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building custom axles things i did not know link placement and such.

chaplinfj60

chaplinfj60

Well-known member
Joined
Nov 17, 2020
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3057
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marshalltown iowa
good am all

we been chatting alot around home about getting good steering angles and all that jazz,
so watching some vids last night i noticed there front axle, some sort of fab 9 and the front diff is damn near centered. no wonder its so hard to get a standard SD or KP to get sharp steering with the pumpkin so close to the knuckle. and then i really started to notice the actual link place ment on the axle. the lowers are inboard more than i would have thought.

this is some serious head scratching and for thought for sure.

but links inboard like this i it still just as stable or is there a need for sway bars?

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i am sure you do.

the crazier part of it all is thinking this through. there is alot of thought that goes into these steer axles when it goes custom. lots of little things lead to huge advantages i see.

and yes a local guy. i have heard of him... lol
 
There's no free lunch. If you want 50° of steering, you have to inboard the links some....and you'll likely have a little roll steer because of it in the 4link calculator...but you have to remember it's a steering axle so you can correct for that by steering.
 
Sean said:
There's no free lunch. If you want 50° of steering, you have to inboard the links some....and you'll likely have a little roll steer because of it in the 4link calculator...but you have to remember it's a steering axle so you can correct for that by steering.
Click to expand...
there is that. turn the tires. ahhahahaha

lots and lots of little things for sure and makes more and more since to use a fab 9 type of housing. weld anywhere and smaller
 
chaplinfj60 said:
there is that. turn the tires. ahhahahaha

lots and lots of little things for sure and makes more and more since to use a fab 9 type of housing. weld anywhere and smaller
Click to expand...
That, and wearing through the bottom of a cast housing SUX! Granted RJs use a hardened steel skid, but most 'custom' cast centers don't. Welding them back together holds a while but they seem to regularly start leaking again. The fabbed housings....just weld more plate to it.
 
chaplinfj60 said:
i am sure you do.

the crazier part of it all is thinking this through. there is alot of thought that goes into these steer axles when it goes custom. lots of little things lead to huge advantages i see.

and yes a local guy. i have heard of him... lol
Click to expand...
What are you looking for overall? That answer will dictate the parts than anything else.

Are you wanting a SandHallow trailbraker or a better version of what you have now.

Everything has a compromise. And as stated steer axles are more forgiving on roll steer and such.
 
nothing at the moment. reading up on how it all works. comparing different rigs mainly. more than anything it is eye opening on why things are done. instead of that just the way it is. i like finding the why.
 
There is a good thread about geometry. You should read it and learn how to use the 4 link calculator.
 
Keep in mind the offset of the axles in the 9" third. The ends of the shafts don't meet on the centerline of the diff for whatever reason. This tends to favor the diff being pushed off to one side, which might make an axle look like the diff is more centered.

Yes, you can triangulate the lower links all you want, but at some point its more effective to move the links on the axle more in board. Keep in mind you need enough spread on the links at the subframe to clear the engine, engine skid and snake a driveshaft through.

I haven't seen very many of the comp style buggies out in sand hollow running a sway bar. Stuff like that gets really hard to package with all the steer angles front and rear. They also aren't going very fast. I think as your speeds increase the benefits of a sway bar increase.
 
I'm not entirely sold that stability comes from the spacing between the links. I think people only move one end of the links and think that the width helped when it was really a change in geometry. I put some graphs and stuff looking into link spacing in the linked suspension bible, starting at post #125:
irate4x4.com

Linked Suspensions Bible

Haha you're not obligated to do anything at all, so everything you share is appreciated! Just the fact that we seem to be on the same page helps affirm that I'm not interpreting things incorrectly. I kinda want to design something with this configuration now
irate4x4.com irate4x4.com
 
Treefrog said:
I'm not entirely sold that stability comes from the spacing between the links.
Click to expand...

That's because stability is the end result of the combination of many individual inputs to the whole.:flipoff2:


Where the links mount on the axle is where the link geometry reacts. What's outboard of the reaction point will always have an exaggerated movement compared to what the geometry wants to do.

I probably fucked up that explanation, hopefully the point got across.:homer:
 
Treefrog said:
I'm not entirely sold that stability comes from the spacing between the links. I think people only move one end of the links and think that the width helped when it was really a change in geometry. I put some graphs and stuff looking into link spacing in the linked suspension bible, starting at post #125:
irate4x4.com

Linked Suspensions Bible

Haha you're not obligated to do anything at all, so everything you share is appreciated! Just the fact that we seem to be on the same page helps affirm that I'm not interpreting things incorrectly. I kinda want to design something with this configuration now
irate4x4.com irate4x4.com
Click to expand...
so i can get behind its more about the actual angle than the mounting point on the axle for instance. that makes perfect since. because they are one unit at that point. now if they are closer together for instance the mounting location would have more force on the brackets and bolts. so i get it. i was reading that link you provided and thats some deep diving information i will re read a couple times.
thanks for the link by the way. :beer:
 
chaplinfj60 said:
so i can get behind its more about the actual angle than the mounting point on the axle for instance. that makes perfect since. because they are one unit at that point. now if they are closer together for instance the mounting location would have more force on the brackets and bolts. so i get it. i was reading that link you provided and thats some deep diving information i will re read a couple times.
thanks for the link by the way. :beer:
Click to expand...
Non-symmetrical loading like clipping a tree will generate higher forces. But general acceleration should generate the same longitudinal force.
 
gt1guy said:
That's because stability is the end result of the combination of many individual inputs to the whole.:flipoff2:


Where the links mount on the axle is where the link geometry reacts. What's outboard of the reaction point will always have an exaggerated movement compared to what the geometry wants to do.

I probably fucked up that explanation, hopefully the point got across.:homer:
Click to expand...
Right, but the limit to movement and the large majority of the roll resisting torque is from the shocks and anti-roll bar, which are still spaced wide.
 
Treefrog said:
I'm not entirely sold that stability comes from the spacing between the links.
Click to expand...

Hold a broomstick horizontally with your hands close together. Have someone try to twist it out of your grip.

Now do the same with you hands spread apart.


gt1guy said:
That's because stability is the end result of the combination of many individual inputs to the whole.:flipoff2:


Where the links mount on the axle is where the link geometry reacts. What's outboard of the reaction point will always have an exaggerated movement compared to what the geometry wants to do.

I probably fucked up that explanation, hopefully the point got across.:homer:
Click to expand...

^^^ This guy gets it.
 
Tech Tim said:
Hold a broomstick horizontally with your hands close together. Have someone try to twist it out of your grip.

Now do the same with you hands spread apart.
Click to expand...
Set the broom on pillows(the springs) and repeat the experiment with someone pushing down. Hands narrow vs wide does not have much effect.
 
i get what your saying about the twisting, but where your hands are are the clamping force needed to hold it in position. or a welded tab and bolt with heim. but once that is solved then thats a complete unit.
in my mind i see it:beer:
 
Bebop said:
Torque twist is a bitch.
Even at 2 mph.
Click to expand...
Right, and so is having your suspension loaded up wrong in an obstacle because your running a sway bar and you can't easily turn it off. Better to have things free and moving and use the suck down winch when needed to load up the suspension.
 
Treefrog said:
Set the broom on pillows(the springs) and repeat the experiment with someone pushing down. Hands narrow vs wide does not have much effect.
Click to expand...

In that experiment, having your hands on the pillows, with the pillows as wide as possible would be best case.

That would put the geometry reaction point and the input from the springs in the same spot. Working "more" together and not through the axle housing. Think of that same scenario but dealing with the Anti's.


Then we throw in packaging restraints and everything gets burned in where it fits.:flipoff2: At least the springs are generally easy to get out wide. If I had to pick one part not to compromise placement on, it would be the springs. I think that's where you have the most to lose.
 
I actually felt the hardest part of getting 50* of steering was all the other BS in the way. I have a GM60 narrowed off the long side to 65" and with a double triangulated 4 link and the PS lower mount on the cast there's nothing special there. However, it made packaging my coil overs, air bumps a but tough, and my tire sweeps right into the area my uppers and lowers kind of intersect. Keeping the tire outta stuff when it sweeps that far without a wide axle requires some planning. My rig was built a around a 40" trep and 4.5 BSing, if I swapped to a 42 it would make sweet love to basically everything.
 
Ghetto Fab. said:
Right, and so is having your suspension loaded up wrong in an obstacle because your running a sway bar and you can't easily turn it off. Better to have things free and moving and use the suck down winch when needed to load up the suspension.
Click to expand...
That’s why you tune your shocks and sway bar.
I drove my car with 3 different bars and without it.
Even slow rockcrawling I like it better with a bar.

And suck down winch is a super low mph game. I don’t even have a winch on my car.

On the other hand, turning at 30/40mph with no sway bar and 20"+ of travel is borderline impossible. And no suck down winch will ever solve that.
 
gt1guy said:
In that experiment, having your hands on the pillows, with the pillows as wide as possible would be best case.

That would put the geometry reaction point and the input from the springs in the same spot. Working "more" together and not through the axle housing. Think of that same scenario but dealing with the Anti's.


Then we throw in packaging restraints and everything gets burned in where it fits.:flipoff2: At least the springs are generally easy to get out wide. If I had to pick one part not to compromise placement on, it would be the springs. I think that's where you have the most to lose.
Click to expand...
Agreed
 
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