Lawn mower help, of all things...

[LoHo]

Hey, multi-tasking mechanics, I need some help.

I inherited a Toro 6.5hp rotary mower, and it has worked well after some carb work. But now it has gotten to the point that about every other mowing event begins with replacing a sheared Woodruff key. It has an odd key that looks like some miniature angle iron. The recesses for the key look and feel fine, the key fits snuggly, and I torque the flywheel nut to the recommended 40 ft/lbs. Would raising or lowering the torque help? Greasing the key? I've used three keys in the last six weeks. Any ideas? By the way, converting to chain drive or fitting wide rear tires won't help....

[soccer4m]

weld

Hi Larry,,,,break out the arc or mig welder and " finalize " the movement, weld the flywheel to the part and no more movement. Actually, without seeing a pic I am guessing the allen screw thing is moving and stripping out, maybe retap it with a slightly larger screw to make it more secure.........a pic would help us.......also hope your injuries are healing up, your xs1100 is getting some love, and the kids aren't driving you loco,,,,,,,,,,Mike in Sun Diego

[3Phase]

Are the flywheel and crankshaft in good shape?

If the flywheel is wallowed out the key won't be able to hold it unless you use get another flywheel or use some of that Loctite 660 goop. It works with their 7240 activator and I think it'll fill up to a 0.015" or 0.020" void.

[BA80]

Quit mowing rocks! It's not the spinning that sheers them, it's the sudden stops.

[DGXSER]

Only other thought is if your timing is off. Not sure on that engine, but if you check the gap on the magneto it can get out and might move the timing just enough to shock the key. Just a thought. I had an old mower that did this before, I cured it with a newer mower.

[petejw]

[QUOTE=LoHo;345514

replacing a sheared Woodruff key. It has an odd key that looks like some miniature angle iron. The recesses for the key look and feel fine, the key fits snuggly, and I torque the flywheel nut to the recommended 40 ft/lbs. Would raising or lowering the torque help? Greasing the key? I've used three keys in the last six weeks. Any ideas? By the way, converting to chain drive or fitting wide rear tires won't help....[/QUOTE]



hi loho,
that took me back as a kid when i had a mini bike that had
that woodruff key holding the magneto onto the shaft,
i would shear it off all the time, the shaft was tapered
and i needed a thicker washer under the nut to hold
the magneto lighter onto the shaft, is the shaft on ur lawn engine tapered?
the other thing i can think off , is the thread on the shaft long enuff?
if the magneto is worn on the shaft it will tend to sit deeper,
adding a thicker washer might work as well.
not sure if this is relevent to ur lawn engine, just a cpl of thoughts.

i also wouldnt put any grease on the key, put them in dry.

[latexeses]

I live next door to a mower repair man. I'll ask him this question. How old is the mower?
You may have a bent crankshaft. That can be fixed too.

[latexeses]

Torque for the flywheel is something like 160 inch/pounds. Be sure to check the wobble on the blade.

[latexeses]

I am sorry for the 160 inch pound torque. I missed a column and was reading off a brigs touque list. My bad...

[mikubuilder]

Quit mowing rocks! It's not the spinning that sheers them, it's the sudden stops.

I'm with you on that one, ask my wife how do I know....Every time she mowes the lawn(not very often) I gotta replace key or straighten the crank

[trdriver71]

i would check the timing, look at the key way and make sure they are not damaged and then i would look at your blade and make sure it is not bent and make sure it is still balanced and even if it is sitting in the right spot as some of the lawnmower use the blade as a flywheel as they use lighter flywheel up top and depend on the blade to run properly.

[STEPPENWOLF]

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