M62 Boom Swing Bushing

[AaronM]

My M62 upper backhoe swing bushing has never really taken grease like it should. I only have 50 hours on it and very little backhoe use so far. I could eventually force a very tiny bit of grease out of that area but I knew something was not right.

The swing movement made a little groaning sound the last time I used it so I finally investigated a little more. I found the grease was actually coming out around the outside of the bushing between the casting and the bushing. The pin itself is bone dry. I did a little more investigating and the threaded grease zerk hole is completely blocked by the bushing. Im thinking the factory maybe installed the bushing upside down or something? The bottom bushing has a nice groove across the grease zerk hole to get the grease to the pin but the top is solid and completely closed off.

My initial thought was I could drive the pin up enough to clear that area and drill a small hole through the bushing (hoping it was brass) but the bushing was harder than my drill bit and I decided to just call the dealer since it is still under warranty.

Well... it has rained almost every week and I made the bad decision to leave my trailer down by the river where I won't be able to get to it for at least a couple weeks after the rain stops (more rain still in the forecast). Plus the dealer said they are at least 2 weeks behind on service work once I finally get it there.

Im getting behind on some backhoe projects and really need to use the backhoe now.

Has anyone ever replaced those bushings themselves? Should I just run it dry and plan on having the dealer just replace the pin & bushing if it gets damaged? Is pulling the pin & rubbing some grease on it worth the time?

Any suggestions would be welcome.

Thanks!
Aaron

 

[mikester]

My M59 BH had that problem...Dealer fixed it under warranty - the pin/bushing didnt have a hole for the grease to flow through.

If its a new machine tell the dealer to fix it. I would be interested in finding out if you have the same problem, keep us posted.

 

[rScotty]

My M59 BH had that problem...Dealer fixed it under warranty - the pin/bushing didnt have a hole for the grease to flow through.

If its a new machine tell the dealer to fix it. I would be interested in finding out if you have the same problem, keep us posted.

Our M59 backhoe swing bushing squawked and groaned when it was new. I never did look at the bushing itself to see if it was lined up properly or had the proper grooves cut into it. I just assumed that the part was made correctly - although now that I think about it, I've seen plenty of bushings in equipment that didn't have a proper grease path between zerk and pin. I need to take another look at outs...

In fact, I've seen this grease path problem on any number of machines and dating back at least 50 years. I just had to fix that very same bushing problem on some of my JD310 TLB loader arm bushings. About half of the loader arm bushings came from the factory wrong.

Apparently a couple of generations of US, German, Brit, and Japanese engineers haven't been able to figure out how or why to machine grease grooves into bushings - a problem that wouldn't confuse most sixth graders.
Maybe now we'll see if the Chinese can figure it out.

On our M59 I cured the squawking by switching to a high moly grease. That made the noise stop immediately, whereas no amount of normal grease made a difference. It might have been that that moly grease - which is very runny stuff - somehow crept into the pin-to-bushing interface. Whatever happened, the noise went away immediately. For BH swing spindles ONLY, I use Valvoline Palladium 3% moly - which is a higher percent moly than most moly greases. This makes for a terrible messy nasty black grease that sticks and stains everything it touches. I keep it in a special grease gun in it's own bucket - and I don't use the vile stuff anywhere else but the backhoe spindle bushings.

If yours really doesn't have a proper grease path, a short term fix might be to drip a penetrating oil laced with moly disulphide (i.e. moly spindle oil) onto the bushing and pin - this does work on vertical pins, and is exactly what spindle oil was made to do. Most machine shops have some.

I've never tried drilling a bushing through the zerk hole, but the problem is common enough that someone probably has made a special bit to do just that. I envision a 1/16" four-flute carbide milling bit inside of sleeve that has an OD that matches the zerk hole. More simply, there are good cobalt drill bits that cut right through hardened steel. The drilling trick is to go slow, good support, and lube. You could even order a bushing to practice on.

Since the manufacturer and the dealer both got it wrong, why would you be sending it back to them instead of just fixing it properly yourself???
rScotty

 

[Jchonline]

I’m going to check mine next week. Thanks for the question and great answers!

 

[rScotty]

I’m going to check mine next week. Thanks for the question and great answers!

Did yours ever moan when swinging? Mine did, and the moly lube cured it right then. It didn't occur to me that the bushing might be defective - I'll check mine this weekend too. BTW, NAPA carries Valvoline Palladium grease & others.
Like I said, moly is messy so I use it in only for those two swing bushings on the hoe & keep it in a separate grease gun.
rScotty

 

[Hersheyfarm]

I will say that the swing bushings on both my m59 and m62 were/are the hardest to get grease in.

 

[rScotty]

I will say that the swing bushings on both my m59 and m62 were/are the hardest to get grease
in.

I went out and looked at our M59 this morning, cleaned the swing pivots (ugh), and pumped some moly grease in. It is easy to pump the grease in and easy to see it emerge at the top and bottom of the bushing area.

But I realized that I have no way to tell if the grease is getting between bushing and pin, or coming out between bushing and casting. However.... I am going to make the reasonable assumption that if the pumping is easy that the grease is going in the proper place - which is between the bushing and pin.

That is because I am also assuming that the fit between the swing casting and the bushing will always be a very tight press fit.
At least that's has been the case on every single other bushing-to-casting fit that I've ever seen - regardless if it is engine, axles, steering, or backhoe.

So to repeat: The test is::
If we can accept that a bushing will always fit tightly in it's casting, the only way the grease would pump easily is if the path between pin and bushing was properly open.

I think that is a valid test, and thanks to Hersheyfarm's comment that got me thinking about how to test this grease path.
Do the rest agree with this??

rSCOTTY

BTW, there is one other thing that will block a grease path, and that is that incompatability between certain grease chemistry in older greases would sometimes cause the grease to harden where the greases mixed. Specifically - if my memory was right - this would happen when a lithium based grease encountered an old style polyurea base grease.
I've seen the resulting hard grease plug and it's real. But the result is not a terribly hard substance, and that hardened grease plug can usually be forced out with more pressure, and sometimes a little heat. When the hardened plug is forcedout, then grease again pumps normally.

Modern greases - made within the last decade or so - have mostly addressed this grease chemistry problem with the "stabilized polyurea grease". Also, some grease vendors like John Deere have developed a line of greases that are compatible regardless of the grease base chemistry.

Hmmm....There was on old grease technology using bentonite based (clay-based) greases that also had a hardening problem.....but that was for a different reason. I don't think anyone makes those types of clay-based grease gun tubes anymore. Anyway, use modern grease & be aware of chemistry.
rScotty

 

[AaronM]

I think if it takes grease easily then the grease is probably going through the correct path. All of my other bushings take grease easily. The top bushing was so hard I had to max out my 10,000 psi grease gun and let it set for several minutes before I could get another pump.

One other thing I thought was interesting is that both swing bushing grease zerk holes were 1/2 full of what looked like small bird shot pellets. Maybe a little bigger than a ball point pen tip. I blew out the grease holes with de-greaser & compressed air so I could see the bushing and the bottom half of the holes were blocked with a lumpy, Kubota gray paint covered mound. I poked a wire into the mound and all of these little balls rolled out of the hole. Nice and round and all uniform size. Weird. It looked like maybe from some kind of media blasting process that didn't get cleaned out before going to paint? Apparently quality control was out to lunch when my boom swing assembly was built.

 

[Hersheyfarm]

I will say that I do believe grease is going through. I think they use the tightest tolerances on these because just a little slop there translates to a lot of slop at the end.