Hoe frame welding question.

[wmasmith]

I searched for this but i didn't have any luck. I have a 2017 XR4140H with LB3104 hoe with the factory frame. I worked it real hard this past weekend and the 8 bolts that mount the hoe frame to the sub frame kept working loose. What kind of trouble am I looking at if I weld the frame together instead of just relying on the bolts. I can probably take it apart one bolt at a time and red loctite it, or tighten it up and tack weld the nuts. I'm just worried if I tack them or loctite I'll still have it shift around under load no matter how tight I get the bolts. There's provisions for using a toplink but I would be worried about breaking the rear axle housing. I've attached part of the manual that shows the mount of the frame to the subframe. What do you guys think?

 

[Shield Arc]

What do you think about making some short welds to hold it together? Place the welds where they are easy to cut out at a later date.

 

[wmasmith]

That's an idea. Was planning to retain the bolts but grind away the powder coat and bevel the areas that I can get to to provide a good clean surface. I can probably get to all of the areas with a 4" grinder and a cutoff wheel if need be. I'm just concerned about moving the stresses from the bolts to the box tubing. Of course if that happens I can always just heavier wall tubing and rebuild the subframe if need be. Thanks for the input. Anyone else.

 

[Shield Arc]

When you make your welds, use 7018. And make sure you fill in the crater / stop good, do not leave the crater under filled. The crater will be the first place the weld will start to crack.

 

[dfkrug]

There's provisions for using a toplink but I would be worried about breaking the rear
axle housing.

There's your answer: use the toplink connection.

That type of subframe has been around a long time and is used on lots of tractors. It just flexes too much if you
don't use the toplink. Stress on the toplink connection on your tractor is not severe; it is nothing like
you would have with a 3-point hoe.

Kioti hoes use that design and I have seen where the braces are welded, but the flex does not go away.
It is near impossible to keep those bolts tight if you have that kind of flex.

 

[Billself]

when welding anything the heat from the weld makes it a little more brittle so if you do weld it up to take flex out, some thing has to give. If i was to weld it I think i'd tack the bolt heads enough to keep them tight but not all the way around then i think i'd brace it by using top link or bracing sub frame with steel brackets to solid it up a little but in the long run something will give if worked really hard.

 

[wmasmith]

Thanks for all the input. I think I'll start with the top link and go from there. I can always do more if I need too.

 

[dfkrug]

I think I'll start with the top link and go from there.

I have been making subframes for a while and I have never heard of a tractor incurring
toplink bracket damage when bracing a ladder-style undermount subframe. This issue
is moot with the more popular 4-point subframes. There is a reason that the big
makers (Woods, JD, Kubota) have all gone to 4-point setups.

If you go to YouTube, you can watch many tractors with subframes in operation. Some
of them have HUGE amounts of flex.

 

[farm boy00]

I searched for this but i didn't have any luck. I have a 2017 XR4140H with LB3104 hoe with the factory frame. I worked it real hard this past weekend and the 8 bolts that mount the hoe frame to the sub frame kept working loose. What kind of trouble am I looking at if I weld the frame together instead of just relying on the bolts. I can probably take it apart one bolt at a time and red loctite it, or tighten it up and tack weld the nuts. I'm just worried if I tack them or loctite I'll still have it shift around under load no matter how tight I get the bolts. There's provisions for using a toplink but I would be worried about breaking the rear axle housing. I've attached part of the manual that shows the mount of the frame to the subframe. What do you guys think?
View attachment 527639

You say it is a 2017. If so I wouldn't modify it until it is no longer under warranty or talk to the dealer with these problems and see what their advice is. Unless you don't have a warranty. I would imagine welding it would void all warranties of the machine.

 

[3Lfarms]

It should have been delivered with the top link in place. Install it and your problems will disappear.
Locktite on the bolts is fine if it makes you feel better.
You can see the top link installed the day I picked up my tractor.

 

[CincyFlyer]

You say it is a 2017. If so I wouldn't modify it until it is no longer under warranty or talk to the dealer with these problems and see what their advice is. Unless you don't have a warranty. I would imagine welding it would void all warranties of the machine.

Naw, it's his machine. According to US law, the manufacturer must prove that your modifications caused a failure, or your item (vehicle, shovel, whatever) is covered. So if his oil pump dies, it's obviously not because he welded his subframe to his backhoe. Of course, he's gonna put in the top link, and that will help greatly.

 

[dfkrug]

You can see the top link installed the day I picked up my tractor.

I can't really see it in the photo, but it is good the dealer did that.

There was quite a controversy for a while about the similar Kioti subframes. Some
dealers, and some US factory people were telling customers not to use the toplink.
Some factory people and documents were saying install the toplink.

Meanwhile, the hoe maker continued to supply a mounting point for a toplink on
their hoes from Day One. Use it, or suffer the consequences.

 

[wmasmith]

That was part of my confusion. The hoe manual said nothing either way about the toplink. The dealer said it wasn't needed when I asked at delivery.

 

[dfkrug]

That was part of my confusion. The hoe manual said nothing either way about the
toplink. The dealer said it wasn't needed when I asked at delivery.

I remember being shown one or 2 installation manuals that showed the hole, but made
no mention of the toplink. Like you saw.

With this kind of subframe, the toplink you should use can be the tractor's regular toplink,
not the enhanced toplinks you get with 3-point mounted hoes.

RE dealers, there are some great ones out there, but they do not always (usually) use
the tractors they sell in actual work. So when there is no clear instruction from the
maker, they may be just guessing.

 

[airrj]

I ran into this same problem with the similar backhoe on a Kioti. Mine came with the top links and even with the bolts torqued to the proper torque, the backhoe would pivot on the lower mount just a fraction of a degree each time that you dug. We were in the middle of excavating the basement of our house at the time so I didn't have time to investigate right away, so each morning we would re-torque all of the fasteners.

My solution was to remove the backhoe from the tractor and then separate the backhoe from the sub-frame. I saw that there was power coat on both the sub-frame and the backhoe at the mounting points. I took an angle grinder with a flap disc and removed all of the coating so that the mounting points were bare metal. The dealer gave me new fasteners and I bolted everything back together and torqued properly. Problem completely gone. I have been using the hoe for 3 years since and I check the torque on the fasteners maybe once a year and they are always fine now.

The paint/powder coat can act like a lubricant under extreme pressures and in this case is allowed the joint to pivot the amount of distance that the holes had clearance. I learned that trick from an old bulldozer mechanic that made us grind every spec of paint off of the mounting surfaces between new track plates and the chain. The plates were torqued to something like 400 ft-lbs and if you didn't remove the paint they would work themselves loose.

Good Luck.

 

[1stDeuce]

airrj is exactly correct. All that powder coating looks great, but it relaxes, and is pretty slick, which means that joint moves some when you stress it. Grind it off, bolt it tight, and repaint an you'll probably not have further issues.

Locktite, or even welding the bolts will NOT keep them tight, since the powdercoat will mush out over time, and they'll lose clamp as it does. (They're not turning loose, they're probably relaxing loose as the joint moves...) Welding the structure will work if you can put on enough weld to keep it from flexing, but it's more likely it'll just crack eventually where you weld it unless you really put some time in it.

I would also suggest adding the top link as a brace when you're working it hard. It'll take some of the stress off the frame, and I'm sure your top mount bracket is plenty strong for sharing the load. As pointed out above, running it with the top link is nothing like most 3pt hoes, which put 100% of the vertical stress into the top link mount... Yours has a frame that takes that, and the top link just becomes a stabilizer.

 

[wmasmith]

Thanks for all the input folks. I hope you all have a great Thanksgiving. I'll be flying to Chicago for work tomorrow afternoon so everyone have a bite of food for me.

 

[airrj]

Thanks and good luck with the project.