3pt stabilizer fell off, 2nd one busted too

[Fallon]

I've got over 1,000 hours on my L4060hstc. The other day my left side 3pt stabilizer fell off the lift arm. It looks like the bolt holding it onto the lift arm broke. Pulled it apart & it looks like the head of the bolt was welded onto the yoke & broke off. $50 at Messicks https://www.messicks.com/parts/kubota/ta140-71353, part 130 in https://www.messicks.com/catalogs/kubota/l4060hstc/3-point-linkage-drawbar-hitch/j11000-lower-link. But it should be as easy weld job to replace the bolt & weld it in. So I pull the other side to get some measurements as the entire head of the bolt is missing. Pull the other bolt & find it's got a funky T head on it not a normal hex head. It's also busted the weld & fracture the bolt.

Looking at the breaks on both bolts they have been fractured a long time with lots of rust. The one that fell off was holding on by about 25% of the head & finished fracturing very recently.

Anybody else had this happen?
Debating tracking down what looks to be a 16mm fine thread bolt & welding it up vs buying a couple new Yokes. Getting the right length shank before the threads start might be fun. None of the thread gauges I have do fine threaded that big. I'm assuming they used that funky T bolt as it would be hard to weld at the bottom of the yoke, but it looks like that didn't end up being that strong.

 

[LouNY]

You can make your own T bolt quite easily, cut the head of a bolt cut your T and bore a hole for the bolt to fit, slide the bolt half way or more and then plug weld it.

 

[Thomas]

Not sure but is the wear on bolt head?

 

[CH4Ohio]

I was looking at mine. L5740 so older than yours. Why can’t you just put a shoulder bolt through that hole? Mine looks like it has bolts in it with lock washers and nylon nuts. Seems to have clearance but if yours rubs, just grind a little off the bolt head.

Could be they were replaced before I got it, but they’re still tight and intact after about 15 years that I know of.

 

[rScotty]

Not sure but is the wear on bolt head?

It looks to me like the problem is that the T-heads weren't pulled down tight to the bottom of the yoke before they were welded. then later when the nut was torqued, all of the clamping stress was on the weld instead of the bottom of the T-head.

They would have been much better off not to have welded those parts to begin with....then the torque would have pulled the head down flat onto the yoke.

Or...If the people who made the part just can't help themselves from welding something, they should simply lay a bead on the yoke along the side of the T-head so that the bead itseflf prevents rotation.
There is nothing to be gained by welding the T-head to the Yoke.
rScotty

 

[SDT]

I've got over 1,000 hours on my L4060hstc. The other day my left side 3pt stabilizer fell off the lift arm. It looks like the bolt holding it onto the lift arm broke. Pulled it apart & it looks like the head of the bolt was welded onto the yoke & broke off. $50 at Messicks https://www.messicks.com/parts/kubota/ta140-71353, part 130 in https://www.messicks.com/catalogs/kubota/l4060hstc/3-point-linkage-drawbar-hitch/j11000-lower-link. But it should be as easy weld job to replace the bolt & weld it in. So I pull the other side to get some measurements as the entire head of the bolt is missing. Pull the other bolt & find it's got a funky T head on it not a normal hex head. It's also busted the weld & fracture the bolt.

Looking at the breaks on both bolts they have been fractured a long time with lots of rust. The one that fell off was holding on by about 25% of the head & finished fracturing very recently.

Anybody else had this happen?
Debating tracking down what looks to be a 16mm fine thread bolt & welding it up vs buying a couple new Yokes. Getting the right length shank before the threads start might be fun. None of the thread gauges I have do fine threaded that big. I'm assuming they used that funky T bolt as it would be hard to weld at the bottom of the yoke, but it looks like that didn't end up being that strong.

Yes,

Three times on my L6060. First lift arm bracket on left side. Then lift arm bracket on right side. Then bolt connecting stabilizer to axle bracket on left side. Started carrying new bolts and brackets in tool box.

HD 6' Woods cutter about about 150-200 Lbs. above Kubota recommended rotary cutter weight with F & R chains so removed front chains and replaced with belting to reduce weight a bit. Belting much more effective keeping debris from back of tractor anyway.

This is one reason why I have repeatedly recommended that owners not exceed Kubota recommended implement weights, despite critique by others herein and on orange site.

 

[Fallon]

16mm x 1.5mm pitch grade 12.5 bolts $6 each at Ace. I got ones that are to long, but I think the shoulder should match up better. Need to grind off the broken welds, but it looks like it will fit. I think I'll try & bolt it up without welding it in. I doubt I can get a socket or wrench on it, maybe jam it in a chisel to keep it from turning.

 

[CH4Ohio]

16mm x 1.5mm pitch grade 12.5 bolts $6 each at Ace. I got ones that are to long, but I think the shoulder should match up better. Need to grind off the broken welds, but it looks like it will fit. I think I'll try & bolt it up without welding it in. I doubt I can get a socket or wrench on it, maybe jam it in a chisel to keep it from turning.

Right!! That's what I'd do. Slide anything flat alongside the head of the bolt to keep it from turning. I don't really see why it needs to be welded anyway. Maybe I'm missing something. Doesn't matter if your bolts are too long, but if you want to cut them after they're installed, just cut with a hacksaw / sawzall.

 

[Fallon]

Slapped it all back together. A washer wouldn't fit under the bolt head without catching on the corners of the yoke. Lock washer fit though. Jammed a chisel between the bolt head & yoke to hold it while the impact tightened everything up. Ground a radius on the ends of the bar so it wouldn't hit. Have to see how it holds up. Easy enough to replace the bolt in the future.

A 70mm bolt has a good shoulder on it that fit well, the next side down had no shoulder, so I went with the longer one. May or may not get around to trimming it down.

 

[CH4Ohio]

You can buy a LOT of bolts for what Kubota wants for that welded assembly!

 

[Fallon]

You can buy a LOT of bolts for what Kubota wants for that welded assembly!

About 8 if you don't include lock nuts or washers. I'd pay it if it looked stronger than a bolt, but I just don't see the value of that funky nut welded in there.

 

[number two]

Good job!
Grade 12.5 must be one damn hard bolt!
Isn't grade 10.9 like SAE grade 8?
Good Luck!

 

[Fallon]

Good job!
Grade 12.5 must be one damn hard bolt!
Isn't grade 10.9 like SAE grade 8?
Good Luck!

It was a 10.9, which is the metric grade 8. Not sure why I mistyped 12.5. Given the failures & shock loading I'm questioning if harder is better. Harder is usually more brittle.

 

[hojolabo]

I've got over 1,000 hours on my L4060hstc. The other day my left side 3pt stabilizer fell off the lift arm. It looks like the bolt holding it onto the lift arm broke. Pulled it apart & it looks like the head of the bolt was welded onto the yoke & broke off. $50 at Messicks https://www.messicks.com/parts/kubota/ta140-71353, part 130 in https://www.messicks.com/catalogs/kubota/l4060hstc/3-point-linkage-drawbar-hitch/j11000-lower-link. But it should be as easy weld job to replace the bolt & weld it in. So I pull the other side to get some measurements as the entire head of the bolt is missing. Pull the other bolt & find it's got a funky T head on it not a normal hex head. It's also busted the weld & fracture the bolt.

Looking at the breaks on both bolts they have been fractured a long time with lots of rust. The one that fell off was holding on by about 25% of the head & finished fracturing very recently.

Anybody else had this happen?
Debating tracking down what looks to be a 16mm fine thread bolt & welding it up vs buying a couple new Yokes. Getting the right length shank before the threads start might be fun. None of the thread gauges I have do fine threaded that big. I'm assuming they used that funky T bolt as it would be hard to weld at the bottom of the yoke, but it looks like that didn't end up being that strong.

So why not just buy hardened socket head bolts, or a traditional head, modify some if needed, and call it a day.
You could put on your imaginary hat and simply re-engoneer it, that'd be a fun thing to do. Why throw good $$ after bad ?
Don't forget a little Never-Seize grease on the threads too, although after re-engineering, you shouldn't have to ever remove them.
Just my opinion is all, but thats what id do.

 

[CoyPatton]

It was a 10.9, which is the metric grade 8. Not sure why I mistyped 12.5. Given the failures & shock loading I'm questioning if harder is better. Harder is usually more brittle.

I agree the harder the bolt, the more brittle and the more likely to shear if any shear force is present. If you geel the need for a flat washer, but it hits stuff. Trial fit the washer (no need to tighten the bolt, mark what needs to be trimmed away with a sharpie, fit again and keep grinding till it fits.

 

[Gord Baker]

Glad it is fixed. Perhaps too much Side loading when turning?

 

[SDT]

Glad it is fixed. Perhaps too much Side loading when turning?

Yes, bracket and front attachment bolt subjected to heavy shock loads when turning, especially if mower hits obstacle and/or is beyond Kubota recommended weight limit.

Having used both telescoping and chain/adjustable stabilizers for decades, I'm no longer sold on telescoping stabilizers.

 

[jmc]

For what it's worth to the next people with this problem, 16mm x 1.5 pitch is real real close to
5/8 - 18. The SAE for this application might be cheaper and easier to find in the US.