effect of wheels on stability

[Guest]

Folks,

On one of the other threads it was implied that wheels had an effect on the high speed stability of the GT40 ... and perhaps that they had contributed to the Ken Miles J-car accident.

Had been planning to go with 17" Compomotives as they are available, allow designer offsetting, and reasonably priced.

Is there a real problem with wheel air flow dynamics at higher speeds?

thanks,

 

[Guest]

Mike, just a shadetree engineer educated guess here, but I would think anything the wheels would cause could be compensated by front internal aerodynamics. With a Sabre you might be doing some of the things suggested on the other thread anyway.

have you looked at team 3 wheels
http://www.cobracountry.com/team3/home_frm.html

not as many offsets as compomotive but doesn't have the 3 piece assembly bolts either

 

Hi, wheel offset can have a large effect on controlability, especially were one wheel hits a bump.
The primary ingredient here is "scrub radius", the point at which the tire ratates as it is steered, to the point at the contact patch centerline.
Excessive scrub radius can make impossibly heavy steering, pull the steering wheel out of a driver's hands, or just knock the car offline.
It also exaggerated castor weighting effects, and if extreme, can make the car over react to steering inputs.
It would have to be engineered in a sloppy way to reach these levels I should think.
A well designed front end would have enough steering offset, combines with the correct relative trail and castor to give nice steering feel.
King pin inclination also plays it's part when steering lock is applied.

 

Hi, wheel offset can have a large effect on controlability, especially were one wheel hits a bump, and under very heavy braking..
The culprit here is "scrub radius", the point at which the tire rotates on the ground as it is steered, to the point at the contact patch centerline.
Excessive scrub radius can make impossibly heavy steering, pull the steering wheel out of a driver's hands, or just knock the car offline.It can give non linear feel, and not tell the driver what is happening out there.
It also exaggerates castor weighting effects, and if extreme, can make the car over react to even very small steering inputs. Kart racers will have no doubt been there, done that!
It would have to be engineered in a sloppy way to reach these levels I should think.
A well designed front end would have enough steering offset, combined with the correct relative trail and castor to give nice steering feel.
King pin inclination also plays it's part when steering lock is applied.
Rob