Ring Gear Migrating?

[stewartb]

A friend asked me to look at their Cub because it was making a "tinking" noise. In a 360* rotation of the prop the ring gear was touching the starter drive enough to make it chatter a little. With a closer look we found the ring gear has separated from the shoulder on the ring support, so appears to be creeping toward the engine. No damage or wear marks yet so a recent development. I've never heard anyone mention this issue before. We pulled the ring gear support to take to the local engine shop hoping they can re-seat it it or replace it if necessary.

Has anyone had this happen? What was the fix, re-seat or replace?

 

[wireweinie]

Only time I've seen that, the ring gear was never seated against the shoulder at install.

If you gave me that support/gear to repair, I'd replace the ring gear or go up the hill to Leisner and get another assembly. You can't simply press the ring gear back into place as it's designed to be heated and placed onto a chilled support. Just pressing would damage the support.

To replace that gear, you'd cut the gear to remove it and inspect the support for condition. Then place the support in a freezer overnight. Heat the ring gear evenly and then slap it onto the support as quickly as reasonable. On contact the ring gear will loose heat and shrink to clamp onto the support.

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[stewartb]

News. Custom Aircraft said it wasn't seated properly from the beginning. They pressed it into place, inspected it, and sent it home to reinstall. I sure like those guys. Good expertise and great customer service!

 

[frequent_flyer]

See https://www.lycoming.com/sites/defa...1A_Replacement_of_Worn_Starter_Ring_Gears.pdf

 

[brownbear]

See https://www.lycoming.com/sites/defa...1A_Replacement_of_Worn_Starter_Ring_Gears.pdf[/QUOTE
i’m going from memory here but I think that there is minimum clearance between the ring gear and the starter Bendix when you install 149 tooth ring gear on a support made for 122 two ring gear
Old car mechanic trick to install ring gear is useing a Rosebud torch heat the ringgear in a circular motion while counting to 50 slowly it’ll almost fall on

 

[Grant]

Just for reference if anyone finds themselves needing to install a new ring gear.

I did mine last winter.

- Flywheel outsite for about an hour @ 20ºF
- Ring Gear in the oven for about 15 min @ 400ºF

Bring the flywheel inside and place the ring on the shoulder....

It falls right in to place and by the time you can check to see if you did it right its already tight.

 

[Steve Pierce]

- Flywheel outsite for about an hour @ 20ºF

But it doesn't get that cold here.

 

[wireweinie]

But it doesn't get that cold here.

You can always put the ring ear out in the sun.

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