how to build your own custom backhoe subframe

[LouNY]

Just a thought, all of the older farm tractor loaders and dozer type blades always came back to the rear ends for push/lift strength.
Very few used the bolts in the axle ends for the strength even though many of them bolted to the ends, they almost always utilized the square axle housing as the support either from flanges or plates that sandwiched the square housing to the sub frame often with 4 bolts often 3/4" bolts to squeeze the subframe and reinforcement to the axle housing. Looking at your pic woodsframe2 it seems like the angle pieces # 37 and ?? serve in that manner some what. But securing your sub frame to the axle housing would likely be securing it to the strongest casting of the tractor.

 

[manytoyman]

Thanks for the reply LouNY. In your last sentence above, are you saying the "axle housing" as in the ends where the axles come out or the back side where the ROPS connects? Just want to be sure I am tracking with you

Something like this is going through my head...

 

[LouNY]

On the square housing at the ends were the axles come out.

Edited to add;
this is a picture clipped from a Miller front end loader,
the long legs go under the rear axle housing and the short bars on top with large bolts joining the two,
the bolts fit very close to the front and rear of the axle housing.

 

[dfkrug]

The way woods attaches their subframe at the end of the axle housing using the 4 pre existing bolt holes APPEARS to also be the way some of the kubota sub frames attached on the L series as best I can tell from the first picture. One key I had not picked up on is that both of them also have some type of extension that goes over to the ROPS or similar location for additional support (photo 1 is a kubota bracket and photo 4 is the woods diagram where you can see part 37) . I'm beginning to think that is the key: the combination of axle housing connection WITH a connection at the ROPS area would be pretty strong.

The L -series used all-steel structural components in the rear, including the trumpet housings, but also featured axle hubs that were part of the axle. Earlier Bs had removable hubs; I am not sure of the later ones. That would allow you to put the axle thru a hole in the subframe.

I am reposting 2 pix of Woods 4-pt subframes for B and L Kubotas. There are brackets you can not see that provide additional support. BTW, I am not a fan of these subframes as they are way too long, sticking the hoe too far out back.

Some tractors, like L Kubotas, and my own Kioti have many unused threaded holes underneath the final drive gearbox, some for the drawbar. Those are fair game for a subframe. I did use them for my Kioti subframe.

 

[manytoyman]

It appears that my B2400 hubs slide off of the axle (they are held with a large pin and a squeeze bolt and two wedges) so it appears I could make my subframe with a hole for the axle and thus be solid all the way around. This was my assumption in my first two design ideas in a previous post. I will take a look to see what other options might present themselves down near the drawbar.

I now get LouNYs squash method. That is the idea that I think dfkrug used on his first sub frame earlier in this thread. Unfortunately the axle support housing is not a smooth square so it wouldn't be quite as effective - but probably effective enough. This may end up being the most effective depending on where the final hoe mounting plates need to be.

I guess the next thing to do is get the measurements for a BH600 or BH601 as that is my target hoe at this time (small enough not to damage anything and weighs in at around 620 pounds without the bucket). Once I know the width and height of the hoe bracket that will allow me to fully assess my options as to mounting at the rear. The front is a no brainer - bolt to the FEL housing.

 

[manytoyman]

I saw a BT603 today at the local dealer and grabbed some numbers. I was surprised that the mount is basically a 16 by 10 inch rectangle (16 wide by 10 high).

It's looking like my subframe will come out an inch of so wide on each side based on the axle housing but I can deal with that. It appears I can also utilize the ROPS mounting bracket. In the second photo the red lines are the approx location of where my subframe will be. You can see how far I will need to come in to connect to the ROPS area. But I think an axle mash set up with ROPS connection would be plenty strong (and of course up to the FEL).

 

[dfkrug]

I saw a BT603 today at the local dealer and grabbed some numbers. I was surprised that the mount is basically a 16 by 10 inch rectangle (16 wide by 10 high).

I imagine the BT603 is similar to the BT600. I like the 4-point mount and how the maker close-coupled the hoe with the tractor.

Here is a new BT600 on a subcompact BX22.

 

[manytoyman]

OK, now on to construction basics. What thickness of steel should I fabricate the sub frame from? I am looking at two different ways/methods:
1. flat stock like OEM Kubota and Woods uses that runs from FEL to Hoe attachment
2. channel (3x1.5?) under the axle as many have used on their DIY subframes

If using #1 I think I can use a plasma cutter and a template (wood) to guide my cutter. I likely would not use a squash method but rather the 4 holes already in the axle housing then also attach it to the the ROPs mounting point. My hubs come off the axle so I can slide it over the axle and into place.

If using #2 then I likely am looking at a squash the rear axle housing and still attach also to the ROPs brackets. A possible advantage of this method is the width could be made to be exactly what is needed to match the mounting on the hoe. I will need to remeasure that.

 

[dfkrug]

OK, now on to construction basics. What thickness of steel should I fabricate the sub frame from? I am looking at two different ways/methods:
1. flat stock like OEM Kubota and Woods uses that runs from FEL to Hoe attachment
2. channel (3x1.5?) under the axle as many have used on their DIY subframes

I have done most of my subframes with channel stock, much of which I acquired, free, from a local Kubota dealer. They were the base of tractor crates.

If you go with flat stock, it will have to be quite thick (at least 3/4") to reduce sideways flex. I used 1/2" plates on one of my subframes, and it had too much sideways flex. Woods and Kubota both use very thick plate, which is hard to handle and cut. My plasma cutter is only good for 40A, which means anything over 1/2" cutting is tedious at best. Maybe you can get away with only 1/2" plate if you stick will a 6' hoe, and add lots of side bracing.

A third choice is tubing, but that is not as simple as channel or plate in that secure weldments really need to fully surround the tube. There are numerous postings on the internet of Kioti OEM subframe failures of tubing.

 

[manytoyman]

How this of channel is needed if I go that route?