S550 Suspension School - Integral Link IRS

[Whiskey11]

No, you can not adjust the caster via the Tension or Lateral Links. Nor is Virtual Pivot and MacP the same. You are welcome to show me different instead of not showing me. I am open to new ideas...

The geometry supports adjusting caster at the tension link. You can argue all you want but any change in the length of the Tension link is going to adjust caster, some camber and toe. Whether you can do that from the factory has yet to be seen and you probably can't. I imagine the lateral link might be, if Ford was smart they would make it adjustable but we all know how that works out.

I've already explained in TWO posts why this Strut configuration IS a Virtual Pivot suspension and you have either ignored it entirely or don't understand it. I'm not sure what would prove it to you.

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[thePill]

The geometry supports adjusting caster at the tension link. You can argue all you want but any change in the length of the Tension link is going to adjust caster, some camber and toe. Whether you can do that from the factory has yet to be seen and you probably can't. I imagine the lateral link might be, if Ford was smart they would make it adjustable but we all know how that works out.

I've already explained in TWO posts why this Strut configuration IS a Virtual Pivot suspension and you have either ignored it entirely or don't understand it. I'm not sure what would prove it to you.

Again, in order for this suspension to be Virtual Pivot, it needs an upper control arm to "pivot".

All virtual pivot has an upper control arm. From Ford to Buick, that is what made it VP. Please show me a Virtual Pivot system that uses a MacP strut.

I know you think a Double-Ball Joint MacP strut and a Virtual Pivot are the same, they are not. I posted about this very topic months ago...

Edit: Pull up a pic of Fords current Virtual Pivot Control Link from the Falcon and tell me what you see. Currently, Ford, Buick, Honda, BMW and Merc have all abandon the Virtual Pivot Double Wishbone for the Double Ball-Joint MacP Strut.

 

[Whiskey11]

Again, in order for this suspension to be Virtual Pivot, it needs an upper control arm to "pivot".

All virtual pivot has an upper control arm. From Ford to Buick, that is what made it VP. Please show me a Virtual Pivot system that uses a MacP strut.

I know you think a Double-Ball Joint MacP strut and a Virtual Pivot are the same, they are not. I posted about this very topic months ago...

Edit: Pull up a pic of Fords current Virtual Pivot Control Link from the Falcon and tell me what you see. Currently, Ford, Buick, Honda, BMW and Merc have all abandon the Virtual Pivot Double Wishbone for the Double Ball-Joint MacP Strut.

I'm not sure you understand what you are typing because you make it sound as if a strut suspension has no upper pivot point on which the suspension rotates around. That is false.

The upper pivot point is the upper strut mount bearing. The lower pivot is the virtual pivot point created by the intersection of lines drawn through the chassis side pick up points of both lower control arms and both lower ball joints. On a strut based suspension the strut is the upper control arm, you said it yourself in this very thread.

Here is the F30 M3's front suspension setup:

Tell me that doesn't pivot around a virtual point in space... news flash, it's a strut based car and guess what, Ford is using a similar setup with the Mustang. Edmunds had this to say:

The key advantage of this arrangement is the ability to move the virtual steering pivot point outboard to a spot that would be physically impossible with a single ball joint. This in turn allows the engineers to reduce the scrub radius and do other cool things with steering geometry. Of course the "instantaneous virtual" intersection point shown above is constantly moving, so figuring it out properly is a bit more complicated than just overlaying a couple of yellow lines.

GASP! Link if you don't believe me: http://www.edmunds.com/car-reviews/track-tests/2012-bmw-328i-suspension-walkaround.html

It's a virtual pivot point suspension, because the suspension pivots around a virtual point in space created by the intersection of lines drawn through both lower arms at the chassis pickup point and the ball joints on the control arms... the other pivot point is the upper bearing plate in the strut mount.

Yes and guess what, their dual ball joint system operates on a principle of creating a virtual point in space on which a line drawn through that virtual point and the bearing plate at the upper strut mount becomes the steering axis on which the entire suspension pivots around... hence Virtual Pivot Point... Ford has a dual wishbone setup that operates in the same way but it is not specific to dual wishbones, it's a concept in suspension design that is executable with a strut suspension as well as the dual wishbone setup.

 

[thePill]

I'm not sure you understand what you are typing because you make it sound as if a strut suspension has no upper pivot point on which the suspension rotates around. That is false.

The upper pivot point is the upper strut mount bearing. The lower pivot is the virtual pivot point created by the intersection of lines drawn through the chassis side pick up points of both lower control arms and both lower ball joints. On a strut based suspension the strut is the upper control arm, you said it yourself in this very thread.

Here is the F30 M3's front suspension setup:

Tell me that doesn't pivot around a virtual point in space... news flash, it's a strut based car and guess what, Ford is using a similar setup with the Mustang. Edmunds had this to say:


GASP! Link if you don't believe me: http://www.edmunds.com/car-reviews/track-tests/2012-bmw-328i-suspension-walkaround.html

It's a virtual pivot point suspension, because the suspension pivots around a virtual point in space created by the intersection of lines drawn through both lower arms at the chassis pickup point and the ball joints on the control arms... the other pivot point is the upper bearing plate in the strut mount.

Lol, I knew it... Please do not get "Dual Pivot" or "Double Ball" confused with Ford's "Virtual Pivot Control Link"

The "Virtual Pivot" they are talking about is an imaginary point that pushed the center of the wheel outward. It has NOTHING to do with Fords VPCL. The image above is BMW's (Insert long name here) suspension and is NOT Virtual Pivot Control Link. It is a Double Ball MacP system.

As I said before, both systems use a double jointed system to benefit from the extra clearance... Both systems operate on a "Virtual Pivot"

An imaginary axis that has nothing to do with bushings or bearing. Two completely different systems. Look at the Falcons and S550... You will see how different they are.

Don't be fooled by marketing names...

Edit: Ford's VPCL is an SLA system and Double Wishbone Hybrid. The lower arm is longer though...

 

[Whiskey11]

Lol, I knew it... Please do not get "Dual Pivot" or "Double Ball" confused with Ford's "Virtual Pivot Control Link"

The "Virtual Pivot" they are talking about is an imaginary point that pushed the center of the wheel outward. It has NOTHING to do with Fords VPCL. The image above is BMW's (Insert long name here) suspension and is NOT Virtual Pivot Control Link. It is a Double Ball MacP system.

As I said before, both systems use a double jointed system to benefit from the extra clearance... Both systems operate on a "Virtual Pivot"

An imaginary axis that has nothing to do with bushings or bearing. Two completely different systems. Look at the Falcons and S550... You will see how different they are.

Don't be fooled by marketing names...

I give up with you, you win. :hail:


:frusty:

 

[thePill]

I give up with you, you win. :hail:


:frusty:

Good, I knew people would get confused. The two systems are nothing alike...

 

[Grimace427]

Virtual pivot suspension vs. virtual pivot steering, seems like a completely semantic argument. Both of you guys are clearly very smart and experienced. Thanks for the info, we all greatly appreciate it!

 

[JohnZiraldo]

..seems like a completely semantic argument...

+1

Can I suggest we just call the new S550 front suspension "Fred" for now and discuss it's advantages over other designs.

 

[JohnZiraldo]

Just saw the video here: http://www.mustang6g.com/forums/showthread.php?p=23047#post23047 where Raj Nair said (at 17:20) the front suspension has a 'virtual joint'.

I hope that doesn't reopen the semantics debate. :shocked:

Maybe I should delete this comment. :doh:

Shucks. Let's keep going. addle:

 

[thePill]

Just saw the video here: http://www.mustang6g.com/forums/showthread.php?p=23047#post23047 where Raj Nair said (at 17:20) the front suspension has a 'virtual joint'.

I hope that doesn't reopen the semantics debate. :shocked:

Maybe I should delete this comment. :doh:

Shucks. Let's keep going. addle:

Virtual meaning "Imaginary" and the pivot point (or joint) is the axis. All modern suspension (SLA and MacP) has to incorporate more moving parts to get the clearance a Double Wishbone does.

The suspension diagram above is the basic (and true) Virtual Pivot Control Link. You can see the "Pivot Point" is an imaginary joint beyond the wheel. You can see, on VPCL, you need an upper and lower arm to create the point.

The MacP system uses NO upper control arm but still uses two links that push and pull. Both links house the "Double Ball" joints. and pretty much try am create it's own "Pivot Point" even though the suspension geometry is much lower on the MacP system than it is in an Short/Long Arm.


Virtual Pivot Control Link

The S550

Virtual pivot steering doesn't change a MacP system into a SLA/Double Lower Control Arm. A MacP system is a MacP...

 

[Whiskey11]

Virtual meaning "Imaginary" and the pivot point (or joint) is the axis. All modern suspension (SLA and MacP) has to incorporate more moving parts to get the clearance a Double Wishbone does.

The suspension diagram above is the basic (and true) Virtual Pivot Control Link. You can see the "Pivot Point" is an imaginary joint beyond the wheel. You can see, on VPCL, you need an upper and lower arm to create the point.

You do realize that no SLA setup has converging upper and control arm links at one point on the back of the spindle right? That would be the most useless SLA setup known to man kind and would still require something to keep the wheel upright. That picture is clearly plan view (top down), in which case there is no specific need for an upper and lower control arm, just two arms with separated ball joints on the same plane or near the same plane such as the S550's lower control arms. You could also have two upper arms as well for added tuneability. The strut configuration works the same way only it is just the lower arms. Think of the strut bearing plate as the upper ball joint on an SLA setup.

The MacP system uses NO upper control arm but still uses two links that push and pull. Both links house the "Double Ball" joints. and pretty much try am create it's own "Pivot Point" even though the suspension geometry is much lower on the MacP system than it is in an Short/Long Arm.

I'm not sure what you mean by two links that push and pull. The lateral link, at least from what we have seen, is purely lateral, IE, no ability to push or pull the suspension fore/aft or in any direction but under lateral loads. The Tension link certainly carries the fore/aft forces created by the tires as well as some of the lateral forces. The lower control arms on the S550's strut setup creates a virtual pivot point which is the lower point of two that the suspension rotates around. The other point is the upper strut bearing plate and the line between them is known as the steering axis inclination. By using two ball joints on the lower "arm" you move the SAI away from the bottom of the spindle.

Virtual pivot steering doesn't change a MacP system into a SLA/Double Lower Control Arm. A MacP system is a MacP...

I'm not sure who the heck you think is suggesting that it does. NO one is disputing that the S550 front suspension is a strut based setup, what I'm disputing is your assertion that the lower arms do not form a virtual pivot point, you know, that thing you seem to think can only be formed by an SLA setup.

I also don't agree with your assertion that it is being done for more clearance for brakes, wheels or tires. The S197 chassis, with a conventional MacPhearson strut setup could quite easily swallow 18x11" wheels with no poke and very little need for additional negative camber. It could also swallow 315's with ease. On the brake front, the same 15" rotors and 6 pot calipers in the new GT PP were standard on the 2013-2014 GT500's which used the same conventional strut setup as the rest of the S197 chassis. There are noticeable gains in front end grip from using the S550 type suspension. Sure, you'll gain the ability to use lower offset wheels which creates brake clearance with the spokes but that was hardly a problem on the S197 chassis.

 

[Fenderaddict2]

I get what The Pill is saying; as sold you can't adjust caster, and likely shouldn't. Aftermarket, all bets are off.

 

[qwkcoupe]

Just saw the video here: http://www.mustang6g.com/forums/showthread.php?p=23047#post23047 where Raj Nair said (at 17:20) the front suspension has a 'virtual joint'.

I hope that doesn't reopen the semantics debate. :shocked:

Maybe I should delete this comment. :doh:

Shucks. Let's keep going. addle:

:doh:

Settled. No semantics.

Raj Nair said

"... go to the double ball joint front end which gets us that virtual joint. "
:clap2:

Double Ball Joint (DBJ Part numbers) enables the Virtual Joint (VJ Trigonometry)


One day down the road we'll return to chapter 2 about:
Steering Axis Inclination Angle, Ankerman Steering, Roll Center height, Instant Center, Scrub Radius, and blah blah.

Back to chapter 1

Take Raj Nair's very next sentence as an example

"Allows us package a lot bigger brake system."

Up to this point I have been counting on Ford's definition authority.
:frusty:
DBJ allowing bigger brakes does not compute. DBJ actually consumes more space in the DBJ area.
I'm fine with keeping it simple and saying the bigger and wider more space consuming DBJ is kept cool by using larger rotors maintain the same ball joint to brake distance as a single BJ setup, thus brake rotor-pad surface heat is further from the joint's rubber and grease.... maybe, that is a stretch of my experience, and is not evident because they carried over same size brakes from previous single ball joint mustangs. The formula for larger brakes is wheels that have room so the caliper doesn't hit the wheel.

The following preamble makes tons of sense when Mr. Nair closed the suspension discussion with

" And um, it's the most capable platform we've ever had for the Mustang."



:ford:

 

[qwkcoupe]

Before we go further, let's recognize and thank Ford for what we anticipate will be a huge improvement thanks to those double ball joints resulting in a virtual pivot that should greatly help Steering Axis Inclination and Scrub Radius.

:amen:

Back to our regularly scheduled nit-picking.

I get what The Pill is saying; as sold you can't adjust caster, and likely shouldn't. Aftermarket, all bets are off.

Not quite. Caster adjustment would be like before left up to the aftermarket to adjust the strut top or bottom arms each with its own considerations, neither will affect the car's caster much.

I for one vote to save all conversation about ball joints and virtual pivots until the day when someone can actually provide measurements through the range of steering angle and wheel compression and rebound.


How about let's have the fun begin!
:clap2:

 

[qwkcoupe]

Here is the deal with aftermarket adjustable control arms for 6th gen, it takes a little more thought than doing a DIY wheel alignment in your driveway.

And honestly, this probably isn't even worth mentioning because I have a hunch Ford has this pretty well figured out from the pictures and "beat the Boss" --- within the confines of the wheel well space dictated by the engine width needs (Trinity fits) that are in fact what encourage the McPherson strut versus the upper a-arm(s) option.

Assuming Ford nailed it, we probably will not have as much reward for adjusting the length of the front control arms, which is greater than the adjustable camber plate reward. Adjusting the arms would let us play around within the limits of tire-body interference and/or racing sanctioning body rules.

The most significantly influenced reward for adjustable lower arm lengths: "track width", "camber", "King Pin"/"Steering Axis Inclination", and "Ankerman Steering". Of course, changing that requires re-dialing in Bump-Steer, Toe and Camber, and caster isn't something your going to dial in.

Going further requires talking about roll center, virtual pivot scrub radius, anti-dive, and ?? Those changes require the lower arm mounts to be re-positioned.

We still need to get back to the IRS. Much of this front stuff applies like roll center, anti-dive/squat, camber, toe.

Suspension is a rabbit hole, there are many ways in and out. Just have to take one need at a time. Right now, we think Ford nailed a good solution for the mustang.

Speaking of which, I can't figure out how we are going to be able to adjust the IRS anti-squat, if needed. It also looks like the spring's motion ratio took a back seat, well, to the back seat :-)

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