Steering knuckle failure

[PILOON]

While I am not an expert, but from experience I'd say that is a fresh break caused by serious stresses like wheel jammed between 2 rocks and forcing with power steering or some such forces, or hitting a curb while turning etc.

An old break or crack would have much more tell tale rust and also maybe some chatter or polished faces in crack area. I don't detect any from your pics.

For sure you are not responsible in my opinion.

 

[nh DRAGON]

While I am not an expert, but from experience I'd say that is a fresh break caused by serious stresses like wheel jammed between 2 rocks and forcing with power steering or some such forces, or hitting a curb while turning etc.

An old break or crack would have much more tell tale rust and also maybe some chatter or polished faces in crack area. I don't detect any from your pics.

For sure you are not responsible in my opinion.

Agreed, We all feel terrible when this type of thing happens but it does.
And no matter whether he was forcing it to see what it would do or just cruising the back nine, Still a fresh break and not your fault!

 

[Chilly807]

We see this kind of thing at work quite often, although it's more often rotating machinery in our case.

In my opinion, the upper portion of the taper wasn't in contact with the stud for quite a while, maybe from new. It was probably not a good angular match from the get-go.

The presence of old rust in that area means there was no contact metal-to-metal. A tapered fit requires 80-90 % contact for good working strength.

The only part of the hole that was providing support to the stud was the bottom 30%. When the housing finally broke, the stud was tough enough that the cast housing broke first, for the stud to break it would have had to pull apart which is unlikely in this application.

The darker area at the upper part of the knuckle may have been the beginning of the crack for a few months, it's hard to tell without metal analysis.

Great photo George ! We have techs at work that do only that and we often don't get such good quality !

Chilly

 

[gwdixon]

Chilly807: Thanks for taking the time to do such a detailed anaylsis. Your reply and the others on this thread is what makes TBN such a wonderfully helpful site.

I'd apply for a photography job at your work but Nova Scotia is a little too severe for us California wimps!

 

[taborekle]

Am I the only one that things that $1200 for a small tappered casting is outrageous. Wow.

 

[RickB]

Am I the only one that things that $1200 for a small tappered casting is outrageous. Wow.

It's the entire swivel housing less the hub cover and internals. Still plenty costly.

 

[Chilly807]

I suspect that is the out-the-door price, labour and taxes, etc. Still plenty expensive, I'd be pale for a couple days after that kind of bleeding..

You're welcome George, figuring out why things break is part of the fun of my job... You'd get used to the cold after a couple days, I hardly even notice anymore til it's -20C !

Chilly

 

[dfkrug]

The owner had it hauled to the local Kubota dealer today for a brand new casting.

Oh, too bad. A burnt L3350DT just came up on CraigsList yesterday in
San Jose.

 

[gwdixon]

Oh, too bad. A burnt L3350DT just came up on CraigsList yesterday in
San Jose.

I saw that burned L3350. How pitifully ugly. What a shame. Below is a low-res picture.

RickB is correct. The parts manual shows that the whole housing is cast in one unit including the attachment point.

The casting alone was $650. The replacement price OTD was negotiated down to $1100 for everything but now, since the thing is apart, the gaskets and seals will be replaced so it will come in just under $1300. Hope the dealer isn't pulling a fast one for a few bucks. However, I'd probably have the gaskets and seals done voluntarily if the tractor was still mine.

Oh, and my first name is Gary but you can call me George if you want.

 

[Willl]

Your not footing the bill for this are you ?