fly wheel

[4vern]

Hello
I have a craftsman 16 HP mower with 38 in cut
The flywheel broke a pin..
When I went to take the fly wheel bolt off it was loose.
I replaced the pin and torque it to 80 pounds and it did it again.
So I replaced another pin and torqued to 100 pounds.
Ran for a while and then broke another pin.
So I am thinking I am installing the bolt wrong
How do you hold the fLy wheel while u tighten the bolt?

WHAT makes a fly wheel brake a key?

 

[DaveTN]

Make sure you put the washer with the domed side up and then torque it down. The flywheel moving when the engine stops is what shears a pin. I've seen valves out of adjustment causing kick back and shear a pin occasionally. Or hit a stump or brick and the crankshaft comes to a sudden stop, but the mass of the flywheel wants to keep moving and the key is designed to shear and thats what it does. If it didn't you'd bend the crankshaft. I've heard of go cart racers who don't even use a key, but use a lock washer and tighten the flywheel down with a lot of torque and go on. I've never done it, but know guys who have. That's the way they advanced the timing on the engine to give it extra power. You can't advance timing with the key in a slot!

 

[4vern]

thanks i will look but i did not see a washer
i think i will try and tighten it with a pipe wreck on the bottom on the shaft

 

[4vern]

Well I replaced two more pins yesterday.
Finally on last try I put 110 pounds of torque on the bolt.
It ran for a while. I will try and start it today and see what happens

 

[4vern]

Well I sheared six pins now. Not sure how tight the fly wheel bolt should be. Does anyone no?

 

[DaveTN]

Well I sheared six pins now. Not sure how tight the fly wheel bolt should be. Does anyone no?

I recall you asking about the cupped washer that goes under the flywheel nut. I mentioned it was cupped on one side and bowed out on the other. You didn't seem to have it or recognize it at the time. May have been lost or never one on it perhaps. Seems I've always seen those cupped washers used with flywheel nuts just for that purpose to hold the torque. I don't believe that flywheel will hold proper torque and tightness without it. The convex , bowed-up side has to go UP and the flywheel nut basically flattens it out and it holds pressure against the flywheel and acts similar to a lock washer. Might find one at a local repair shop. That lack of washer may be your problem. Sorry to hear about the 6 sheared keys. What kind of washer do you have under the flywheel nut you're torquing down? You shouldn't have to over-torque it really. Maybe a few pounds past the specs, but no heavy gorilla torquing with a pipe wrench etc.

 

[4vern]

thanks
i found the manual
it does not show a washer
the manual has the model number of 917.27535
so i.was wondering if anyone knows.that the torque should be?
if you need more info let me no
the manual does not give allot of info
thanks

 

[reynoldston]

Just what brand engine do you have in the mower?

 

[4vern]

b and s it is on a craftsman mower

 

[Fish]

I think that you are not torquing the nut enough, or else you have a cracked flywheel or crankshaft.