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AU85 Flywheel Removal?


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  #1  
Old 08-19-2017, 07:32:18 AM
oldmotorette oldmotorette is offline
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Default AU85 Flywheel Removal?

I have a Continental AU85 engine I'm trying to get running...as of now, the flywheel is jammed too far onto its shaft, causing the flywheel to be very tightly jammed against what I assume is the stator plate. I need to pull it away just a bit - ideally, I'd like to be able to remove the flywheel for inspection/wiring replacement. My trouble is, there are NO access holes to fabricate some kind of a puller mount, nor is there any room whatsoever to access the flywheel's rim from behind it. Anybody have a clever way to get the flywheel off? My only solution seems to be drilling through the flywheel face and threading the holes so's I can get some puller bolts mounted. I'm just a touch hesitant. Is there any other way? Thanks!
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Old 08-19-2017, 11:24:17 AM
AngrySailor AngrySailor is offline
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Default Re: AU85 flywheel removal??

Can you hold onto it by the flywheel and have someone hit the crank with a BFH? Maybe the B should stand for Brass in this case though Pretty crude but...
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Old 08-19-2017, 11:22:24 PM
tdmidget tdmidget is offline
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Default Re: AU85 flywheel removal??

Clean the shaft as much as possible, wire wheel is good. Apply penetrant such as Kroil. No witch doctor crap. Suspend it from the flywheel rim with as much weight as possible hanging from the flywheel rim. Heat the rim ONLY with as much heat as you can apply rapidly, rosette tip is good. Heat the rim evenly , to about 700 F if you have an IF thermometer. Tap the shaft with a brass hammer. It should move, maybe fall out.
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Old 08-20-2017, 10:49:24 AM
oldmotorette oldmotorette is offline
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Default Re: AU85 flywheel removal?

Thanks for the advice! Thing is, there's no real way for me to get a grip on the flywheel - it's smacked tight up against the stator plate/engine block, and there are no edges, bolt holes, access slots, etc. that would give me a chance of exerting any kind of grip/force whatsoever on the flywheel. I've already tried giving the the end of the crank a fairly healthy smack in the hopes that just that alone would shock the the system enough to cause the entire engine to "jump" back from the flywheel...certainly, heat on the flywheel would've been a great idea (and maybe would have worked) - along with maybe a harder hit. But I was too chicken to really hit the end of the crank with however much King Kong force I could apply. Makes me wonder how in the world someone would have gone about removing the flywheel if it hadn't been tightened the extra micron that has it now too firmly wedged in place. Under normal circumstances, there couldn't have been more than 1/16" of clearance between the flywheel rim and what it's now pressed up against. But I will try heat and another hammer hit. Thanks!
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Old 08-20-2017, 01:07:44 PM
tdmidget tdmidget is offline
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Default Re: AU85 flywheel removal?

You are wise to be careful of the hammer. Mushrooming the crankshaft will make it much worse. Any way to post a pic of the situation?
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Old 08-21-2017, 10:07:13 AM
beezerbill beezerbill is offline
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Default Re: AU85 Flywheel Removal?

Any chance you can post a few photos, including a face-on view of the flywheel? I am not familiar with the Continental engine, but I have seen a few engines where they have bosses for flywheel puller holes cast into the flywheel, complete with centering divots, but not drilled out and tapped. Is the flywheel iron or aluminum alloy? If it is iron then sometimes a wack on the rim of the flywheel with a brass hammer can cause it to come loose. Sounds brutal but I have seen it work. DON"T try this with an alloy flywheel! Agreed that hammering on the end of the crank can cause mushrooming - sometimes a close-fitting cap on the end of the crank can be used to prevent this. One thing to remember - if you do resort to the hammer you need one good solid blow to shock the flywheel loose- a lot of light tapping is guaranteed to mushroom the crank (or protection cap if you use one) without ever getting the flywheel to shock free. And use a steel (or brass) hammer - any thing softer (lead or plastic "dead blow") won't give you the shock you need to have it come loose.
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Old 08-21-2017, 06:02:17 PM
oldmotorette oldmotorette is offline
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Default Re: AU85 Flywheel Removal?

beezerbill, thanks for your reply. Here're two pictures of my flywheel situation: one, attempting to show how the outer rim of the flywheel is jammed against the rest of the engine, preventing me from getting behind the flywheel in any way. The other picture, is the face of the flywheel: there are, indeed, three concave bosses(?) around the hub - they look like places to carefully drill/tap for puller bolts. There are a series of dead-end holes around the outer edge of the flywheel. They look like the wrong places to attempt a drill/tap/puller attempt. Sorry - forgot to check whether the flywheel is iron or alloy. What do you think? Readymade places to drill and tap? Thanks.
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Old 08-21-2017, 06:24:15 PM
Dustin D Ehli Dustin D Ehli is offline
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Default Re: AU85 Flywheel Removal?

Sharpen a few cheap flat screwdrivers, hammer them in on opposite sides, they will go in if sharp
Give shaft hit as mentioned.
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Old 08-21-2017, 06:51:59 PM
Pete Spaco Pete Spaco is offline
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Default Re: AU85 Flywheel Removal?

I'd assume that the shaft is tapered where the flywheel fits on to it. Is that a fair thing to think? If so, it's hard to believe that the flywheel could have been pushed "too far onto the shaft".

What's the chance that either the "stator Plate" has moved forward, or that some shimming of the crankshaft to make up for end play is to blame?

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Old 08-21-2017, 08:19:56 PM
oldmotorette oldmotorette is offline
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Default Re: AU85 Flywheel Removal?

I'm not positive, but reasonably sure, that the shaft is tapered. But, regardless, the flywheel is jammed onto the shaft far enough so that the flywheel is now bound tight against the engine. The problem occurred when some idiot who looks very much like me thought it might be a good idea to spin the engine (instead of endlessly cranking it over) with an impact driver.
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Old 08-21-2017, 08:43:02 PM
beezerbill beezerbill is offline
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Default Re: AU85 Flywheel Removal?

Quote:
Originally Posted by oldmotorette View Post
The problem occurred when some idiot who looks very much like me thought it might be a good idea to spin the engine (instead of endlessly cranking it over) with an impact driver.
Oops! The flywheel looks to be alloy (not actually aluminum but probably some zinc / aluminum alloy) and may very well now be distorted to where it is unusable. Hopefully the crank fared better, and it probably did. No harm in drilling and tapping the flywheel - go to about 3/8 - 16 on the threads because you might be pulling pretty hard. Don't use a fine thread (3/8 - 24) as they are likely to strip. Put the nut back on the crank before putting the puller on but leave the nut backed off several turns. When the flywheel does let go it might pop off pretty good and you don't want it flying across the room. Be sure the tip on the puller screw fits the center in the crank well, and grease it up good so it doesn't gall into the crank center. Also a good idea to grease up the puller draw bolt threads. Tighten the puller on real good (guess about 60 footpounds or more on it) and then clout the puller drawbolt head good with a steel hammer. With luck the flywheel will pop off.

Forgot to mention - be careful when drilling the puller holes to not wreck the magneto stuff under the flywheel. Be a good idea to have a drill stop on the bit - same goes for the tap - might consider a bottoming tap - cuts threads all the way to the end of the hole without anything poking through.

There is an idiot that looks like me that works on a lot of my stuff also so don't feel bad.

Last edited by beezerbill; 08-21-2017 at 08:56:28 PM.
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Old 08-21-2017, 10:37:17 PM
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Default Re: AU85 Flywheel Removal?

Well, there's a Paul Harvey moment... (The rest of the story).
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Old 08-22-2017, 05:35:27 PM
tdmidget tdmidget is offline
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Default Re: AU85 Flywheel Removal?

I don't see a center in the crankshaft end so make a cap to fit over it with a center drilled center in it. I would go ahead and drill those 3 places. I doubt that the flywheelis damaged if the engine actually was turning. A taper fit is very strong. Usually these have a woodruff key which hopefully has not sheared and caused damage to the taper.
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Old 08-22-2017, 07:17:38 PM
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John Newman, Jr. John Newman, Jr. is offline
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Default Re: AU85 Flywheel Removal?

I am finding some questionable advice here.
In no particular order, I found:
Suggestion to heat the rim of the flywheel. What would that accomplish? It is stuck at the hub. Remember, there is a mag coil behind the flywheel and it won't respond well to excess heat.
Hammer 2 screwdrivers in - presumably between flywheel and block. Good way to damage something. Most probably destroy the mag plate.
Sounds like the flywheel got over tightened. Possibly forced on the taper farther than it should be. This would cause stress cracks at the hub. I would not use that flywheel again.
My go-to stuck FW tool is a piece of steel hex stock (round OK too, but it's what I had) 1-1/4" across the flats and about 4" long drilled and tapped to fit the crank threads. Blind hole the same length as the crank threads. Screw on tight and hit it with a good blow. No damaged crank.
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Old 08-22-2017, 10:30:24 PM
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Default Re: AU85 Flywheel Removal?

Everything the OP has told us reinforces the notion that he will soon be in the market for a replacement flywheel. There is no magic answer here, If the flywheel has crawled too far up onto the taper, enlarging the hole there's no going back. The hole is too big and that's that. The flywheel may or may not be broken, That zinc is awfully soft and can distort easily, but it likes to crack too. If there is a thin steel insert cast in (not familiar with the Continentals, but I know Briggs did this at one time) it may have cracked, probably around the keyway, allowing it to expand. End of story.

Those three unmachined dimples were probably intended for an optional recoil starter or something. Follow the excellent advice from Beezerbill to machine the dimples then make a puller and yank 'er off.

Pretty much nothing is beyond saving. If this engine was handed down to Moses with the ten commandments and so is priceless, and if the flywheel is ruined, as it most likely is, the hub may be machined away and a replacement steel hub made and installed to the bored-out flywheel, retaining with some flat head screws and maybe some Loctite. But this is a big deal and a lot of bother. Find another one, but first throw your impact gun away. Too many good parts have been ruined with them! I saw the same thing happen once before, back in the 70's. I was at my friend's shop and his mechanic was working on one of the then brand-new original tiny displacement green machines. For some reason he had the recoil off and used an impact gun to spin the engine. Even with that tiny engine, though, there was enough impact that the air gun wrenched the entire threaded portion right off the end of the crankshaft! That was the end of that engine. The guy replaced the whole engine and gave me the broken one. it's still out in the archives someplace.
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Old 08-24-2017, 12:03:57 AM
tdmidget tdmidget is offline
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Default Re: AU85 Flywheel Removal?

Quote:
Originally Posted by John Newman, Jr. View Post
I am finding some questionable advice here.
In no particular order, I found:
Suggestion to heat the rim of the flywheel. What would that accomplish? It is stuck at the hub. Remember, there is a mag coil behind the flywheel and it won't respond well to excess heat.
Hammer 2 screwdrivers in - presumably between flywheel and block. Good way to damage something. Most probably destroy the mag plate.
Sounds like the flywheel got over tightened. Possibly forced on the taper farther than it should be. This would cause stress cracks at the hub. I would not use that flywheel again.
My go-to stuck FW tool is a piece of steel hex stock (round OK too, but it's what I had) 1-1/4" across the flats and about 4" long drilled and tapped to fit the crank threads. Blind hole the same length as the crank threads. Screw on tight and hit it with a good blow. No damaged crank.
The major part of the mass of a flywheel is at the outer rim. The OP's engine has a combination flywheel and fan but still the greatest portion of the mass is near the circumference. Heating this area will expand the entire wheel. as the diameter grows the hub ID will also grow , releasing the grip somewhat, usually enough to easily remove it.
Now that we know about the impact wrench, we need to know a couple of other things.
1. Was the engine turning freely before the impact episode? If not then there may be more damage, such as a sheared key or enlarged taper.
2. Did it turn at all before the impact? There could have been an object or obstruction in the cylinder or crankcase which was overwhelmed by the impact wrench. If so, this may be beyond realistic repair.
In any case the first order of business is a non destructive removal of the flywheel. A combination of heat and a puller is about the only solution.
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Old 08-29-2017, 06:55:44 AM
oldmotorette oldmotorette is offline
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Default Re: AU85 Flywheel Removal?

So. The flywheel is off. I drilled out those dimples with a 5/16; then tapped them with a 3/8X16 bottom tap...wound up drilling all the way through - there just wasn't enough material to get a couple of good threads going, given that the thickness was hardly approaching 3/8". Luckily, there was nothing behind those holes that could've been damaged. The puller managed to suck the flywheel free; there doesn't SEEM to be any damage. Once the flywheel popped, I checked to see if the engine turned freely. It did.Was the woodruff intact? It was. And then I stopped. Took a deep breath. And I haven't yet returned to the scene of that crime. Is the flywheel ruined in one way or another? I'll find out soon enough. But I wanted to report back...and sincerely thank everyone for their sage advice, here. I really, really appreciate all of it! I'll post a post-mortem on the flywheel soon's I get there.
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Old 08-29-2017, 09:31:59 AM
AngrySailor AngrySailor is offline
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Default Re: AU85 Flywheel Removal?

Great to hear you got it removed. I would check for any cracks around the hub then check it's reinstalled depth as it's taper is probably stretched. If it is stretched and another flywheel cant be found, maybe you could machine a little off the back of the rim to remove interference with the block? This would also depend on interference with the ignition and such under the flywheel. Its also likely that if the taper is stretched it will not run true anyways. If this was for myself and I knew it would be a "show only" application I would probably repair it, but over the years running a machine shop I refused a lot of flywheel jobs for obvious reasons
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Old 09-03-2017, 12:39:33 PM
oldmotorette oldmotorette is offline
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Default Re: AU85 Flywheel Removal?

Ok...success of a sort. The original flywheel? Yep, the taper was stretched. BUT...I stumbled across a whole new (to me) barn-find engine. Popped the flywheel off of it, slipped it on, and it works as it should. Now if I could just sort out my Carter N problems (I'm fairly sure the needle is clogged at least a bit), I'd be in business.
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Old 09-09-2017, 02:37:58 AM
maxdub maxdub is offline
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Default Re: AU85 flywheel removal??

i know you got it off but half tranny fluid and half acetone does a better job than kroil and any other penetrating fluid. just saying might be heplful next time.
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