Onan 45.0EM Starter Ring Gear

[mazdaboi]

All,

A few months ago, I posted about buying a 45.0EM for use to power my hobby needs, and for a backup generator for the household. The road to get to where I'm at has been a bit long, and I have not reached my destination yet, for a variety of reasons. One thing after another....

The latest is that the starter ring gear has came off the flywheel. I'm assuming that the ring gear is heat fitted to the flywheel, as it would be on a standard Ford flywheel. I've not pulled the engine yet... Pulled the starter to confirm the diagnosis. Was a bit frustrated, so I let it be for a week. But, I obviously need a new ring gear.

My question is this... Does Onan use a standard sized Ford ring gear, or is it specific to Onan? I looked in one of the parts manuals and found part # 104-0723 seems to be the Onan #. But if it's a standard Ford sized part, might be easier to find it from a standard parts house. I'd like to go ahead and order one and get it shipped in so I can perhaps separate the head and engine this weekend, and get the ring gear fitted.

Next hurdle will be realigning the rotor and crankshaft.. Better start researching that procedure now, while I wait for a ring gear to be ordered and arrive.

Appreciate any info in advance.

Thanks!
Brad

[Birken Vogt]

Your safest bet will probably be to get one from a Ford Power Products (industrial engines) dealer. Onan will have it but it will be expensive. Ford might be pricey also but at least you will know it is right. Chances are the auto parts store will have it also but you will need to remove the old one and bring it in and possibly wait for a replacement.

[mazdaboi]

Thank you for the input.

I will get it pulled apart this weekend, and get the ring gear and flywheel out. Will examine the ring gear and compare it to the stock Ford options out there....

I have been looking for the Onan part number I mentioned previously.... I'm finding it listed as discontinued on every site I've found it referenced, and no cross referenced replacement.

*Fingers crossed* Really hope a Ford part will match up. This genny has been one trial after another. Just worried about what issue I'll run into after the ring gear is repaired.

Thanks,
Brad

[Birken Vogt]

Maybe I made an inaccurate statement about Onan/Cummins having one available.

But I have bought lots of parts from Cummins that showed on all the web sites as NLA. On the other hand I have also been surprised that something in recent production was listed as obsolete. Plus the prices are all over the map.

Ring gears are something there has been pretty good aftermarket support for. A friend of mine had a GM Bedford engine which needed a ring gear. He looked all over and wound up at a clutch shop. They had a ring gear for some kind of Cat engine with the right teeth but quite a bit smaller I.D. They turned the flywheel on a lathe to make it fit and it worked great.

You should not have to go to that length on a common Ford engine.

At the absolute worst case, get it off by heat and not by chisel. Then if you absolutely cannot find one you can flip it over and/or turn it so the starter lands on good spots. Engines usually stop at the same spot when they come to rest so there will be chewed spots and spots that are not chewed.

[Oldpart]

If the ring gear simply came off because of too little shrink fit interference it could probably be reused by pressing it back on the flywheel using loctite sleeve retainer. The stuff is incredible. You could not heat the ring gear to drop it on but you could press it on after cleaning both parts perfectly. If the ring is junk - well that's another matter.

[Troll]

Eight evenly spaced tack welds using 309L stainless rod will retain a ring gear that is not salvageable by other means also. Rather permanent however.

[Power]

Originally Posted by Oldpart

If the ring gear simply came off because of too little shrink fit interference it could probably be reused by pressing it back on the flywheel using loctite sleeve retainer. The stuff is incredible. You could not heat the ring gear to drop it on but you could press it on after cleaning both parts perfectly. If the ring is junk - well that's another matter.

I agree. flip it, clean up contact surfaces and use locktite bearing lock or sleeve retainer. Last resort is tack welds. A new ring gear may not be the answer. If the existing ring gear had been slipping before it fell off, the flywheel contact surfaces may have been milled undersize, and the new ring gear will slip.

[Gunny]

If my memory is correct, that is a standard Ford part, nothing special about it.

Can't flip it over, teeth on the drive side are beveled.

Have never seen one slip, usually have a tooth or teeth missing or damaged. Consider a new starter to go with a new ring gear.

Pretty easy to align, can take 2 bolts a little longer than the original bolts, cut the heads off and grind a bevel. Don't run them all the way in so you can grip them and screw them back out when the others are started. Pretty easy to do, go carefully and you shouldn't need much force.

I've never used any adhesive to hold it together. Just heat it barely red and drop it on, might need to tap it a little. Be sure to get the bevel end right. Take the old one off by grinding through it.

If slipping, you could do some tack welds evenly spaced. Could grind the welds back off if you need to take it off. Not how I'd do it but if that's what you have to do....

[mazdaboi]

Thank you all very much for the additional advice. I've now got a few options to look at, depending on what I find when I pull the engine.

This happened a couple weeks ago, when I was trying to get the gas regulator adjusted. The last time I fired it up, the starter spun up, but the engine did not. Tapped the starter to make sure the throw out wasn't sticking. No change. Figured I hit a bad spot on the ring gear, so I turned the engine over by hand, then tried again. This time, it sounded like a metal hula hoop in a tin can. Pulled the starter to confirm what my ears had told me... Ring gear had came off.

The real question is why. It has never sounded like it was slipping previously. Best case, the ring gear broke somehow and a replacement ring gear will get me back to where I was. Worst case, if the flywheel mating surface is somehow not the exact diameter it's supposed to be, then I guess I'll be in the market for a new flywheel.

So, yeah.... I need to get the engine hoist up to the barn tonight and start to pull the engine. Can't order parts until I know what I'm dealing with. Thanks to you guys, I have a few options to explore, depending upon what I see.

I'll let you know what I find.

Thanks!
Brad

[Gunny]

I never pulled the engine in the couple of dozen I've done through the years.

Slide the generator back about 12 to 18", after unbolting from the engine and you';; have plenty of room to get the flywheel out.

There was a campaign in the mid 90's to replace the bolts on thew flex plate, made up a jig with some wheels (casters) and most of the time was a quick and easy job. Unless the installing sparktrician did something wild, that happened too often.

Really an easy job in the overall scope of things.