[teamhog]

Maybe the taper is off on the crank and doesnt let the mag tighten up good? To me it doesnt seen like the key is to keep it from spinning it seems like it would be more to index the mag so it fires at the right time. Just a theory.

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X2..bolt torque and taper fit keeps the flywheel from turning on the crank. Key is only intended to index the wheel during install imo abd may provide a little help keeping it lined up but that in my mind is the main job of the taper fit. Id inspect the flywheel bore, crank taper, hardware fit ect JMO

Ahh. The taper connection holds it. Like the primary clutch.
Just tig weld it on. LOL

Don't you think for a minute that I haven't thought about it...

 

[Guest]

IMO you want to hold the flywheel in place, not the crank..maybe you are damaging the keys during the install by holding the only the crank?? If that's what you have been doing? But maybe you have been holding the flywheel,Ie maybe the toque is being transferred to the flywheel and loading the key before the taper is tight. Maybe a long shot but even so securing the flywheel is what I'd do. Maybe a good strap wrench.

Edit..ok I re-read sounds like you have been holding the flywheel, not the crank, using the puller?
In that case I guess nevermind on my theory lol
Personally I'd get my mic's out...

Maybe the taper is off on the crank and doesnt let the mag tighten up good? To me it doesnt seen like the key is to keep it from spinning it seems like it would be more to index the mag so it fires at the right time. Just a theory.

Sent from my DROID RAZR using Tapatalk 2

X2..bolt torque and taper fit keeps the flywheel from turning on the crank. Key is only intended to index the wheel during install. Id inspect the flywheel bore, crank taper, hardware fit ect JMO

In line with the torque issue; what's the best way to hold the crank shaft in place while torquing the flywheel down.

I've torqued it using these two methods:

1) By hand: Holding the crank in place using the bolt puller as a way to keep it from moving and using my torque wrench

2) Air Impact Wrench: Using a Snap-On impact wrench with the air pressure set and then checking with the torque wrench.

Each time I do this I then spin the engine over by hand to ensure that everything is rotating smoothly.

 

[teamhog]

IMO you want to hold the flywheel in place, not the crank..maybe you are damaging the keys during the install by holding the only the crank?? If that's what you have been doing? Ie maybe the toque is being transferred to the flywheel and loading the key before the taper is tight. Maybe a long shot but even so securing the flywheel is what I'd do. Maybe a good strap wrench.

Okay; We're saying the same thing.
I'm actually holding the flywheel so that it can't turn the crank during the torquing process thus preventing the crank from turning.

I'd have to refer to the service manual again, but I believe the flywheel nut gets torqued to 65 ft-lbs.
Will a strap wrench hold it? or are people using other methods?

 

[teamhog]

Here's my response from HotRods re: the crank:

Chris,

I am sorry to hear of your technical difficulties, I have heard stories of people having issues with woodruff keys after install any new crankshaft. There was one solution that was told to me by a shop:

Apply grinding paste to the crank’s taper. Hand press the flywheel onto the crank and turn it back and forth for five minutes. This will hone down the high spots on the surfaces of each part so the flywheel won’t ever loosen up and shear the woodruff key.

Now I have something to do...

My nephew is going to come over tonight and help me pull the engine out again. I should have it out and possibly polished up tonight.
My wife has to work late so it'll give me something to do...

 

[Guest]

The metal style that you tighten with a ratched works on the XP and its
Torqued to like 88 or so iirc. Obviously you need a quality tool..

IMO you want to hold the flywheel in place, not the crank..maybe you are damaging the keys during the install by holding the only the crank?? If that's what you have been doing? Ie maybe the toque is being transferred to the flywheel and loading the key before the taper is tight. Maybe a long shot but even so securing the flywheel is what I'd do. Maybe a good strap wrench.

Okay; We're saying the same thing.
I'm actually holding the flywheel so that it can't turn the crank during the torquing process thus preventing the crank from turning.

I'd have to refer to the service manual again, but I believe the flywheel nut gets torqued to 65 ft-lbs.
Will a strap wrench hold it? or are people using other methods?

 

[teamhog]

I'll have to find one...

Thanks...
I'm gonna go work on it now

 

[teamhog]

Well; the engine is out...
I'll start working on it tomorrow.....

 

[rardoin]

Chris, I think Hotrod's advice will solve your problem. Waaaay back when I raced 4-cycle karts running B&S motors we would remove the flywheel key so we could set the ignition timing different from stock. My engine builder would lap the Morse taper of the crank/flywheel with valve lapping compound as described by Hotrods. The interference fit of the taper is what retains the wheel and the key is just to index timing (as already described). Periodically, even though the tapers "looked" good the timing would "slip" and we would re-lap the tapers and it would solve the problem. Very quick and easy to do...at least on a Briggs motor.

 

[teamhog]

I'll be lapping it later today....

Thanks for the help guys.

You'll know when I have it fixed.

 

[coker6303]

Are you having any hard starting issues? maybe tuning at startup/idle is off? If it kicks back or back fires you will have a ton of shear force against the key.

or tac weld it! lol

 

[teamhog]

Are you having any hard starting issues? maybe tuning at startup/idle is off? If it kicks back or back fires you will have a ton of shear force against the key.

or tac weld it! lol

No starting issues whatsoever.

Yes! I'm pissed enough to tack it. But I know better

 

[allcool]

Here's my response from HotRods re: the crank:

Chris,
I am sorry to hear of your technical difficulties, I have heard stories of people having issues with woodruff keys after install any new crankshaft. There was one solution that was told to me by a shop:

Apply grinding paste to the crank’s taper. Hand press the flywheel onto the crank and turn it back and forth for five minutes. This will hone down the high spots on the surfaces of each part so the flywheel won’t ever loosen up and shear the woodruff key.

Now I have something to do...

I'll be lapping it later today....
Thanks for the help guys.
You'll know when I have it fixed.

Make sure to remove any burrs on the keyway in the crank and on the key itself, a good file will do this no problem.
Make sure the key is seated fully in its slot in the crank with no burrs holding it up not letting it seat fully.

Keep in mind, the interference fit of the flywheel to crank only comes into play after the crank bolt is torqued fully, and the flywheel is pulled into is final position on the crank. "Hand pressing the flywheel" and Lapping it before it is pulled into its interference fit final position could remove small burrs or high areas from poor machining on the flywheel or crank snout, but not in the key-way or key. After the crank bolt is torqued, flywheel is pulled maybe .100+ thousand's of an inch farther up on the crank snout, so lapping it in the non torqued position really does not improve the interference fit. Not that you could possibly lap it in the torqued position. The proper machining on the crank snout taper and the flywheel bore's taper, is what makes the correct interference fit, not lapping.

IMO, don't go over board on the lapping, as you don't want to remove much/any of the interference fit. Or make a ridge that will hurt the fit once the flywheel is torqued farther onto the crank into its final position.

Sounds like the guy you got the response from at Hotrods was not a tech engineer, but more of a customer service guy just trying to help by relaying some info he heard from a shop.

I would lap it back and forth for maybe 20-30 seconds and then check for shinny spots on the crank snout and flywheel bore taper to see what you are actually doing/accomplishing.
I would never lap it for 5 minutes, ever.

jmo

 

[allcool]

Just looked at your picture of the key...
Is it just me, or is that keyway look like it has cancer pits. Was there rust on it that was cleaned off ?

That has to be the worst looking key I've ever seen, its terrible. Wondering if it fit all the way down into its keyway slot in the crank and or flywheel...???

 

[BarRZR]

The taper on both the crankshaft stub AND the hole in the flywheel are machined/reamed to what is known as a Morse-Taper. Both MUST have an almost perfectly smooth finish in order to work properly. Also, sometimes the key-slot in the flywheel flange will crack and open-up, generally due to over-torquing. Suggest you examine corners at the base of the key-slot in the flywheel under bright light and magnification, looking for a tell-tale crack. A little heat, some Zyglo and a black-light would be optimal. FWIW, a properly machined and torqued Morse-Taper is almost impossible to rotate/spin; The Woodruff key is just there for proper indexing: I'd be looking for damage/expansion in the flywheel-flange. My two-bits.........

Cheers

 

[rardoin]

^^^ Excellent point about minute crack in the flywheel. It would certainly cause a failure of the interference fit. A dye penetration test would be advised.

 

[RMR Man]

Didnt have time to read every post, so I am just going to throw this out there:
Absolutely NO OIL, or any kind of lubricant on the tapers. NONE! This will cause a woodruff or a small profile key of any kind to fail almost instantly.
Second, if whatever is on the other end of the crankshaft is either loose or missing, you will also shear a key. Most small engine makers rely heavilly on the load end of the crankshaft to add the needed weight to make the engine run smoothly. The ring gear side of the engine is kept as light as possible so more HP can be realized at the PTO end.

 

[teamhog]

Didnt have time to read every post, so I am just going to throw this out there:
Absolutely NO OIL, or any kind of lubricant on the tapers. NONE! This will cause a woodruff or a small profile key of any kind to fail almost instantly.
Second, if whatever is on the other end of the crankshaft is either loose or missing, you will also shear a key. Most small engine makers rely heavilly on the load end of the crankshaft to add the needed weight to make the engine run smoothly. The ring gear side of the engine is kept as light as possible so more HP can be realized at the PTO end.

Yep; got the "NO OIL" thing. It was dry as a bone; cleaned it off with TB Cleaner; wiped it down and cleaned it off again.

So are you saying that I have to have the primary clutch on in order to run it without snapping the woodruff key?

If that's the case; then why does it only snap when I'm starting the engine not when I'm running it.

Any ideas?

 

[western196611]

^^^ Excellent point about minute crack in the flywheel. It would certainly cause a failure of the interference fit. A dye penetration test would be advised.

I agree with the inspection for cracks but,
Dye penetrant is "old school" have some one do a magnetic particle test on it it will show the smallest indications. If not done correctly you could miss more with the dye test. It will definatly "bleed" in the key way with the dye.
Just my .02.

 

[RMR Man]

Chris, there are several factors included in keeping an engine in forward rotation, esp during start up. If the timing is very close to TDC, then, if the engine begins to crank and immediately hits the compression cycle, there is a very good possibility that it is kicking back and shearing the key. If the cranking begins on the power stroke, exhaust stoke, or intake stroke, then there is time for the crankshaft to get it's mind right and head in the right rotation, and of course maintain that direction. Is your primary clutch in place right now?

 

[teamhog]

Chris, there are several factors included in keeping an engine in forward rotation, esp during start up. If the timing is very close to TDC, then, if the engine begins to crank and immediately hits the compression cycle, there is a very good possibility that it is kicking back and shearing the key. If the cranking begins on the power stroke, exhaust stoke, or intake stroke, then there is time for the crankshaft to get it's mind right and head in the right rotation, and of course maintain that direction. Is your primary clutch in place right now?

I'm an engineer, so I understand the concept behind your point.

No, the Primary is NOT (and has NOT) been in place.

I just don't see anything in the service manual about it being a requirement to be in place.