D-6

[MetalCraftSolved]

I would recommend either not cutting out these windows, or at least making them an X or other triagular based form. The amount you have weakened it is exponentially greater than the weight you are saving.
View attachment 332828

I’m no train driver, but you are missing some material where the amount of greatest load is cantilevered. I foresee bent control arms in the future.

Revision needed or push the rear LCA rear some more to eliminate the cantilevered load.

Your material need in that plane stops at the first shock mount. This combined with HAZ from assembly is a poor recipe.

I see a weld tab with nothing underneath it. Need to change the pockets there, or move/delete the weld tab. Minor detail though, and easy to fix.

There's some other causes for concern for buckling as well, but this is not my project. I like the "torsion box" concept for the control arm though, kinda fun.

Also, what is the purpose of the long pocketed strip that's along the side at an angle? Is that to zip-tie hoses to or something?

Nope, not that one. The one in front of that.

Also, you should put a radius at the "V" between the two inboard legs, even if it's just a generous fillet in the top and bottom skin and not the bent plate pieces.. Else, the skins are going to crack there.

Okay, makes sense. I'd still move the weld tabs to the left and right of the unsupported area on top. If you're going to have a weld tab, make it do work. Else you're just adding a buckling point. Remember that if you're stressing the skin of the control arm to make a torsion box, you don't want to add unnecessary features that could add local stress.
You're doing a cool design, it just needs to be thought through a little more.

This is the culmination moving forward from what we last talked about. I suppose now, I need to make a decision on gussets around those runner intersections.

 

[Fabrik8]

I"m going to ask a question of fundamentals here: Is there a packaging reason (related to the front end) that prevents you from mounting one set of tabs on the other side of the control arm, instead of your current config of offsetting one set and REALLY offsetting the other set? I imagine the answer is buried about 10 pages back.

Also, looking at your top view, I can see a very easy path to reconfigure (hint: extend) what is already there, instead of adding a piece of tubing. BUT, it is still preferable to change to a more symmetrical damper/coilover/bump/whatever mounting configuration and get rid of that cantilever.

 

[MetalCraftSolved]

I"m going to ask a question of fundamentals here

The simultaneous shock configuration I've been after since the beginning actually began with one of the shocks in front of the axle. This was quickly deemed inappropriate, because the shock placement intersected with the steering linkage.

Is there a packaging reason (related to the front end) that prevents you from mounting one set of tabs on the other side of the control arm, instead of your current config of offsetting one set and REALLY offsetting the other set?

The simultaneous shock configuration is actually hindering some technical aspects of the car. One example would be moving the engine forward some. The simultaneous shock configuration is something that I've had to argue with myself over, and over personally. It's an aspect of the car that I will go out of my way to achieve.

Also, looking at your top view, I can see a very easy path to reconfigure (hint: extend) what is already there, instead of adding a piece of tubing. BUT, it is still preferable to change to a more symmetrical damper/coilover/bump/whatever mounting configuration and get rid of that cantilever.

I hear what your saying about extending the central plate next to the tube. It was my first thought - Extending that rail from front to back. It turns out the tube is critical for the jack, and has to be in the control arm anyway. I chose to extend the tube. I felt like that in the pro-vs-con battle towards extending the plate or the tube - the tube gives it more complete strength.

Over all, I'm not going to back away from the simultaneous shock configuration. It's one of the key features that will give the D-6 it's name. The coil-over can be placed in the front or the rear. Either way, the front shock cannot be placed any further forward towards the axle, and more importantly, that front shock position is the "only" fulcrum point "if" the control arm was going to twist. That alone, is probably something that most over look.

 

[Fabrik8]

So, without many other changes, here's maybe an easy way to get rid of the pipe, if you're determined to keep the damper/coilover/whatever tabs in the same location.
The blue plates take the place of the tubing, to distribute the bending loads from that cantilever.
I changed the red plates to be a more direct tension/compression/bending load path between the monoballs. The "center" red plate does dual duty; it's a tension/compression/bending load path between the inboard monoballs and the outer monoball, and will also stiffen the outer monoball mounting.

There are more elegant ways to do the blue plates, but I was just using what was already there, to show simple changes. Could probably remove a lot of redundant material, probably that center blue plate.

I'm not saying my illustration is the best way to make your control arm, but sometimes it's good to start with the main load paths, and then figure out what needs to be added to do the extra tasks (cantilever loads in this case), and then figure out how to integrate them together for better strength or lower weight or simple fabrication or whatever.

 

[MetalCraftSolved]

I'm gonna take a break from the lower control arm, and let it soak. I need to shape the knuckle, so I can figure out how much gusset I can get on the outboard side of the lower control arm. I'd like to get the sway bar placed in there again, before I close in the upper control arm. It may be time to place the steering rack.

 

[Fabrik8]

I'm so confused by some of the packaging decisions going on here. I think your forward UCA joints want to be where your rear UCA joints are.

 

[MetalCraftSolved]

I'm so confused by some of the packaging decisions going on here. I think your forward UCA joints want to be where your rear UCA joints are.

I don't have room in between the shocks to come out there with the rear joint, and the engine is in the way coming from behind the shocks with the rear joint. The only option I see to to make a change would be to de-simplify the bulkhead and move the rear joint backwards a couple inches.

 

[mcconnell]

The simultaneous shock configuration is actually hindering some technical aspects of the car. One example would be moving the engine forward some. The simultaneous shock configuration is something that I've had to argue with myself over, and over personally. It's an aspect of the car that I will go out of my way to achieve.

Care to explain what a "simultaneous shock configuration" is to us lay people? Seems like a lot of compromises to make it happen so it must be something special?

 

[Fabrik8]

Care to explain what a "simultaneous shock configuration" is to us lay people? Seems like a lot of compromises to make it happen so it must be something special?

It appears to be a coilover next to a bypass damper. The compromises seem to be self-inflicted, and are likely avoidable.. Dampers don't have to be next to each other, just connected to the same moving object, and ideally on the same axis of motion to make things easier, so there are definitely solutions to whatever cryptic packaging issues are happening here.

 

[Scooter402]

I'm so confused by some of the packaging decisions going on here. I think your forward UCA joints want to be where your rear UCA joints are.

Me thinks some of this reminds me of Stuart from Mad TV.

 

[mcconnell]

@Fabrik8 the tabs in models told me it meant side-by-side, but the fancy name had me wondering what I was missing.

 

[Mac5005]

@Fabrik8 the tabs in models told me it meant side-by-side, but the fancy name had me wondering what I was missing.

I’m guessing to use the same length and travel coil carrier and bypass. Both mounted with the same identical motion ratio.

Which to me is a frivolous thing to work around when one is speed sensitive and the other is position sensitive.

There are more advantages to having them different than identical.

The coil carrier’s job is to hold the springs, and any valving in it designed to dampen through the center bypass zones, when most of the oil is bypassing the piston in the bypass shock.

Then outside of the bypass zones, the bypass main valving takes over the damping & dampening, (depending on humidititty).

Now, the motion ratio of the bypass shock mounting sets the piston speed of the bypass, and the main valving in it is speed sensitive, when the bypass ports are closed, or the piston is out of the bypass zones.

Having both motion ratios the same, means piston speed is the same for both.

Then getting into what the spring force is at certain suspension positions plays into the length, spring rate(s), crossover rings, and how those suspension positions correlate to the bypass tube positions.

 

[MetalCraftSolved]

Care to explain what a "simultaneous shock configuration" is to us lay people? Seems like a lot of compromises to make it happen so it must be something special?

It appears to be a coilover next to a bypass damper. The compromises seem to be self-inflicted, and are likely avoidable.. Dampers don't have to be next to each other, just connected to the same moving object, and ideally on the same axis of motion to make things easier, so there are definitely solutions to whatever cryptic packaging issues are happening here.

@Fabrik8 the tabs in models told me it meant side-by-side, but the fancy name had me wondering what I was missing.

I’m guessing to use the same length and travel coil carrier and bypass. Both mounted with the same identical motion ratio.

Which to me is a frivolous thing to work around when one is speed sensitive and the other is position sensitive.

There are more advantages to having them different than identical.

The coil carrier’s job is to hold the springs, and any valving in it designed to dampen through the center bypass zones, when most of the oil is bypassing the piston in the bypass shock.

Then outside of the bypass zones, the bypass main valving takes over the damping & dampening, (depending on humidititty).

Now, the motion ratio of the bypass shock mounting sets the piston speed of the bypass, and the main valving in it is speed sensitive, when the bypass ports are closed, or the piston is out of the bypass zones.

Having both motion ratios the same, means piston speed is the same for both.

Then getting into what the spring force is at certain suspension positions plays into the length, spring rate(s), crossover rings, and how those suspension positions correlate to the bypass tube positions.

Gives the front end a substantially lighter spring rate allowing the compression stack on the bottom of the piston to sit higher in the cylinder at low speed (articulation)

 

[Fabrik8]

Gives the front end substantial lighter spring rate allowing the compression stack on the bottom of the piston to sit higher in the cylinder at low speed (articulation)

None of that explains why both dampers have to be on the same side of the axle, with one cantilevered out past the ball joints, or why the inboard UCA monoball position has to be so compromised because of that.

I'm still confused about why you can't put one damper on either side of the axle (for example), which then frees up all the room you need to put the inboard UCA joints in proper position for UCA strength. That would probably locate one of the dampers to be through the middle of the UCA, just like almost every other double-wishbone suspension design ever designed. I would suggest the coilover for that position, for the same reasons it's usually in that position (spring forces and LCA bending compliance, mostly).

To paraphrase: Why do you feel that the dampers have to be right next to each other?

 

[MetalCraftSolved]

None of that explains why both dampers have to be on the same side of the axle, with one cantilevered out past the ball joints, or why the inboard UCA monoball position has to be so compromised because of that.

I'm still confused about why you can't put one damper on either side of the axle (for example), which then frees up all the room you need to put the inboard UCA joints in proper position for UCA strength. That would probably locate one of the dampers to be through the middle of the UCA, just like almost every other double-wishbone suspension design ever designed. I would suggest the coilover for that position, for the same reasons it's usually in that position (spring forces and LCA bending compliance, mostly).

To paraphrase: Why do you feel that the dampers have to be right next to each other?

It was setup like that initially. I changed it somewhere after page 3. It interferes with the steering linkage.

 

[Fabrik8]

I'm missing the steering linkage in the pictures; there isn't a linkage shown anywhere.. Are the 4 cylinders (together in a quadrant under the engine) the bore of the steering rack?

You should probably figure out where the steering tie rod joint is going to be on the outboard side, and show that while you're making packaging decisions.

 

[braxton357]

I'm missing the steering linkage in the pictures; there isn't a linkage shown anywhere.. Are the 4 cylinders (together in a quadrant under the engine) the bore of the steering rack?

You should probably figure out where the steering tie rod joint is going to be on the outboard side, and show that while you're making packaging decisions.

Clearly an overcomplicated header. That comes first.

 

[MetalCraftSolved]

You should probably figure out where the steering tie rod joint is going to be on the outboard side, and show that while you're making packaging decisions.

Sure. We looked into the steering setup at one point, but I basically started over from scratch with the entire IFS system when I changed the front differential. We're fairly close to placing the steering rack again, but at the moment I'm in the midst of developing at least a decent percentage of this new billet portal knuckle.

 

[MetalCraftSolved]

More work to go, but here's a peek at the lower side of the knuckle.

 

[MetalCraftSolved]

Ground clearance @ center - 16.5 inches
Wheel travel - 25.5 inches
Steering angle capability - 35 degrees
D-6 IFS system - Christmas 2020

 

[Tacoma747]

I can't even afford to THINK about what this thing world cost to build.

 

[Monkeynono]

How much leverage is that knuckle going to have on that upper arm. I'm just curious with it being behind the rear most arm mount.

 

[MetalCraftSolved]

How much leverage is that knuckle going to have on that upper arm. I'm just curious with it being behind the rear most arm mount.

I'll end up moving that rear upper control arm uni-ball towards the rear about 2 inches, because the strength gains are free for the taking. It still clears the axle back that far. When I move it, I won't have any questions about the upper control arm being strong enough to do it's job.

 

[MetalCraftSolved]

I've been after the steering link locations for a couple days now. I've made jumps from 25 degrees of back swing to over 33 degrees of steering angle with no bump steer. It has climbed to 33.19 degrees on the back swing, and 33.67 on the front swing. It feels good, and I feel lucky to get the opportunity to really sync up over the last 4 days. The knuckle and the steering geometry proved to be a beast of a challenge. It's a relief to look at them now, and know I can get them right with minor modifications.

I'm going to save my work, and shoot for that 35 degree steering angle this week, but "phew, damn"..... Right now I'm just stoked to see that 33.19/33.67

 

[MetalCraftSolved]

Before I forget, I was going to show you guys these closed in lower control arms I got finished up. These parts are ready to cut and bend. The lower control arms both add up to 26 pieces I'll ship in from Moto-Bilt. Looks like it's going to be a truck load more. This is the first completed part.