PDA

View Full Version : So I'm reading this performance handling book...


enkeivette
08-07-2008, 06:04 PM
And I think I know now why Skunk was so adament about using stiffer springs as opposed to using sway bars. I still don't think that he was right, but I think I understand his argument.

A huge part of handling is driver skill, more specifically, corner entry and corner exit speed. As many of you already know I'm sure, you never want to brake into a turn or throw the car into a turn too fast, or whip the wheel. You want slow gradual transition, and the fastest possible exit speed. Throwing the cars weight more quickly than necessary, by whipping the wheel causes less favorable weight transfer and therefore a greater load on the tires. This in turn will cause traction to suffer and therefore you will not be able to exit the corner as fast as you would had you entered the turn gradually.

The second erratic weight transfer is hard braking, a necessary evil that we have less control over. Obviously you can't brake slowly into the turn, while racing you should almost always be hard on the brakes or hard on the gas. So this is where Skunks argument comes into play. Having a higher spring rate will cause the car to dive less into a turn and therefore the erratic weight transfer on the tires will be less severe. Although, a roll bar does something that stiffer springs can't do, it links the suspension. The sway bar uses the opposing force of the outside arm to pull against the inside arm effectively increasing the spring rate. Springs cannot take advantage of this on their own.

So the problem now becomes, more spring rate or a stiffer roll bar? The book does call for a roll bar, in all applications (racing or street) so it's not a question of whether or not, just how much.

94cobra69ss396
08-07-2008, 09:22 PM
In my opinion a little bit of body roll (just a little) helps plant the outside tire. If the spring rate is to stiff the car will drift.

Vettezuki
08-07-2008, 10:28 PM
It also depends on what kind of surfaces you'll be going over. The more rough, and pitted the surface, the more problematic high springs rates becomes as the chassis will tend to "float" by bouncing off the road as opposed to following the surface.

enkeivette
08-08-2008, 02:25 AM
In my opinion a little bit of body roll (just a little) helps plant the outside tire. If the spring rate is to stiff the car will drift.

Ya, matching the stiffness to the traction would be a big one too.

BADDASSC6
10-14-2008, 07:13 PM
And I think I know now why Skunk was so adament about using stiffer springs as opposed to using sway bars. I still don't think that he was right, but I think I understand his argument.

A huge part of handling is driver skill, more specifically, corner entry and corner exit speed. As many of you already know I'm sure, you never want to brake into a turn or throw the car into a turn too fast, or whip the wheel. You want slow gradual transition, and the fastest possible exit speed. Throwing the cars weight more quickly than necessary, by whipping the wheel causes less favorable weight transfer and therefore a greater load on the tires. This in turn will cause traction to suffer and therefore you will not be able to exit the corner as fast as you would had you entered the turn gradually.

The second erratic weight transfer is hard braking, a necessary evil that we have less control over. Obviously you can't brake slowly into the turn, while racing you should almost always be hard on the brakes or hard on the gas. So this is where Skunks argument comes into play. Having a higher spring rate will cause the car to dive less into a turn and therefore the erratic weight transfer on the tires will be less severe. Although, a roll bar does something that stiffer springs can't do, it links the suspension. The sway bar uses the opposing force of the outside arm to pull against the inside arm effectively increasing the spring rate. Springs cannot take advantage of this on their own.

So the problem now becomes, more spring rate or a stiffer roll bar? The book does call for a roll bar, in all applications (racing or street) so it's not a question of whether or not, just how much.

Alot of your causes and effects are wrong. Corner entry and exit speed are the result of a good driver (all else incommon). The driver is responsible for driving a good line and getting the most out of the car's capability (i.e. threshold braking, maximum cornering loads). The key is being aware of hte vehicles capabilities and providing smooth inputs.

There is no theoretical answer, just go do some track days and figure it out. Most likely someone has already done the experimenting and there are proven solutions out there.

I will tell you that bang for the buck go with sway bars. If you going all out, get springs shocks and then see where you are att then correct with a sway bar.

Vettezuki
10-14-2008, 08:34 PM
Alot of your causes and effects are wrong. Corner entry and exit speed are the result of a good driver (all else incommon). The driver is responsible for driving a good line and getting the most out of the car's capability (i.e. threshold braking, maximum cornering loads). The key is being aware of hte vehicles capabilities and providing smooth inputs.

There is no theoretical answer, just go do some track days and figure it out. Most likely someone has already done the experimenting and there are proven solutions out there.

I will tell you that bang for the buck go with sway bars. If you going all out, get springs shocks and then see where you are att then correct with a sway bar.

I don't know where, but I saw a documentary that did data overlays of Schumacher against his teamate back in the day. His lap times were faster, but he actually braked more gradually and earlier, as well as getting on the gas sooner coming out of a corner, but again somewhat progressively. I never did quite understand the jam on the gas, jam on the brakes approach to speed.