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Flywheel to Crankshaft

bill_w

bill_w

Advanced Contributor
I know that the mating surfaces have to clean, almost polished for the flywheel to seat properly to the crank taper. Just wondering, is it OK to hit the surfaces with a shot of something like WD-40 before assembly? So that when they have to pulled apart, they might come apart easier, with out any rust or corrosion causing them to 'stick' together?
 
You misunderstand what is happening here.--------------The tapers must be absolutely clean !!!!!-----------The torque of the nut pushes the tapers together and stretches the flywheel taper to grip on the crank taper.----It is this locking action that drives the flywheel and the key merely locates it for proper ignition timing.-----Do not even think about lubricating this assembly !-----With a proper puller removing the flywheel is easy every time.
 
I was just thinking if it didn't rust, it would be easier to remove when it had to come off. I see your logic, I'm thinking that my 150 wasn't assembled quite right when the last owner had it rebuilt. There was some traces of rust on the crank, and it was a b***ch to get off, with the proper puller. I did polish all the rust off the crank and flywheel when I re-assembled it. This was just an afterthought. I guess if it is put together right, there would be no way for rust to start in between the two. Thanks for the input!!
 
The rust had nothing to do with it being hard to take off.-----Likely the flywheel nut was overtorqued !!----For a proper fit the tapers should be " lapped together " with some fine valve grinding compound.-----Clearly stated in the factory manual for the 235 HP model ( same parts as the 150 model ) for many years.
 
So if they are lapped together, it makes them easier to take apart? And the flywheel nut was NOT overtorqued, it was nowhere near 100 ft/lbs tight. Took it off with a regular socket/ratchet, with a flat screwdriver stuck in the ring gear to hold the flywheel. Being loose maybe allowed the rust to start?? Next time it's apart, I'll lap it. I've got a 115 apart at the moment, I'll lap that one too when it's time to put it back together.

thanks Racer.
 
to get flywheel off the puller has to be very very tight.
now tighten it even more and your getting near it.
give the centre bolt a good wallop with 4 pound hammer now tight it again.
Hit it a few more times then tighten it again.

leave it for about 30 minutes and have another tighten, if still not off tighten it a bit more and leave till next day.

Next day
Hit centre bolt very hard with hammer.
try and turn just a touch more
give it one more hit.......now lift off the flywheel.
they are meant to be very tight fit, the more they stick the better, thats why its a taper.
Do not hit the flywheel on the sides, that will just do damage and wont help.

if you use wd40 or any other lubricant, make sure you get every trace of it off.

tighten to 100ft pounds then check it again after a quick run.


phill
 
I was tightening the center bolt with an air gun. And hitting it with a 5 pound sledge. Still took a day and a half to get it off. I know better than to hit the flywheel itself!! The top of the crank, and the inside of the flywheel hole were rusty!!
 
That sounds about right.

Obviously the fit of the crank and flywheel cannot be perfect or it would never hold so well.
Rust would no way of been holding it, a puller would just rip through the rust in a few moments as the even pull
would be enough to get past rust.

Now when a flywheel is tightened down to 100ft lbs, its not going to be 100 to release it.
Its only for a split second that its tight.
On my engines i needed a scaffold pole to undo one flywheel nut and just a 2ft socket bar the other.
Both flywheels were on very tight.
what is the poundage of your Air gun ? unless its about 250psi it aint gonna do much good.
I was bending a 3ft x 1 inch drive socket bar when tighten the puller, it realy is a stressfull job
getting the flywheel off as you think its never gonna move.

Anyway as long as you have it off now you can get to work on the engine.
But i personaly would not put anything on the crank taper other than a wire brush to clean it.
Same with internal hole in flywheel.

phill
 
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