Push rod on upright suspension - an examination

[PlatinumZealot]

Does loading the outboard side of the wing of the inside tyre help load the inside tyre, or does it transfer to both front wheels equally?

I'd assume it would transfer load to the inside pylon, and "tilt" the nose in that direction, but im not sure. Part of my brain says it would, and possibly lift the outside pylon like a lever, but with zero real world experience, I'm simply not sure, and would like some professional input.

Because the moment has to be balanced it should add load to the inside wheel.

Maybe this is what is being done to even out the tyre loads.

Normally that side of the wing would be higher off the ground because of body roll and thus generate less downforce.

[Zynerji]

Thanks for your answer. I would upvote if it worked on Chrome mobile...

[Greg Locock]

I would expect that with the amount of pontificating going on here some enthusiast would have hacked together CAD or whatever and actually plotted some curves out. K&C=kinematics and compliance. As I said I'm not going to as that's my job at work.

[henry]

I would expect that with the amount of pontificating going on here some enthusiast would have hacked together CAD or whatever and actually plotted some curves out. K&C=kinematics and compliance. As I said I'm not going to as that's my job at work.

No doubt someone could scan photographs to get the geometric constraints and hence kinematic behaviour but, bus driver or no, from whence would they get the compliance values of the flexible elements and, in particular, the change in aero downforce with ground clearance?

[Greg Locock]

aero-Katz or Wright

The compliances won't change the shapes all that much.Spring rate matters.

[henry]

spring rates would come from? And they’re not compliance?

[Greg Locock]

Usually by compliances we'd mean bushings and the structural stiffness. Spring rates are a tunable parameter.

[Sevach]

I'm suspecting the primary use of the DAS is not for tyre scrub but to change the ride height down the straights for lower drag.

No way they could be doing that and avoid the "movable aero" hammer.

[henry]

Usually by compliances we'd mean bushings and the structural stiffness. Spring rates are a tunable parameter.

I see. Since the F1 suspension has no bushings, or at least mightily stiff ones, and the stiffness of the other components are also pretty much unknowable, what you meant was a Kinematic study.

Edit: having looked at what K&C rigs do they seem to measure parameters that are invoked by mechanism movement due to spring stiffnesses. So while springs are tuneable the results are measured for one set of tuned springs.

I guess the difference with F1 is that the movements affect the loads, and hence movements themselves, due to the change in aero loads created. After all that’s why they have run with the POU setup.

[PlatinumZealot]

I would expect that with the amount of pontificating going on here some enthusiast would have hacked together CAD or whatever and actually plotted some curves out. K&C=kinematics and compliance. As I said I'm not going to as that's my job at work.

That's exactly why you should!

I did a kinematic sketch in CAD after i did the ackerman post. That's why i stood corrected when i wrongfully stated it was anti-ackerman.
I'm very rusty though so didnt bother to put in all the details in the sketch.

[godlameroso]

Usually by compliances we'd mean bushings and the structural stiffness. Spring rates are a tunable parameter.

I see. Since the F1 suspension has no bushings, or at least mightily stiff ones, and the stiffness of the other components are also pretty much unknowable, what you meant was a Kinematic study.

Edit: having looked at what K&C rigs do they seem to measure parameters that are invoked by mechanism movement due to spring stiffnesses. So while springs are tuneable the results are measured for one set of tuned springs.

I guess the difference with F1 is that the movements affect the loads, and hence movements themselves, due to the change in aero loads created. After all that’s why they have run with the POU setup.

Rose joints have very little compliance beyond their intended articulation. Road cars use rubber bushings, especially the front compliance bushing that controls caster because of NVH, things that don't matter in a race car. A lot of performance cars coming out today with double wishbone suspensions still use steel reinforced rubber bushings for the lower arms, and rose joints in the upper arms. They're finally catching up to what people in the S2k scene have been doing for over 5 years

[PhillipM]

Road cars have used rotoball versions of spherical bearings with rubber/polymer outer races for decades, way longer than 5 years.
They only get used where absolutely required though because they're worse than a normal bonded bush for friction and NVH

[Greg Locock]

15 or 20 years ago one of my coworkers designed a rubber bushing that was as stiff as a typical rose joint (at least as installed, the installation stiffness of most cars is way less than that of a rose joint), and had very little coning or torsional stiffness, originally used to reduce the side load in the shocks. A fine and useful bush which is used in several of 'my' suspension designs.

[MtthsMlw]

I think this is the W10

Source

[Stu]

So in plan view is the pushrod to spindle joint in front of, or behind, the kingpin axis?

The attachment ‘link’ on the Mercedes one is so long/offset that it could conceivably be both, depending on whereabouts within the steering range it is!!