Motoscrubs.com

Hello everyone.
New guy here with a 1970 450 scrambler. I have made it through a good bit of the engine disassembly but hit a road block on the flywheel. I pulled the off the crankshaft gear and can't seem to get the flywheel extractor to work. It seems to be stripping the threads and popping off. I can't manage to screw it down far enough. I tried pulling it off with a 5" gear puller but it simply bent the arms and popped off too. The I was worried I might be tugging the stator too. I would appreciate any guidance. Thanks in advance.
Richard

" can't seem to get the flywheel extractor to work. It seems to be stripping the threads and popping off. I can't manage to screw it down far enough. "

____ Too bad that it seems you didn't get your Ducati-type rotor-puller threaded-on far enough before actually trying to pull-off the rotor/flywheel,, cuz now with the rotor's threads messed-up, it's going to be a more difficult job.
__ Have you tried heat & cold yet ?
If not, then before attempting to actually pull it off again, (but with your puller-tool already attached & preloaded),, try slightly heating-up the rotor, and THEN, put some chucks of ice against the crankshaft, just before next further attempting to pull-off the warmed-up rotor.
If it doesn't work your first-try, then try it again with the rotor heated-up a bit hotter. _ It may take three or more attempts (with the rotor heated-up higher than before, each time), cuz you don't want to cook the rotor's magnets any hotter than is needed.
When quickly applying lots of ice/ice-water onto the exposed shaft-surface, you might even get real-lucky and snap-shock & break-loose the rotor's grip from the shaft without need of any further puller-tool tightening-action, (but your story of the bent arms, makes that slim-possibility seem rather unlikely).
__ If you can't get your threaded-type puller threaded-on at least 3-turns (over good/complete rotor-threads, then I'm afraid you'll have to acquire a good-quality universal-type flywheel-puller with arms that won't bend & slip-off.
____ BTW, don't forget to add a mark on the flywheel-rotor, so as to keep-track of it's current TDC.crankshaft-location.


Hopeful-Cheers,
-Bob

For spot freezing I recommend using an electronic troubleshooting aid commonly referred to as 'quick freeze.' That may work faster and easier than trying to use ice.

See GC's "Freeze Mist":
http://www.alliedelec.com/search/produc ... u=70159785

This stuff can give you instant frostbite if you get it on your skin, it's that powerful.

If you can't abide the cost or the wait to order and receive a can of quick freeze those aerosol cans of spray air used to blow chunks of dust and debris out of computer keyboards and fans will do the same thing if you hold them upside down when you spray them. You can get spray cans of air at Radio Shack or most office supply stores.

Thanks guys! I will dig into it and let you know how it goes.
The thread damage is minor so I am going to try to brace the rotor and screw it down.
The threads on the other part of the shaft on the other side of the engine are wrecked.... the bolt was barely attached on when I removed it... so I might be able to vice grip that down since it needs replacement anyway. I will also try the temperature remedy too.
I really appreciate the guidance.
Best regards!

" the bolt was barely attached on when I removed it... "

____ What "bolt" ? _ Do you actually mean the lefthand-threaded 'nut' (for the right-side end of the crankshaft) ?


" so I might be able to vice grip that down since it needs replacement anyway. "

____ You mean "vice grip" the threaded part of the shaft ? _ That would seem quite a harsh/drastic method to attempt !


Hopeful-Cheers,
-Bob

Hey Bob,
Yes, I meant to say nut. That is just embarrassing. I correct my son all the time so I guess I deserve it!

I thought that if I need to replace the threaded shaft anyway I could go ahead and completely sacrifice the part and be able to get a good anchor point to hold the shaft in place so I can completely seat the puller tool. Thanks again for all your help. It is greatly appreciated.
Best regards,
Richard

" I thought that if I need to replace the threaded shaft anyway I could go ahead and completely sacrifice the part and be able to get a good anchor point to hold the shaft in place so I can completely seat the puller tool. "

____ Sacrificing the crankshaft would be quite expensive !
I believe others have repaired the threads, (often damaged by people who didn't realise that they were dealing with LEFThand-threads), well enough sp that a NEW LH.nut grasps the shaft-threads adequately.
__ There are other ways to keep the crankshaft held in place ! ...
You could either block-up the con.rod (with a pin/rod through the small-end, resting on wood-blocks), for one,, or put the trans in gear and block the drive-sprocket from turning,, or hold the protruding tower-shaft's upper-tip with as crescent-wrench.


Hopeful-Cheers,
-Bob

There’s another approach you might try to remove your flywheel, but before resorting to this method, let’s verify that the factory type flywheel puller method has been properly executed. You should be using one of the bell shaped pullers with the large ID thread, The flywheel only has about three or four threads to engage the puller. You have to thread the puller all the way on to these threads so the puller is bottomed out on the flywheel. If the puller won’t thread all the way on, you need to chase the threads on the flywheel so the puller will thread all the way on. Also, are the threads on the puller OK? I’ve seen flywheels where these threads are completely gone. If the threads are stripped such that the puller won’t work, try this method as a last resort. Get a can of the keyboard cleaner Jim suggested. Remove the small threaded plug from the internal thread on the end of the crankshaft. This is a slotted screw, usually pretty tight and can be difficult to remove so be careful not to strip the slot. Spray contact cleaner in this oil passage and blow with compressed air to flush the oil out and vaporize the contact cleaner. Since you’re going to be heating the parts you don’t want a fire hazard. The flywheel is a brass or aluminum flywheel riveted to a steel flange (the threaded part that your flywheel puller threads on to). Apply some moderate heat to the steel flange; not smoking hot, just hot to the touch. It shouldn’t be so hot that the steel flange starts blueing. Then, holding the compressed air can upside down, spray down the hole in the crankshaft and on the crank spindle. The objective is to get the flywheel flange to expand from heat and the crankshaft spindle to contract from cold. Then, before there’s to much heat transfer, tap on the outer shoulder of the flywheel with a big rubber or plastic mallet. If you don’t have fairly heavy rubber or plastic mallet, use a block of hardwood between the flywheel and a metal hammer. Your blows should be parallel with the crankshaft. Sometimes the flywheel will pop right off, others take a little more persuasion. No need to keep the crank from turning with this method. The claw pullers usually won’t work because the flywheel has a bevel on the inner shoulder that the claws grip so they just slip off. Matt

Success! Many thanks to all. Yes I had the right puller tool but threads seem to be my reoccurring nemesis on this lady.
I went to harbor freight and picked up a 2 arm 6" gear puller. I had to grind off part of the ends to fit behind the flywheel.
I preloaded and then heated the flywheel and cooled the shaft with an upside down down duster can and after a muscle down it popped. Oh boy did it pop.
Thanks for all the help guys.
So does any one know where I can get a replacement crankshaft for a 450?
Threads missing on right side.....