some have had used when using a 6 volt starter at 12 volts is to use smaller battery cables (drops more voltage) and/or a lesser CCA battery then normally used.

Obviously if the ring gear is damaged it needs replaced (or at the least rotated) and while at it you might want to upgrade to a 12 volt starter even if the 6 volt may not cause problems for yearsssssssssss your tractor and money your choice.

John T

Thanks for the info. Previous owner replaced the 6 volt starter in 2014 prior to my 12 volt conversion. I don't think I'll replace it if it's not a likely cause of my problem.

As said, it is a common practice, and usually causes little problem.

If the flywheel gear is just experiencing normal wear, as in the front edge of the teeth getting worn down, it will probably last a while longer. You can let it go until there is reason to split the tractor, then replace it.

But if there is a tooth missing, or they are worn to the point the drive gear grinds instead of engaging, it is time to replace it.

Some things you can do in the meantime...

Keep the starter in good condition. Make sure the shaft bushings are good, the drive is in good shape, and the mount bolts are kept tight. If you replace the drive gear, use a premium brand gear, not the cheapest ones on the market.

Keep the engine well tuned and easy to start. A healthy engine will be very easy to start, no excess cranking needed. Learn it's mannerisms, if it's taking longer than usual to start, find out why.

Plan the starts, try to start as few times a day as needed.

And the most important, pay close attention when starting. Plan your start. Have everything set and ready before hitting the switch. Listen to and watch the engine closely. Many times as an engine is starting or rolling to a stop, it will kick backward coming off a compression stroke. Make sure the engine is completely stopped before engaging the starter. Last thing you want to do is jamb the starter gear in while the engine is turning!

It's not surprising that your 65 year old tractor has a worn ring gear. Even if it's been replaced before. Usually the starter fails to engage when the ring gear is worn out, but I suppose it could prevent the drive from releasing as well. You might try touching up the ring gear with a triangular file, since replacing the gear requires a tractor split.

There are plenty of four cylinder Fords converted to 12 volts running the original 6 volt starter, including mine. I really don't think it causes damage to the ring gear, at least not enough to worry about.