General Category => Engine & Transmission => Topic started by: ramwing7 on April 08, 2023, 07:23:31 AM

Title: Flywheel torque
Post by: ramwing7 on April 08, 2023, 07:23:31 AM
Anybody know the flywheel nut torque spec?

Thanks.
Title: Re: Flywheel torque
Post by: pd on April 09, 2023, 06:28:14 AM
I sure don't know the specific spec .
I always just make sure that nut is good and tight . Too loose and the flywheel can shear the woodruff key without much trouble . That , specially if the crankshaft taper and the flywheel tapers don't match well . It's why I recommend lapping the flywheel to the crankshaft . The better the tapers match , the better chance of the flywheel not spinning on the crankshaft .

Pete . :)
Title: Re: Flywheel torque
Post by: Ricks on April 09, 2023, 02:10:34 PM
I don’t have a spec either, but I’ve never seen a broken key on a Simplex. What I have seen many times is a cracked keyway in the flywheel. A quick google search shows Cushman flywheel nuts get torqued to about 50-60 lb-ft.
Title: Re: Flywheel torque
Post by: pd on April 09, 2023, 03:08:04 PM
Quote from: Ricks on April 09, 2023, 02:10:34 PM
I don’t have a spec either, but I’ve never seen a broken key on a Simplex. What I have seen many times is a cracked keyway in the flywheel. A quick google search shows Cushman flywheel nuts get torqued to about 50-60 lb-ft.

I should have taken pics of the few sheared keys that I had happen . I will say that I haven't had it happen since I welded the keyway . But , that wasn't all that long ago .

Pete . :)
Title: Re: Flywheel torque
Post by: Ricks on April 09, 2023, 06:36:55 PM
Pete, did they shear when running or trying to start it? How sloppy was your keyway? How bad was the flywheel to crank fit. I think all mine would run without a key at all!
Title: Re: Flywheel torque
Post by: pd on April 10, 2023, 06:21:13 AM
Quote from: Ricks on April 09, 2023, 06:36:55 PM
Pete, did they shear when running or trying to start it? How sloppy was your keyway? How bad was the flywheel to crank fit. I think all mine would run without a key at all!

Rick ,
All would shear very soon after starting . It would run for only a few RPMs and done .
The keyway was much like ramwing7s' :
(https://i.postimg.cc/L5XWWTqc/wallowed-keyway.jpg)
And , the taper fit wasn't near as pitted as in that^ pic . It seemed fairly good , but I did notice a bit of surface rust on the crank taper after it had sat for a few months , flywheel mounted and untouched . So , I knew that the taper needed some lapping to be better .

Pete . :)
Title: Re: Flywheel torque
Post by: Ricks on April 10, 2023, 06:33:01 PM
That keyway looks terrible. I would weld it up and remachine it.
Title: Re: Flywheel torque
Post by: pd on April 11, 2023, 05:39:07 AM
Quote from: Ricks on April 10, 2023, 06:33:01 PM
That keyway looks terrible. I would weld it up and remachine it.

I did weld it and I hand filed it back to size .
Holds the key nicely . ;)

Pete . :)