Torn up LA723 - and the repair

[BobinNM]

Hey guys,

I have been lurking around the board since we got our L3830 HST back in March of 2010. I really appreciate all the knowledge and expertise here, Quite a resource, Now its my turn to contribute.

The L3830 has been a good tractor; we got it from craigslist locally. It was a good price and we always wondered why... until now.

Apparently, the PO made a repair to the loader that he did not clue us in to. When we bought the Kubota the front of the loader was a bit singed, like it was used to push in embers in a fire, which is common around here when clearcutting land. Anyway, didn't think much of it. The 3830 had 360 hrs when we got it, I did the major at 400 and now its close to 450. I had always greased the links on the loader but hadn't noticed any issue. No big deals...

Then the other weekend, the bucket just plain cocked funny any nearly fell of the loader. The lower pins on the QA had pulled clean out of the the loader arm on the left and the bushing had broken the weld and was rotating free on the right! Now it makes sense. The burns were discoloring due to welding!

Searched and searched and seems no one has ever had this issue before. What kind of abuse could have caused this damage? The repair was obviously performed very poorly on close inspection.

Anyway, this post shows the damage and my progress on the repair, just in case someone else has the same issue. One request for help though, could some with an LA723 please measure the center-to-center distance on the pins that go throught the loader arms and let me know the distance in mm's? My pins were too tore up to get an accurate measure and I need that spec for the repair.

I will carry this post forward with some pics on progress, first, the damage....

 

[BobinNM]

So, the loader arms are 5mm steel. I used 1/4" to build the new ends from and machined new heftier mounts out of 4140. Oh, got new pins too from Coleman and Messicks. Lots and lots of measurements....

 

[BobinNM]

More pics of the repair. The machined mount is 78mm long, 2" dia., much more substantial than the original. I do not understand why Kubota left so little meat at the end of the arm. I checked interference on the linkage and the bump stop is the limiting dimension at 2" radius from the center of the pin.

 

[BobinNM]

Tonight's work... almost ready for final welding

 

[birddogger]

Clearly you have the correct tools to put it back right.
I had to weld up a new mower-hanger bracket, but no where near that level of fabrication.

 

[BobinNM]

Thanks for the compliment - this is a first-time project for me.

Still would appreciate if someone out there could take a quick measurement on the pin C-C distance. I'd like to get her welded up tonight. Anybody out there with an LA 723? Thanks - Bob

 

[birddogger]

- this is a first-time project for me.

Ah, beginners luck!

If I understand the measurement you need wouldn't it be better, after wear, bending and deformation, to get that off the bucket? Measure the inside/outside of the gudgeons on the scoop and make it fit.

 

[BobinNM]

That was my thought too, I've kinda been estimating and shooting for the nearest metric, which has worked surprisingly well thus far. Looks like 195mm C-C to me.

With all the slop in the balance of the bucket lnks, it won't make much of a difference. In fact, I was thinking about rebushing the balance of the links and tightening the whole thing up. But then again, it's a loader bucket not an engine. As long as it doesn't bind I'm good and this repair is light years ahead of where it was before.

I still don't understand why there is so little "meat" surrounding this portion of the arm, though. Just doesn't make sense when everything else is so well made on the kubota. I know someone will say its cost; 1lb of steel = $. etc.

 

[Lil Foot]

Nice repair work! Looking forward to seeing pics when it's complete!
Nice lathe, Too!

But I fail to understand what the PO did to produce such damage.

 

[birddogger]

I still don't understand why there is so little "meat" surrounding this portion of the arm,

?dunno? But in picture #1 it seems you can see light between the bushing and the hole in the arm; that one was stretching on the way to letting go like the other arm. If I remember my meager bit of metallurgy; once you exceed the modulus of elasticity that's it, the tensile strength is gone.

They must have been jerk lifting some boulders.

 

[BobinNM]

Because of the way the metal is pulled out at the end (it split toward the front of the tractor first and then apppears to have spread, right at the narrowest portion of the profile) it looks as if it was stressed in tension. Almost as if the tractor was used to pull from the bucket in reverse. I have seen this done when pulling out brush and bushes. Chain up to the offending shrubbery and back the tractor up. Still, you'd really have to abuse the heck out of the thing... like trying to pull down big trees or something.

Birddogger is correct in his assesment on the right side too, the entire bushing was spinning in the arm. Somebody had to be abusing this bucket.

I have pics from when I picked up the tractor and you can see the singe marks from the welding on the arms. I can't believe I missed it. Live and learn. Guess I was just excited about buying a new (to me) tractor.

Regardless, we did get a good deal, the tractor will soon be fixed better than new for about $50 and my time, and I reeeeaaaallly like the Kubota.... almost as much as my Cat D4!

 

[BobinNM]

On reflection, rather than the original C-C measurement, the more critical issue is the alignment of the stop block on the QA/Bucket pivot as shown. Any thoughts?

 

[BobinNM]

More like this...

 

[bcbull378]

Looks like your doing a great repair job I have a L3830 also great tractor but I know what you mean by likeing it almost as much as you cat D4 .Here are a few old cats on our ranch. D2 5U series, D4 5U series and a D6 9U series

 

[birddogger]

Looking agin at your pictures, there are no peaning marks on those stopper blocks. The cylinders must be bottoming out before the bucket tilts that far forward. I'd forget about it.

 

[BobinNM]

Thanks everyone for chiming in on this. I appreciate all the comments.

Nice dozers - glad to see I'm not the only one with the "equipment disease." Anyone else a member of ACMOC as well?
By the way, I discovered you can do a whole lot more unintentional damage much more quickly with a dozer than you can with a Kubota. I'll be replacing some fence this spring.

Birddogger, you are again exactly correct, there is no peening on the stop. But the paint clearly is worn on the frontside of the stop face indicating the contact, so I'd have to say the geometry is working well, probably exactly as designed, keeping the cylinder from bottoming too forcefully. I will do my best to keep it as close to factory dimensions as possible.

I have been busy at work so not much more progress this week. I'm going to try and finish up this weekend. Will take pics of the final process. I need my loader back to spread some gravel in the drive before the next snow.

Hopefully at some point this thread will help someone else needing to make the same repair. I was never able to find anything of this nature in my searches online. - Bob

 

[skeets]

Dayum.... I would like to get him and Wildfire together on a project

 

[BobinNM]

Skeets... Washington PA? I'm originally from Altoona many years ago. Still have family there.

Don't be too impressed. Just takes patience and planning.

Cheers - Bob

 

[BobinNM]

OK - I was sidetracked for a while but have made a bit of progress on the repair. Got everything fitted welded up and in primer now. Wish my welding was better, more like Wildfire's. Why is it your best welding always occurs at the END of the project?

 

[BobinNM]

More pics