B670 Backhoe Rebuild

morson82 · Sep 13, 2011

Does anyone have a working knowledge of the older B670 (KUW200) backhoes that were made for the older B6100 Kubota tractors. I am trying to rebuild one and have found that the area that the bottom pin of the swing weldment goes into is worn out and out of round. The raised round piece of metal that is welded at this location is completely shot. The repair manual calls for a "ball joint" at this location but does not go into specifics about how it goes on. If one is supposed to be there, its not on mine. I am going to have to cut off the raised ring where the pin goes in and find a piece of pipe that is similiar in OD and ID and weld that on. The part number for the ball joint is 70020-00784 but I have not confirmed the part is still available. I have attached the address of a site that has the manual for this backhoe. If anyone has worked on this type of backhoe or even better, has this type of backhoe and can get me pics that would be great. Any suggestions on how to go about repairing this would be greatly appreciated. I have just finished rebuilding both swing cylinders and cannot put them back until I resolve this issue. Thanks, Glenn

www.kubotabooks.com/AutoIndex/index.php?dir=Backhoes/&file...

Lil Foot · Sep 13, 2011

Re: Backhoe rebuild

Previous owner neglect is hell. I had planned to post on this after I completed the rebuild, but this now seems like a great time to dive in.
I am in the process of rebuilding that exact backhoe right now. The damage you describe sounds almost identical to mine. The upper & lower pins of the swing weldment are supposed to pivot in bronze bearings that are pressed into the removable top plate & the fixed bottom plate. The top bearing in mine was almost gone, but no damage had ocurred to the steel pin or bearing pocket, so it was just a matter of machining a new replacement bearing.
The bottom, however was a different story.... the bearing was gone completely, and the pin was worn about 1/8", and the bearing pocket was worn about 1/4". I remachined the pin, reducing it's diameter until it cleaned up, then bored the bearing pocket oversize to cleanup, made & pressed in a DOM steel sleeve, and then machined a new bronze bearing. I am currently waiting to finish bore the lower bearing to suit the new lower pin size, but other projects have relegated this to a lower priority for now.
In addition, the top plate on mine was left loose for many years, and wallowed out the mounting holes horribly. I had to weld extra material around them (a couple had almost broke thru the sidewall of the plate) and I will ream the holes for oversize bolts after aligning everything with the new bearing & pin surfaces. I will probably add a couple of press fit hardened pins to aid in keeping the top plate aligned.
Some pics of the process:

Lil Foot · Sep 13, 2011

Re: Backhoe rebuild

More pics:

Lil Foot · Sep 13, 2011

Re: Backhoe rebuild

And still more:

Lil Foot · Sep 13, 2011

Re: Backhoe rebuild

I'm not sure about the "ball joint" you mention; my B670 (KUW200) manual shows two bronze bearings (upper & lower) and even gives their original sizes.
No mention of a ball joint, nor would one be necessary or desireable in this location, as far as I can see.
Once my repair is complete, with the top plate tight and the bearings regularily greased, I see no reason to ever have to go thru this again.

If there are any questions on what the pics show, sing out and I'll try to clarify.

Lil Foot · Sep 13, 2011

Re: Backhoe rebuild

Correction: I found the "ball joint"..... it appears to be the lower bearing grease fitting (zerk).

That is the only possible part in that location.

The bronze pivot bearings are #32, part number 70020-00776.

morson82 · Sep 15, 2011

Re: Backhoe rebuild

Well, looks like you are in the same position as me, however, I dont not have access to nor know how to use a milling machine (lol) Looks like your doing some great work there! I am looking to cut off the bottom bearing socket and replace it with another. I am in contact with the manufactor of the backhoe, now called Ameriquip, and am trying to get the necessary specs for the replacement. As a result of the "owner neglect" both swing arm cylinder pistions were bent and gouged and I just finished rebuilding them. The "removable" top plate on my backhoe had the bolts welded into place so I will have to cut those as well.....guess I wont be getting to those projects any time soon.........Here are some pics of what I am up against on mine.....I will keep you updated on my progress.

Glenn

,

Lil Foot · Sep 15, 2011

Re: Backhoe rebuild

Looks like your doing some great work there!

Thanks! I guess there are some advantages to being a toolmaker after 36+ years in the field.

Yup, the bearing/pin problem looks nearly identical, maybe yours looks a little worse. I see no evidence of the grease fitting on that lower bearing pocket.... I assume it broke off or fell out long ago, and that lack of lube plus neglect created the problem in the first place.

What does the top bearing/pin look like? Is any of the bronze bearing still left?
If there is no (or very little) damage to the steel, it was a standard size bronze bearing. (1.750 OD X 1.500 ID X 1" long) Rather than buy new, I made a new one because I can get a better fit custom sizeing it myself, and I had to make the lower one anyway.

I have rebuilt some of the cylnders, and have the kits ready to do the rest when I get time, but the only one with real any damage besides leaking seals was one of the stabilizer rams. It appeared that someone took a large cold chisel & cut out a couple of big chunks, and also filed a couple of deep gouges in the ram.

It definately was not rock damage, as is somewhat common with stabilizer jacks. Who knows what that was about. Anyway, I had it rechromed & ground, and now it's better than new. (not cheap)

Ameriquip was not able to help me with my questions, except they were the only people on the planet who knew that a KUW200 backhoe was a B670 backhoe, and they sent me an electronic copy of the manual.

Welded top plate bolts? Man, I'm not sure which would be worse to deal with- yours or mine.

Definately keep us informed of your progress, and I will do the same.

morson82 · Sep 20, 2011

Re: Backhoe rebuild

Well, spoke with AmeriQuip today and they cannot determine the demensions of the bearing socket as I had hoped. My top socket looks to be in good shape and still has the bronze bearing in it. I will take the measurements and try and have a socket made at a machine shop. The person I spoke to at AmeriQuip sent me a sketch of the backhoe that she had found; I tried to attach it but it says the file is too large and will not let me. If ur interested in having it, send me ur email address and I will email it to you.

Glenn

Lil Foot · Sep 20, 2011

Re: Backhoe rebuild

I also spoke with a woman engineer at Ameriquip; it seemed that she really wanted to help, but it's just been too long since they supported this backhoe.

You might want to replace the top bronze bearing- it must be pretty worn.... there has to be a lot of play in it in order for the bottom end to wallow around like it did. Should be easy if you can find one, (or have one made) it just presses out & the new one presses in. Don't forget to drill the grease hole for the zerk.

I sent you a PM with my e-mail. Thanks.

morson82 · Sep 25, 2011

Re: Backhoe rebuild

Well, finally broke down the backhoe and opened a huge can of worms @#$$*%! The bottom pin is in very rough shape, the top bearing socket plate attaching holes are all buggered up as are the holes in the mounting beam. The swing weldment has a slight bend in it as well.....Looking for used or new parts....If I cant, might have to have the plates fabed out......$$$$$
Here are some pics...Keep you up to date
Glenn

morson82 · Sep 25, 2011

Re: Backhoe rebuild

more pics of my quest for perfection

Lil Foot · Sep 25, 2011

Re: Backhoe rebuild

Wow, deja vu!

I think yours is a little worse than mine. I just finished the lower bearing machining, so now I will assemble the swing weldment into the frame, place the top plate & align, then drill out the holes for oversize bolts. I'm thinking 18mm, possibly 3/4". (the original bolts were 9/16")

Oh, thanks for the drawing.

Lil Foot · Sep 28, 2011

Re: Backhoe rebuild

Drilling (milling) the holes for the new 3/4" bolts to hold the top plate.

morson82 · Sep 30, 2011

Re: Backhoe rebuild

Looks great...wish I had the tools and knowledge like you!!!

I took the swing weldment and the top plate to a machine shop. After much discussion, the machinist is going to completely cut out the entire pin rod from the weldment and replace it. He is also going to fab out 2 socket bearing plates (top and bottom) as well. He gave me a price of about 450.00 for all the work and materials. I tried in vain to locate a new or used swing weldment and socket plates, but it just wasn't going to happen. I am happy with the price as the cost for the new swing weldment and plates, if available, would have run me over 600.00. While waiting for the weldment to get done, I plan on rebuilding the controls and replacing all the hoses....Let you know when I get the swing weldment back and will post pics.

Lil Foot · Oct 3, 2011

Re: Backhoe rebuild

Sounds like a plan, I'll be interested to see what he comes up with.
I have already rebuilt my control block, (lots of o-rings) pretty simple, worst part was cleaning 30 years of dirt & neglect from the outside before disassembly. Thank god for pressure washers.
I already have all the hoses except the 4 short ones with 1/4" fittings on one end & 3/8" on the other; I'll probably have to have them made up locally.

Painted the top plate (note hardened guide pins added) and the swing weldment.

morson82 · Oct 24, 2011

Re: Backhoe rebuild

wow...looks awesome!!! I got my swing weldment back and it turned out great. The guy replaced the entire pivot pin back to OEM specs. He also did a great job with the new top and bottom bearing socket plates. I had him over size the holes to 5/8. Do you think it would be sufficient to just bolt the new bottom plate on with grade 8 bolts or do you think I should weld it in place or both? I have also completely rebuilt the controls for the backhoe as well. I was able to get a set of nos load check balls and retainers for the controls. Mine was missing the load check ball retainers.
According to the guy I got them from, they were the last set available anywhere. I am now redoing the rest of the backhoe frame and the hydro fluid tank area. Here are some pics....

Lil Foot · Oct 25, 2011

Re: Backhoe rebuild

Looks like your machinist/fabricator did a great job; I'd keep his number handy and maybe even send him a little Christmas bonus!

I'd be tempted to bolt & weld the bottom plate, after seeing how much the top plate moved around when it came loose. Just more peace of mind, one less thing to worry about.

My control block was complete & worked very well, except for leaks.

I haven't done much on this project lately, been working on my place up north trying to fix all the woodpecker damage and get it painted before it gets too cold. Because I had to take time to help a buddy with some problems, I'm probably not going to be able to paint this year.... then I'll probably shift back to the backhoe rebuild.

Below is a pic of one end (the least damaged) of the building. Pretty much all the white you see is replaced trim and patched woodpecker holes.

morson82 · Oct 26, 2011

Re: Backhoe rebuild

WOW......some serious damage there! It has been my experience that the reason the woodpeckers are attacking the building is there are insects within the wood. This was a problem on my house and barn. The large wood boring bees, they look like bumble bees, burrow into the wood and lay eggs and the woodpeckers go after them. The bees make a perfect 3/8 inch hole where they enter and leave very fine sawdust below the entry point......Good luck

Lil Foot · Oct 26, 2011

Re: Backhoe rebuild

It has been my experience that the reason the woodpeckers are attacking the building is there are insects within the wood.

Not in this case.... house was checked, no bugs. These are Acorn woodpeckers, only interested in acorns, and they drill holes in trees, telephone poles, houses, etc. to stuff acorns and other nuts in them for later consumption.... except they seem to be too stupid to ever remember to get any acorns from the building, they just keep adding more. I have cleaned at least two 55 galllon drums of acorns from behind trim & siding and I'd guess there is that much left in inaccessable areas. The cabin was "natural" finish, (looks like a dead tree to them) and I've talked to others who had the same problem, who had luck fixing the damage and painting the building a dark color. So that's what I'm doing, with my fingers crossed.
The power pole near the house has been replaced twice after woodpecker damage, and is now scheduled to be replaced again, with steel this time.
Here is the little SOB....

B670 Backhoe Rebuild

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