JD 120 general rebuild thread, bushings, pins, CWS thumb wedge QC bushings, hoses

[Keith Merrell]

Is that 6000lbs on the hitch with the machine all the way forward? Or is that all you want / need to put on the truck?

 

[skyking1]

I put 6 on the hitch to keep the trailer axles at 34. I am forward but not all the way by any means. it is a position I figured out at a scale near my house, about 15 years ago. It has not failed me, I have never been waved in at the scales.
I was able to unchain the machine and fine tune it at a state scale that was recently closed on the Mountain Highway.

 

[skyking1]

Boom is shakalaka. I was able to pull the pin with the mini and no hammering.

 

[skyking1]

Now I'm left with the question of how much play is too much? I know there has to be some assembly clearance. I don't have a dial indicator here or bore gauges but I can get the bore gauge. The hole is pretty concentric when I get it balanced in the center of it it moves front and back about the same amount as up and down.

One of the boom bushings has a crack. I was told that's a bad sign as far as keeping that bore. The other side does not have a crack.

 

[skyking1]

There is a company in California selling a slewing bearing for 2500 plus freight on Ebay. Time to run that by the boss. The machine is relatively fast for it's age, if not for the crappy slops.
I'd have to tool up to get those inside bolts out, I bet they require a torque multiplier or something.

 

[Gary Layton]

You're not talking to yourself...cool thread but I'm like a dog watching TV for some of it. I like your input and pictures and am learning from it. I have a Takeuchi TB370, only about 150 hrs so far...excavator newb...but what you are doing is teaching me stuff. Thanks for taking the time to share.

 

[John C.]

The crack is likely from the pounding on the worn spot. The give away on needing a weld and bore there is how tight the old bushings are in the boom bore. If you can't move them with a punch and eight pound hammer, the bores are good. I've usually taken them out with a carbon arc.

 

[skyking1]

Today's mission it to get the bore gauges and micrometers together. I was thinking just give those bushings a few licks with an oxyacetylene torch to weaken them up. Will that suffice?
There is a spacer in the end of the boom between the bushings, so I expect them to be tight to the spacer.

 

[John C.]

It’s a land in the boom itself. That’s why I used the carbon arc. You can just pull bushing material and barely scuff to the boom material all the way to the land. You can also try welding rings in the bushing and hope it shrinks it enough to loosen them.

 

[skyking1]

This boom end does have a spacer, floating in a sea of old grease. I had quite the dumpster fire going getting that first bushing torched out. With one out I could pull the spacer and scoop out pounds of old cooked grease.

The mobile machinist stopped by and looked it all over. amd we made a plan. The carbody cylinder bosses are around .030 play, and a relatively expensive and time consuming setup. We are going to heat those bosses with a rosebud and shrink them as much as possible and run with that.
The boom pin bosses are more like .060 so that bore will get welded up and line bored. I pulled the tool box out of the way, but the fuel tank can stay.


The top pin bore in the middle of the boom was really hammered out. I did not get that pin in advance, but the shop will make a new one for us. He will line bore that one and I do have the top and bottom cylinder bushings on hand.

 

[skyking1]

he had to grind a little on the tank to get the line boring equipment on.


I cut a couple of troughs in each bushing, but not clear through. That took all the fight out of them.


All done and test fit, and johnny yellow.

 

[skyking1]

I am working on getting a new Rotec or slewing bearing, and talking through the job. I need to crib up the house SAFELY and pull the carbody assembly out from under it.
I was scratching my head about how to block it up, and then I remembered I took this picture the other day to illustrate the clearance at the loading dock that I made with those huge blocks.
DoH!
I can crib to one of those and it is truly not going anywhere. 6200 pounds of concrete. Just a couple of 4x6 blocks on top.

 

[skyking1]

The boom cylinder top bore is welded and line bored, a new pin fitted, and the boom is back on the machine. Now I wait on the cylinder repair.

 

[Don.S]

We just rebuilt our 135d this winter doing every pin a bushing and build a hydraulic quick attach and paint. In the fall i was working in our pit and had the boom cylinder smash out the side window so the boss decided it was time. We had to lift the cab to do those bushings. My boss had a machine shop before he got into excavation so we did everything in house. Great size machine and runs like a top with 11000 hours on it.

 

[skyking1]

We decided to leave those lower bores at about .040 slop on a new pin, because it was at least $2000 for that setup. I'd have to cut out that portion of the carbody that the toolbox sits on to give clearance for the machine. With everything else new I can live with that.
That was quite a failure to break the glass, I am wondering what gave way?
I'd need a new trailer to haul a 135D, so we will keep this 120 going. The other thing is, a new machine means emissions and that hit on reliability on a machine that does not get too much use.
All my buckets are the CWS wedge fit. I'd love a hydraulic coupler.

 

[Dakota_56]

Thanks for sharing your experience on the rebuild, very interesting and useful information.

 

[skyking1]

you're welcome.
The machinist has a fancy 8000 pound crane on his truck, and we picked up the end of the boom at that upper pin. I gave a guess of 2500~3000 pounds at that point, and his remote readout was 2470. Pretty close for a WAG
I was really glad to pay him for the help getting that pin in. The tolerance is now 0.005, and we spent a lot of time tracking and swinging the house, I took a burke bar and a steel wedge to the bucket to roll the boom slightly and it went most of the way in by hand.
The original tolerance at that bore was probably 0.015 according to him.

 

[kenworth]

Great rebuild project!
That machine is definitely worth the time and money spent to freshen it up.
The JD120c is one of the best machine that Deere ever made.
Too bad they still don't make them anymore, no emissions and minimal electronics.
Keep us posted on the rest of the project.

 

[brianbulldozer]

Nice work. Hopefully the guy that replaces you after you retire doesn’t have any success at convincing the boss to trade it in for a new machine, after all the effort and expense that went into it.

 

[skyking1]

There's no way, the boss is balking at these parts prices lol!