Greg, if we are talking about weight, (measured on a force scale), and not mass then sway bars can transfer weight front to rear and vice-versa diagonally which in a corner means that the most critical outside pair of wheels can experience a direct dynamic transfer of weight from front to rear...
Noah,
I was going to add more to the discussion on the effects of slip angle, but the post would have been excessively long. However, I think you might find this interesting.
Remember that the slip angle points the side force generated by a tire in cornering actually behind the center of the...
"Greg: "Sta bars change the left to right distribution of Fz, but they do not change the fore aft distribution. if they did one end of the car would rise up . Draw a free body disgram in side view."
Airpower140: Greg, you haven't seen racing cars where in a corner one end rises up?
Ah I get...
"IOW, it wasn't the same car any more, so an approach that implies linear behavior cannot be used to explain what was going on."
Norm, the crew knew what was going on because the reaction of the car was explained by a loss of rear roll stiffness. Note that the exaggerated lifting only occurred...
"GregLocock (Automotive)
18 Sep 16 05:53
blaa blaa blaa. Look at the FBD I posted. Criticise it. "
Greg, your diagram is irrelevant to what I'm talking about. Since you seem not to know that, we must be talking past each other.
gruntguru, You imply that the inside wheels exert an equal force...
"gruntguru (Mechanical)140A.
That is not a correct assessment either. If the roll moment is purely moment, the chassis will rotate about the roll axis so no "jacking" will occur - unless a wheel lifts off the ground. OTOH "jacking" can also be caused by suspension design (eg swing-axle) where...
It just so happens that today in qualifying for Sunday’s F1 race in Singapore Sebastian Vettel’s car experienced some kind of suspension failure that had his front end lifting up in a corner with the inside wheel high off the ground. It was absolutely spectacular and it was a perfect example of...
"Ah, not ironic then. Incapable."
Greg, I'm surprised you seem to believe "The" or "A" free body diagram can decide this question.
Of all the attitudes the suspension of a car on road or track can take for any condition of loading, side force and instantaneous ride height, the car would seek...
"RE FWD lifting inside rear wheels. You have drawn an incorrect conclusion from a correct observation."
Greg, the observation is that ALL normal car suspensions raise the CG of the car upon cornering. The ones that have one end with roll stiffness disproportionately high compared to the weight...
"Just about all farm tractors have zero front roll stiffness due to a center pivoting solid front axle. Rear suspension is the tires, which operate at low pressure. On ag tires, they roll quite a bit. Can-Am Spyder motorcycles with only 1 rear wheel also have, you guessed it."
True!
"Sta bars change the left to right distribution of Fz, but they do not change the fore aft distribution. if they did one end of the car would rise up . Draw a free body disgram in side view."
Greg, you haven't seen racing cars where in a corner one end rises up?
Seen on FWD, forward weight...
The "zero" roll stiffness in the example is used for illustration of why and how load transfer diminishes cornering power. I don't know of a suspension with actually zero roll stiffness.
One of the effects of caster is an effect called "trail". The steering axis does not have to be angled to get this effect. It occurs when the vertical rotation axis is in front of or behind the spindle to contact patch axis. This kind of geometry can introduce compliance steer and that can be...
The illustration about the zero roll stiffness with both tires sharing the vertical and cornering loads equally vs total weight transfer onto one tire shows the lessening in the geometric cornering power due to higher slip angle, as you acknowledge, and the poorer performance of the contact...
"NoahLKatz (Mechanical)(OP)12 Sep 16 02:50
...Why doesn't transferring weight from inside to outside tires increase their lateral tractive capability?
Seems to me that's what would should happen when increasing normal force w/o increasing the lateral force.
I understand that increased slip...
IMHO, modern tweaks that work tend to show up on almost all cars. For example, if you compare the cowl/windshield treatment of cars from 20 years ago with those of today you will notice a deeper windshield recess today with the recess extending up just about to the roof.
I've read research...
"Stiff frames give you a very abrupt impulse against your momentum when those horizontal/longitudinal vectors of force impact the wheels. The extremely tight undampened spring that is your frame will rebound violently and often before you are even clear of the bump."
To what Noah said above I...
Buggar, If I interpret them correctly, the diagrams you presented show the static force from a spring in one instance and then a comparative force from a "shock absorber" and then it talks about damping. Is that right?
I seem to remember from back in the day they measured chassis torsional stiffness with fixtures bolted to the spring perches. Vibration modes are different, you need to account for the whole system.
