Fabricators Corner

[Stairgod]

I thought anything over the diameter of the threaded part was irrelevant in terms of strength? (which is why lug nuts aren't any thicker than they are)
No?



I'm with you here - either a large weld flange on the nut, or don't weld it at all.. Looks like 10.9 nuts/bolts combo (or grade 8 for imperialists) is the only route here? (It's still sexier than ubolts though)

I would say that anything thicker than the diameter of the bolt is irrelevant if materials of equal strength are being used. In this case a grade 5 or 8 bolt and a mild steel plate of less than equal thickness kinda makes the plate the weak point.
Unfortunately my knowledge of metallurgy is quite limited.
Bolting spring steel(i.e. leaf springs) to a mild steel unit subject to every changing dynamic loads can prove to be quite an elaborate problem. Hence the torque to yield system of a u bolt. And complete replacement of said u bolt when changes are made takes a failure point out of the equation.

 

[malburg114]

Get a tap for the threads and before you put it together run it through. There’s a lot of crap in them once you get them. I stripped one and I re tapped it and run it with a nut loss on the bottom. No issues with them loosening up.

kind of a positive and negative is there’s nothing under the axle tube. Which means rocks won’t get caught but also mean no place to jack one side up haha. When trying to cycle the suspension had to weld a block on the bottom to jack it up by.

 

[malburg114]

Just Incase I ever have any issues I carry extra bolts that are extra long that I can I put through the plate and tighten with a nut on the bottom. Just a back up.

 

[Arcticelf]

I would say that anything thicker than the diameter of the bolt is irrelevant if materials of equal strength are being used. In this case a grade 5 or 8 bolt and a mild steel plate of less than equal thickness kinda makes the plate the weak point.
Unfortunately my knowledge of metallurgy is quite limited.
Bolting spring steel(i.e. leaf springs) to a mild steel unit subject to every changing dynamic loads can prove to be quite an elaborate problem. Hence the torque to yield system of a u bolt. And complete replacement of said u bolt when changes are made takes a failure point out of the equation.

You're very right about the material hardness vs thread pitch vs thickness. There is math to figure out if 1/2 mild steel is enough for the load. But you'd need to know what the actual load is.

Fortunately the major loading isn't parallel to the bolt. It's either compression (hitting the bump stop) or twisting/shearing (when you hit a large rock and try to rip the axle off).

So probably enough? But I wouldn't without seeing the math.

 

[85straight]

Good points made about the heat being that close to the threads , but I’m leaning on ruffstuffs reputation and other quality products that they make. If they had any sort of issues with threads stripping after install and wheeling I’m sure they wouldn’t be selling it. Aaaand I already bought the damn things so too late haha

 

[Itaro]

Good points made about the heat being that close to the threads , but I’m leaning on ruffstuffs reputation and other quality products that they make. If they had any sort of issues with threads stripping after install and wheeling I’m sure they wouldn’t be selling it. Aaaand I already bought the damn things so too late haha

 

[Arcticelf]

Good points made about the heat being that close to the threads , but I’m leaning on ruffstuffs reputation and other quality products that they make. If they had any sort of issues with threads stripping after install and wheeling I’m sure they wouldn’t be selling it. Aaaand I already bought the damn things so too late haha

I suspect it's okay based on your logic, but who knows what the safety margin is. And they don't make one the right width of my springs, so it doesn't matter to me.

 

[Slim-Whitey]

Grade 2 bolts are low/medium carbon steel. That the closest to "mild" you are going to get.

A 9/16x12 (coarse thread) grade 2 bolts has a minimum tensile strength of 13,000 lbs.
A 9/16x18 (fine) grade 2 bolts has a tensile strength of 15,000 lb.

If you've got 4 of those things per axle end, and your threaded area is equal to the diameter of the bolt, AND your plate is nearly the same grade as those grade 2 bolts, you're talking about a force moment parallel to the bolts of 60,000 lb to start breaking them.

I can't think of a time where a single axle corner faces 60,000lb of force while out wheeling. We're talking a distributed force of 120,000lb across the front axle.

Other shit is gonna break long. . . Long before that.

The shear strength is based more on the plate. You aren't shearing a grade 8 9/16 bolt into a mild steel plate with even 3/4" of "meat" around the outside of the bolts. You'd have to tear that steel out.

Again, other shit is breaking way... Way before that.

Not to mention that the bolts, being bolted downward and tight to the plate, aren't directly encountering undistributed moment load anyway. They're holding the plates in place as the area transfer force.

 

[Stairgod]

Grade 2 bolts are low/medium carbon steel. That the closest to "mild" you are going to get.

A 9/16x12 (coarse thread) grade 2 bolts has a minimum tensile strength of 13,000 lbs.
A 9/16x18 (fine) grade 2 bolts has a tensile strength of 15,000 lb.

If you've got 4 of those things per axle end, and your threaded area is equal to the diameter of the bolt, AND your plate is nearly the same grade as those grade 2 bolts, you're talking about a force moment parallel to the bolts of 60,000 lb to start breaking them.

I can't think of a time where a single axle corner faces 60,000lb of force while out wheeling. We're talking a distributed force of 120,000lb across the front axle.

Other shit is gonna break long. . . Long before that.

The shear strength is based more on the plate. You aren't shearing a grade 8 9/16 bolt into a mild steel plate with even 3/4" of "meat" around the outside of the bolts. You'd have to tear that steel out.

Again, other shit is breaking way... Way before that.

Not to mention that the bolts, being bolted downward and tight to the plate, aren't directly encountering undistributed moment load anyway. They're holding the plates in place as the area transfer force.

Comment redacted

 

[Slim-Whitey]

FYI: the reason U bolts are not re-used isn't because they are torque to yield.

It's because they are structural pieces which are subjected to tensile stress.
Very few pieces of a vehicle actually see tensile stress, and because U-bolts are under constant tensile stress, they are not re-used, as the grain structure of the metal can be deformed from regular use. That sounds like TTY, but it's not. Not every U bolt will see deformation. Every TTY bolt will. But when it's something that holds the structure holding your vehicle up in place, you don't reuse it.

If you draw a U bolt to its yield point, you run the risk of snapping them. TTY bolts are used (mainly) in engine assemblies to get the maximum, uniform hold from pieces which see constant stresses. Head bolts, for instance. Head bolts are under tensile stress, but their stress load and the force moments applied do not vary wildly during use.

The other side of this is that U bolts and the nuts used are not normal steel. They aren't even grade 8 steel. They are considered structural steel.
If you take a 9/16 U bolt (9/16x20, might be finer actually, with a 1" nut), and you put an impact on it, "tight" is "when the gun won't physically spin anymore". A TTY bolt is tightened in a specific sequence. U bolts are "tight as they fuckin go". For reference, that's how structural steel buildings are rattled together.
Now factor in that the upgraded U bolts guys use are 5/8 or even 11/16 at times. That's alotta fuckin iron to deform.

Dunno if any of that helped, but I felt like rambling.

--DAMN, that's the most I've ever edited a post. Sheeit.

 

[Stairgod]

FYI: the reason U bolts are not re-used isn't because they are torque to yield.

It's because they are structural pieces which are subjected to tensile stress.
Very few pieces of a vehicle actually see tensile stress, and because U-bolts are under constant tensile stress, they are not re-used, as the grain structure of the metal can be deformed from regular use.

If you draw a U bolt to its yield point, you run the risk of snapping them. TTY bolts are used (mainly) in engine assemblies to get the maximum, uniform hold from pieces which see constant stresses. Head bolts, for instance. Head bolts are under tensile stress, but their stress load and the for e moments applied do not vary wildly during use.

The other side of this is that U bolts and the nuts used are not normal steel. They aren't even grade 8 steel. They are considered structural steel.
If you take a 9/16 U bolt (9/16x20, with a 1" thick nut), and you put an impact on it, "tight" is "when the gun won't physically spin anymore". A TTY bolt is tightened in a specific sequence. U bolts are "tight as they fuckin go". For reference, that's how structural steel buildings are rattled together.
Now factor in that the upgraded U bolts guys use are 5/8 or even 11/16 at times. That's alotta fuckin iron to deform.

Dunno if any of that helped, but I felt like rambling.

U bolts do in fact deform when properly tightened. The term TTY may have been used erroneously as that does seem to be a very specific term for a type of fastener in a specific use.
The reason that the nuts never come off a u bolt easily is not due to crud and/or corrosion but from the fact that they stretch and the threads get fuckered.
And yes u bolts are graded.
As are any "structural" bolt used in any industry.

I know of a certain utility company that just spent $5 mil to source and install new bolts at a nuclear plant because the bolts were not the right grade.

 

[eimkeith]

FYI: the reason U bolts are not re-used isn't because they are torque to yield.

It's because they are structural pieces which are subjected to tensile stress.
Very few pieces of a vehicle actually see tensile stress, and because U-bolts are under constant tensile stress, they are not re-used, as the grain structure of the metal can be deformed from regular use. That sounds like TTY, but it's not. Not every U bolt will see deformation. Every TTY bolt will. But when it's something that holds the structure holding your vehicle up in place, you don't reuse it.

If you draw a U bolt to its yield point, you run the risk of snapping them. TTY bolts are used (mainly) in engine assemblies to get the maximum, uniform hold from pieces which see constant stresses. Head bolts, for instance. Head bolts are under tensile stress, but their stress load and the force moments applied do not vary wildly during use.

The other side of this is that U bolts and the nuts used are not normal steel. They aren't even grade 8 steel. They are considered structural steel.
If you take a 9/16 U bolt (9/16x20, might be finer actually, with a 1" nut), and you put an impact on it, "tight" is "when the gun won't physically spin anymore". A TTY bolt is tightened in a specific sequence. U bolts are "tight as they fuckin go". For reference, that's how structural steel buildings are rattled together.
Now factor in that the upgraded U bolts guys use are 5/8 or even 11/16 at times. That's alotta fuckin iron to deform.

Dunno if any of that helped, but I felt like rambling.

--DAMN, that's the most I've ever edited a post. Sheeit.

well, I like learning things.

 

[Stairgod]

Ok Slim. You seem to know things. And you should know what this is.
What do you think the torque spec is for this fastener?
What grade is it?
How is the clamping force developed?

 

[Slim-Whitey]

U bolts do in fact deform when properly tightened. The term TTY may have been used erroneously as that does seem to be a very specific term for a type of fastener in a specific use.
The reason that the nuts never come off a u bolt easily is not due to crud and/or corrosion but from the fact that they stretch and the threads get fuckered.
And yes u bolts are graded.
As are any "structural" bolt used in any industry.

I know of a certain utility company that just spent $5 mil to source and install new bolts at a nuclear plant because the bolts were not the right grade.

Agreed almost all round.
Minus the thread bit. Maybe I've just never had them tight enough, which is possible, but you shouldn't be deforming the threads on that nut. Because you cannot control that deformation without a specific torque sequence.
Now maybe suspension isn't finicky enough to need that specific sequence like, say, a head or a valvecover.
But I don't see vehicle design just going willy Milly like that.

On a given vehicle, if you tighten one side and I tighten the other, you and I will get different deformation amounts. You're (probably ) stronger than I am, you tighten them harder. That's no bueno.

You're right, they're graded. But it's not the same as a grade 5 or 8 or 10.9(M) or 12.9(M) or what have you. They are their own thing, in relation to a vehicle.

View attachment 15158
Ok Slim. You seem to know things. And you should know what this is.
What do you think the torque spec is for this fastener?
What grade is it?
How is the clamping force developed?

I couldn't tell you what that is, minus a photo of a rusted nut on a rusted bolt. The torque spec should be noted by a manufacturer, and if not, a general approximation can be made by the type of bolt, type of material being clamped, thread and shank thickness. I used to know a ton of them (3/8 fine thread steel shank into iron threads, clamping aluminum is about 30ftlb, as I recall. But I might just be remembering Cummins accessory torque specs).

I see no easy notation of bolt and nut grade, although the tall nut and thick washer tells me it's something structural.
Edit: removed note about coarse thread. Better look, that's not coarse. Although these days I deal mainly with ultra fine hardware, so anything looks coarse.

I don't know what to tell you, if I was sent that photo of something on a jobsite I'd be wanting more before I said "just rattle on er till she's tight".

But hell, maybe I'm overthinking it.
What is it exactly? I'm curious now. You've got me thinking.

 

[Stairgod]

Agreed almost all round.
Minus the thread bit. Maybe I've just never had them tight enough, which is possible, but you shouldn't be deforming the threads on that nut. Because you cannot control that deformation without a specific torque sequence.
Now maybe suspension isn't finicky enough to need that specific sequence like, say, a head or a valvecover.
But I don't see vehicle design just going willy Milly like that.

On a given vehicle, if you tighten one side and I tighten the other, you and I will get different deformation amounts. You're (probably ) stronger than I am, you tighten them harder. That's no bueno.

You're right, they're graded. But it's not the same as a grade 8 or 10. They are their own thing, in relation to a vehicle..



I couldn't tell you what that is, minus a photo of a rusted nut on a rusted bolt. The torque spec should be noted by a manufacturer, and if not, a general approximation can be made by the type of bolt, type of material being clamped, thread and shank thickness. I used to know a ton of them (3/8 fine thread steel shank into iron threads, clamping aluminum is about 30ftlb, as I recall. But I might just be remembering Cummins accessory torque specs).

I see no easy notation of bolt and nut grade, although the tall nut and thick washer tells me it's something structural.

I don't know what to tell you, if I was sent that photo of something on a jobsite I'd be wanting more before I said "just rattle on er till she's tight".

But hell, maybe I'm overthinking it.
What is it exactly? I'm curious now. You've got me thinking.

It's a tension control bolt. My only experience with them comes from bolted connections on A36 and A575 W beams.
This one is 3/4" and has a minimum tensile strength of 40k lbft. Which happens to match a grade 8 bolt.
The tool used to tightened it only develops about 1200 lbft but the spline part of the bolt shears at around 1000 lbft.
Believe it or not but the clamping force comes not from the bolt itself but from the beam and/or clip material. So much force developed over a small area actually causes the beam to slightly deform. That way the bolts are not overstressed and maintain their full shear properties.
Not to mention that having twelve bolts on a single connection that only sees a 40k pound load...lol.

 

[Stairgod]

Oh, interesting fact. Rusty ones like this are unusable. They come in bags and are prelubed. Only the manufacturer can lube them so as to guarantee proper torque.
These things are pickier than head bolts on an engine apparently

 

[Slim-Whitey]

View attachment 15159
It's a tension control bolt. My only experience with them comes from bolted connections on A36 and A575 W beams.
This one is 3/4" and has a minimum tensile strength of 40k lbft. Which happens to match a grade 8 bolt.
The tool used to tightened it only develops about 1200 lbft but the spline part of the bolt shears at around 1000 lbft.
Believe it or not but the clamping force comes not from the bolt itself but from the beam and/or clip material. So much force developed over a small area actually causes the beam to slightly deform. That way the bolts are not overstressed and maintain their full shear properties.
Not to mention that having twelve bolts on a single connection that only sees a 40k pound load...lol.

Right on all accounts. Although that was really skeevy of you to try to bait me into saying what it was with poor information so you could say I was wrong. Poor form, old boy.

AAAAANYHOOZLE
Mounting two beams of similar metallurgy to each other in a direct connection, is not the same as sandwiching a multi-plate spring steel member between a two mild steel members (perch and plate). Your leaf spring pack will not deform like your beams will. Nor should they, as that deformation would change the spring rate.

And, a note about your impact gun:
Unless things have changed, maximum torque is the breakaway force of the gun. Your typical "max 1200ftlb" gun is running a max fastening force of around 700. That's from the structural/pre-eng guy I know. He runs Hilti impacts.
It was the same for my old pneumatic guns. My mac was Max 700 breakaway, 450 fastening.

Oh, interesting fact. Rusty ones like this are unusable. They come in bags and are prelubed. Only the manufacturer can lube them so as to guarantee proper torque.
These things are pickier than head bolts on an engine apparently

Yeah I brought a box of hex head ones home for shits because they were beginning to corrode on site. Had to get new ones. They were headed to the dumpster, and I snagged em.
Probably never see them used, but hey, free is free. Could fishplate and bolt the frame I guess, hahaha.

 

[Stairgod]

Right on all accounts. Although that was really skeevy of you to try to bait me into saying what it was with poor information so you could say I was wrong. Poor form, old boy.

AAAAANYHOOZLE
Mounting two beams of similar metallurgy to each other in a direct connection, is not the same as sandwiching a multi-plate spring steel member between a two mild steel members (perch and plate). Your leaf spring pack will not deform like your beams will. Nor should they, as that deformation would change the spring rate.

And, a note about your impact gun:
Unless things have changed, maximum torque is the breakaway force of the gun. Your typical "max 1200ftlb" gun is running a max fastening force of around 700. That's from the structural/pre-eng guy I know. He runs Hilti impacts.
It was the same for my old pneumatic guns. My mac was Max 700 breakaway, 450 fastening.



Yeah I brought a box of hex head ones home for shits because they were beginning to corrode on site. Had to get new ones. They were headed to the dumpster, and I snagged em.
Probably never see them used, but hey, free is free. Could fishplate and bolt the frame I guess, hahaha.

Actually those guns are rated at fastening torque. They don't have reverse.

 

[Slim-Whitey]

Actually those guns are rated at fastening torque. They don't have reverse.

Damn.
That's pretty cool.

Haven't had any struc guys come in with those.
Couple of big Hilti or Makita 3/4 drives that are rated at like 1100 fastening and I don't even know what breakaway, and then all half drive Hiltis.

Mainly cause he ran over a Hilti with his zoomboom and not only did it still function for a full day, but Hilti fucking warrantied it. Like. . . Wtf.

 

[Stairgod]

Damn.
That's pretty cool.

Haven't had any struc guys come in with those.
Couple of big Hilti or Makita 3/4 drives that are rated at like 1100 fastening and I don't even know what breakaway, and then all half drive Hiltis.

Mainly cause he ran over a Hilti with his zoomboom and not only did it still function for a full day, but Hilti fucking warrantied it. Like. . . Wtf.

Hilti does make good shit. Ever watch AvE on YouTube? He adores everything Hilti. And hates Festool.