Fixed a bent crank on my commercial Snapper mower

[Cujet]

I decided to clear next to the fence on the South side of my property. After cutting all the trees, vines, poison ivy and brush away, I used my bush hog to mulch everything up, I was almost finished when it broke.

So, being the smart guy that I am, I cranked up my Kawasaki powered Snapper mower and mulched up the rest of the stuff. Oops, I forgot about that stump. Not good.

The crank bent by 0.060 inches and the Ninja blade was seriously deformed.

Being very sad, hot and tired, I put it away. I searched and found a tool designed to straighten crankshafts. Plus a few utube video's on "how to". So, I measured carefully, marked the high and low spots and proceeded to wail on it with a 2 pound brass hammer. No luck.

So, if that fails, move up to a bigger hammer. The 5 pound sledge did the trick. After some trial and error, I was able to get the runout to about 0.003 inches. Not bad.

Then I put my brand new pretzel Ninja blade in the press and worked on that. Sure enough, it took some serious pressure, but it is now straight.

Put it all back together and it's smoother than before I hit the stump.

An oil change and some TLC and my old Snapper is back in business.

 

[callbay]

Wow! Great job. I would probably not even attempt it.

 

[JTK]

Good deal, sounds like you're good to go.

That's been my main concern with my Snapper mulcher with the ninja blade. That blade is so big and heavy with so much surface area, it's gotta put more stress on the crankshaft, especially when un-mowable objects are mowed.

Joel

 

[FNFAL308]

Originally Posted By: JTK
Good deal, sounds like you're good to go.

That's been my main concern with my Snapper mulcher with the ninja blade. That blade is so big and heavy with so much surface area, it's gotta put more stress on the crankshaft, especially when un-mowable objects are mowed.

Joel


It doesn't put anymore stress on the Crank then any other blade.. Hit something like a stump or pipe and it won't matter what blade is on it..
BTW, the Ninja (I hate that name)is a great blade, I've been using them for many years and never found a blade that cuts better..

To the OP..
Keep an eye on that bottom crank seal it may start leaking.. Wailing on the crank with a sledge hammer puts way more stress on that sump then it was ever designed for..
If you didnt crack the sump and if the seal holds you should be GTG..

 

[Cujet]

Well, so far, it's not leaking. I mowed a good bit of my lawn afterwards without trouble.

I use Mobil 1 15W-50.

 

[morris]

yep .003 is more than close enough.

 

[greenaccord02]

Nice job. That 15W-50 will treat it right, too.

 

[steve20]

wow-!!! smoother than factory new-great job

 

[TFB1]

I straightened one on a 4Hp Briggs but after a few uses it was back approx where it was before I started(.050)... I used a four pound hand maul to massage that one, had it down to .002 runout on the tip of the shaft...

 

[Cujet]

Originally Posted By: TFB1
I straightened one on a 4Hp Briggs but after a few uses it was back approx where it was before I started(.050)... I used a four pound hand maul to massage that one, had it down to .002 runout on the tip of the shaft...


Oh, so it had "memory". I'll make sure to check it again after a few mows and report back if it's out of round again.

 

[TFB1]

Originally Posted By: Cujet


Oh, so it had "memory". I'll make sure to check it again after a few mows and report back if it's out of round again.


That was defiantly the case with mine, I dunno maybe some heat would relax the metal so it didn't happen again... Still I'd be leery that the lower seal would be damaged and leak if too much heat was applied...

I have a identical crank in another 4Hp engine that has a loose valve seat, if I ever need a project I can swap that one in...

BTW mine never did leak oil, I wouldn't be too concerned with that issue...