Hustler raptor kawasaki crankshaft end snapped off

T

turboawd

Well-Known Member
Joined
Jun 27, 2015
Threads
11
Messages
226
The machine is 3 years old. Not used a whole lot, but used hard when we do. Cuts lot of tall grass.
Anyways the crankshaft snapped off flush with the engine case. Why would this happen? And how hard would it be to just replace the crank?
Click on the link for pictures :
https://imgur.com/a/f1AfydK
 
B

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,705
That is a fatigue fracture and should be a warranty claim
Take the clutch to your dealer and ask him politely to send a warranty claim into Kawasaki for you.
If he says it is too old just tell him a metallurgist friend of yours ( me ) has identified it as a materials failure in fatigue mode.
Kawasaki are pretty good with warranty claims down here and if there was a bad batch of crankshafts they will either want to know about them or already know about it & will do the replacement.
Down here you will get the crank installed into your engine free, but you will have to pay for the removal & refitting of the engine + consumables like oil filters & oil.
Hustler are the party who will need to pay for the engine removal & fitting but their warranty down here is nowhere near as good.
We get 3 year warranty on Kawasaki products down here don't know what it is in the USA.
And please next time you post pictures, post them directly to the forum not via a 3rd party hosting site you make things difficult for the people who you are expecting to help you for free.

If you get the fracture surface in the right light you will be able to see rings in it, just like growth rings in a tree.
Each ring is the progression of a crak that started in the upper left of the image and progressed towards the centre.
The shinny spot in the middle is a brittle fracture because the amount of uncracked crankshaft was not enough to take the shock loading when you turned the blades on so it just snapped.

IT is funny because it is the wrong shape for a torsional load failure and has the look of a cross axis loading like what you would get if you smacked the clutch with a VBFH
 
T

turboawd

Well-Known Member
Joined
Jun 27, 2015
Threads
11
Messages
226
bertsmobile1 said:
That is a fatigue fracture and should be a warranty claim
Take the clutch to your dealer and ask him politely to send a warranty claim into Kawasaki for you.
If he says it is too old just tell him a metallurgist friend of yours ( me ) has identified it as a materials failure in fatigue mode.
Kawasaki are pretty good with warranty claims down here and if there was a bad batch of crankshafts they will either want to know about them or already know about it & will do the replacement.
Down here you will get the crank installed into your engine free, but you will have to pay for the removal & refitting of the engine + consumables like oil filters & oil.
Hustler are the party who will need to pay for the engine removal & fitting but their warranty down here is nowhere near as good.
We get 3 year warranty on Kawasaki products down here don't know what it is in the USA.
And please next time you post pictures, post them directly to the forum not via a 3rd party hosting site you make things difficult for the people who you are expecting to help you for free.

If you get the fracture surface in the right light you will be able to see rings in it, just like growth rings in a tree.
Each ring is the progression of a crak that started in the upper left of the image and progressed towards the centre.
The shinny spot in the middle is a brittle fracture because the amount of uncracked crankshaft was not enough to take the shock loading when you turned the blades on so it just snapped.

IT is funny because it is the wrong shape for a torsional load failure and has the look of a cross axis loading like what you would get if you smacked the clutch with a VBFH
Click to expand...

Thanks for lengthy reply.
So you think this crank was cracked from the beginning and just slowly growed?
Also, I'm posting from my mobile phone, and the mobile site does not have a picture attachment.
 
B

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,705
turboawd said:
Thanks for lengthy reply.
So you think this crank was cracked from the beginning and just slowly growed?
Also, I'm posting from my mobile phone, and the mobile site does not have a picture attachment.
Click to expand...

Yes no maybe.
I would need it here in my hands to make those sorts of determinations
However I can catagorically state it was faulty from the factory
Weather this was a machining flaw, a heat treating flaw or materials flaw is a moot point.
The fact is it was flawed and it should not have fractured and not in the way that it did.
If you troll through the web for images of a tortional failure you will see they all have a distinctive twisted look and some sharp edges
Then search Charpy or Izod fracture surfaces and you will see a structure like the bright section in your photo.
That is a brittle fracture.
Cranks should never ever fracture like that
There are probably a pile of fatigue fracture images as well
Your fracture surface is even not typical of a rotational fatigue failure of sound material.

To get a lab result like yours we would put a rod in a machine that supported each end of the rotating shaft
We then apply a load between the two ends via a wheel and keep the pressure up till the shaft breaks.
Even then we would have to machine in a stress raiser like a groove around the outside.

However as stated before, be nice about it and even if the dealer says Kawasaki will not do anything ask him to submit the claim in writing and request a copy for your file.
 
7394

7394

Lawn Addict
Joined
Sep 5, 2014
Threads
84
Messages
4,718
Bert- here in the U.S., Kawasaki has 3 year warranty also.

Just FYI.
 
cpurvis

cpurvis

Lawn Addict
Joined
Aug 25, 2015
Threads
21
Messages
2,256
Your signature says "Midwest." How far are you from Hesston, Kansas, the home of Hustler?
 
I

ILENGINE

Lawn Pro
Joined
May 6, 2010
Threads
39
Messages
9,966
May not of been cracked at the onset, but occurred very quickly since there is no rust progression into the crack rings. Definitely warranty, not much on a riding lawnmower that would create enough force to shear an 1" crankshaft. Like Bert commented on. would take multiple strikes with a big hammer, and that type of striking would most likely crack the oil pan before the crank snapped off.
 
T

turboawd

Well-Known Member
Joined
Jun 27, 2015
Threads
11
Messages
226
I'll ask the dealer Monday. But i may be 1 or 2 months past warranty.
 
I

ILENGINE

Lawn Pro
Joined
May 6, 2010
Threads
39
Messages
9,966
Sometimes manufacturers will allow warranty repairs if it is a defect and fails shortly after the factory warranty ends. Or in some cases they will offer to pay for parts but you pay the labor.
 
cpurvis

cpurvis

Lawn Addict
Joined
Aug 25, 2015
Threads
21
Messages
2,256
I have never seen a crank break outside of the crankcase.

Definitely a manufacturing defect. Kawasaki need to make this right.
 
You must log in or register to reply here.

Footer Links 1

Top