Custom Backhoe Subframe for Kubota L3710

   / Custom Backhoe Subframe for Kubota L3710 #1  

mng

New member
Joined
Jun 14, 2009
Messages
12
Tractor
Kubota L3710
I have been reading this forum extensively for the past few years. I taught that it would be time that I post a project that might help others. Sot here goes.

Last year bought a Wallenstein GX700 Backhoe with a 3 pt hitch attachment for our Kubota L3710. We have use this implement allot more that we had anticipated, our land is quite flat and heavily wooded. Making the need for ditches and small scale drainage work a necessity. The problem was that after on summer of work with the BH we found a few problems with the 3pt setup.

1. The stability of the whole thing was not great, this thing would flop around all over the place while working. making it difficult to maneuver the tractor from the BH seat (I know, I know... but I like to get the most out of the equipment). I ended up calling Wallenstein about this. It turned out that I was missing a piece going to the draw bar, they wanted 350$ for the missing parts, I built it for less that 30$ ( it's discussed in more details lower) .

2. the distance between the BH and the tractor was too great making it difficult to go over rough terrain in the bush.

3. With the BH wobbling around all over the place the top link holder was taking quite a beating. The holes are no longer round but oval.

Then there are all of the other issues related to having so much stress on the back of the machine. There are other excellent threads about this subject The best one is probably http://www.tractorbynet.com/forums/build-yourself/171760-how-build-your-own-custom.html.

I called Wallenstein to get more information about their sub frame kit for the GX700 they told me that sub frame was of the ladder type (this is also available in their documentation), it does not couple the tractor and the BH any closer than the 3pt arrangement and it attaches via the pins where the 3pt arms attach to the tractor. They also wanted over 1000$ for the kit plus freight.


We (I say "we" because my wife and I both worked on the design and building of it) had a few requirements.

1. it has to be stable

2. it has to be easy to install and remove. This had to include not having to remove the 3pt arms I tired to do this on the tractor and it was not an easy job.

3. it must not be of the ladder type ( I didn't like the idea of having to trip over that thing when it is not mounted)

4. it must not reduce the ground clearance, In the bush I need all of the clearance I can get

5. as all the stuff I build for the tractor it must not permanently modify the tractor.


So here are the details for the build.

There are 3 main components to the build

1. the tractor mounting bracket, This is basically a modification to the loader bracket to attach the front of the tractor portion of the sub frame to the tractor and the FEL frame. It is based on the woods design.

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2. The main tractor frame. This component is made out of 0.25 2x3 and 0.25 2x4 rectangular tubing. The front attachment plate is 0.5 x 4 inches and the rear hooks are 5/8 plate . The brackets for the ROPS mount are 0.5 welded in a angle. It permanently attaches to the tractor via the tractor mounting bracket in the front, the mounting holes in the bottom of the transmission housing at the rear, this is what the two holes at the top of frame are for (this idea came from the woods kit), and the ROPS mounting plates at the rear.


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3. The BH frame. The BH Frame is built out of 0.25 2X4 rectangular tubing, the hooks are 5/8 and the permanent pin it 1" cat 2 top link pin. To attach the BH to the tractor I use the standard cat 1 pins. The bracing is done with 4 in C channel and 0.25 2x2 square tubing

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4. the other pieces to the kit. To attach the top BH I use the top link from the 3 pt kit, a three holed 5/8 plate, a ratchet load binder and a modified draw bar. This arrangement makes the the top link really easy to attach and the load binder tightens every thing down once all the pins are in. Most of these components where build and added last year to try to stabilize the 3 pt version.

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Here are a few picture of the whole thing assembled. I still have to work on finishing the seat mount and the hydraulic hose mount on the tractor as it was in the way of the seat.

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I have already put about 20 hours of BH time on it with the new sub frame and I am entirely pleased with the results. I even tried it with out the top link and load binder to make sure the frame was strong enough, it was surprisingly quite rigid although I would not want to be between the BH and the tractor should it fail :eek:.

There are still a few tweaks to do on it. It will need more alignment brackets and new seat mount. I also found out once every thing is built that the stabilizer hoses are rubbing on the rear tires. At this point in time I am not too worried about it, I did put a covering on the hoses to try and protect them, when they fail I'll try and figure a better way to route them.

The total cost for the project was about 500$. There is about 350 $ of new steel 100 $ on paint and about 50 $ on bolts load binders and consumables . Kubota paint is stupidly expensive and I will not waist my money on this any more, I also realized that I can't pain worth s&^% . So the 10$ pint of black Tremclad will be fine for the next projects.

It was very pleasant to build and allowed me to spend allot of time working with my wife. We both spent numerous meals discussing designs over candle light and napkin plans. She did most of the cutting and the clamping I did the marking and welding.

I hope that this thread will help give ideas to others who wish to built this type of equipment.
 

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   / Custom Backhoe Subframe for Kubota L3710 #2  
MNG and spouse:

Very, very nice build. I have an l4310 and a Woods 751 backhoe, looks very similar to your set up. Can you please post a picture of the tractor mounting bracket where it joins the FEL mount. I see the bracket, I am having problems visualizing how it connects up front and my machine is 300 miles away.

Maybe one other question, what is the dimension along the lower arm of the rear tractor mount that bolts to the ROPS. Mounting boss. I am trying to figure out what dimension one needs to avoid interference with the 3 point when the backhoe is removed.

Thanks for your help.
 
   / Custom Backhoe Subframe for Kubota L3710
  • Thread Starter
#3  
Thanks for you comments cycle_gator.

Here is a picture of the front bracket. What i did for this one is to take the original bracket that was installed and weld a 1/2 inch plate into which I cut a notch for the clutch housing water purge valve. I also made it such that it bolts into two extra threaded holes in the bottom of the tractor.

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If you take a on page 5 of the woods sub frame manual woods sub frame manual you will see where I got the idea from.


For the distance between the ROPS mount and the end of the hooks where the BH portion attaches I have 9 inches (see image below), allot of that will depend on the width and the height of that part of the frame. While I we where building it, we started by building the top portion of the tractor portion of the frame and the bottom two arms with the hooks. we then assembled the top part onto the tractor and roughed in the two arms using floor jacks to hold them in place. this way we made sure that they would not impact the 3 pt hitch. we had the advantage of having the tractor in front of us for the build.

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Hope this helps.
 

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   / Custom Backhoe Subframe for Kubota L3710 #4  
MNG:

I looked at this yesterday and got so excited, I forgot to say thank you for the effort. Very helpful.
 
   / Custom Backhoe Subframe for Kubota L3710
  • Thread Starter
#5  
Not a problem cycle_gator.

After some use and allot of attaching and detaching I came to the conclusion that it will need more alignment tabs. I will also have to modify the ones I already have on there because they tend to hit the bolts on the transmission housing on the tractor. Other that that the sub frame is still performing marvelously well.

On a side note. I was starting to find that the back hoe was lacking a bit of power especially in those situations where the ground is really hard or when we are removing a stump. So I bought a pressure gauge ans a few fittings at princess auto and T it in the system it turns out that the pressure relief valve was set to 1500 PSI. The manufacturer recommends having it at 2000 psi. I then connected it to the tractor and found that it was releasing at 1950 PSI. so I adjusted the PRV such that it is the tractor that dumps when the pressure is too high. After I replaced the last 2 original hoses (which burst almost instantaneously ) it is like having a completely new backhoe.
 
   / Custom Backhoe Subframe for Kubota L3710 #6  
So I bought a pressure gauge ans a few fittings at princess auto and T it in the system it turns out that the pressure relief valve was set to 1500 PSI. The manufacturer recommends having it at 2000 psi. I then connected it to the tractor and found that it was releasing at 1950 PSI. so I adjusted the PRV such that it is the tractor that dumps when the pressure is too high. After I replaced the last 2 original hoses (which burst almost instantaneously ) it is like having a completely new backhoe.

Looks great, MNG.

I just saw this thread, or I would have commented earlier.

You got the GX700 mounted very close-in to the tractor....I am sure
that makes a Huge difference.

Using the load binder to add stiffness is a good idea. Subframe flex
should definitely be minimized.

Perhaps the most amazing: you and the wife both worked on it.
Congratulations.

On the subject of the Wallenstein hoes, I have seen them, and I was
concerned that they were only rated to 2000psi. That means if you set
its RV to 2000, your loader is limited to 2000psi also. That's a nice
2500psi Kubota....it's a shame to waste its power.
 
   / Custom Backhoe Subframe for Kubota L3710 #7  
I agree you did an excellent job designing and building your subframe. Thanks for posting.

I was getting ready to build a BH subframe this winter for my Kubota L3130 and spent a lot of time going over the many subframe threads and taking lots of notes. Then, fellow TBN member, RickB mentioned in thread that he had a 4 point Subframe for sale which was made for my Kubota and the BH80X. All it needed was a little cleanup and some fresh paint. I cleaned it up last night and primed it this evening and will give it a coat of paint on the weekend. It's not made for my Italian BH but with the addition of a few brackets it will fit fine, much better that I could ever fabricate myself.
 

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   / Custom Backhoe Subframe for Kubota L3710 #8  
That is a great site! I saw the information is very usefule!
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   / Custom Backhoe Subframe for Kubota L3710
  • Thread Starter
#9  
Thanks for your great comments, it is true this site is great.

I haven't quite figured out how to set the PRV on the tractor to the 2500 psi that it is supposed to be. Although I have never really found that the tractor has not been able to do something I wanted it to. I figure that I have not really seen it's full potential yet :).

I noticed that the top link bracket connected to the tractor is still taking quite a beating, although allot less than it was before. We discussed modyfing the sub frame to a 4 point system instead, but we don't think that it is worth the effort.

LureMaker I am sure that it would not be that difficult to get that sub frame to fit you BH. For us the tractor side was by far the most difficult. For the BH side we just looked at how the 3 pt hitch was attached to the unit and went from there.
 
   / Custom Backhoe Subframe for Kubota L3710 #10  
Thanks for your great comments, it is true this site is great. ...
LureMaker I am sure that it would not be that difficult to get that sub frame to fit you BH. For us the tractor side was by far the most difficult. For the BH side we just looked at how the 3 pt hitch was attached to the unit and went from there.

Attaching the backhoe subframe section to the backhoe will be relatively easy. I figure I have to make 4 brackets. It will be great to able to install and remove the backhoe in only a few minutes. After this I plan on making a backhoe dolly.
 

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