B6100 w/ Loader+Backhoe

Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
So i drilled the pin holes from a very 'wallered' 5/8" to 3/4 using a stepper bit so the 5/8-to-3/4 spacers would fit. Drilled the washers to 3/4" as well. You can see the drill and a flange-style vise grip with a washer in it on the ground there.
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Split the spacer/sleeve in two using the press as a vise, which i am prone to doing.
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Then put the sleeves in both sides of the arm with a 5/8" rod through the middle to fix the alignment.
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I left the sleeves standing a little proud of the washers so i could weld the two together without getting weld into the bore and having to clean that up. This was a weird idea in the first place, but my thinking was basically to weld straight through the thin washer to the thick metal below, going in a circle around the sleeve and just bumping the weld puddle over to the sleeve enough to melt into the sleeve without going through it and trying to weld to the pin. Sounds finicky? Cuz it was a dumb idea! But it worked, well enough for purpose i suppose. Of course the washer distorted slightly from heat so i pressed them down parallel and flat in the press or with a big c-clamp (cant remember) when i welded the washer edges down to the stabilizer arm. Then cut off the protruding sleeve and flap disced everything flat. Here's a pic of a 'finished' one (out of 4). You can kinda see what i was doing with the weld penetration into the sleeve but not through it, but its inconsistent from one side to the other. I dont remember if the others were better, this is the only pic like this.
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So WHY did i even do this?!

Well.. when looking at all the bent up parts originally and thinking about it, there was a lot of slack/clearance in all the parts. The way i saw it, if you think about bending metal you first go through the 'elastic' deformation range where you're just flexing it and it's going to bounce back, and if you go past that you get into the 'plastic' deformation range where it STAYS bent.

When all the parts had slack, the various parts were allowed to flex independently to some extent and could only rely on their own strength because for the most part the parts were not 'bracing' each other, so you only had to hit the 'plastic deformation' point of the weakest link, and then the whole assembly of parts would bend one after the other like dominoes.

On the other hand, if i removed all the clearance between the arms/brackets/pins and braced the arms and brackets, they would strengthen each other and while there would still be a weakest link, it would be at a much higher threshold. Plus, if the arms had 0 clearance inside their subframe brackets, they would not be allowed to 'rack' and come out of plane and bend the pins. The pins 'should' only fail in shear. That was the thought. And here's the pins that came out, for reference.. Every single one bent.
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So here's an arm sitting inside a bracket. Am i a good welder? Maybe not. But i might be as good as the guy that built this thing, and I THINK im improving it, so.. onwards!
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Not much lash left to take up! And a wider 'bearing' surface both on the pin surface and the bracket faces, then there had been.
 

Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
So, not having an unlimited assortment of large shims with which to shim out the clearance, my plan had always been to just get the bare parts close, and then close up the remaining clearance by tensioning the assembly with a bolt instead of a regular pin. As long as you are only flexing the metal in its 'elastic' range this is a perfectly normal repeatable tactic and, for example, is holding the steering knuckle to the lower ball joints on a lot of our cars, etc.

So i needed bolts. BIG bolts. Very particular bolts. And have yall ever noticed that big bolts, especially if you want them 'just so', are absurdly expensive!? So i decided to make them! Boy, what a learning experience..

So, ingredients. 5/8" rod, a 5/8-18 die (cheap on amazon), and some kind of nut to weld on the top as a head (i had a pile of those, mostly 5/8-11). I wanted the finer thread for finer adjustment. I already had the nuts of both sizes and some 5/8" rod.

So, measure for length, cut to length, weld a nut on one end, and cut threads onto the other end. Sounds easy, right? 😅

Ok, first step, weld nut onto end of bolt to form a bolt head. First thing is to get that square to the bolt, so i used a tight fitting 5/8" sleeve on the rod and slid it up to the nut until the nut was resting 'squarely' on it before i began the weld. Now the weld which i originally thought went fine turned out to be totally insufficient. My Yeswelder 205ds goes up to "205" amps on 240v so i just cranked it to 205a and went at it. I ASSUMED if i just pointed the gun straight into the nut and let it fill up with weld puddle that it would have good penetration to the nut as it filled up. That turned out not to be true. Of course, i couldn't find that out until i tried to tighten them, and i needed threads first so i had to make the threads before finding out the welding i had already done was not going to work.

Ok, making threads then.. First problem there was my die wouldn't start on the rod so i had to 'lathe' down and bevel the end before i could start the die. Not having a lathe I ended up doing this..
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Which is, put some oil on the bolt so that it would spin nicely inside the arm, use an impact as a drill to spin it, and use the tiny belt sander across the end to 'turn down' the thread area and bevel the end. There is a repair bushing sitting on there in the pic that i was using to check how far up i had 'lathed' it. 😂

Then, I dont have a die holder big enough for a 5/8-18 die, so back to the vise/press.
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Now how ok is it to squeeze something that is supposed to stay round, with something that could easily shatter it? I am very good at making up for a lack of proper equipment with sheer finesse. I've been feeling out the edges of how far you can push on things before they break for my entire life, so while i did pull this off, it's still dumb and i don't recommend it.

Ok, so now i got a bolt or two. You can see i did not weld the nut all the way to the top because by that point the nut was getting hot enough to lose shape, so these must be the 2nd and 3rd after i learned that.😂 Time to test?
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No pics, but when i would tighten the bolt on the tractor it pulled the welded nut right off the end. So what i figured out is i had to actually weld around the inside corners of the nut/rod interface to get good penetration into the nut. Sticking the weld tip into a 5/8" deep hole less than 5/8" across and going in a circle is kinda hard, and wouldn't even be possible with a gas nozzle in place, but i got it figured out and EVENTUALLY i had 4 very large homemade bolts that could take enough tension to do the job i needed done. 🥴
 
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
Another thing i did for the stabilizers was build bigger pads for them. The stock pads, if that's what these were, were too small in my opinion and both sank in too easily AND slid on the surface too easily with their radiused edges. I think the stock pads were about 7x4". I cut some 9x6" pieces of 6" channel, blew holes through them with the plasma cutter to match the hole locations on the stock pads, and bolted them on facing downward to hopefully both penetrate the surface better with the same weight, and not allow the tractor to slide forward and back on the ground so easily.

Unfortunately i do not have good pics of this, but i took snips out of other pics where they are visible (poorly). You can also see the finished bolts installed in the 2nd pic.
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Last thing i did that was stabilizer related was fix the cylinders. Both of them got rebuilt with new seals, had bulky cast fluid elbows replaced with compact 90 degree swivel fittings, and had their base end pin holes repaired.

One interesting thing about these cylinders is that they are basically the same that are used on the B219 front end loader on these tractors and use the same seals. The gland is retained by a snapring so they are very easy to get apart.

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Stabilizer cylinders on left, swing cylinders (single acting) on right. The rods on the stabilizer cylinders were pretty nicked up but they still weren't leaking profusely and the seals are cheap and easy to replace on these cylinders so i ignored the rod condition and kept going (which worked out fine).
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I believe the piston nut was about a 34mm. I had to use the press to push the rod out of the piston on both. So that was a slight added trickiness. Another slight trickiness to these is the wiper seal is a press fit which makes them a bit harder to get out. There's no way to strike it from the backside, so i had to cave it in from the side to both loosen it and get something to pry on to pop it out.
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After meticulous cleaning I drove the new seals back in with the press as well, although they can also be hammered in. I replaced the rest of the seals and the rod/piston/gland assembly was ready.

Then onto the cylinder body. One problem was that a cast elbow snapped while trying to unthread the hose from it. Much care with an extractor was able to deal with the cylinder end of it.
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The other side was stuck on the hose. I tried turning the hose out of it with an open end wrench, but it began to round the corners on the hose fitting. Usually my next step would be some V-jaw Knipex Cobras or this style of locking pliers:
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I don't recall why exactly i didn't do that but for some reason i ended up just using TWO open end wrenches IN THE PRESS (because im starting to think half of what i did to this tractor i did in the press) and then grabbed the broken elbow with a pipe wrench.
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
The last part of the stabilizer cylinder repairs was fixing the super sloppy base end holes which had been subjected to a lot of fore/aft swinging of the cylinder because the stabilizer arm itself was not strong enough to avoid flexing fore/aft and took the cylinder with it, wallerin' the base end pin hole all 'ta shit.
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So i wanted to fix that AND give a flat surface for me to tighten down onto with my custom bolts and some shims. These parts still have to articulate so all im doing is tightening to zero lash, not actually preloading and adding a bunch of friction.

So, decided to use repair bushings again. I made a mostly flat surface just holding the thing against my bench grinder and then drilled the hole out to 3/4" again.
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So, did that 4 times and welded em in with a pin holding them in alignment, stuck new grease fittings everywhere, and was finally done with the stabilizers.
 

Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
Ok, one month later, we continue a story that technically ended in March.

So the next thing i built onto the subframe is what i would call the 'swing base', the part that the arm mounts to which rotates on the subframe.

When i originally disassembled the swing base from the subframe i of course disassembled the digging arms off of it, which was pretty easy because they are light enough to be carried by hand on this tiny backhoe. I had to pound a couple of pins through with long punch/drift but in my mind that's to be expected and all the bad pin holes were getting fixed anyway.

The swing base has a 1.5" pin going through it from top to bottom and sits in some brass bushings mounted in an upper and lower plate. The lower plate is fixed ie welded to the subframe, while the upper plate is bolted. So, you remove the swingbase by unbolting the upper mount plate. It does use very large tapered nuts and seats (think lug nuts) to keep the plate located by more than just clamping force, but i suppose these may have had a habit of shifting around under use, as this top plate was also welded to the subframe in three places and when i removed it i could see that the holes in the subframe has been wallowed somewhat by plate movement in the past. I cut through the welds as well as i could without digging into the base material too much, then inserted a bottle jack between the upper and lower mount plates and pushed until i got the PING of the remaining weld splitting, and the upper plate popped loose. I was then able to lift the swing base out of the lower bushing. You can see a stack of shims there on the lower plate as well.
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Here's another shot showing the tapered bolt holes on the upper plate, and the welds i had to cut/pop. Can also see the deteriorated and missing 'swing bumpers' to either side of the lower mount plate, which i fixed/upgraded later.
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Can also tell by the look of that grease fitting how often this thing was getting greased in its recent life. The top bushing was so loose the pin was able to bang around and there were bits of the top edge of that bushing which had been broken/spalled off as if from impact. I imagine driving the tractor over bumpy ground at speed would have subjected those loose bushings to some serious banging around.

Anywho, here's the swing base when viewed from the tractor/subframe end.
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You can see that that upper mount plate for the swing cylinders is bent. Initially i took a quick and dirty approach to bend it most of the way back with a floor jack as seen below.
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I finished the bend more 'precisely' using some threaded rod, nuts, and washers. You gotta bend it slightly past where you want it so it will pop back to proper position and this gave me more fine control than the floor jack without requiring a porta power i didn't own (still dont, but i need one!!).
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
Time to push a bunch of bushings out. I found all the bushing dimensions in the manual which i found free online because this Kubota community is pretty great. They were all readily available and cheap on ebay. Anyway, i pushed the bushings out with a combination of a ball joint press (big fancy C clamp) and the shop press, and a bunch of adapters. One thing i have learned about presses is they are only as good as the adapters you can come up with, so i collect random bits that look like they may someday come in useful as press adapters, and that helped me here.
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So these i was able to push back in using the same adapter pretty easily. I then had to drill new holes through the bushings so that the grease fittings didn't lead to dead ends. I replaced all the grease fittings as i went so pulling the fittings and cleaning/tapping through the threads when necessary was par for the course. Unfortunately i was working late, past my brain's bedtime and managed to break a damn tap in one of these grease fitting holes (how!?) so i had to cut my losses there and just weld that hole shut on the outside and drill and tap a new hole next to it. 🤬 According to this pic this happened with the old bushings still in, whatever. Good thing i have multiple 1/4-28 taps... sigh..
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Lil Foot

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Lifetime Member

Equipment
1979 B7100DT Gear, Nissan Hanix N150-2 Excavator
May 19, 2011
7,281
2,233
113
Peoria, AZ
Wow, so much deja vu for me in thie thread.
Keep up the good work, and keep the updates coming.
 
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fried1765

Well-known member

Equipment
Kubota L48 TLB, Ford 1920 FEL, Ford 8N, SCAG Liberty Z, Gravely Pro.
Nov 14, 2019
6,543
4,142
113
Eastham, Ma
Time to push a bunch of bushings out. I found all the bushing dimensions in the manual which i found free online because this Kubota community is pretty great. They were all readily available and cheap on ebay. Anyway, i pushed the bushings out with a combination of a ball joint press (big fancy C clamp) and the shop press, and a bunch of adapters. One thing i have learned about presses is they are only as good as the adapters you can come up with, so i collect random bits that look like they may someday come in useful as press adapters, and that helped me here.
View attachment 109805 View attachment 109806
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So these i was able to push back in using the same adapter pretty easily. I then had to drill new holes through the bushings so that the grease fittings didn't lead to dead ends. I replaced all the grease fittings as i went so pulling the fittings and cleaning/tapping through the threads when necessary was par for the course. Unfortunately i was working late, past my brain's bedtime and managed to break a damn tap in one of these grease fitting holes (how!?) so i had to cut my losses there and just weld that hole shut on the outside and drill and tap a new hole next to it. 🤬 According to this pic this happened with the old bushings still in, whatever. Good thing i have multiple 1/4-28 taps... sigh..
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Fantastic chronological reporting!
 
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
I don't know if these bushing holes were tighter than what's typical to install said bushings into, but they all seemed to 'crush' enough that the pins wouldn't nicely fit through them, even considering that the pins themselves were all somewhat worn. I DID check for and grind back 'mushroomed' tops of pins, except for a moment i had with the swing cylinders which will be explained later..

So anyway, i used a brake cylinder hone for that. It didn't seem like a great match of tool to task but i wasn't going to use that brake hone for anything else anyway.
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Here are some pics of pressing the the top swing base bushing in and out. It seems i dont have pics of how i did the bottom, and i also can't remember.. Guessing i just hammered that one in since the lower mount plate could not be removed from the subframe (welded).
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Not sure where that top adapter piece came from but the bottom piece is definitely a brake caliper piston. Like i said, i collect 'press adapters'.
Install:
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In some of the pics above you can see the wear on the lower pivot pin of the swing base. Here's a pic of the wear on the pin and its bushing.
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It ALMOST wore through (which would have hugely accelerated damage to the top pin) but thankfully didn't and compared to what i started with, i was happy enough with the fit between worn pins and new bushings that i left the 1.5" pin alone. Restoring that surface to proper dimensions would have been beyond my DIY at-home abilities and as long as one didn't let the pin wear all the way through the bushings, keeping up with bushing replacements would not be all that difficult or frequent a process anyway. I suspect it will never happen with the amount of hours the hoe will get from here on out.
 

Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
The next two posts elaborate on what i mentioned in post #49 about the swing base brackets:

So the lower mount plate for the swing base is welded to the subframe of the backhoe. I didn't need to remove it to install the new bushing but i DID need to bend it back to its proper position. It had been bent downwards at some point, and although the bushings had worn 'to suit', with new bushings the swing base would not align with the bushing in the upper plate without misaligning the plate with its mounting holes. It's possible i could have gotten bolts through it and left it alone but it would have 'preloaded' the swing base bushings so hard in one direction that it surely would have worn through in a short time, so.. the lower mount needed to be bent back into alignment.

It did show signs (discoloration) that it had been heated with a torch across the middle to aid in bending it back to proper position, but.. it never DID make it back to proper position, probably because the backhoe wasn't disassembled during the repair attempt (ie taking the lazy / quick and dirty approach) and it needed to be bent more. Unfortunately, whenever that last bend was attempted, they had welded in a huge brace once they thought it was located properly. I had a thought that it may not have been welded on all that well, so i did take a couple of really good swings at it with the 4lb hand sledge to test that, but it turned out it really was attached quite well and i did not really feel like undoing that. So, i bent the lower mount plate 'in situ'. I had the subframe on the tractor, but braced the mount plate to the ground below, in the area just inboard of where i wanted the bend to occur. Then, if i remember correctly i put a 4x4 wood block across the end of it and went at it very scientifically with an EIGHT lb sledge (it takes a lot for me to admit that i can't do something with the 4lb'er, but this qualified) until it was correct-er. I judged that by the turning effort of the swing place when it was sitting in both bushings and the upper plate was clamped in proper position. Eventually my scientific method resulted in pretty good alignment and low turning effort, so i stopped there.

This is what i ended up with:
 
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
So the upper mount plate showed no signs of ever having bent or bent back. In my mind this is probably because the upper plate's bushing only locates/retains the swing base pin radially, but not vertically in the downward direction. Basically, it can just slip out the bottom of the bushing if the lower mount were to move enough. As far as retaining the pin vertically the most load it will ever have to take is lifting the back of the tractor off the ground, as you cant push down any harder with the hoe then you have weight to keep the tractor on the ground. On this tractor that is very little!!

As another layer of making the backhoe stronger by making the same input force have to act on more pieces of metal ie 'spreading the load', i wanted to make some minor effort to have the upper mount be able to resist the downward bending force on the lower mount when the backhoe is lifting or prying up dirt. So, i decided to add a form of 'thrust bearing'/retainer on the top of the swing base pin.

To do that, i had to install the swingbase and upper mount plate and determine how to get rid of the vertical lash or 'endplay' with shims between the lower pin and lower mount plate. If vertical play between the two mount plates, any force added by the swing base would not 'engage' the two mount plates simultaneously and you would only need enough force to bend one plate before the deformation started. The shims needed to go between the lower pin and plate (vs the upper) because almost all forces created by the hoe would be pulling the swing base against the lower mount, and the stack of shims, as long as there remained any grease between them, would act a bit like a bearing and slow the wear of either 'thrust' surface. That was my read, anyway. So i shimmed the bottom until the top plate bolted on over the top with very little slack or lash remaining.

Then, i flattened out the domed head of a carriage bolt with the bench grinder, and welded that to the top of the swing base pin as a stud.
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Then, i found another stack of 'shims' with a 1.5" center hole (again, mechanics who are also hoarders have advantages here) that would sit slightly 'proud' or above the top of the pin.
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Then, a much thicker washer to get the stack 'above' the head of the carriage bolt so i could tension onto it without dragging on the carriage bolt head, and a large washer over that with an appropriate center hole to tension this shimstack. It even had a little flared edge making it look fancy, as this was probably originally used over a bushing (in the same way as a shock absorber or strut rod on an older car would have such bushings and curved washers).
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Then, another washer (to clear the slight bit of square shank left standing on the carriage bolt) and a locknut to actually tension this with. It was sort of critical that this be a locking nut because its 'position holding' feature (whatever makes a locknut lock, basically) is independent of torque or clamp load, unlike a locking washer of some kind. I didn't want to actually squeeze this stack of shims very hard or make it the primary wear surface from downward digging forces on the swing base, i just wanted it to provide enough support that those forces would be SPLIT somwhat between the upper and lower mounting plates.


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Ultimately, the strength of the welds holding the carriage bolt to the top of the pin are far less than what it would take to bend the lower mounting plate in the first place.. but if that big shiny washer makes a plink noise and hits the ground it might still be useful telltale that the operator is about to bend the hoe again and should find a different way to do their work before that happens. Until then, it kinda looks nice and definitely deflects rain and dust/grit from falling onto the pin/bushing interface and migrating in to chew it up. It was a silly thing to do, but a fun thought exercise at least and i'll be interested to hear if it ever DOES snap off or not!
 
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
So in the last picture above you can see the swing cylinder 'links' hung in their bushings with simple 'hairpins' holding them together.

This was another part of the design that i didn't really like because if you think about the swing links as basically a piece of thick flat bar with pins at either end, you really need those pins to extend out BOTH sides of each end to have the force be centered. In that case it would be like a link of chain, and it would pull 'straight'. But in this case, on one end of the flat bar a pin extends out one side, and on the other end the pin acts on the other side of the flat bar, make it act a bit like a 'z'. If you can imagine pulling on the two ends of a Z as if you were stretching it vertically, it would have a tendency to try to 'unbend' the corners, and rotate the line in the middle. The flat bar and pins themselves are strong enough to resist bending, but what WOULD happen is that it would wear the pins/holes diagonally as the link tries to 'twist' itself out of its pinholes or off of its pins, etc.
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So, after i got the swingbase end of these links to fit into the new bushings nicely (had to hone the bushings) i also tried to address that tendency somewhat by giving those links some kind of up/down 'thrust' or endplay control that would mitigate them trying to pull of their hole or start wearing the bushings diagonally.

From the factory, there were large cotter pins holding the pins in, which were retained by the cotter pins being bolted down through the eyelet end of the cotter pin. But, those were not all in place, and what was still around didn't look great.
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In an attempt to add some thrust control, i switched the method of retainment to.. shaft collars. I welded shaft collars over the hole end of the swing link , which both 'fixed' the slop worn into the holes, and would allow me to tighten the collars over the pin while the assembly had a small amount of lash. I used shims between the swing base and swing links to bring the lash of the other end, where the swing cylinder connected, down to a comfortable level.

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Now, there are 1 piece and 2 piece shaft collars. 1pc collars need to flex to squeeze onto a shaft/pin, and 2 piece don't. If welding a 1pc shaft collar to something, it still has to be able to flex when you're done. The more weld you put between the shaft collar and the flange you are mounting it to (or mounting to it), the more you 'fix' the collar to that surface and prevent it from flexing to squeeze onto a shaft. With either 1pc or 2pc, you're limited to only welding on one side of it. It's probably not even recommended, but i did it anyway.

So on the swing base end of the links, shims and a shaft collar. On the swing cylinder end, shaft collars welded over the existing waller'd holes (which had to be welded while the whole thing was basically assembled because welding them in different positions over wallowed out holes would make the swing links different 'lengths' and result in the same problem i was trying to address). I also cut new 1" pins for the cylinder end and welded a large washer to the top of the pin so they could simply plop down on into place and then be tightened onto. I really liked how clean that ended up looking.

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Can't remember if i already mentioned it but i made the majority of the new 1" pins that i made, out of a ~24" long 1" pin i pulled out of a broken pallet jack. Here's driving out that pin with a piece of black pipe which i left in there to keep the thing 'rollable'. You can also see the main arm of the backhoe laying on the ground in the background.
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
Time to rebuild and the swing cylinders. These are single-acting cylinders, which means they are designed to either push or pull, but not both. These cylinders push, sohe base end of the cylinder gets fluid, but everything past the piston gets exposed to air. This CAN be a liability for the cylinder because that means the rod (and possibly part of the tube, depending on whether the application allows the cylinder to fully extend) NEVER gets coated in oil, unlike a double-acting cylinder. Since air has to be able to go in and out of the 'rod end' of the cylinder as it travels, with it can come moisture and in the worst case, other physical debris if that air passage is not 'filtered' or otherwise pretty tight.

In the case of these cylinders, there is no rod wiper seal at all, just a bushing in the gland. There is also a hole straight through the gland to let air in and out, but no filter over it, so any dust floating in the air could easily be sucked in along with the air, but probably not come back out because the cylinder walls are likely coated with either moisture from condensation, or oil residue from imperfect piston sealing.

So that's why single acting cylinders are more likely to be trashed than double acting, in my opinion. I rebuilt these and they worked but the design bothered me conceptually so i.. wrote 2 paragraphs complaining about it? Ok, sorry.:censored: One plus of having a single acting cylinder that only pushes is that rod condition doesn't really matter because the rod doesn't have to seal fluid.

The cylinders were easy to get apart because it was only a snapring retaining the gland. Gotta love that!
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I got seals for the pistons (just took them and local shop matched them up) and bushings for the glands (off ebay).
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Pressing bushings in and out was fine, but then i had a decent little goof. At this point i was already used to honing out these 1" bushings to fit them to their pins/shafts, but this time i overlooked something important.. The piston end of the rod was actually SLIGHTLY mushroomed. Of course, since its not like i took calipers to the rods at any point, let alone to that exact spot, the way i found this out was when i finally honed the bushings enough to get them onto the rod and then immediately after they slid on they felt.. loose?!
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No feeler gauge or micrometer readings but the fact that you can even see the dark ring of shadow in the clearance between bushing and rod gives you some idea. I can't remember if i noticed this during the first or second cylinder rebuild, so either one or both of those swing cylinders has a rather loose gland bushing, but i didnt have any more bushings and figured the clearance was probably not any worse than when i started, so i said 'oh well' and moved on.

The rod crosspin tubes on cylinders i rebuilt would generally just get cleaned out with round wire brush on a drill/impact, but if i remember correctly when i cleaned out the zerk fitting holes with a tap it raised some kind of snag on the inside, so i ended up running a little 1" flap disc through with a dremel.
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One of these cylinders also had an oddly worn-on npt swivel fitting on it, so where in most cases i was ADDING swivel fittings, this one had to be replaced from wear! Whatever originally caused this was not still occurring when i got the tractor, and i could find no metal-to-metal interference issue to fix, so.. it is a mystery. Just weird.
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I wanted to make SOME minor attempt to address the whole 'unfiltered filth ending up inside the cylinders' issue due to the air ports. I have read some people have tapped them for barb fittings and run filtered vent hoses to a higher location like a vehicle differential might have, but i took the lazier way out and simply put some 'accordion boots' or bellows boots over the ends of the cylinders. The ones i used would have come off of mcpherson struts on the front of cars. Yes i had some because i saved some. I have a 5gal bucket of random bellows boots. I've even thought of harvesting 'pin material' from the rods of used shocks are struts i would throw away (recycle), but turns out most shock rods are 1/2" which is not very useful, with only a small amount being 5/8", and most rods on mcpherson struts (which are way bigger than shock rods because they have to resist bending loads) turn out to be metric and not conveniently 19mm or 16mm which i could probably still use as 3/4" or 5/8" pins. So, hoarding fail on that idea, but accordion boots? Yes, i have some.
 
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
Well, on to the digging arms!

The digging arm assembly attaches to the swing base at two places: The main boom pins on at the bottom, and the rod end of the cylinder for the main boom attaches at the top. The top pin had originally been a bit of a B to get out but i pounded it out with help from a long punch/drift i made by cutting down an old 'rock bar' that had been bent, and of course the 4lb hand sledge. This pic is from the original teardown so it's very out of sequence with the prior posts, but i thought maybe someone else might need a big drift and cutting a rock bar might be a useful idea to them.

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That pin hole on the swingbase turned out to be fine because it has such a wide surface to spread the load over. I just cleaned it and used/made a new pin for that location.

On the bottom, the pin holes in the digging arm were indeed worn. I tried various different methods of repairing worn pin holes on this backhoe, and in this case i decided since there weren't any clearance issues i could just use a longer pin and weld shaft collars over the outside which would essentially restore the hole to tight. Only thing is, i used clamping collars in this location with a pinch bolt (vs a set screw) so the 'strength' of the collar is theoretically limited by the bolt snapping or stretching or stripping the threads. Because of that i decided to offset them over the existing worn hole so that the pin would touch one side of the existing hole in addition to the pinch clamp. I figured that when digging that generally the dipper arm or bucket hydraulics are trying to pull the main boom away from the tractor, so i put a pin through, pulled the main boom away from the tractor to make sure the pin was already hitting that side of the existing hole loose, and then welded the collars in that position. The main boom may have gotten 'longer' by like 1/16" in this process. I also installed shims to take up the side to side slack between the swingbase pin hole, and the 'yoke' of the main boom.

Upon using the hoe later i noticed that this pin seemed to be migrating slightly with use despite the clamp of the shaft collars, so i added a more positive retention method for both side to side and rotation. The main boom already had bolt holes where previously large cotter pins had been bolted through their eyelets to keep that pin from rotating or sliding out. You can see one of the bolts and the remnant of a broken-off cotter pin in the picture preceding this one, so you can see how bulletproof that idea is. I decided to make use of one of those existing holes by welding a flat bar onto the end of the pin extending off to one side, then welded a bolt to that that would slide through the existing bolt hole in the boom (I may have drilled out the threads). So now, a nut on the inside of the the main boom 'yoke' keeps the pin from drifting out on that side, the flat bar keeps the pin from drifting out the other side, and the bolt 'indexes' the pin to the boom so that it cannot rotate in use.
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Bad pic barely shows the flat bar welded to end of the pin. In this pic you can also see how the shaft collars on the swing links ended up looking, as well as the bellows boots i put on the swing cylinders.

So thats the first worn joint on the main boom repaired. The other pin holes where the base end of the boom cylinder and base end of the cylinder for the dipper arm didn't need to be repaired. However, the 'yoke' that the dipper arm pinned to was definitely worn out, as shown below. I elected to weld on set-screw style shaft collars as 'external bushings' here.
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I think i did try drilling all the way across from the setscrew hole to make it able to take a lynch pin, but i found out it is pretty easy to not go STRAIGHT across, so when i used these collars in other locations i just used the set screw to make a mark on the pin and then bumped the pin out the side a bit and drilled that to a good dimple so that the set screw could sink into the pin a little more.
 
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
Ok, on to the dipper arm. The dipper arm had.. big issues but starting from the main boom connection and moving outwards:

The main boom connection was fine because the dipper had the full width 'sleeve' while the main boom had the narrow 'yokes', so the main boom was the side that needed fixing there.

Then comes the pinholes where the dipper arm cylinder pinned to the dipper arm. I drilled those out and welded these weird bushings in.
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These ended up looking the worst of all the things i welded on the backhoe. I either don't have pics or i do but i won't post them, i dont even want to look for those to see which it is. I think one contributor to this is because when i originally didn't think i was going to pull the thing all the way apart and fix everything, this was one of the first repairs i attempted.. my welding got a lot better over the course of the time i spent on this thing.

The base end mounting holes for the bucket cylinder did not need repair.

Ok, the rest of the dipper arm is a whole exciting story! Down at the bucket end of the dipper arm there are two pin holes, one for the bucket itself, and one about 5" up from that for the bucket 'links'. The bucket pin had come out just fine, but the pin going through the other hole was THOROUGHLY seized in place inside the sleeve. No movement whatsoever with my 4lb hand sledge skills, but i was mushrooming the pin enough that i had to grind that back down and take the bucket links off so i could keep mushrooming the ends of the pin just beating the shit out of it. Which didn't work! I figured maybe i could use the ball joint press to push it out, that didn't work.. so off comes the dipper arm so i can stick it in a press. Which sounds funny because on almost any backhoe that would be pretty unwieldy but the dipper arm on this thing is basically the size of a baseball bat and doesn't weigh THAT much more.
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My little 20 ton harbor freight shop press didn't touch it..
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I ended up maxing out a 25 ton press on it, and at first i was hopeful because i would get a loud pop/ping of tiny movement, but repeatedly flipping it over and over and pushing it back and forth, banging the arm side to side to break it loose or move it rotationally, and eventually flexing the walls of the rectangular tube section back and forth like this: (_____( / )_____) so much that welds were cracking, i eventually decided i was going to cut off and rebuild the end of the dipper arm.
 
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Vigo

Well-known member

Equipment
B6100, B8200
Jan 9, 2022
595
339
63
San Antonio Texas
I was half tempted to rebuild the dipper arm to begin with because it didn't seem to share its 'pin pattern' or spacing with anything else, whereas the backhoe on my B8200 i had come to find out through comparing measurements was compatible with the BX series backhoe attachments as well as the northern tool towable hoe attachments which opened the door to a variety of pretty cool and affordable attachments such as the $159 ripper tooth i used on my backhoe which Northern Tool sold for their towable hoe. So i'd already had the temptation to change the dipper arm for that reason, but i needed a lot more justification than that to do it as a voluntary optional upgrade. But, once the seized pin in the dipper arm seemed like it was going to require me to get the whole end of the arm glowing red and id have to reweld all the welds i cracked maxing out a 25 ton press on it... well that was the justification i needed to take it on. :cautious:

First step was to determine what i was going to use as materials. I noticed that a 3x3" square tube was a reasonable facsimile for the bucket end of the dipper arm on my BL4520, and fit within the ears of the stock bucket (for the BL4520) with just the right amount of room to spare. The piece i had was 0.25" wall if i remember correctly, far thicker than the factory dipper arm of either backhoe, so i figured it was sufficient if not a little overweight for the job.
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That's the fairly hammered 16" bucket i got with my hoe. Anyway, time to figure out how much to cut out of the old dipper arm..
 
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tsp159

Member

Equipment
B7100D
Feb 8, 2023
94
48
18
Fort Bend Texas
I was half tempted to rebuild the dipper arm to begin with because it didn't seem to share its 'pin pattern' or spacing with anything else, whereas the backhoe on my B8200 i had come to find out through comparing measurements was compatible with the BX series backhoe attachments as well as the northern tool towable hoe attachments which opened the door to a variety of pretty cool and affordable attachments such as the $159 ripper tooth i used on my backhoe which Northern Tool sold for their towable hoe. So i'd already had the temptation to change the dipper arm for that reason, but i needed a lot more justification than that to do it as a voluntary optional upgrade. But, once the seized pin in the dipper arm seemed like it was going to require me to get the whole end of the arm glowing red and id have to reweld all the welds i cracked maxing out a 25 ton press on it... well that was the justification i needed to take it on. :cautious:

First step was to determine what i was going to use as materials. I noticed that a 3x3" square tube was a reasonable facsimile for the bucket end of the dipper arm on my BL4520, and fit within the ears of the stock bucket with just the right amount of room to spare. The piece i had was 0.25" wall if i remember correctly, far thicker than the factory dipper arm of either backhoe, so i figured it was sufficient if not a little overweight for the job.
View attachment 110670
That's the fairly hammered 16" bucket i got with my hoe. Anyway, time to figure out how much to cut out of the old dipper arm..
Oof, that bucket is rough! Considering how much re-engineering you've done already, making a new dipper arm should be almost trivial! Almost!
 
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