I need to remove a Flywheel on a 1982 Johnson 4hp. I do not wont to try the hammer method when you hit the flywheel with a hammer as I dont wont to break the crank. I know i cant buy a proper one, so I was thinking, Will this work.Get a dome nut and tighten it to the crankshaft thread. Then hold the flywheel by screwing 2 bolts into 2 of the 3 holes in the centre of the flywheel, put a spanner of a rod between them and hold. Then if I continue to tighten the dome nut and hold the flywheel still, the flywheel should come off right?Is this the same way a real puller works?And Will this work?And what will I do if it does not?Thankyou
The puller BoatBouy is showing will most certainly work, but it would be better to use shouldered bolts with it, that's what the factory puller use's . These are called stripper bolt's, and are available from most machine supply houses. Using the bolt's shown, it's possible to pull the thread's out of the aluminum flywheel.
R.Johnson, is the advantage of stripper/shoulder bolts the close thread fit? Or are they designed with a (helpful) failure point?You'll likely need to pick up some 1/4"-20tpi bolts 3 or 4 inches long, and perhaps some thick washers. Those pullers never seem to come with that size. I got the much beefier Lisle one but that will work fine for your 4hp.Another idea is to take a peice of steel plate and drill three holes in it to correspond to the three flywheel hub screws, run some bolts through it and tighten them evenly until the flywheel pops. You'll want to use a screw that will get a minimum of 8 full turns into the flywheel before it tightens up. But much more than that starts getting pointlessly long.
Will an automotive store sell a Flywheel puller like Boatboy metioned? Are they the same as a harmonic balancer?One question, What actually removes the flywheel, Is it when the flywheel and crank are pulled oposite ways, or when the crank is pushed down and the flywheel up?PAUL, The way you mentioned, is the purpose to screw the bolts in far enough so they go almost through the flywheel and start to push on the armature support plate or the block? So it lifts off the Flywheel,?
Bozza, no, what I ment is to construct a simple puller that as you screw into the flywheel pushes down on the crankshaft. Picture Boatbouy's puller with no centre hole. Just thread in shorter bolts until the the puller is forced into the top of the crankshaft. Eight complete turns, just shy of 1/2 inch, gets the bolts reasonably far into the flywheel so they can take the force without stripping.Any automotive store that sells tools will have that puller. It is a harmonic balancer puller. The harmonic balancer is the pulley on the end of an auto's crankshaft which powers accessories.The purpose of all these pullers is to pull the flywheel off the crank. This is done by simutaneously pushing down on the crank and pulling up on the flywheel equally.Oh, hey, I've got a picture of my setup:
These are the dimention's of the stripper bolt's as supplied with the factory tool. 1/4-20 thread, length of thread,1/2" to shoulder. Length of main body, 1 1/2", Dia. of body .312. Allen cap screw head. 5/16-24 thread, length of thread, 1/2" to shoulder. Length of main body, 1 11/16, Dia. of body .375. 9/16 Hex head. The washer's are 1/8" thick, and tempered. I don't know the temper of these bolts', but they are about file hard, or in other words, they can barely be scratched by a file. In use, these bolts' are pulled down to the shoulder, and tightened. This put's an even tension on all three bolts', and reduce's the chance of pulling out, or breaking. The Machinery Handbook call's these a shoulder bolt, but a have found them under either name.
Thank you R.Johnson. That is very informative. I clearly hadn't considered getting the puller bolts evenly installed, although naturally I try to get it close when setting up the puller. And the limited length of the puller bolt's threaded section no doubt offers some protection for the components below the flywheel.I also found out that the stripper bolts have a class 3A thread, while those Grade 8 hex heads like those above are normally manufactured with a class 2A thread. The closer fitting 3A thread has an advantage since the thread engages more towards the root where there's more material. This gives the stripper bolt an advantage against shearing the thread in the flywheel. Socket head cap screws are also commonly manufactured with 3A thread fits.It only makes for a hundred pounds per screw or so difference, but sometimes that's enough.
I have one of the home made ones like Paul was talking about. 1/4 steel plate with three holes. Works like a champ. If you're worried about getting the holes in the exact spot,, drill them a little big and use a washer. I think you'll want to screw the flywheel nut down flush with the end of the crankshaft to protect your threads and to keep from flaring the end of the shaft. It also makes a bigger area to level the puller plate across.