Tyre grip-understeer and slip angle

[ParkerArt]

There is an inertia that needs to be overcome when you place weight at an extremity of a car, it's why Subarus are so stable, they have a wide, and low center of gravity over the front wheels.

You mean why stock Subaru's terminally understeer like a snow plow, just like most Audis.

[Greg Locock]

Oh please do tell which consumer oriented production cars don't do terminal understeer? Do you understand why?

[Jersey Tom]

Oh please do tell which consumer oriented production cars don't do terminal understeer? Do you understand why?

Some more so than others, though

Doing some handling & tire evaluations on Z06 Corvette and a Camaro a few years back... what a difference!

[Ciro Pabón]

Hi, Tom. Just curious: in favor of which car?

No understeering! or so I think


And.. can I say merry christmas already? I just FINISHED my work for this year. Yay!

Prepare yourselves for many long posts with bad jokes and poorly chosen pictures!!!!

My condolences, guys.

Samantha Claus. She KNOWS you're a naughty boy! Ho, ho, ho.

[ParkerArt]

Oh please do tell which consumer oriented production cars don't do terminal understeer? Do you understand why?

Safety.

Plenty of mechanical reasons; too stiff front roll bar, too much brake dive, square tire sizes despite the fronts needing ~20% for grip, but it is done to keep Joe Schmoe from slide off the road backwards. Most crash structures are designed to protect in front end collisions.

[Jersey Tom]

Hi, Tom. Just curious: in favor of which car?

Corvette was reasonably well balanced. To the earlier point, obviously all OEM cars are going to have some amount of limit U/S trim. Camaro from my recollection though was pretty extreme.

[Tim.Wright]

square tire sizes despite the fronts needing ~20% for grip

Say wha??

[Tommy Cookers]

car certification now demands understeer? including throttle-off ?
and there is the related rollover/lane change certification ? (the reason suspensions are usually too hard now)

Mr Olley surely meant that it was steady state behaviour that was to be characterised as understeer or oversteer
the power (tractive thrust) required to maintain that state will be rather large even with modern tyres
and the effect of throttling-off, especially in a lower gear, will be significant

and there's the throttling-up case, an LSD potentially helps breakaway, so is driver-selectable traction control mandated ?

[Greg Locock]

I have more than a suspicion that ESC, which includes traction control, is already mandatory in some markets,and an inkling that in many cases the off button doesn't mean off exactly.

Also bear in mind that if you have an accident the historical state of TC button is logged and remembered in the black box. Your insurance company will doubtless be very interested in that data.

[Smokes]

Please remember....

Car companies don't want the customer to end up dead, or generate a lawsuit due to the car being difficult to drive.
This because
It is more profitable if the customer survives an accident with minor injuries and buys another car after the old one is written off. Than killing or disabling the customer.

Also insurance companies want to minimize medical bills and risk of accidents which is why cars tend to be heavier due to the safety requirement that the insurance company lobbied into the government type approval standards. This also why road cars are set up to under steer as most drivers would not be able to correct or expect snap over steer on a road car.

[olefud]

Oh please do tell which consumer oriented production cars don't do terminal understeer? Do you understand why?

It’s less traumatic to go off the road and through the fence frontwards than it is to do so backwards.

[dynatune]

Grip is an indication/coefficient of how much lateral force can be created out of vertical force on a tire. Understeer is the difference between front and rear slip angle. Understeer Gradient is the difference of front vehicle side slip angle gradient and rear vehicle side slip angle gradient. All of those (tire) parameters do have sometimes rather particular effects on vehicles and are usually investigated with more or less complex tire models and more or less complex vehicle models. If you want to learn start simple with a bicycle model and a simple cornering stiffness tire model and work your way up from there. Have Fun.

Cheers,
dynatune, http://www.dynatune-xl.com