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'05+ Ford Super Duty Dana 60 Axle Tech & Info

Are there any weak links to the stock steering setup beyond it being in the dirt?
Stock steering is set up for a y link style draglink / tie rod, so having one knuckle set for high steer can help with drag link/ track bar geometry
 
Stock steering is set up for a y link style draglink / tie rod, so having one knuckle set for high steer can help with drag link/ track bar geometry
Would you clarify "y link style? My uninformed knowledge is the drag link has a long tie rod with a hole in the end attaches to the passenger side. The tie rod attaches to this hole and forms a Y looking structure.

From the pictures I've seen of the Ford setup, the drag link has a long shank tie rod that goes through the knuckle on the top and connects to the drag link with an unknown tie rod end.
 
Would you clarify "y link style? My uninformed knowledge is the drag link has a long tie rod with a hole in the end attaches to the passenger side. The tie rod attaches to this hole and forms a Y looking structure.

From the pictures I've seen of the Ford setup, the drag link has a long shank tie rod that goes through the knuckle on the top and connects to the drag link with an unknown tie rod end.
Y link is like you described in the top paragraph, I might be thinking of 99-04 steering
 
nOOB questions:
a) What is usually the pinion angle on said front axle?
b) What is usually the caster angle on said front axle?
c) With the 6" lift will I have to compromise greatly with the caster and pinion angle?
d) How bad would it be on steering if I set the caster to 0* in order to have a more proper pinion angle?
e) How bad would it be on steering if I set the caster to -1* in order to have a more proper pinion angle?
f) Where on said axle could I use as a reference point when setting/determining caster?

Stock '19 F350:
Pinion is about 7 degrees
Caster is about 5 degrees
6" lift on a formerly-stock truck, you'll be compromising one or the other of them.
Caster at zero will SUUUUUCK. Don't do that.
Caster at stock 5 degrees... well... there's a recall on my truck for weak steering stabilizer resulting in death wobble. I would recommend 5 as minimum for caster, and prefer more. 6-8 would be good. More than 8 is excessive IMO.
The upper ball joint pad has a flat top on it that matches angle with the caster.

Also, what is the difference between a 2017+ knuckle and a 2012.5 to 16? Weaver fab is showing they are different but it isn't clear if it is same "brakes" with aluminum knuckles. If it is aluminum knuckles, what is the weight saving?

I'm starting to shop for a front axle and the cost difference between 05-08, 09-12, 13-16, and 17+ are within striking distance of each other depending on the drive(+/- 100 miles).

'17-up is bigger knuckles and 1550 shafts stock. I think it's also bigger brakes but not 100% sure. I have a '19 if you want measurements off of it.
 
'17-up is bigger knuckles and 1550 shafts stock. I think it's also bigger brakes but not 100% sure. I have a '19 if you want measurements off of it.
I haven't looked at Rockauto for the brake size yet but are you thinking the brakes are bigger than the '12+?

Since you have one in hand, pictures and measurements would be awesome in this thread. Are the knuckles still steel/iron?
 
The picture you linked is of the first gen that I scraped. It was up to show the difference. It was was all laser cut plate, looked cool, but the geometry was a little off and the wheel clearance wasn't great. I made a gen 2 with simple flat bar and only two laser cut tabs. The gen 2 would be easy for anyone to make in their garage. Substitute the laser cut tabs for flat bar or notch some premade link tabs to fit. I also decided the lower stock ear was useless for the high steer attachment so I cut it off and sanded the knuckle flat to clean up the looks. The centerline of the ball joints to steering rod end is 5.5" for 45* of angle using a 8" cylinder.
I believe a bolt through design that covers more area is going to be more bombproof than a keyed top with tapped bolts. I have seen weld on staying strong on some beat up axles and rigs and have also seen some pop right off. I am confident in my cast welding enough to do a 205 shave but not for steering when it its a matter of driving off a cliff.
You cant get much cheaper than the gen 2 version either. You would need to buy or have a 5/8" tap and drill for the two top bolts and a 3/4" drill for the lower through bolts. Its all hand drilled no mill work.

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Read everything below at your own risk.
My real life job is to develop welded structures and bolted joints and I can go into more detail or try to clarify what I wrote but in the end these are my personal opinions.

This style of bolt on arm still puts the bolted joint in shear and bending. If there is a gap between the bolt shank and the hole through the knuckle and bracket the bolted joint can loosen over time. You would also need to mill the casting flat to get a good flat surface as well. Any small surface irregularities will lead to bolt loosening.

This issue can be minimized by drilling the holes undersized, reaming them to exact size and running ground body bolts that are essentially dowels at that point. There may still be bending issues.

Most of the high steer arms I've seen also put the bolts in shear.

I should explain why shear on a bolted joint is bad. A bolt joint is strongest in direct tension. Pulling along the length of the bolt. Shear loading is a force perpendicular to the bolt or along the joint between the two pieces being bolted together. In this direction the bolted joint can only handle 10-15% of the bolt clamp load and this is completely dependent on the friction between the two surfaces. As soon as the friction is overcome the joint will slip. When it does the bolt sees bending and there is a tiny amount of microscopic wear that relieves some of the bolt preload. Over time the bolt bends back and forth and the surfaces continues to wear relieving more preload and ultimately the bolt breaks or is completely loose. In the bolted joint design world the joint has failed as soon as slip occurs.

If there is no reversal this isn't typically a problem. But when the joint is cycled back and forth the bolt will either loosen from the wear at the interface or break due to bending. I've seen many examples where both happen in the same joint.

There just isn't a large enough surface to put enough bolts in to get enough shear capacity in the stock steering knuckle to keep it from slipping.

A key or dowel or ground body bolt can be added to take the shear force and the bolt is then only responsible for holding the two parts together.

A keyed or doweled high steer arm using the stock knuckles can have one inherent problem. On some of the knuckles I've seen there isn't enough material to get good thread engagement. I don't know if this is a core shift during the casting pour or the machinist didn't set the knuckle up correctly in the mill. I haven't seen all that many and they were all machined locally so I don't know how much of an issue it is.

Critical bolted joints should have at least 1.5x thread diameter thread engagement for steel. On rare occasions where I've done a full nonlinear FEA with max forces I will design for 1x thread diameter. These are for a system that will basically never fail in bending or come loose.

So the aftermarket knuckle with extra material is a good choice but it really needs to have a key or a couple of dowels to handle the shear load. I haven't seen any aftermarket superduty knuckles with a key. I understand some have dowels but I haven't seen how they're used.

The next issue is the dowel or key fit. Theoretically, a line to line fit would work but realistically we can't machine the parts that closely so a very small interference between the dowel and it'd mating hole or the key and it's slot would be necessary to ensure the joint doesn't slip. If there is a slight gap between the dowel and hole or key and slot the bolted joint will eventually loosen.
 
I haven't looked at Rockauto for the brake size yet but are you thinking the brakes are bigger than the '12+?

Since you have one in hand, pictures and measurements would be awesome in this thread. Are the knuckles still steel/iron?
I think so but I don't have parts to compare. Rotors off of mine are 14.25 OD/1.5 thick. Not sure on the calipers for comparison. Knuckles are iron. I believe the '12-16 would fit 16" wheels (not sure) but I'm quite sure the '17+ will not fit smaller than 17's, and may not clear aluminum 17's.

On a side note, I'm unimpressed with the rotors, the OEM ones warped well under 20k miles, the aftermarket ones I put on when Ford wouldn't take care of that, warped already, truck has less than 42k on it, looks like it'll be getting a third pair of rotors here shortly. I don't haul heavy, the most it's ever pulled is about 8k, but I also don't tow much on flat ground. A friend of mine has a '17 with 25k or so on it, and is seeing the beginnings of warped rotors on his as well, his has never pulled more than 2k.
 
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Stock '19 F350:
Pinion is about 7 degrees
Caster is about 5 degrees
6" lift on a formerly-stock truck, you'll be compromising one or the other of them.
Caster at zero will SUUUUUCK. Don't do that.
Caster at stock 5 degrees... well... there's a recall on my truck for weak steering stabilizer resulting in death wobble. I would recommend 5 as minimum for caster, and prefer more. 6-8 would be good. More than 8 is excessive IMO.
The upper ball joint pad has a flat top on it that matches angle with the caster.



'17-up is bigger knuckles and 1550 shafts stock. I think it's also bigger brakes but not 100% sure. I have a '19 if you want measurements off of it.
My cad model of the 2005 F550 shows 10.155* between the pinion and the caster plane. Ride height is 8.57* caster with 1.57* pinion pointing up. Because the king pin inclination cants the caster pad on the top of the axle depending on how and what you use to measure with, I created a single plane between the ball joints to isolate the caster measurement. The cad model and the as built pictures look identical, but I have not field verified the angles.
 
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I think so but I don't have parts to compare. Rotors off of mine are 14.25 OD/1.5 thick. Not sure on the calipers for comparison. Knuckles are iron. I believe the '12-16 would fit 16" wheels (not sure) but I'm quite sure the '17+ will not fit smaller than 17's, and may not clear aluminum 17's.

On a side note, I'm unimpressed with the rotors, the OEM ones warped well under 20k miles, the aftermarket ones I put on when Ford wouldn't take care of that, warped already, truck has less than 42k on it, looks like it'll be getting a third pair of rotors here shortly. I don't haul heavy, the most it's ever pulled is about 8k, but I also don't tow much on flat ground. A friend of mine has a '17 with 25k or so on it, and is seeing the beginnings of warped rotors on his as well, his has never pulled more than 2k.
I don't believe you have warped rotors. You have uneven pad build up on the rotors from hot stops. You need to break in or bed your brakes again whenever you have worked them hard enough to create uneven build up. Keep in mind ambient temps will change how easy brakes heat up and cool down.

Break in your PowerStop Brakes as follows:

5 moderate to aggressive stops from 40 mph down to 10 mph in rapid succession without letting the brakes cool and do not come to a complete stop. If you’re forced to stop, either shift into neutral or give room in front so you can allow the vehicle to roll slightly while waiting for the light. The rotors will be very hot and holding down the brake pedal will allow the pad to create an imprint on the rotor. This is where the judder can originate from.

Then do 5 moderate stops from 35 mph to 5 mph in rapid succession without letting the brakes cool. You should expect to smell some resin as the brakes get hot.

After this is complete, drive around for as long as possible without excessively heating the brakes and without coming to a complete stop (Try for about 5 minutes at moderate speed). This is the cooling stage. It allows the heated resin in the brake pads to cool and cure.

After the brakes have cooled to standard operating temperature, you may use the brakes normally.
 
I think the brakes went to to the 14 1/4" in 2013.
Here are the two numbers I pulled from Rockauto:
Ford under 2012 13.66" 1.495" thick ~4" tall
Ford over 2012 14.29" 1.515" thick ~4" tall

I don't know if 17+ fall under the above or are another size. I haven't looked.
 
Here are the two numbers I pulled from Rockauto:
Ford under 2012 13.66" 1.495" thick ~4" tall
Ford over 2012 14.29" 1.515" thick ~4" tall

I don't know if 17+ fall under the above or are another size. I haven't looked.
I stand corrected on when the bigger rotors came into play then, your 2012+ and Welndmn's gut suggest that they've been around quite a bit longer than I thought.
 
Are there any weak links to the stock steering setup beyond it being in the dirt?
I don't know that it has a weak link, but the problem is everything else is super strong. You can rest the weight of the entire truck on the diff or the axle tubes. You can't rest the truck on the tierod. I'm not sure what would give (tierod, ends or knuckle mounts), but something would. If you look below a stock truck, the tierod is the lowest point between the diff and knuckle. Of course, depending on your bumper, it's also the first thing the truck will hit.
 
I don't know that it has a weak link, but the problem is everything else is super strong. You can rest the weight of the entire truck on the diff or the axle tubes. You can't rest the truck on the tierod. I'm not sure what would give (tierod, ends or knuckle mounts), but something would. If you look below a stock truck, the tierod is the lowest point between the diff and knuckle. Of course, depending on your bumper, it's also the first thing the truck will hit.
So in other words, don't go play truck pinball in the rocks:homer:
 
I think so but I don't have parts to compare. Rotors off of mine are 14.25 OD/1.5 thick. Not sure on the calipers for comparison. Knuckles are iron. I believe the '12-16 would fit 16" wheels (not sure) but I'm quite sure the '17+ will not fit smaller than 17's, and may not clear aluminum 17's.

On a side note, I'm unimpressed with the rotors, the OEM ones warped well under 20k miles, the aftermarket ones I put on when Ford wouldn't take care of that, warped already, truck has less than 42k on it, looks like it'll be getting a third pair of rotors here shortly. I don't haul heavy, the most it's ever pulled is about 8k, but I also don't tow much on flat ground. A friend of mine has a '17 with 25k or so on it, and is seeing the beginnings of warped rotors on his as well, his has never pulled more than 2k.

Grendel will probably be in here shortly to disagree with me again, but 17" steel wheels are a factory option on '17+ trucks and I know of people running aftermarket aluminum 17" wheels on '17+ trucks (same rotor diameter as '13-'16 trucks). There may be issues with some afternarket wheels, but 17" are certainly doable.
 
Read everything below at your own risk.
My real life job is to develop welded structures and bolted joints and I can go into more detail or try to clarify what I wrote but in the end these are my personal opinions.

This style of bolt on arm still puts the bolted joint in shear and bending. If there is a gap between the bolt shank and the hole through the knuckle and bracket the bolted joint can loosen over time. You would also need to mill the casting flat to get a good flat surface as well. Any small surface irregularities will lead to bolt loosening.

This issue can be minimized by drilling the holes undersized, reaming them to exact size and running ground body bolts that are essentially dowels at that point. There may still be bending issues.

Most of the high steer arms I've seen also put the bolts in shear.

I should explain why shear on a bolted joint is bad. A bolt joint is strongest in direct tension. Pulling along the length of the bolt. Shear loading is a force perpendicular to the bolt or along the joint between the two pieces being bolted together. In this direction the bolted joint can only handle 10-15% of the bolt clamp load and this is completely dependent on the friction between the two surfaces. As soon as the friction is overcome the joint will slip. When it does the bolt sees bending and there is a tiny amount of microscopic wear that relieves some of the bolt preload. Over time the bolt bends back and forth and the surfaces continues to wear relieving more preload and ultimately the bolt breaks or is completely loose. In the bolted joint design world the joint has failed as soon as slip occurs.

If there is no reversal this isn't typically a problem. But when the joint is cycled back and forth the bolt will either loosen from the wear at the interface or break due to bending. I've seen many examples where both happen in the same joint.

There just isn't a large enough surface to put enough bolts in to get enough shear capacity in the stock steering knuckle to keep it from slipping.

A key or dowel or ground body bolt can be added to take the shear force and the bolt is then only responsible for holding the two parts together.

A keyed or doweled high steer arm using the stock knuckles can have one inherent problem. On some of the knuckles I've seen there isn't enough material to get good thread engagement. I don't know if this is a core shift during the casting pour or the machinist didn't set the knuckle up correctly in the mill. I haven't seen all that many and they were all machined locally so I don't know how much of an issue it is.

Critical bolted joints should have at least 1.5x thread diameter thread engagement for steel. On rare occasions where I've done a full nonlinear FEA with max forces I will design for 1x thread diameter. These are for a system that will basically never fail in bending or come loose.

So the aftermarket knuckle with extra material is a good choice but it really needs to have a key or a couple of dowels to handle the shear load. I haven't seen any aftermarket superduty knuckles with a key. I understand some have dowels but I haven't seen how they're used.

The next issue is the dowel or key fit. Theoretically, a line to line fit would work but realistically we can't machine the parts that closely so a very small interference between the dowel and it'd mating hole or the key and it's slot would be necessary to ensure the joint doesn't slip. If there is a slight gap between the dowel and hole or key and slot the bolted joint will eventually loosen.
This man speaks the truth. Not knocking Hydrodynamic in any way, but I had similar thoughts looking at the pictures of his design.
 
Read everything below at your own risk.
My real life job is to develop welded structures and bolted joints and I can go into more detail or try to clarify what I wrote but in the end these are my personal opinions.

This style of bolt on arm still puts the bolted joint in shear and bending. If there is a gap between the bolt shank and the hole through the knuckle and bracket the bolted joint can loosen over time. You would also need to mill the casting flat to get a good flat surface as well. Any small surface irregularities will lead to bolt loosening.

This issue can be minimized by drilling the holes undersized, reaming them to exact size and running ground body bolts that are essentially dowels at that point. There may still be bending issues.

Most of the high steer arms I've seen also put the bolts in shear.

I should explain why shear on a bolted joint is bad. A bolt joint is strongest in direct tension. Pulling along the length of the bolt. Shear loading is a force perpendicular to the bolt or along the joint between the two pieces being bolted together. In this direction the bolted joint can only handle 10-15% of the bolt clamp load and this is completely dependent on the friction between the two surfaces. As soon as the friction is overcome the joint will slip. When it does the bolt sees bending and there is a tiny amount of microscopic wear that relieves some of the bolt preload. Over time the bolt bends back and forth and the surfaces continues to wear relieving more preload and ultimately the bolt breaks or is completely loose. In the bolted joint design world the joint has failed as soon as slip occurs.

If there is no reversal this isn't typically a problem. But when the joint is cycled back and forth the bolt will either loosen from the wear at the interface or break due to bending. I've seen many examples where both happen in the same joint.

There just isn't a large enough surface to put enough bolts in to get enough shear capacity in the stock steering knuckle to keep it from slipping.

A key or dowel or ground body bolt can be added to take the shear force and the bolt is then only responsible for holding the two parts together.

A keyed or doweled high steer arm using the stock knuckles can have one inherent problem. On some of the knuckles I've seen there isn't enough material to get good thread engagement. I don't know if this is a core shift during the casting pour or the machinist didn't set the knuckle up correctly in the mill. I haven't seen all that many and they were all machined locally so I don't know how much of an issue it is.

Critical bolted joints should have at least 1.5x thread diameter thread engagement for steel. On rare occasions where I've done a full nonlinear FEA with max forces I will design for 1x thread diameter. These are for a system that will basically never fail in bending or come loose.

So the aftermarket knuckle with extra material is a good choice but it really needs to have a key or a couple of dowels to handle the shear load. I haven't seen any aftermarket superduty knuckles with a key. I understand some have dowels but I haven't seen how they're used.

The next issue is the dowel or key fit. Theoretically, a line to line fit would work but realistically we can't machine the parts that closely so a very small interference between the dowel and it'd mating hole or the key and it's slot would be necessary to ensure the joint doesn't slip. If there is a slight gap between the dowel and hole or key and slot the bolted joint will eventually loosen.
Everything you are saying is text book, and the same as I was taught.

I went through a number of different bolt designs trying to calculate what was the strongest. Where to attach the plate or bars to the knuckles for best fit. Distance from bolt centers, angles of bolts, thickness of knuckle, thread engagement.

What you can not see if how the assembly was put together.
The flats of the knuckles were ground flat to eliminate gap with the bars.
All the holes were drilled in steps and bolted tight as others were drilled so the bores are aligned.
The individual bars were welded once bolted to the knuckle so the bars were true to the surface without binding. This is important and not something that is normally done in industry.

Your comment "There just isn't a large enough surface to put enough bolts in to get enough shear capacity in the stock steering knuckle to keep it from slipping."
This why I don't care for the stock milled knuckles. All the bolts and or keys are on one shear plane and close together and of small diameter with minimal thread engagement into the cast.
That is why I went with 3/4" through bolts with full shank through the casting and halfway through the bar to mimic a dowel even though the bolt shaft is not precision. Using a fine thread bolt and metal locking nut allows for full torque and a permanent hold rather than a under torqued tapped cast connection with threadlocker.
To triangulate the bolted connections to eliminate shifting by grabbing multiple planes, I went as far of a distance as possible to lower the leverage on the bolts.
The 5/8" tapped bolt near the brake is 1.4X thread engagement
The 5/8" tapped bolt near the bearing is 1.6X thread engagement
 
Your comment "There just isn't a large enough surface to put enough bolts in to get enough shear capacity in the stock steering knuckle to keep it from slipping."
This why I don't care for the stock milled knuckles. All the bolts and or keys are on one shear plane and close together and of small diameter with minimal thread engagement into the cast.

I wasn't trying to pick your design apart. It's an interesting take. I was trying to bring more technical detail into bolted joints in general and steering arms in particular.

On the keyed or doweled approach, the bolts become secondary and the number of bolts can be reduced. I think an interference fit key with 4 bolts would be fine. But...I had an old timer tell me "no one will ever complain you used too many bolts, they will if you use one less than you needed." So I would put a few extras since it's a critical joint.
 
I wasn't trying to pick your design apart. It's an interesting take. I was trying to bring more technical detail into bolted joints in general and steering arms in particular.
My response wasn't so much in defense of what I did, but more to include the important info for those who want to build something similar. Pictures don't show how it was made or all the important parts or details.
I would be all for someone to do the same thing and then weld it solid to the knuckle along with the bolts if they are worried about it shifting.
I would not trust welded alone for a hard hit even though I think a welded version of this is going to be stronger than most of the weld on plate kits on the market. But I would trust the bolts alone for a hard hit even if something stretched and play developed. Bolted and welded is the best of both. I just don't think it is necessary until proven it needs to be welded.
I have a feeling the upper ball joint would let go before the steering arms feel off.
 
I would be all for someone to do the same thing and then weld it solid to the knuckle along with the bolts if they are worried about it shifting.
I would not trust welded alone for a hard hit even though I think a welded version of this is going to be stronger than most of the weld on plate kits on the market. But I would trust the bolts alone for a hard hit even if something stretched and play developed. Bolted and welded is the best of both. I just don't think it is necessary until proven it needs to be welded.
I have a feeling the upper ball joint would let go before the steering arms feel off.
This is my plan for the 4800 build. With regular inspection, I don't see any issues. Some good food for thought with all the bolted connection stuff for those of us who are not engineers!
 
This is a great conversation. It involves safety and strength increase, possibly even saving a few pennies.

I like Hydrodynamic's design and it could be altered for using tie rod ends as well..but I have a question.

When a joint is assembled and the hardware torqued, then it welded to the knuckle. The heat from the welding will have an effect the bolt torque/stretch.

What is the proper order of assembly? Re-torque after welds cool?
 
This is a great conversation. It involves safety and strength increase, possibly even saving a few pennies.

I like Hydrodynamic's design and it could be altered for using tie rod ends as well..but I have a question.

When a joint is assembled and the hardware torqued, then it welded to the knuckle. The heat from the welding will have an effect the bolt torque/stretch.

What is the proper order of assembly? Re-torque after welds cool?
I usually use different hardware during assembly and disassembly as metal lock nuts should only be used once, plus its a pain to use any locking fastener when you intend to take it off multiple times before it goes on for good. Once it was welded and painted then I applied threadlocker and torqued the final nuts and bolts.
 
What if someone was to replicate your design, then weld the assembly to the knuckle?

Assemble > weld the assembly > weld to the knuckle > replace and torque hardware after cooling?
 
So the aftermarket knuckle with extra material is a good choice but it really needs to have a key or a couple of dowels to handle the shear load. I haven't seen any aftermarket superduty knuckles with a key. I understand some have dowels but I haven't seen how they're used.

Weaver has dowels on their milled stock knuckle setup.
BKOR has keyed Reid knuckles for a SD application.

Not arguing with the strength debate, but I've been happy with my stock milled/bolted setup and beat my buggy pretty good.
 
What if someone was to replicate your design, then weld the assembly to the knuckle?

Assemble > weld the assembly > weld to the knuckle > replace and torque hardware after cooling?

Assuming the weld is on both sides of the bolted joint and the plates are adequately sized.......

This is counter intuitive but the bolts wouldn't carry any load until AFTER the weld fails. This is a very general statement but is true in the vast majority of welded connections.

The bolts would only be there as a safety connection. Failure doesn't necessarily mean complete separation of the parts. A weld that cracked through the section would then allow load to transfer to the bolts. In this case the bolt could slow the crack growth rate.

Another interesting tidbit. The weld will fail at the same number of cycles whether the bolts are in the assembly or not. So if it's going to fail with no bolts it's going to fail with bolts.

This is theoretical but pretty spot on. I have done one coupled weld fatigue nonlinear bolted joint FEA with and without welds to prove this to a customer. The bolted joint did carry 1-2% of the external load due to deflection of the components and that did slightly impact the weld fatigue life but not significantly.
 
Weaver has dowels on their milled stock knuckle setup.
BKOR has keyed Reid knuckles for a SD application.

Not arguing with the strength debate, but I've been happy with my stock milled/bolted setup and beat my buggy pretty good.

I talked to Tom at Reid about keyed superduty knuckles. They don't offer them. Does BKOR machine them? I didn't find them on their website.

Edit: I just talked to BKOR and they do offer machined keyed knuckles and steering arms for the 05-12 superduty and will machine an interference fit keyway if asked. Their standard arm is made with a slip fit.

Weaver did my knuckles and steering arms for the PO of my LJ. I haven't had it apart in the year I've owned it and haven't had a loose bolt either. I don't beat on my Jeep so I'm not a good baseline.

It's more a safety concern. If you're vigilant about checking your steering arm bolt torque and keep them tight you're fine. If you're not you could have bolts fail and loose steering.
 
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Assuming the weld is on both sides of the bolted joint and the plates are adequately sized.......

This is counter intuitive but the bolts wouldn't carry any load until AFTER the weld fails. This is a very general statement but is true in the vast majority of welded connections.

The bolts would only be there as a safety connection. Failure doesn't necessarily mean complete separation of the parts. A weld that cracked through the section would then allow load to transfer to the bolts. In this case the bolt could slow the crack growth rate.

Another interesting tidbit. The weld will fail at the same number of cycles whether the bolts are in the assembly or not. So if it's going to fail with no bolts it's going to fail with bolts.

This is theoretical but pretty spot on. I have done one coupled weld fatigue nonlinear bolted joint FEA with and without welds to prove this to a customer. The bolted joint did carry 1-2% of the external load due to deflection of the components and that did slightly impact the weld fatigue life but not significantly.
Pretty much every weld on high steer kit made includes a bolted connection to the stock drag link hole. If your theory was true then all those bolts could be taken out since they offer no more holding capacity once the welding is complete. The shape of weld on high steer arms, knuckles, and materials involved shift from a clean theoretical plane like most flat top bolt on arms to a complicated mess of forces as welds wrap around contours and bolts create preload and the welds and bolts take on varying loads as the weldment flexes.

Regarding the key or dowel on some of the milled stock knuckles. Some are calling a "key" a machined fork that grabs near the caliper ear which is also machined, furthest distance from the load being applied at the other end of the arm. This is not the same as the old non super duty keys that run a much longer distance or are on both sides of the ball joint. Some are calling the "dowel" a short tube that sits around the bolt hole that can take greater shear force than the bolt alone. The dowel is also of larger diameter than the bolt. Since all the bolts are fully threaded and the load would be applied to the threads the tubes take the load off the threads. If this is the case then really any bolt that is used that has the load applied to the solid shank with a non oversized hole could be considered a dowel. A key could be a notch with a big gap due to crappy machining that only transfers load when the arms have shifted.
What I'm getting at is marketing throws around terms that sound strong, but can really differ from one design to another or one brand to another with the same design. One low res picture captured with a iPotatoe and a short caption is not a good method for determining what is good or not and how the tolerances add up. Same goes for evaluating a weld on high steer, was it welded on with a 110V flux core wire or TIG'd with proper rod and heating. Its hard to compare one to another until you have the full story and know all the details.
 
Pretty much every weld on high steer kit made includes a bolted connection to the stock drag link hole. If your theory was true then all those bolts could be taken out since they offer no more holding capacity once the welding is complete. The shape of weld on high steer arms, knuckles, and materials involved shift from a clean theoretical plane like most flat top bolt on arms to a complicated mess of forces as welds wrap around contours and bolts create preload and the welds and bolts take on varying loads as the weldment flexes.

Regarding the key or dowel on some of the milled stock knuckles. Some are calling a "key" a machined fork that grabs near the caliper ear which is also machined, furthest distance from the load being applied at the other end of the arm. This is not the same as the old non super duty keys that run a much longer distance or are on both sides of the ball joint. Some are calling the "dowel" a short tube that sits around the bolt hole that can take greater shear force than the bolt alone. The dowel is also of larger diameter than the bolt. Since all the bolts are fully threaded and the load would be applied to the threads the tubes take the load off the threads. If this is the case then really any bolt that is used that has the load applied to the solid shank with a non oversized hole could be considered a dowel. A key could be a notch with a big gap due to crappy machining that only transfers load when the arms have shifted.
What I'm getting at is marketing throws around terms that sound strong, but can really differ from one design to another or one brand to another with the same design. One low res picture captured with a iPotatoe and a short caption is not a good method for determining what is good or not and how the tolerances add up. Same goes for evaluating a weld on high steer, was it welded on with a 110V flux core wire or TIG'd with proper rod and heating. Its hard to compare one to another until you have the full story and know all the details.
I was specifically talking about your concept with continuous welds around the perimeter. I was overly broad in my statement and hoped it would lead to discussion. There are rarely absolutes. The more complex the system the more my statement falls apart. But in general if you encapsulate a geometrically simple bolted joint with weld the bolts will not see external load until the weld has failed, excepting some deformation induced forces.

The example you brought up with a large bolt connecting the weld on knuckle to the existing tie rod hole is a different animal. In that case the bolt adds an alternative load path to the system and adds bending stiffness to the assembly. That design will improve the weld life. How much is completely dependent on the relative stiffness of the bolt versus the other components. The stiffer the other components the less impact the bolt has. It will still fail in the welds but any stress range reduction ratio will lead to a cubic weld life improvement. For extremely low cycle fatigue it could even be as high as 6x improvement.

You are absolutely right about the technical terms that are often misused and misunderstood by many manufacturers. The hollow dowels you mentioned are a good example. They are typically used to accurately locate parts relative to each other so that other features line up, I have never seen an application in my professional career where they were used to carry shear in a bolted joint.

Dowels require line to line or interference fits to be effective. Keys require line to line or interference fit to be effective. A clearance fit is the same as no dowel or no key. Both keys and dowels need to be placed in locations that carry the load so the bolts don't. That means the key has to extend past the bolts towards the load application point. One dowel should also be placed between the load application point and the first bolt. The second dowel should be placed close to the furthest bolt in the pattern. There needs to adequate material around the dowel and the key, as well as sufficient shear area for the key to be effective based on the yield strength of the material.

I could go on but it's sufficient to say there are a lot of factors that need to be taken into account that are often overlooked that can cause what looks like an adequate design to be substandard.

We haven't even touched on bolt stretch length, compression zones, edge distance, torque, washer diameter , washer thickness, surface finish, component flatness, and component hardness. There are so many factors that if ignored can doom a bolted joint or if corrected can make it live.

I'd like to see the aftermarket step up and actually do the engineering to get a good, reliable, safe product. Back on the old board Crane seemed to listen and developed the keyed kingpin knuckles. It would be nice to see a superduty setup from them. In the meantime BKOR sounds like they'd be a great option using Reid knuckles. Not cheap but probably the safest option. Sometime I'll pull the Weaver arms apart to see how they're done. In the meantime I'll keep checking bolt torque before every wheeling trip.
 
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