Broken Mount For LA724

[kcender]

The back yard is finished now,trying to get some ground cover to grow on it.The brackets are around 1100 dollars each if I remember correctly.Did you try adding plates to each side like I did?The Kubota rep that looked at my tractor said it was the first failure of this kind that Kubota had ever experienced.Good luck with getting it fixed.

 

[RedNeckGeek]

Looking around today at older photos I came across these two that showed one of the failed FEL mounts after it broke the second time. The previous repair consisted of scabbing on a plate to the outside of the arm, and as you can see the second crack propagated right through both mount and repair plate.

I have no idea what kind of material was used for the patch, but it wasn't strong or thick enough to prevent the failure from happening again. It's pretty clear from looking at the bottom of the broken cross section that it had been cracked a while before it failed completely, and that the crack started at the back of the mount.

I weld repaired this failure by grinding a bevel on the scab plate side, welding it, then back grinding the other side to sound weld metal. I then completed the weld ensuring 100% penetration across the failure zone. Used 400F preheat, let it cool by itself in still air. Now another crack started about a quarter inch below the newest repair weld on the back of the mount, pretty much parallel to the failure in the picture.

Haven't talked to my local dealer yet, but I'm hoping that these pictures will help him understand what's been going on.

 

[RedNeckGeek]

I talked to my local Kubota dealer a few weeks ago about the broken mounts. They had never heard of the problem, and I found out later that the regional warranty rep hadn't either until he checked up his line. That turned up four additional cases, not exactly proof of a design problem, but not a clean bill of health, either. I was offered a replacement mount at cost, with an additional cash discount, but I reminded them that both mounts had been broken. At the end of the day I was offered two mounts at cost ($610.76 + tax and shipping each) and a $500 discount. That still left an eight hundred dollar + hole in my pocket, but I guess it was better than nothing. I bought the tractor used three years ago and the mounts had already been repaired once, so it wasn't like I went into this with my eyes closed. The thing's been out of warranty for a long time (it's an '05), and I'm thinking I should be satisfied. Even though the replacement parts weren't served up gratis, I really appreciate the way my local dealer went to bat for me with Kubota. I didn't buy the tractor from them (though I have purchased a 4-in-1 bucket, several chain saws, and a big string trimmer) and they could have just said sorry, you're out of luck.

Picked up the new mounts yesterday, and the design is unchanged from the broken mounts on my tractor. When I asked what would happen if the new ones failed, the dealer rolled his eyes and made noises like it would be my fault because it could only happen through abuse. I've never abused this tractor, unless you consider hauling buckets full of gravel and fill dirt across a side hill abuse. That job's done now, and all that remains to finish the house is laying down another layer of gravel on the driveway. We're looking to move this year, so depending on where we end up I may get rid of this Kubota. It's been a hard workin' machine, but it just hasn't been up to the task of clearing trees and setting grades for new construction. It's been great for landscaping, but I'll let the big boys handle the heavy stuff from now on.




One in the box, one out. Now the fun starts.

 

[kcender]

Looking at the picture of your new mounts brings back memories for me,but not good memories:laughing:Good luck with replacing the mounts.Good to see Kubota did something for you.

 

[crazyal]

If it breaks again (let's hope not) I think a flat piece of steel welded perpendicular to the plates you've welded on that would cover where the cracks are starting in the rear would do a lot to strengthen it. I would start from as low as I could all the way up to the upper hole for the pin and use something thick, like 3/8", since you wouldn't need to bend it much and a couple inches wide. That way every time you lifted something you would be trying to stretch the 3/8" flat stock.

 

[Chilly807]

It always seems to be the casting that breaks, or forging, whatever it is. If it was a wider-spread problem, they'd likely switch to a completely fabricated design using flat plate. Then again, Kubota doesn't always acknowledge there's a problem with one of their designs.

Sean

 

[RedNeckGeek]

Yesterday I replaced the old repaired FEL mounts with the new ones from the dealer. In the process I took some photos that show there are significant differences between old and new.



The most obvious difference is that the webbing is much more shallow on the new part which significantly increases stiffness cross wise to the tractor. I also see that the webbing has been eliminated alltogether at the back side of the upper mount arm in exactly the location that cracks were starting on my old parts. In light of this new info I'm thinking it might be worth while to have another go with the Kubota warranty person, who claimed that there were no changes between old and new parts. In my mind it's clear that Kubota engineers understood there was a problem and changed the casting design in an effort to correct it. They did the right thing, maybe there's a chance the rest of the company could follow suit. Do you guys think I should push my luck, or just be satisfied with less than half the repair cost?

 

[WaxMan]

Yesterday I replaced the old repaired FEL mounts with the new ones from the dealer. In the process I took some photos that show there are significant differences between old and new.

View attachment 322206

The most obvious difference is that the webbing is much more shallow on the new part which significantly increases stiffness cross wise to the tractor. I also see that the webbing has been eliminated alltogether at the back side of the upper mount arm in exactly the location that cracks were starting on my old parts. In light of this new info I'm thinking it might be worth while to have another go with the Kubota warranty person, who claimed that there were no changes between old and new parts. In my mind it's clear that Kubota engineers understood there was a problem and changed the casting design in an effort to correct it. They did the right thing, maybe there's a chance the rest of the company could follow suit. Do you guys think I should push my luck, or just be satisfied with less than half the repair cost?

Why have the webbing at all would be my answer

 

[Chilly807]

Why have the webbing at all would be my answer

And that's my question too.. unless there's some engineering theory that says a webbed section is stronger than solid, or less susceptible to cracking, it seems like a really poor place to try and save weight.

Sean

 

[Chilly807]

Yesterday I replaced the old repaired FEL mounts with the new ones from the dealer. In the process I took some photos that show there are significant differences between old and new.

View attachment 322206

The most obvious difference is that the webbing is much more shallow on the new part which significantly increases stiffness cross wise to the tractor. I also see that the webbing has been eliminated alltogether at the back side of the upper mount arm in exactly the location that cracks were starting on my old parts. In light of this new info I'm thinking it might be worth while to have another go with the Kubota warranty person, who claimed that there were no changes between old and new parts. In my mind it's clear that Kubota engineers understood there was a problem and changed the casting design in an effort to correct it. They did the right thing, maybe there's a chance the rest of the company could follow suit. Do you guys think I should push my luck, or just be satisfied with less than half the repair cost?

I doubt you'd get much more from them than you already have, unless it was only a couple months out of warranty.

Sean