Build Getting back with the ex

[ScottRS]

Assembly time. Size 105 O-rings are about perfect for this.
Stick the copper line through the bulkhead fitting you've made, O-ring down inside, and tighten the AN-3 union into it. Not gorilla tight, if you overtighten this severely it will crush the copper line. So gentle-tight is your friend here.

Well, maybe install the ARB and put the bulkhead into the diff housing somewhere along the way. I'll get to that one of these days. But I now have a bulkhead fitting of the flavor I like, ready for when I do actually hang a gearset.

 

[ScottRS]

On the solenoid end, you can just remove ARB's hose adapter and screw in a 1/8 NPT to AN-3 (screw the 1/8 NPT side into the solenoid) adapter into the solenoid. I recommend using either an aluminum or brass adapter here because the solenoid is BSP and not NPT, so this is technically wrong, but it's off by 1 TPI and a taper instead of straight. It'll be fine. From there, plumb to the locker just like running AN-3 brake line. Or you can sub AN-4 for everywhere I said AN-3 if you prefer.

 

[ScottRS]

A quick snick in the mill makes short work of the steering stop grinding ordeal, cut at 3.5" up from the unit bearing face, or 0.5" down from the caliper ear, to be really close to 50deg. That's as close as I can figure out how to get it with the mill, still needs a little grinder/bandfile love, but it's 5-10 minutes of love instead of an hour.

 

[ScottRS]

Probably a pile of dumb ideas here, but I'm in this deep now.
14b center, two SuperDuty long sides stripped of all brackets. 14b tubes will be turned down to fit inside the Ford tubes, so the only visible axle tubes in the rear, will be SuperDuty.
Plan is to match width to stock SuperDuty front, with the pinion center at or near 3" right of center because that's how far off center my engine normally lives.
Still TBD: exactly where does the 14b center pin land with the pinion 3" over? If shifting the pinion minimally from ideal nets me equal length inners, I'll take that. Inners are not bought yet.

 

[ScottRS]

I have lathe envy, and feel the need to share it with my imaginary Internet friends here.
I wish I had a lathe big enough to chuck up and spin a 14 bolt, but thankfully I know someone who does. Barely, the bottom pinion bolt boss only cleared the ways by about 1/16", but if it fits, it ships.

 

[JayMcJay]

It’s a serious machine that’ll spin a 14b and both clear the swing and not dance across the shop!

 

[ScottRS]

It’s a serious machine that’ll spin a 14b and both clear the swing and not dance across the shop!

Nameplate claims to be 17x80, but appears to be 9" from spindle bore center to the closest way. Dwarfs mine by a good bit, and didn't so much as wobble with the housing spinning. I don't think we ever got above 300rpm though.

 

[ScottRS]

After the lowest effort slam-in I can even vaguely refer to as gear setup, it appears that center of center pin to center of pinion will net out at 3.625". So dead center center pin nets me 5/8" more pinion offset than ideal. With the anticipated ~22" operating length of my rear driveshaft, that's about 1.6 degrees of lateral angle at the pinion from perfect. I'm calling that good enough for equal length shafts.

Actually, with the impending reality of needing to re-hang engine mounts in the chassis, I might just further-offset the engine/trans/case to match.

Side note, with thick cut 5.38s and an ARB, there's only about 0.010" of carrier bearing lateral adjustment available between the locker hitting the internal housing ribs on the left, and the ring gear hitting the pinion pocket bearing surround on the right, on this housing. I'll have to do some grinding when I get to actually setting up the gears, this slam-together was just to confirm tube and inner shaft lengths.

 

[Grendel]

You'll love the 14B front.

 

[posford]

You'll love the 14B front.

I believe he's building a centered diff steering rear

 

[Grendel]

I believe he's building a centered diff steering rear

Same difference.

 

[ScottRS]

Yep, centered-ish rear steer, but it's (deliberately) as commonized with the matching front I'm building alongside it, as I reasonably can do.

 

[Blase]

I love it! I do have a couple of question though:
You ended up with really thick tubes correct?
How much clearance did you leave between the OD of the 14 bolt tube that you turned and the ID of the SD housing that isn't perfectly machined?
Was it hard to get them seated all the way together?
Did you consider boring out the factory ford tube inside the knuckle so it would slide over the 14 bolt tube and weld that in place?

Seems like a lot of work to end up with really thick wall axle tubes that will likely still get a truss to weld link mounts too. I love this build and all the out of the box old school, improve upon OEM parts approach!!!

 

[ScottRS]

I love it! I do have a couple of question though:
You ended up with really thick tubes correct?
How much clearance did you leave between the OD of the 14 bolt tube that you turned and the ID of the SD housing that isn't perfectly machined?
Was it hard to get them seated all the way together?
Did you consider boring out the factory ford tube inside the knuckle so it would slide over the 14 bolt tube and weld that in place?

Seems like a lot of work to end up with really thick wall axle tubes that will likely still get a truss to weld link mounts too. I love this build and all the out of the box old school, improve upon OEM parts approach!!!

This is gonna be long, but hopefully makes sense...

The 14b tubes were turned to 3.04" OD. In reality, that's about a +/- 0.005" tolerance in this case.
The SD tubes are about 3.05" ID. About +0.005/-0ish but they're not perfectly clean inside, so that's an "about that much".
The remaining 14b tube stubs are around 2.6something ID for much of the length, so a little over 0.120 wall. 14b axles have swedged tubes, so they neck down to 2.22ish ID from about an inch out from the casting, to the adjuster nuts.

Timing wise, there's a lot of "doing this but I'm not ready to finish the job" going on here; it's the whole project, not just the rear axle. I don't have a setup kit or inner shafts for this axle yet, but the lathe time was available this weekend, so I took it when I could.

I have not yet cut the SD tubes to length. I have test pushed them on, they slide smooth about halfway down before the drag gets to where I go "I'm not ready to go this far yet". There's about 6" of tube stub on one side and about 11" on the other side of the 14b. They were cut at the inboard side of the leaf spring perches. I may cut the 11" down farther before pushing the SD tubes on.

To your "seems like a lot of work", yes. There's more to the madness of my assembly process that makes sense to me. Also sequencing of "I can do this if I do it before that, but if I do that first, I won't be able to do this".

You are also correct on the "will be getting a truss and a basher bar and and and ...."

My last rear steer axle under this car, is now under my jeep. I screwed up building it and ended up with excess rear caster, so once bitten twice shy, I'm trying to avoid that. As such, I need to be able to set pinion angle relative to caster, for a rear axle that needs to be holding up the car in question, that doesn't have a transfer case right now. It's a mess of out of order.

The 14b will be shaved, and as I am lazy and like to use power tools, that'll be done in the mill. Plan there is to match(ish) it to a cover that I don't have yet, but because of weight and size, I want to do that milling on an empty center section with as minimal of tube on it as possible.

After that, tubes can go on, but won't be welded in place. They may end up tacked to a basher bar, may just get ratchet strapped c to c. That way I can rotate for caster/pinion later.

I can at least tack on shock and lower link tabs as the shock angles will be relative to caster. Uppers need to be set to clear diff, so chances are, they'll end up tacked to a link bridge/truss that's anchored to the center and not the tubes.

Once the housing is more or less under, I can set it at ride height with the transfer case in (need engine/trans in by then as well) and set pinion angle to the driveshaft. After that, I can burn the tubes to the center, figure out the link bridge and bump stop locations to not conflict, fully hang the upper links to clear the diff, hang the basher bar to have the steering cylinder clear the diff and fuel tank, etc.

Net is that I'm trying to set up to be able to spin the pinion to angle after the axle goes under the car to deal with packaging concerns around having never had this flavor of rear axle under this chassis.

 

[ScottRS]

What would make all of the above easier is if I built it in normal order: tubes into center, then C's onto tubes, like people who think things through, do. Trying to use C's that are already stuck to tubes as whole "units" turns that process on its ear. So, if anybody's read this far and learned nothing else from me, reread this singular post until you can chant it.

 

[ScottRS]

If I was smart, I'd take my own advice, realize that my tubes are still longer than I need them to be, cut off enough of the tubes to get the housing to width, put those tubes on the center and hang the center as a C-less housing the easy way, knock the C's off of their respective tube stumps, and put them on the housing when I'm ready.
Doesn't materially impact what happens overall, adds a little work to remove and re-hang the C's, but it makes everything in between easier.

 

['84 Bronco II]

My last rear steer axle under this car, is now under my jeep. I screwed up building it and ended up with excess rear caster, so once bitten twice shy

I'm curious, how much was too much caster?

 

[ScottRS]

I'm curious, how much was too much caster?

15ish degrees IIRC.
Being non-reactive joystick controlled full hydro, rear caster is of basically no help for centering; I prefer zero ideally (and that's what the jeep is set up with) so that was what I'm planning for this one as well.
Any caster converts some portion of steering angle into "push the car sideways" motion, so if there's no benefit to the centering action that comes with front caster, less is more.

 

['84 Bronco II]

15ish degrees IIRC.
Being non-reactive joystick controlled full hydro, rear caster is of basically no help for centering; I prefer zero ideally (and that's what the jeep is set up with) so that was what I'm planning for this one as well.
Any caster converts some portion of steering angle into "push the car sideways" motion, so if there's no benefit to the centering action that comes with front caster, less is more.

Interesting; I am in the **** tons of caster camp, and my opinion has nothing to do with self centering. Is your concern over pushing the car sideways about hitting cones or pushing the car off the desired line?

 

[ScottRS]

Interesting; I am in the **** tons of caster camp, and my opinion has nothing to do with self centering. Is your concern about pushing the car sideways about hitting cones or pushing the car off the desired line?

They're sort of the same thing in my mind, if I was dodging cones I'd have a line in mind and wouldn't want the car pushed off of it by weird steering action, which a lot of rear caster does with the weird some-scrub some-lift move-sideways pivoting in directions not quite "right" to direction of travel.

Numerically, what do you consider "**** tons of caster"? And I assume you're in that camp deliberately, so I'm curious about your reasons?

Relatedly, with rear caster, which direction is positive/negative? The rear caster I've run was 15ish degrees top-towards-rear-bumper (pinion angle needed to be higher than the axle was built for).

Having run zero and 15ish degrees, of the two, I prefer zero. I've not tried "tuning" between them or reversing the rear caster to see how that felt.

Ideally in my mind, I want the rear steer to pivot on the ground (I know it'll scrub/scuff) but not materially move the car if I'm cycling it while sitting still. Lots of caster "fish wiggles" the rear and it bugs me in ways that zero caster doesn't. Of course, since we don't drive on flat ground things change dynamically, but starting from center and having equal action both ways makes more sense to me.

Additionally, I'm of the opinion that excessive caster "wastes" steering angle: if you have 45 degrees of angle, but you're castered way over, your effective steering angle max is potentially closer to 40, because some of that movement is going into the top-bottom "flop" direction. I don't know how to mathematically model it, I suspect it's somewhere close to effective angle = cos(caster)*steer angle but not really sure there. If that's mathematically close, 15 degrees isn't "that bad", but zero feels more predictable in action.

At the end of the day, I suspect probably anything up to 20ish degrees would be workable, just not sure how I'd like the behavior that'd net out.

 

['84 Bronco II]

Relatedly, with rear caster, which direction is positive/negative? The rear caster I've run was 15ish degrees top-towards-rear-bumper (pinion angle needed to be higher than the axle was built for).

This is the wrong direction, so in that case, I would agree, zero is better. I don't have the time to type out an in depth reply right now, but I'll try to remember to type something up tonight.

 

['84 Bronco II]

They're sort of the same thing in my mind, if I was dodging cones I'd have a line in mind and wouldn't want the car pushed off of it by weird steering action, which a lot of rear caster does with the weird some-scrub some-lift move-sideways pivoting in directions not quite "right" to direction of travel.

Numerically, what do you consider "**** tons of caster"? And I assume you're in that camp deliberately, so I'm curious about your reasons?

Relatedly, with rear caster, which direction is positive/negative? The rear caster I've run was 15ish degrees top-towards-rear-bumper (pinion angle needed to be higher than the axle was built for).

Having run zero and 15ish degrees, of the two, I prefer zero. I've not tried "tuning" between them or reversing the rear caster to see how that felt.

Ideally in my mind, I want the rear steer to pivot on the ground (I know it'll scrub/scuff) but not materially move the car if I'm cycling it while sitting still. Lots of caster "fish wiggles" the rear and it bugs me in ways that zero caster doesn't. Of course, since we don't drive on flat ground things change dynamically, but starting from center and having equal action both ways makes more sense to me.

Additionally, I'm of the opinion that excessive caster "wastes" steering angle: if you have 45 degrees of angle, but you're castered way over, your effective steering angle max is potentially closer to 40, because some of that movement is going into the top-bottom "flop" direction. I don't know how to mathematically model it, I suspect it's somewhere close to effective angle = cos(caster)*steer angle but not really sure there. If that's mathematically close, 15 degrees isn't "that bad", but zero feels more predictable in action.

At the end of the day, I suspect probably anything up to 20ish degrees would be workable, just not sure how I'd like the behavior that'd net out.

Just so we are on the same page, when I am talking caster, I am only discussing caster in the positive direction in the front, and negative in the rear as it is typically referenced for front applications, i.e. upper ball joints canted towards the center of the vehicle like so: Front / ------ \ Rear

As far as rear steering is concerned, negative caster will lessen how much you are steering into the ground and upsetting the front of the car when you are on steep waterfalls. In your example of positive caster on the rear axle, especially 15°, it will greatly exacerbate this effect, and I can see why you would prefer 0° Specifically for rear steer axles, Jesse Haines was running 5-6° Negative caster explicitly for the reason I stated; however, I believe there is benefit to be had running significantly more. How much more, I have trouble saying since I haven't messed around much with rear steer, but I would think 15° (negative) would be a good starting point.

As far as what I think an appropriate caster number is, that is going to depend on the king pin inclination angle. Aside from reducing scrub steer, king pin inclination is bad. 0° would be ideal, but maintaining a reasonable scrub without the hub sticking way out is basically impossible. It is the entire reason the new Can-Am Mavericks have the goofy-looking upper A-arm and knuckle configuration. The '05+ Superduty outers have 12° of king pin inclination which is a lot. At a minimum, as a rough rule of thumb, I would run caster equal to the king pin inclination angle. This is due to the positive camber gain of the outside tire due to king pin inclination. Positive caster in the front, or negative in the rear, will create a negative camber gain on the outside tire to counteract the positive camber gain of the king pin inclination angle. This will help the outside tire hook and keep from rolling over itself and understeering.

Another benefit of running fairly extreme caster is that the tire will rotate under the links/shocks allowing for more steering angle. Yes on flat ground with high traction and for an equal amount of steering angle, less caster will steer tighter. However, with the additional steering angle increased caster can allow for and poor traction, or steering against gravity, increased caster will perform better. Add in sidewall stability, and running more caster is a home run.

Additionally, the same jacking forces produced by high caster angles can force tires into the ground or effectively extend wheelbase on a side to help grab a hook or wiggle the belly off of a hang up. It also aids in shifting the car over with steering input.

While less pertinent to rock crawlers, caster also aids in stability at speed and steering return to center.

As for numbers for a buggy, I think over 20° on the front axle is a good place to be. Over 30° is starting to do more harm than good. If I ever put my buggy together, which I am building with a 2007 Dana 60, I am planning on 25°. As I said, I am not as confident for rear steer, but I don't see why running similar caster numbers wouldn't provide many of the same benefits.

The biggest cons to running extreme caster are considerably increased steering effort (with a properly-sized hydraulic system, that isn't really a concern), and as you mentioned, at a certain point you are just steering into the ground and effectively losing turning, even on loose and off-camber situations.

 

[ScottRS]

Additionally, the same jacking forces produced by high caster angles can force tires into the ground or effectively extend wheelbase on a side to help grab a hook or wiggle the belly off of a hang up. It also aids in shifting the car over with steering input.

First off, thank you for the insight and the time spent typing it out. I probably thought more last night about why I didn't like the rear caster I had before and did like zero, and questioned that choice more, than at any one time before that.

Not going to quote the whole post, but you make a number of very valid points, and I've had more than a bit of experience with the "forcing the tires into the ground" and the "grab-hook-wiggle" action you noted here, and those are certainly of value crawling.

Your point on kingpin inclination is good and had me sitting there mentally steering back and forth and pondering what the term is for "steered caster" as the tires do at severe steering angles with the fore-aft angle changing due to the KPI of the knuckle moving out from being the "right" direction for KPI.

Agreed on that getting rid of KPI requires interesting building, some of which is impractical for us. Giant wheels with the knuckle inside the wheel like some aerial equipment has is another option, the straight axle (and tire size agnostic) equivalent of the CanAm setup you noted. If I was competing, designing an axle from scratch would be on the table, at this stage, using, and modifying mildly from, the existing (compromised) designs is much more viable.

 

[ScottRS]

I love welding to cast. Not really.
But it's a bit of a given at this stage.
I didn't want to cut down the housing on the short side to expose more tube, but did want weldable steel over there to land a link in back, basher bar in front, and a bump pad on top. Solution: sleeve the casting after cutting away all the proprietary Ford junk.
Round ring of 1/4x2 in a 5" OD circle, split into two C's, is about a perfect fit.
I laid a 1/4x3 cap over the top of the diff as well, this will eventually have a link bridge landed on it for the upper links since they both need to land to the right of the diff itself with how offset the SD60 diff is.
Pre/post heat with a camp stove.

 

[DesertCJ]

I love welding to cast. Not really.
But it's a bit of a given at this stage.
I didn't want to cut down the housing on the short side to expose more tube, but did want weldable steel over there to land a link in back, basher bar in front, and a bump pad on top. Solution: sleeve the casting after cutting away all the proprietary Ford junk.
Round ring of 1/4x2 in a 5" OD circle, split into two C's, is about a perfect fit.
I laid a 1/4x3 cap over the top of the diff as well, this will eventually have a link bridge landed on it for the upper links since they both need to land to the right of the diff itself with how offset the SD60 diff is.
Pre/post heat with a camp stove.

Looks like you MIG welded it with ER70?

 

[ScottRS]

Looks like you MIG welded it with ER70?

That's a little creepy, can you call out the shield gas too?

 

[Duc]

That's a little creepy, can you call out the shield gas too?

my crystal ball says C25 since additional bottles are pricey...... Ive looked into SS wire for welding to cast but screw additional bottles.

 

[ScottRS]

my crystal ball says C25 since additional bottles are pricey...... Ive looked into SS wire for welding to cast but screw additional bottles.

Good call. I do have SS wire and both straight Ar and straight CO2 available but the ER70 and C25 seems to be where I get the best results.

 

[DesertCJ]

That's a little creepy, can you call out the shield gas too?

That's a little creepy, can you call out the shield gas too?

I’ll guess 90/10 but it’s hard to tell the difference between that and C25. I’m still debating between narrowing my 05+ housing or building out a fabricated 9” housing but if I do the 60 I’m going to buy a spool of 309L stainless wire. I’ve had good success using the 309L in housings with TIG.

 

[DesertCJ]

Good call. I do have SS wire and both straight Ar and straight CO2 available but the ER70 and C25 seems to be where I get the best results.

Straight Argon doesn’t penetrate as well and straight CO2 spatters like crazy…