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Antique Engine Archives All archived posts from 1999 to 2004 when SmokStak was on EnginAds. This is a read-only board.

Antique Engine Archives

Loose Flywheel

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Old 01-18-2001, 01:12:14 AM
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Default Loose Flywheel

I am looking at a 6 hp engine that has a loose flywheel. Does anyone have any ideas how to fix this? Is there any Locktite type product that works for this? It is the type that uses a bolt to tighten it down (not a taper key) The person that has it has tried to tighten it up, but it didn't stay tight. Thanks.
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Old 01-18-2001, 07:52:47 PM
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Default Re: Loose Flywheel

I would clean up the shaft and flywheel bore and install the wheel loose with jb weld let it setup good then tighten the bolt .
Old 01-18-2001, 07:55:36 PM
Paul Gray
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Default Re: Loose Flywheel

Try this- Drive a wedge into the gap to spread the flywheel a bit. Be careful to put it in where there is least chance of splitting the hub. You don't need a lot of force. Get a piece of steel shim stock like 0.005 or what is needed to take up slop with spread flywheel. Insert a piece around the entire shaft to either side of the key the entire length of the hub. Take your time and buy the right shim made of steel; no soda cans. Remove wedges and try tightening the flywheel hub bolt (s). BE SURE the key and keyways are tight. No matter what you do with shimming, a loose key will work loose. I buy a new gib key and very carefully knock in until I hit a bit of resistance with the hub spread. A new key is 4-6 bucks from a supplier on this site and is the right way to fix the problem. If it ain't right, it will eventually work loose. Then I pull out the key and look for where it was rubbing in the keyway. File a bit off and repeat insert/ remove/file until it goes in snug. Then insert and tighten the hub. If the keyway on the crank is tapered, recut on opposite side of shaft and refit the key. I recently did this to a key/ crank keyway on an oilfield engine with a 3.25" dia crank. The key was 8" long x 0.8" square ! And DO ALWAYS wear safety glasses when knocking wedges and keys; one piece of shrapnel can ruin a fun hobby. Be safe and have fun.
Old 01-18-2001, 07:56:54 PM
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Default Re: Loose Flywheel

How worn is the shaft? Were the flywheel mounts. if worn bad it could be built up with weld and turned down. How worn is the hole in the flywheel?
Old 01-18-2001, 08:51:24 PM
Joe Morris
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Default Re: Loose Flywheel

If the engine is a Hercules built engine it never had a tapered gib key They only used straight key stock as do many engines that have a split hub. At least that has been the case in all the Hercules built engines That I have ever restored so there is a possibility that a gib key might not solve the problem.
Old 01-18-2001, 10:11:18 PM
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Default Re: Loose Flywheel

I don't believe it is wore too bad. The flywheel doesn't wobble around, just rotates a little. The engine is a Sparta Economy.
Old 01-19-2001, 02:28:56 AM
Russ Hughes
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Default Re: Loose Flywheel

What do you mean "It just rotates a little"? Do you mean it can move back and forth in relation to the crankshaft key and in the same plane it normally turns in, or do you mean that it moves back and forth sideways in the direction of the length of the crankshaft? There is a difference between the two that makes the solution a little different too. Or is it loose in both directions?
Old 01-19-2001, 03:51:12 PM
Ted Brookover Ted Brookover is offline
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Default Re: Loose Flywheel

Hi Merlin, I would feel quite confident in using one of the Loc-Tite round retaining compound that are available. However, you have now said this is on a Sparta Economy, an engine that is known for suffering broken flywheels. If I were you, I would look very closely, perhaps even have the flywheel magnefluxed(sp.?) before continuing. I have seen several Sparta engines that have had steel bands placed around the hub in an effort to salvage a broken flywheel.
Old 01-19-2001, 08:01:51 PM
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Default Re: Loose Flywheel

Moves back and forth in the same plane that it should normally run. Not moving out on crankshaft or so loose that it is wobbling.
Old 01-20-2001, 04:29:12 AM
Russ Hughes
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Default Re: Loose Flywheel

OK, it is just a guess on my part, that at some time someone maybe had a gibkey or whatever type key that was a little too narrow for the width of the keyway cut into the crankshaft and flywheel hub. Every time the engine fires the flywheel may have rocked back and forth against the key (gib) and slowly hammered the key way wider, or the key itself a little narrower.

Tightining the flywheel hub bolts would have little effect on reducing this motion. A wider key made to fit the existing keyway might be the cure. Again, not actually having looked at the engine, this is only a suggestion to consider.
Old 01-20-2001, 05:53:24 PM
Ed Deis
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Default Re: Loose Flywheel

Joe-You are correct. I have had a customer or two insist that they took a gib key out and that's what they are putting back as that has to be correct-regardless of me telling them that it's not correct. In fact I believe it can cause problems as a split hub flywheel doesn't lock onto a gib key as well as straight key. May have been what happened here. A straight machinery key should go back in it if there already isn't one and it could be milled and fitted to fit the shaft and flywheel, possibly a two step key. Ed


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