How to install the Flywheel

Darinh · #1 09-02-2010, 08:42 PM

My A&P is out of town for the next week and my new flywheel and MT prop showed up today. Needless to say, I don't really want to wait to install the prop. So here's the question:

What is the correct way to install the flywheel? I think there is a certain way it goes on based on timing of the engine and the marks on the back of the ring gear. Can anyone point me to an illustrated website that explains this? Or, can anyone tell me how to do it?

Thanks,

Darin

Mike S · #2 09-02-2010, 09:55 PM

You probably wont like to hear this, but IMHO, if you need to ask, you should not be doing this yourself.

Installing a prop must be done correctly for safety and when things go wrong, it happens all at once.

az_gila · #3 09-02-2010, 10:28 PM

Quote:

Originally Posted by Mike S

You probably wont like to hear this, but IMHO, if you need to ask, you should not be doing this yourself.

Installing a prop must be done correctly for safety and when things go wrong, it happens all at once.

...on getting help - however, the flywheel should only fit on your engine in one orientation - no hammers required...

Toobuilder · #4 09-02-2010, 10:28 PM

I agree with Mike...

...But if you do try bolt it all up, you need to know that the "flywheel" is indexed by a slightly oversized drive lug shoulder on the prop flange. Get it wrong and you will split the flywheel when you snug it down.

hgerhardt · #5 09-02-2010, 11:39 PM

Also make sure you apply some oil or grease to the O-ring in the prop before assy. And check the crankshaft hub for little nicks and burrs that could cut the O-ring. Use a fine stone to remove if found. A file is too coarse. And I've found using a cherry picker (engine hoist) and a nylon strap to hold the prop while installing the bolts makes it MUCH easier to do. A helper/holder just gets in the way.

Darinh · #6 09-03-2010, 12:12 AM

Maybe I should clarify... I have installed many props just not on Lycoming engines so I have never had to deal with the support assembly (flywheel). Continentals and Rotax engines don't use them at least sandwiched between the prop and the crankshaft flange.

I know how the flywheel goes on and how the prop mates to the flange. What I don't know is if there is a specific position this thing has to be in (i.e. similar to the mag gear and crank gear timing marks). The new flywheel has two marks on the backside for 20 and 25 which I am assuming are degree timing marks but I may be wrong. My engine is an O-540 A4A5 which uses 25 degrees for timing.

I will go take some caliper and see if I can determine the indexing by finding the slightly oversized lug. Thanks for the tips.

az_gila · #7 09-03-2010, 01:49 AM

Quote:

Originally Posted by Darinh

Maybe I should clarify... I have installed many props just not on Lycoming engines so I have never had to deal with the support assembly (flywheel). Continentals and Rotax engines don't use them at least sandwiched between the prop and the crankshaft flange.

I know how the flywheel goes on and how the prop mates to the flange. What I don't know is if there is a specific position this thing has to be in (i.e. similar to the mag gear and crank gear timing marks). The new flywheel has two marks on the backside for 20 and 25 which I am assuming are degree timing marks but I may be wrong. My engine is an O-540 A4A5 which uses 25 degrees for timing.

I will go take some caliper and see if I can determine the indexing by finding the slightly oversized lug. Thanks for the tips.

...the oversize lug goes into should have a "O" stamped near it on the flywheel...

David_Nelson · #8 09-03-2010, 05:20 AM

Hi Darin,

As I recently learned, there may be two sets of timing marks on the flywheel. The ones on the back side line up with the case halves. The ones on the front side line up with a little hole (guessing 1/32" diameter) in your starter.

Regards,

tadsargent · #9 09-03-2010, 05:27 AM

The answer to your post is...
Place the flywheel to the crank flange, if it does not fit flush rotate it
till it falls in place. Its dirt simple, no rocket surgeon degrees necessary.
Enjoy

noelf · #10 09-03-2010, 07:30 AM

...to align the flywheel to the crankshaft.

Rotate the engine, by hand, with all of the spark plugs removed, except for the bottom plug on # 1 cylinder. Put your finger on the top plug hole for # 1, rotating the crank until you feel the compression stroke of that cylinder.

Now, keep rotating until that cylinder reaches TDC. Now, you can place the flywheel on the prop flange with the 0 deg TDC mark (located on the back side of the flywheel) aligned with the case-halves-split-line on the top of the engine.

Hope that helps...