Well I f&@ked it and then f&@ked some more

[farmguywithasaw]

So I was rebuilding my ms310 and got it together and fired it up. Ran good shut it down when two start again and herd a snap. After that no resistance on the pull cord. Long story short the threaded portion of the crank that holds the flywheel on broke off. So either take it all apart and get an new crank and flywheel or make a new flywheel key and drill and tap a hole in the crank and thread a stud in and weld it to the crank. Runs good so far lol

 

[hotshot]

Not good news.
Did you use an air gun to final 28 nm torque on the FW nut?, or just a standard ratchet/socket set? 28nm is right over 20 lb/ft.
I’d definitely suggest a new crankshaft, rather than a weld.

 

[farmguywithasaw]

Well I have a dewalt driver I used just one or two Ugga Duggas. You miss understood I all ready welded it lol did you see my user name

 

[buzz sawyer]

I did similar to a SP125c when the threads on the clutch side broke off. I machined a guide to fit over the crank and center on the taper that was left, then drilled and tapped for left hand threads. I used a high strength allen head bolt and then tightened with a nut on the bolt. worked fine.

 

[farmguywithasaw]

Looks really good

 

[alexcagle]

....ugga dugga.? LoL

 

[farmguywithasaw]

....ugga dugga.?

The measure of torque using an impact just say it 5 times fast and you will get it lol

 

[farmguywithasaw]

I think I’m going to quit being so lazy and not use drivers on this stuff strictly by hand from now on

 

[hotshot]

Well I have a dewalt driver I used just one or two Ugga Duggas. You miss understood I all ready welded it lol did you see my user name

Yep, I missed that you already welded it up

 

[stihl86]

I think I’m going to quit being so lazy and not use drivers on this stuff strictly by hand from now on

Yeah. Probably for the best doing it that way. Someone should invent a tool that tells you how much you're tightening a fastener. Real men and "mechanics" wont use it, but some one like me, who struggles with simple repairs might.

 

[farmguywithasaw]

Well I usually work on bigger stuff

 

[Moncur34]

I did similar to a SP125c when the threads on the clutch side broke off. I machined a guide to fit over the crank and center on the taper that was left, then drilled and tapped for left hand threads. I used a high strength allen head bolt and then tightened with a nut on the bolt. worked fine. View attachment 808940View attachment 808941View attachment 808942

I had a buddy that was working on a bigger McCulloch that didnt know the crank had left hand threads on one side. He went to take off the clutch or flywheel with a brand new unfamiliar impact wrench and snapped the end of the crank off. I always wondered if I could fix it by doing the exact same trick with the allen bolt. Might have to give him a call and try it out!

 

[pioneerguy600]

When one does not have a calibrated wrist a torque wrench can be ones friend. A 3/8" and 1/4" drive will cover all the torques used on chainsaws. The 1/2" and 3/4" drive are way over kill.

 

[Mad Professor]

When one does not have a calibrated wrist a torque wrench can be ones friend. A 3/8" and 1/4" drive will cover all the torques used on chainsaws. The 1/2" and 3/4" drive are way over kill.

3/4" breaker bar comes in handy for those pesky clutches that won't come off. Of course you need the 3/4-1/2-3/8 adapters..........

 

[Old2stroke]

Excellent solution!! Do I understand that just the threaded end of the crank broke off, but the tapered part that mounts the FW was still there? If so, why is there a problem with the key?

 

[pioneerguy600]

Worst case, bring out the 1" drive Ingersol Rand. I have sheared off 3/4" dia grade 8 bolts with it, they either come out or break off, saves getting out the liquid wrench.

 

[farmguywithasaw]

Excellent solution!! Do I understand that just the threaded end of the crank broke off, but the tapered part that mounts the FW was still there? If so, why is there a problem with the key?

it sheared off when I pulled the cord

 

[farmguywithasaw]

Worst case, bring out the 1" drive Ingersol Rand. I have sheared off 3/4" dia grade 8 bolts with it, they either come out or break off, saves getting out the liquid wrench.

And yes the tapered part was fine

 

[farmguywithasaw]

I used a triangular file to make a grove in the center of where the key was on the flywheel and cut a piece of aluminum welding rod for the key

 

[rupedoggy]

Someone should invent a tool that tells you how much you're tightening a fastener.

Hello... it is called a torque wrench.