Kubota M62 TLB Pin Retaining Bolt Snapping / Loose Nylon Lock Nuts

[RedNeckGeek]

FWIW, the M62 here has racked up another 50 hours using the Lucas Xtra Heavy Duty grease with no snapped retaining bolts. I've gone through about five tubes of it now, between the FEL and the 'hoe.

Curious if you've pulled the pin that broken bolt runs through to see if there are any rough spots on it, Jen.

 

[rScotty]

This is all sort of confusing to me and makes me wonder what is different about our M59 and the later M62.
I am always behind on greasing... I frankly don't like the mess, but do try to grease at least once a year. Maybe up to three times if I do a lot of work. Certainly more often if I think it needs it. But every 10 hrs!! no... Most of our work is in very abrasive granite-based dirt and sand. Much of it actually in the water. Maybe that helps.

So far at 1000 hrs I haven't seen that problem. Visually all those bolts look good and the nylocks seem to be where they were 15 years ago. But given the good folks writing this thread, I'm going to pull some or all of those retaining bolts this week to see what is really going on. Will let you know. Be a good time to do my annual greasing too....

Oh, on that silly linch pin that holds the bucket thru-pin into place. They tend to come off. Several people have wrecked that joint when the retaining pin slid half sideways.
But if you are paying attention you will see the BH bucket becoming cocked sideways as that happens. I got lucky there.
Replace the linch pin with a double-nutted bolt or your favorite similar retainer. Our big JD310 backhoe does use a linch pin there, but has a special welded shield to protect it from accidentally being lost. Kubota used a linch pin there, but it is way undersize and they forgot to shield it against abrasion and loss.
rScotty

 

[RedNeckGeek]

I learned a hard lesson when I had to bore out and bush pivots on the FEL of my old L3240. The previous owner apparently didn't own a grease gun, and I wasn't much better at first. Several hundred hours later, and I could stick a pen knife blade between the pin and the boss. I've been pretty good about sticking to the 10 hour recommendation for both FEL and 'hoe pins on the M62. Grease is a LOT cheaper than paying someone with a mobile boring outfit to come and install new bushings.

Kubota LA724 Loader Bushing Repair Questions

I have a Kubota LA724 front end loader and after nearly 2000 hours (only 600 of those are mine) it has developed about 0.060" of wear on the ID of the top rear loader arm pivots. I haven't disassembled the parts yet and don't know what's going on with the inner bore, but the two outer bores are...

www.tractorbynet.com

 

[rScotty]

OK. As promised, I did go out and look at those retaining bolts on our M59 back hoe. Thus far just the BH; I haven't gone through the loader yet.
To summarize my previous post. It has a thousand hard but not abusive hours. I do NOT grease every ten hours, but do try to do so every Spring and will do so again in the Fall or even during Summer if I am using it a lot in the creek or tough digging. Our "soil" is very abrasive decomposed granite and sandy quartz with more rocks than loam. No clay at all. It's typical of the Rocky Mountains.

Here is what I found.... All of the pin retaining bolts and nylocks were properly loose. I agree with keeping them loose. I could wiggle them all with my fingers. The pivot joints themselves are still tight at 1000 hrs. The hoe hasn't yet begun to get sloppy as they all do eventually.

There was no grease in the outer bushings or in the bolt holes, because the pins are such a tight in those outer welden in bushed joints there is no way that grease could get there. By "tight" I mean that they appear to be an deliberate non-rotating interference fit. If so, that makes the bolts a safety back up just in case the pin begins to rotate.
I pulled a couple of the bolts, and sure enough they show none of the wear that I would expect if the pin had ever moved relative to the outer bushing.
Interestingly, if you blow up the second photo & look at the end of the pivot pin in the photo you can see several dozen deliberate even hammer impact marks that must have been from the original assembler. I didn't put those marks there, so I assume he was taking great care to to line up that bolt hole for the pin and welded bushing. That's nice quality work done by someone who cared to fine tune an interference fit. I wonder if the interference fit was done with a temperature differential to start?

Also there's a photo showing the operator's view of that same pivot. You can see that the grease is in the center section only. It only takes one stroke of the grease gun (pictured) to start pushing old grease out. Those clearances are tight! Two strokes just makes a mess.

The grease gun is as good a manual one as I could find. Not cheap, but easy to operate. I have another one like it with a different angled snout. And a third that is dedicated for the two or three pivots that I prefer to use moly grease on.

Most of my backhoe work is done at around 1100 to 1200 RPM. Will drop to 900 idle for delicate work or sometimes up to 1400 for long stretches of ditching if the dirt only has one foot or smaller rocks.
Power is the same regardless of RPM, and any more RPM than that just bangs the hoe around for no gain.
good luck to all,
rScotty

 

[Smokeydog]

OK. As promised, I did go out and look at those retaining bolts on our M59 back hoe. Thus far just the BH; I haven't gone through the loader yet.
To summarize my previous post. It has a thousand hard but not abusive hours. I do NOT grease every ten hours, but do try to do so every Spring and will do so again in the Fall or even during Summer if I am using it a lot in the creek or tough digging. Our "soil" is very abrasive decomposed granite and sandy quartz with more rocks than loam. No clay at all. It's typical of the Rocky Mountains.

Here is what I found.... All of the pin retaining bolts and nylocks were properly loose. I agree with keeping them loose. I could wiggle them all with my fingers. The pivot joints themselves are still tight at 1000 hrs. The hoe hasn't yet begun to get sloppy as they all do eventually.

There was no grease in the outer bushings or in the bolt holes, because the pins are such a tight in those outer welden in bushed joints there is no way that grease could get there. By "tight" I mean that they appear to be an deliberate non-rotating interference fit. If so, that makes the bolts a safety back up just in case the pin begins to rotate.
I pulled a couple of the bolts, and sure enough they show none of the wear that I would expect if the pin had ever moved relative to the outer bushing.
Interestingly, if you blow up the second photo & look at the end of the pivot pin in the photo you can see several dozen deliberate even hammer impact marks that must have been from the original assembler. I didn't put those marks there, so I assume he was taking great care to to line up that bolt hole for the pin and welded bushing. That's nice quality work done by someone who cared to fine tune an interference fit. I wonder if the interference fit was done with a temperature differential to start?

Also there's a photo showing the operator's view of that same pivot. You can see that the grease is in the center section only. It only takes one stroke of the grease gun (pictured) to start pushing old grease out. Those clearances are tight! Two strokes just makes a mess.

The grease gun is as good a manual one as I could find. Not cheap, but easy to operate. I have another one like it with a different angled snout. And a third that is dedicated for the two or three pivots that I prefer to use moly grease on.

Most of my backhoe work is done at around 1100 to 1200 RPM. Will drop to 900 idle for delicate work or sometimes up to 1400 for long stretches of ditching if the dirt only has one foot or smaller rocks.
Power is the same regardless of RPM, and any more RPM than that just bangs the hoe around for no gain.
good luck to all,
rScotty

Nice write up.
What brand of grease? EP rated?
Wonder if the M62 maintains the interference fit? Regardless the cross bolt should see little rotational torque unless there is a lack or lubrication, wrong lubricant or maybe improper fit of the pin and bushing or bushing grease channel?
I think when my current supply of grease needs replace going to try the Lucas extra heavy duty.

 

[rScotty]

Thanks. I see a lot of people using Lucas Heavy Duty red grease, but I've never looked into it. What can you tell me about it? Specs and chemistry compared to others?

For the past decade I have been using John Deere's TY6341 SD Polyurea grease. Good compatibility and it is resistant to age-hardening. That resistance to age-hardening is particularly important to a person like myself who is lazy about grease schedules. It's also good in the cold, doesn't stain too badly, and I like the color. JD publishes a lot of technical papers so you get one source for information. Before the SD Polyurea I used to use their HD Lithium base grease - TY24416. Franlly I didn't like it as well.

I've considered going to JD's full synthetic grease TY25744, but having such good performance with their standard polyurea base that I haven't done it. As far as I can see, for my use the only advantage to the full synthetic would be some temperature range and the non-staining. But Polyurea is pretty good, too.

Yes, all three of those JD greases are EP and NLGI #2 viscosity.

For Moly on the rotation platform of the BH and the front axle pivot I use Valveline's moly product from NAPA. It's commonly 5% whereas most others are 3% moly. No problems with compatibility because I only use it in a few places where low speed sliding friction is very high and I use nothing else there.

I bet the M62 still uses that interference fit. I can't see why they wouldn't and lots of reasons why they would. Agree that you don't want ANY rotational force on that retaining cross bolt. As I see it, it is simply there as a safety feature. If I start to see rotation there, it will be time to figure out why. I haven't done the calculations, but doubt that diameter cross bolt can stand up to the full shearing forces if that main pin hangs up in the center portion and tries to rotate in the outer bushings.
BTW, all those cross bolts on the BH are recessed head type with a stamped "7" - which is probably alloy hardness.
Japan is a huge producer of top grade alloy steels, so I tend to trust their certification.
rScotty

 

[RedNeckGeek]

Thanks. I see a lot of people using Lucas Heavy Duty red grease, but I've never looked into it. What can you tell me about it? Specs and chemistry compared to others?

For the past decade I have been using John Deere's TY6341 SD Polyurea grease. Good compatibility and it is resistant to age-hardening. That resistance to age-hardening is particularly important to a person like myself who is lazy about grease schedules. It's also good in the cold, doesn't stain too badly, and I like the color. JD publishes a lot of technical papers so you get one source for information. Before the SD Polyurea I used to use their HD Lithium base grease - TY24416. Franlly I didn't like it as well.

The description and specs of the Lucas XtraHeavy Grease read very much like the JD TY6341. JD doesn't make their own grease, and the Lucas stuff is also green. Put two and two together and you're probably already using Lucas grease.

I've been using it the past 50 or so hours on the M62 and have had no issues. No runout even in 110F + temperatures, no grabbing retaining pins. That said, after reading up on the Lucas Mining Machine moly grease, I'll be switching to it for the pins on the backhoe and loader. $.02...

 

[Smokeydog]

The Lucas extra heavy duty is polyurea EP grease (green) and is probably better the red grease I’m using now. Don’t go thru as much anymore but try to do the best with maintenance. I do use the 3% moly TSC grease most of the time on pins but It didn’t want to pump this past winter so will switch to a higher % and brand.

 

[rScotty]

On changing to moly.... I'm sure you know this, but most moly greases use a lithium soap based thickener & so they may not be compatible with those polyurea greases you and I currently use. Worst case is you may have to clean the pins & bushings or I guess you could just plan to pump a lot of grease very often for awhile to flush them completely. It sounds like you do that anyway.

I agree that both the Lucas XtraHD grease and John Deere TY6341 are very similar - and both use a polyurea based thickener... and both are green. I'm surprised that the JD TY6341 can sit in a joint for a couple of years or more and still seem like fresh grease when I take that joint apart. Old fashioned greases never lasted so long.

Now having said that, I don't know for sure that I have ever run into the classic compatibility problem we read about in lube literature in the last 20/30 years... Although maybe I did and just didn't realize it. Supposedly if there is a compatibility problem the thickeners will expel their oil load and then react to make a hard clay-like cake that will clog the grease passages. I know I have seen that hard cake in joints when I rebuilt old machinery, but never knew why. Or it may have just been old dry grease...
rScotty