Kubota subframe assembly weld failure

[R_C]

Recently, I swapped the front 5-foot snowblower for the loader on my Kubota B2650. When I went to loosen the T-handle bolt that secures the front of the quick hitch and subframe assembly, it wouldn't budge even though I only hand tighten it during install. After I got it loosened with a bar and hammer, the problem appeared. The welds holding the middle support tube to the subframe (lower right in photo below) had failed on both sides of the tube so all of the weight was on the front support.




Do the two tack welds on each side of the support tube seem adequate to support the rear of the quick hitch and subframe assembly, which probably weighs about 150 lbs? Or does this look like a manufacturing defect? I plan to fix by welding the entire area the support tube contacts the frame on both sides of the two frame legs. Just wondering how you welding pros interpret this failure.

 

[MoonRise]

Obviously those two tack welds are NOT sufficient to hold the parts together.

Also, it sure looks like a poor weld (even for a tack weld). Without being able to look more closely, it looks like the welds had a lack of fusion/penetration to the frame. There is NO evidence that I can see of the tack weld beads even melting INTO the frame at all.

A classic example of a cold weld, lack of fusion, lack of penetration, etc that MIG welds are notorious for. The filler/electrode will always melt, but if the base/parent material never melts as well then the filler/puddle just sits on TOP of the base/parent material and doesn't actually make a valid weld that joins the pieces together.

IMNSHO.

 

[OccupantRJ]

Friday Afternoon! Time for the weekend and a cold one!
looks like both poor design and poor welds to me.

 

[R_C]

Obviously those two tack welds are NOT sufficient to hold the parts together.

Also, it sure looks like a poor weld (even for a tack weld). Without being able to look more closely, it looks like the welds had a lack of fusion/penetration to the frame. There is NO evidence that I can see of the tack weld beads even melting INTO the frame at all.

A classic example of a cold weld, lack of fusion, lack of penetration, etc that MIG welds are notorious for. The filler/electrode will always melt, but if the base/parent material never melts as well then the filler/puddle just sits on TOP of the base/parent material and doesn't actually make a valid weld that joins the pieces together.

IMNSHO.

Thanks for the reality check. I was certain the part made it to paint before someone finished the actual welding. I do have a MIG setup and haven't had any of my welds fail so I'll remove the paint and give it a go and do my best.

 

[OccupantRJ]

Depending on what goes through the tube you may have to ream it or die grind a bit due to welding distortion.

 

[R_C]

Depending on what goes through the tube you may have to ream it or die grind a bit due to welding distortion.

Good point. I'll make sure to test it on the bench before I mount it again. A pin, about 1" dia. and 10" long goes through the tube to secure the rear of the subassembly to the tractor chassis.

 

[NUTTSGT]

Those two little racks are supposed to hold that ! I mean seriously.

I wonder if it's a production line/QA failure or an engineer saying it looks good on paper and will be fine.

 

[R_C]

Those two little racks are supposed to hold that ! I mean seriously.

I wonder if it's a production line/QA failure or an engineer saying it looks good on paper and will be fine.

It's got to be a production line/QA failure. I am amazed those four tack welds made it through three winters. A better design would have been to put the tube through complete holes in the subframe legs.

 

[john.k]

I used to work for sandblasters/painters .........always had stuff outside the workshop that had been blasted and missed welds spotted ......I had to weld them up,regardless if it was a walkway for a silo .....or a big P&H crane boom ......also did a few X ray weld repairs ,dont ask ,dont tell.

 

[scooby074]

Should have been welded all around I think!

 

[rooster59]

Take it to Kubota. It's obvious without argument there never was a weld there.

 

[john.k]

Easier to run a weld around yourself .........whatever happens is hours of mucking around returning it,waiting for a new one to be delivered ,.....IMHO ,the only alternative id accept is for Kubota to bring out and fit a new one and take away the old one .........be funny if the new one had the same defect!..........which is not all that unusual..............as its almost certainly robot welded and the fault will be in the program.

 

[djbmw]

As others have said, poor design and poor quality control with only tack welds.

If you bought this FROM Kubota 3 yrs ago, bring it back and raise hell.

If this is an aftermarket bracket that you bought from a private seller, grind off the paint, weld full beads on both sides of the pipe stopping every inch and swapping sides to minimize distortion

 

[cannuck]

Just be very careful when setting up for the weld. The tacks are where they are to provide correct weld gap to final welds that IMHO should come from both sides. DO NOT tack it with zero gap around the mounting or it WILL distort by pulling the tab off of 90 degrees from first weld and not be able to get it back to square with opposite side. I am sure we don't have to tell you to take all of the paint off first, and leave the tabs bolted to the rest of the structure with pin in place to hold alignment.

 

[thunderalley3]

I would contact Kubota directly and make a contact with customer service and provide them with the pictures and emphasize how much you like their products and how surprised you were to see a component failure on a piece of their quality equipment that has not been abused.

They do not want issues or possible litigation from a faulty or poorly engineered part and I have an idea that they want to make good on this.

If you weld it yourself and have future issues it is 100 percent on you.

I would bypass the dealer as they will just see it as work they are not getting paid for and will not put much effort into getting it resolved.

 

[R_C]

Take it to Kubota. It's obvious without argument there never was a weld there.

Thank you for this picture. It clearly confirms my part was never welded. The quick hitch and subframe assembly was purchased new with the tractor so I've got a call into Kubota to see what they will do. Since that middle support tube just bolts to the subframe, I am hoping they can just supply that part to fix my problem.

 

[R_C]

I would contact Kubota directly and make a contact with customer service and provide them with the pictures and emphasize how much you like their products and how surprised you were to see a component failure on a piece of their quality equipment that has not been abused.

They do not want issues or possible litigation from a faulty or poorly engineered part and I have an idea that they want to make good on this.

If you weld it yourself and have future issues it is 100 percent on you.

I would bypass the dealer as they will just see it as work they are not getting paid for and will not put much effort into getting it resolved.

I started with the dealer I bought the tractor from, but they are no longer a Kubota dealer. So I called Kubota USA customer support and they said I had to go through a dealer. I have a call into the nearest dealer (2 hours away) to see if they can help. Worst case, I found the support tube part for $82 online. It just bolts to the subframe. If Kubota won't help, I'll just buy the part.

 

[Hellpig]

I started with the dealer I bought the tractor from, but they are no longer a Kubota dealer. So I called Kubota USA customer support and they said I had to go through a dealer. I have a call into the nearest dealer (2 hours away) to see if they can help. Worst case, I found the support tube part for $82 online. It just bolts to the subframe. If Kubota won't help, I'll just buy the part.

Oh, I'd cause Kubota WAY more than $82 worth of trouble if they didn't make it right.

That pic, description, and their lack of support would be on EVERY tractor forum, etc

 

[PCustoms]

I started with the dealer I bought the tractor from, but they are no longer a Kubota dealer. So I called Kubota USA customer support and they said I had to go through a dealer. I have a call into the nearest dealer (2 hours away) to see if they can help. Worst case, I found the support tube part for $82 online. It just bolts to the subframe. If Kubota won't help, I'll just buy the part.

Do you have a welder?

Kubota should take care of this, but at the end of the day 15 minutes to weld that back in will be a lot less time then calling a dealer, waiting and driving parts back and forth.

 

[jbfab]

If you do weld it yourself, one trick to avoid too much weld distortion is to weld it with the pin inserted. After welding one side of the joint, slide the pin in and out and spin it around until it cools a bit. If it starts to get stuck pull it out, but often times I do this and the pin acts as a sort of heat sink to prevent distortion in the bore.

 

[R_C]

Do you have a welder?

Kubota should take care of this, but at the end of the day 15 minutes to weld that back in will be a lot less time then calling a dealer, waiting and driving parts back and forth.

I do have a welder. Had I discovered the problem in mid-winter, I would have just welded it up. But since I discovered the manufacturing defect when I removed the snowblower and I won't mount it again until November, I'll see if Kubota will make it right.

 

[R_C]

Oh, I'd cause Kubota WAY more than $82 worth of trouble if they didn't make it right.

That pic, description, and their lack of support would be on EVERY tractor forum, etc

Yesterday, I emailed the Kubota dealer the three pictures at the beginning of this thread. I thought about including a link to this thread for a little added incentive. But that may not be necessary. The dealer replied quickly, and their service guy asked for a picture of the subframe's model/serial no. tag. He believes he can get it replaced under Kubota parts warranty.

 

[R_C]

If you do weld it yourself, one trick to avoid too much weld distortion is to weld it with the pin inserted. After welding one side of the joint, slide the pin in and out and spin it around until it cools a bit. If it starts to get stuck pull it out, but often times I do this and the pin acts as a sort of heat sink to prevent distortion in the bore.

Good tip. Thanks.

 

[IndyGarage]

Somebody missed doing the final welds. Not really a big deal. It wouldn't take more than 10-15 minutes to weld it.

It does make you want to go look at all the other welds to see if anything else got missed.

 

[R_C]

I finally got a reply from the Kubota dealer who submitted the problem to Kubota parts warranty. Kubota's reply:

"Warranty would only consider coverage while within the warranty period."

So, I'm on my own. Kubota will not make this right because my tractor is no longer under warranty. I really thought they would fix something that is clearly their fault. I'm just annoyed that Kubota doesn't stand behind their product and lucky for them the tack welds held during the warranty period.

I will weld it myself and if I don't like the results I can buy the replacement part. Thanks for all the welding tips. They will help.

 

[PCustoms]

I finally got a reply from the Kubota dealer who submitted the problem to Kubota parts warranty. Kubota's reply:

"Warranty would only consider coverage while within the warranty period."

So, I'm on my own. Kubota will not make this right because my tractor is no longer under warranty. I really thought they would fix something that is clearly their fault. I'm just annoyed that Kubota doesn't stand behind their product and lucky for them the tack welds held during the warranty period.

I guess I'm confused by the animosity here? If it's outside of warranty, it's outside of warranty. This isn't like it's some small inconsequential part that's easily swapped out as a good faith gesture

 

[R_C]

I guess I'm confused by the animosity here? If it's outside of warranty, it's outside of warranty. This isn't like it's some small inconsequential part that's easily swapped out as a good faith gesture

Others in this thread have suggested that Kubota should make it right so I turned my focus in that direction. The support tube is an $82 part that bolts to the subframe. Kubota could have earned a little good will at an inconsequential cost to them.

 

[Hellpig]

I guess I'm confused by the animosity here? If it's outside of warranty, it's outside of warranty. This isn't like it's some small inconsequential part that's easily swapped out as a good faith gesture

I understand.

Bought a 3 pack of spindles for finish mower 3 or 4 years ago, as I needed 1, but like to have spares on hand.

Well, needed another couple months ago, too tore up to rebuild, so grabbed another out of the box.

Flange was never drilled.

Contacted seller.
" Sorry, 30 days from purchase. Guess you should've looked at them".

No biggie, marked and drilled holes, but geez...

 

[R_C]

With snow now on the ground as a reminder, I finally got back to this project today. I am a welding novice and I have much to learn. But if the four tack welds held for three winters, I think my welds should hold. Here are pictures of two of the four welds and after paint ready to mount on the tractor. I did put the pin in the tube while welding as suggested but there is enough slack so any distortion wasn't a problem.

 

[djbmw]

With snow now on the ground as a reminder, I finally got back to this project today. I am a welding novice and I have much to learn. But if the four tack welds held for three winters, I think my welds should hold. Here are pictures of two of the four welds and after paint ready to mount on the tractor. I did put the pin in the tube while welding as suggested but there is enough slack so any distortion wasn't a problem.

That'll hold for a while for sure - especially given what it was before!
Some advice for future welds: I would turn the heat/amps up to prevent cold welding (some areas look like the weld was cold while other sections look like a good bond), and make sure you're melting both materials while feeding new wire in.

Good job on the repair!

 

[cannuck]

Yes, a bit more on the amperage but I would be willing to bet you are watching the arc and not the puddle (not as easy to do as to say).

 

[R_C]

I try to watch the puddle. In addition to my inexperience, part of the problem may be that these welds are beyond the capabilities of my Lincoln Electric Weld-Pak 100. About a year ago I added the MIG conversion kit with argon/co2 and 0.025 wire. According to the settings table below, I am limited to material no thicker than 14 gauge with this setup but I am trying to weld 3/16" material. Is that part of my problem here? For these welds I had the amperage at its highest setting (D) and the wire feed speed at 7.

 

[djbmw]

I try to watch the puddle. In addition to my inexperience, part of the problem may be that these welds are beyond the capabilities of my Lincoln Electric Weld-Pak 100. About a year ago I added the MIG conversion kit with argon/co2 and 0.025 wire. According to the settings table below, I am limited to material no thicker than 14 gauge with this setup but I am trying to weld 3/16" material. Is that part of my problem here? For these welds I had the amperage at its highest setting (D) and the wire feed speed at 7.

Your welder can output 88 amps at its max rating.
For the material thickness you're working with It really needs ~110 amps or so.

However,... doing multiple passes SLOWLY would allow you to still do a good weld. Your duty cycle protection would kick in a lot and you'd be forced to take breaks but thats the best way to do it with your machine.

Probably 3 passes... with your initial pass being your root pass, hot and SLOW.
Then your 2nd pass would be on one side of the root pass.... and your 3rd pass on the other side. All on max amps, slower wire feed (maybe 3?).. and just let it melt and blend.

 

[cannuck]

once you get to max amps you may have to back down a bit on feed rate to keep the bead from "piling up". There is a magic point as you slow feed called "spray transfer" where the wire no longer dips into the puddle. If you can get there greatly reduced splatter and much better ability for puddle to penetrate. Also: to get best penetration and control you want to be "pulling" the puddle (torch ahead pointing back at bead) instead of "pushing" arc on top of bead with gun pointing in direction of weld.

 

[R_C]

Ok. Thanks for the tips. I will practice with some scrap. I recall having real problems with slower wire feed but I'm sure more practice will help. The multiple pass technique makes sense for thicker material so I'll give that a try.

 

[mike93lx]

Ok. Thanks for the tips. I will practice with some scrap. I recall having real problems with slower wire feed but I'm sure more practice will help. The multiple pass technique makes sense for thicker material so I'll give that a try.

Did you do all that in one pass?

I'm no expert, but I think I'd grind it back a bit and make a couple more passes

 

[R_C]

Did you do all that in one pass?

I'm no expert, but I think I'd grind it back a bit and make a couple more passes

I began by tacking the tube in place. I had to pull the sides together with clamps so the original tacks lined up. My tacks held when I removed the clamps so I did not consider multiple passes. I know it's not a great job and I could probably do better after the advice I've gotten here. But if the four factory tack welds held for three winters, I think my four welds should work. I'll keep an eye on them this winter and if they all fail, I'll grind and weld again.

 

[cannuck]

I began by tacking the tube in place. I had to pull the sides together with clamps so the original tacks lined up. My tacks held when I removed the clamps so I did not consider multiple passes. I know it's not a great job and I could probably do better after the advice I've gotten here. But if the four factory tack welds held for three winters, I think my four welds should work. I'll keep an eye on them this winter and if they all fail, I'll grind and weld again.

In my haste to point you down the right road, I forgot to give you THE most important advice when it comes to welding: WELD as much as you can. We can tell you all sorts of things to help you along the way, but the road to Hell is paved with the best of intentions but the road to good welds is paved with a LOT of wire, rod, gas, abrasives and scrap. You have already got the big picture clear - just do stuff and don't be shy about cutting it apart and doing it again.

 

[sqznby]

That wasn't a weld failure, that was a failure to weld on Kubota's behalf haha. That's crazy.

I'm sure it'll hold, especially since the 4 tack welds held for 3 winters.
I would've chosen flux-cored over the hard wire only because of the limitations of your machine. I also would've beveled the flat material that the round stock was getting welded to.

 

[Jacko264]

Don’t worry about it it will be ok I’ve seen worse
not my welds