Make your car handle the way you want to: increasing understeer/oversteer

[Safir]

TO INCREASE UNDERSTEER TO INCREASE OVERSTEER
Front Tire Pressure Lower Higher
Rear Tire Pressure Higher Lower
Front Tire Width Smaller Larger
Rear Tire Width Larger Smaller
Front Camber More Positive More Negative
Rear Camber More Negative More Positive
Front Springs Stiffer Softer
Rear Springs Softer Stiffer
Front Anti-Sway Bar Stiffer Softer
Rear Anti-Sway Bar Softer Stiffer
Toe-In Increase Decrease

This is just a guide to help you get the performance you want out of your car, and is in no way a suggestion as to what your goals should be or the best way to accomplish them, thought it i generally accepted that in the hands of a competent driver "loose is fast"

[TehWagon]

very informative- thanks!

[htheduck]

You can induce oversteer with 'higher' rear tire pressures too.
How does that fit into the matrix? :lol:

Can you weave throttle inputs into a matrix for us please?...that would be handy! :thumbup:

-thanks

[99SL2_Modder]

What about Castor? You can definitely use castor for oversteer and understeer, it's just not a wearable adjustment.

[htheduck]

I'm still trying to visualize castor...properly:
Is that the spindle/knuckle distance relative to the verticle axis of the strut?

[99SL2_Modder]

I'm still trying to visualize castor...properly:
Is that the spindle/knuckle distance relative to the verticle axis of the strut?


Correct. Positive woudl allow the car to go straighter, but makes it "harder" to turn...allows wheels to go back to straight after a turn automatically. Used on power steering.

Negative would be harder to keep the car straight, but would glide the front end really easy into corners, and most likely would help to kick out the rear.

*edit*
Well, lbj/ubj positions.

<--front of the car
.........ubj
......../
.....lbj
Positive


<--front of the car
.......ubj
...........\
............lbj
negative

[OptiCon]

The tire pressure matrix you made primarily applies to AWD, where a loss in lateral traction is generally rare and very controllable. And the behavior of the tire sidwall is the greatest variable in corner attitude.

On a FWD or RWD car you really need to consider the size of the contact patch and hardness of the tire over the behavior of the sidwall.

Pump the rear tires on a mustang up to 45PSI and let you fronts down to 25psi. Fronts are soft with alot of rubber touching the road, rears are hard with less rubber touching the road. Oversteer... not understeer.

And castor has more of an effect on steering response than traction in corners.

[99SL2_Modder]

And castor has more of an effect on steering response than traction in corners.

True, but we were talking about oversteer and understeer, which both are loss of traction.

Having the steering be really responsive will jerk the front end around and cause a ripple effect towards the rear, causing a slight "kick". The rest of the settings would regulate how much "kick" there is.

[Safir]

this is assuming SMALL changes - if you go to extremes (45psi rear 25 front is extreme) it will nto nessicarally apply, it also does not take into account that some things make bigger differences than others, for instance, a swaybar or spring rate change will likely make a much larger difference than a few PSI change in tire pressures.

one thing I will concede: this matrix is generally IRS-centric, as not only are many of these changes impossible in a solid axled vehicle, but they often react differently than in an IRS car. Of course, some would argue that you shouldn't be worrying about handling characteristics in a car with a solid rear axle ;)

to help answer other questions i've seen here, although this probably belongs in it's own thread, here is a beginner's guide to alignment: http://www.familycar.com/alignment.htm

[the mike]

Caster folks, not castor. :wink:

[tomustang]

Here's a bigger list :thumbup:

http://rogerkrausracing.com/overundr.html

[ScoobyNubieToo!]

Caster folks, not castor. :wink:
Castor=http://www.thewaytobalance.com/PRODUCTS/ecp-castoroil.jpg

[DropTopChevy]

Caster folks, not castor. :wink:
castors are for pinball machines :banana:

[Silverfc88]

Bump!


I was thinking about this last night and I couldn't remember where to start with tire pressures. Just wanted to to bring it back.