I recently acquired a 1957 Ford 850 with a Sherman Power Digger on it (model 54F100). The problem is that someone cut up the bucket and poorly welded it back together about eight inches wider than factory. I’m looking to replace it, and possibly modernize it a bit. I do have the fabrication skill and equipment, but I do not have the heavy equipment expertise to fully understand how these components interact (and how changing them could impact structural loading) Would it be reasonable or possible to get a modern bucket, and then match the side link and H link lengths to the new bucket size? Or could that cause a problem that I’m not aware of? The dimensions of the current setup are approximately as follows (plus or minus some rust) Pin dia. 1 3/8” Dipper gap 8 1/4” Pin centers 13 7/8” Side link 14 1/4” H link 16 3/4” Also, the goal here is for the unit to be able to do work better, not a restoration. The tractor is not a good candidate for it unfortunately (one of the previous owners was a very earnest, if unskilled welder). I have already picked up a weld-on mechanical thumb for it as well. Thanks in advance!
It has an unusual bucket shape. Not a robust backhoe & mounted on an old Ford tractor I'd avoid excess strain on the tractor. Smaller buckets could be adapted to fit, I think line boring after welding could be an involved process. Probably no bushings in the pin holes. I'd use DOM tubing full width building ears to fit a modern bucket. after the welds cool & distortion has been kept limited, cut away the center of the tube. Pins may still line up, likely they won't. You can correct some distortion by adding weld where you can draw it. Maybe a bit of die grinder work could improve pin alignment. It might make sense to repair the old bucket.
Your assessment of the vehicle is not too far off. It does have some bushings in the pin holes, and some are missing. The whole hydraulic system needs a thorough going through. I’ve already rebuilt two of the cylinders and have the parts on hand for the rest. Unfortunately repairing the bucket isn’t really an option. Because of the way it was cut and resized, the only parts on it worth saving are the ears themselves, and the side faces. You’re absolutely right about the line boring! If I end up fabricating a whole new bucket, then I am absolutely planning on using the DOM tubing while welding and cutting it out. That’s part of why I included dimensions for the side link and H links. I’m wondering if it would be reasonable to change to a non-hydraulic quick coupler off a smaller vehicle, or just a smaller bucket with less space between pin centers on the ears. Switching to smaller tools would definitely help reduce excess strain on the tractor. It runs surprisingly well for being almost 70 years old, and basically ignored for the last ten years.
A friend had a backhoe on a NAA (Golden Jubilee, 1953) The rear casting was broken. He found a replacement, removed the backhoe. He then mounted the hoe on the back of a 1953 Chevy dualie tow truck. He dubbed it the tow hoe, thought he was funny. It was sort of a success, the truck was better suited to the stress of a hoe. If you're up for a project, building a whole bucket is not out of the realm of possibility. I warn you, the tractor/hoe is not all you might hope for. It'll dig, but might be more a museum piece than a real digger.
I don't think it would be too difficult to adapt a more modern bucket. Maybe something about 18-20" wide. It doesn't need to be as deep or curl up as much. Backhoe buckets often sell for pretty cheap at the RB auctions here.
I usually scour used market for buckets. They then need repair, or customizing. Biggest challenge for me is pin alignment. Put the pin in the bores, or bushings, weld the ears to the bucket, still somehow it ends up not quite aligned. Heat & shrinkage leaves a bit of distortion. My steel dealer found DOM tube .004 oversized. It gives a bit of wiggle room for shrinkage after welding. I have a friend who is pretty clever in his fabricating, bought a mini excavator, adapted several different backhoe buckets to fit. He bought the bucket portion of quick connect, welded them to buckets. No need for post weld line boring.