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Ring Gear?

jeffkersey

Well Known Member
Did a search on the forum and could not find an answer to my question so here it is...

A couple months ago I had a starter gear come apart and damage my ring gear. One tooth totally gone and a few others buggered up. I used a grinder and file to straighten and clean it up a little. It had been starting fine. Recently, I heard a change in the sound and I could tell it was slipping and making a bit of a grinding sound. Pulled the cowl and I have lost another tooth on the ring gear. Don't want to get stuck somewhere, would not even attempt a hand prop with my high compression Io-360 with a 3 blade prop. Too dangerous in my opinion.

I have a new ring gear on its way. Anyone have any experience swapping out a ring gear? I found youtube video of an auto mechanic using a torch to heat it up and knock it off. Then heating up the new one on dropping it on the support with no problem. Is this the same process for the lycoming? Does anyone know what metal the support wheel that has the belt pulley is made of?
Should I put it in the freezer then heat up the ring gear? Any tips would be greatly appreciated.

I do plan to go ahead and swap out the alternator belt while I have the prop off.
 
Last edited:
I've done it. Small abrasive cutting disk to very carefully cut the existing gear almost all the way through. A "tap" with a cold chisel to break it the final bit and it will fall right off.
Put the flywheel in the freezer, and the new ring gear in the oven for a bit and it will simply drop right on. Easy.
 
Thanks

I've done it. Small abrasive cutting disk to very carefully cut the existing gear almost all the way through. A "tap" with a cold chisel to break it the final bit and it will fall right off.
Put the flywheel in the freezer, and the new ring gear in the oven for a bit and it will simply drop right on. Easy.


Thanks Scott!
 
Scott beat me to the answer.
Follow instructions and you will laugh as to how easy it is.
I used the freezer torch method. No oven in my hangar.
You will have an experimental RV grin all over again.
I have done many and as of late I replace mine on my 0-360 two months ago because it was looking worn. Hate stuff failing..
Oh by the way. DO NOT put it on backwards. It won't work very good.
Go for it.
Have fun Art
 
Yes, alternator belt replacement would be a good idea, no easier time.

Willing to share what kind of starter came apart?

George
 
prestolite

Yes, alternator belt replacement would be a good idea, no easier time.

Willing to share what kind of starter came apart?

George

The starter is a Prestolite MZ-4222. I have had some issues with these. This is the only time the gear came apart. I keep a fresh one on the shelf. I had thought about trying a Sky-tec because a few friends have had good service with those but I have a FP Catto prop and need the weight up front.
 
Did a search on the forum and could not find an answer to my question so here it is...

A couple months ago I had a starter gear come apart and damage my ring gear. One tooth totally gone and a few others buggered up. I used a grinder and file to straighten and clean it up a little. It had been starting fine. Recently, I heard a change in the sound and I could tell it was slipping and making a bit of a grinding sound. Pulled the cowl and I have lost another tooth on the ring gear. Don't want to get stuck somewhere, would not even attempt a hand prop with my high compression Io-360 with a 3 blade prop. Too dangerous in my opinion.

I have a new ring gear on its way. Anyone have any experience swapping out a ring gear? I found youtube video of an auto mechanic using a torch to heat it up and knock it off. Then heating up the new one on dropping it on the support with no problem. Is this the same process for the lycoming? Does anyone know what metal the support wheel that has the belt pulley is made of?
Should I put it in the freezer then heat up the ring gear? Any tips would be greatly appreciated.

I do plan to go ahead and swap out the alternator belt while I have the prop off.

I actually did this last weekend for my IO-360. The gear cuts easily with a hack saw. A few whacks with the cold chisel and it pops right off. Lycoming Service Instruction 1141A tells you how to replace the gear. In the oven at 450F for 30 minutes. I also chilled the other part in the freezer at the same time. It dropped right on and shrinks very rapidly. Make sure you have the chamfer in the correct direction! The spec also tells you what the gap can be (memory says it was .0015").
 
I used to do this on automotive applications. We would hold the ring gear with a pair of vice grips, pass a torch a couple of revolutions around the ring gear, and drop it right on, maybe give it a little turn to verify that it’s on and flat. It’ll shrink and stick in just a few seconds.
 
I used to do this on automotive applications. We would hold the ring gear with a pair of vice grips, pass a torch a couple of revolutions around the ring gear, and drop it right on, maybe give it a little turn to verify that it’s on and flat. It’ll shrink and stick in just a few seconds.

I used to heat GM connecting rods to get the piston pin in (interference fit) although I have never done a ring gear. The key is to practice and be prepared for how you will put it on and ensure alignment. In my experience you get less than a second after contact before things shrink. Given the ring gears size, it may afford a bit more time.

Larry
 
Starter ring gear replacement and clearance check

Here is the Service Instruction for the steps to replace the starter ring gear. Lycoming Service Instruction 1141A. When the repaired ring gear support assembly is bolted onto the crankshaft check the clearance of the starter drive gear and the new starter ring gear. Lycoming Service Instruction 11447B will help if there is little to no clearance. You can fabricate a shim. Here is another post: https://vansairforce.net/community/showthread.php?t=190016&highlight=starter+shim.
We heard a 350 hour since MOH Lycoming start with no clearance between the starter gear and the ring gear and what a howlll. The gears had polished the "valley" between every tooth! Still amazed that the starter was not blasted from the mount!
 
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