Kubota KX161-2 Boom Rebushing

[Beckbenj]

Hi All,

I've recently acquired a Kubota KX161-2 and looks as though the boom to dipper connection needs rebushed. Looking on Messick's, I'm not able to find a bushing for the part of the boom that receives the dipper (see attached image). Looking at the machine as well, it's tough to tell if there is a bushing at all. It almost appears that the boss is welded on and the connection is steel to steel.

Am I missing something here? If it is in fact a steel to steel connection, what are my repair options?

 

[Clguest]

Related bushing is number 060 in the arm. Pin is bolted so not rotating in the boom.

 

[Beckbenj]

So you're saying that bushing 060 goes in the boom end where the red arrow is pointing to?

The red arrow pointing to the boom bushing is where the pin has worn through.

 

[Clguest]

Bolt 020 holds the pin stationary wrt the boom BOSS. The bushings 060 are fitted in the arm as shown in the drawing. So, the pin is fixed, bolted through the boss, in the boom. Is it the boss which I believe you call 'bushing' that is wearing?

 

[Beckbenj]

You're correct, the boss on the boom opposite of bolt 020 is worn (oblonged). I don't believe there is a serviceable bushing for the boss itself, is that correct?

 

[Clguest]

Yes, no bushing there.

 

[Beckbenj]

In that case, what's the approach to repairing this? Is this a line bore and sleeve type fix?

 

[Clguest]

Great question; but IMO one that a needs to be addressed to someone who can be there to see the excavator, measure the amount of wear, consider the alternatives...bore and sleeve or filler weld and reborn to the original ID... then make his best judgment on what he finds and how he is equipped to resolve the issue.

It might too be determined that a simpler approach would meet the projected usage needs - just bore the boss on the RH side like the one on LH, bore the pin, and bolt the pin in from both sides.

Finally, the wear on the RH boss raises the question, what do the bushings (060) in the arm look like?

Do let us know how things proceed and the best to you on this issue!

 

[Beckbenj]

Having a lathe and welding equipment available to me, I think my first step is going to be making a sleeve to fill in the gap between the boss and the pin. I can temporarily install it and check the dipper stick for movement. If there is little movement, I don't see a need to tear down to inspect the 060 bushings. At that point, I could either weld in the sleeve to the face of the boss or use an industrial epoxy to permanently set it in place.

 

[Tags]

It sounds to me that if just one side of the boom pin boss is oblonged there’s a chance that at some point the keeper for the pin fell out and partially slid out of the other pin boss on the boom allowing the stick to twist in the boom, this possibly could have oblonged the pin boss. I think the correct way to fix it would be to line bore it. You could also probably weld up the oblonged part best you can and grind it back down with a carbide tip on a die grinder till the pin fits back snug. The good thing is the pin is stationary in the boom, all the wear should happen to the bushings in the stick.

 

[Beckbenj]

It sounds to me that if just one side of the boom pin boss is oblonged there’s a chance that at some point the keeper for the pin fell out and partially slid out of the other pin boss on the boom allowing the stick to twist in the boom, this possibly could have oblonged the pin boss. I think the correct way to fix it would be to line bore it. You could also probably weld up the oblonged part best you can and grind it back down with a carbide tip on a die grinder till the pin fits back snug. The good thing is the pin is stationary in the boom, all the wear should happen to the bushings in the stick.

I had the same thought, the keeper fell out and the pin rotated. I may have to fix another few bushing bores and have been considering a line boring setup anyhow.

Not sure if there are any reasonably priced line boring setups for a small / mid-sized excavator. Any experiences with the process and equipment used?