I was looking at Bob's setup program and I must say I'm impressed. One question I have though and it might be silly, is with the under over steer setting. Is it better to set the car setup neutral or have it slightly either oversteering or understeering. I understand this may differ from car to car and also driving style, but as a general rule.
Thanks

I don't know if there is general rule, if you plow straight on corners put it more to oversteering and if your car turns before you were intended to put it more understeering side, maybe start with neutral setting?

Close to neutral I guess, but you also have to consider driving style.

I personally prefer oversteery handling - but some tracks/combos are better/easier with a particular kind of driving - don't think there is a defenite answer to that one.

To be fast you need just enough oversteer so you ovoid understeer but can still keep the back tidy.

I don't think you can really use the setup program to make a set and tell you how its going to handle.

You need to drive the car and get a general feel, pay close attention to the balance with fast vs. slow corners, tight vs. long corners, entry vs. center vs. the exit of corners and the balance over bumps and curbs etc.

I find it very useful to get a quick reference to what I can change to solve a small handling issue, visually I can see what changes will do what and in turn make them quicker and more accurately, rather than sitting there trying to picture what the front bump dampers are doing on a certain corner...I can actually see it with Bob's program.

By all means neutral is the fastest...by my definition anyway(might be different for other people), Neutral is when you turn in and the back rotates very slightly outward and the steering wheel is only slightly turned into the corner.

Your too loose when you feel the back tires scrubbing because the slip angle is too large and your too tight if you dial in my steering angle and it either feels numb and does nothing or begins to push worse.

Thanks for your replies guys. I'll try with a neutral setting do a bit of test driving and if it needs a tweak I'll try for a little bit of oversteer and see how it feels.

slight oversteer is fastest.

if you go into a corner too fast you will scrub off speed one way or another, but with oversteer at least you will be pointing in the right direction and can get back on the gas sooner than if you were understeering and pointing away from where you are trying to go.

and while you can get close to neutral, you can't really ever have perfectly neutral handling past the limit. something has to give up traction first, and even the smallest difference in front/rear grip will be revealed when you push too hard.

Quote from KartRacer :

I don't think you can really use the setup program to make a set and tell you how its going to handle.

You need to drive the car and get a general feel, pay close attention to the balance with fast vs. slow corners, tight vs. long corners, entry vs. center vs. the exit of corners and the balance over bumps and curbs etc.

Your too loose when you feel the back tires scrubbing because the slip angle is too large and your too tight if you dial in my steering angle and it either feels numb and does nothing or begins to push worse.

Good advice this.

One thing I would mention is that you don't have slip angle on non-steering tyres. Slip angle is the difference in angle of the contact patch of the tyre and the angle of the wheel itself.

If you are parked up and you turn the wheel a tiny bit and you feel that resistance but then let go and it springs back. Thats the slip angle of the tyre that you can feel. If you keep turning to the point where you move the tyre on the ground then when you let go the wheel won't spring back all the way. That's because you turned more than the slip angle of the tyre so the tyre began to change angle on the ground.

Slip angle is just the flexibility in the tyre sidewall that allows there to be a difference in the angle of the wheel compared with the angle of the tyre. Low profile, stiff side walled tyres have a smaller slip angle than big baloon tyres. Also, more pressure equals less slip angle because the tyre becomes firmer.

I use Bob's program to give me a base set, normally 3ghz suspension frequency, and a slight bias toward oversteer.

I then drive this base set for a number of laps to get my camber/tyre pressures sorted, then I will use the program again to fine tune the damper/ARB settings to give me the desired understeer/oversteer in the various conditions.

Quote from Gentlefoot :

Good advice this.

One thing I would mention is that you don't have slip angle on non-steering tyres. Slip angle is the difference in angle of the contact patch of the tyre and the angle of the wheel itself.

If you are parked up and you turn the wheel a tiny bit and you feel that resistance but then let go and it springs back. Thats the slip angle of the tyre that you can feel. If you keep turning to the point where you move the tyre on the ground then when you let go the wheel won't spring back all the way. That's because you turned more than the slip angle of the tyre so the tyre began to change angle on the ground.

Slip angle is just the flexibility in the tyre sidewall that allows there to be a difference in the angle of the wheel compared with the angle of the tyre. Low profile, stiff side walled tyres have a smaller slip angle than big baloon tyres. Also, more pressure equals less slip angle because the tyre becomes firmer.

There is always slip angle, well as long as tire is on ground and it's hardly ever is 0 but slip angle of 0 is slip angle, tire itself don't need to turn as when you are turning car there is automatically some slip (or else tire goes straight and leaves car turning and this we know is impossible unless someone forgot wheel nuts).
Also there is lateral slip (which you are referring to) and longitudinal slip so you get slip angle too for both.

Not that it has much meaning for setting up a car, though Getting thing turn and not need to put it sideways to turn should be enough precision needed when making setup.

Quote from danowat :

I use Bob's program to give me a base set, normally 3ghz suspension frequency, and a slight bias toward oversteer.

Hi caramba Batman, that is over 1000 times too much, must be typo that 'g' there? 3Hz is quite stiff already, some very light car or car with wings can have such, certainly too much for road cars, imo.

Quote from JTbo :

There is always slip angle, well as long as tire is on ground and it's hardly ever is 0 but slip angle of 0 is slip angle, tire itself don't need to turn as when you are turning car there is automatically some slip (or else tire goes straight and leaves car turning and this we know is impossible unless someone forgot wheel nuts).
Also there is lateral slip (which you are referring to) and longitudinal slip so you get slip angle too for both.

Not that it has much meaning for setting up a car, though Getting thing turn and not need to put it sideways to turn should be enough precision needed when making setup.

Sorry to disagree mate but that is wrong. If the wheels are not changing their angle then there cannot be any slip angle.

You also refer to lateral and longitudinal slip. I think you are referring to lateral and longitudinal grip not slip angle - OK a slip angle 0 degrees but an angle of 0 degrees is not an angle .

Clearly we have a completely different idea of what is meant by slip angle. It has nothing to do with the tyres sliding across the tarmac. As I said before its the relationship between the angle of the wheel and the angle of the tyre and the fact that they are slightly different when you turn the steering because there is some flexibility in the sidewall of the tyre.

With regards to lateral slip, there is always a small difference between the angle of the tire and the motion vector. This is the slip angle. Both the front and rear tires have their own respective slip angles in a turn. As long as you're even remotely close to the limit, there's always a slip angle. Also, the slip angle of the rear tires is the same as the "angle of attack" (to use an aviation term) of the chassis, that is the difference in angle between the direction in which the car is pointed and the motion vector.

By their very nature, tires produce their maximum grip at a small slip angle, NOT zero, and therefore IS sliding a little bit at maximum grip. Beyond that, I think there is a very gradual decline in grip as the slip angle, and therefore the amount of sliding, increases. Oversteer is caused by having more lateral grip on the front tires than the rears, and vice versa for understeer.

Now the other thing mentioned is a "longitudinal slip angle". This is incorrect. The correct term is logitudinal slip ratio. It is the ratio of speed between a point on the tread surface of the tire and the road. As with slip angle, there is a specific slip ratio at which the tire produces maximum grip. Also as with slip angle, the slip ratio at peak grip is NOT zero, and therefore there is always some small amount of spinning/sliding of the tire at peak grip.

I'm not saying that I would understand all and everything, but read lot of stuff from here I would like to say that when car is moving there can't be 0 slip angle or maybe it is 0 slip ratio, well whatever it is, I'm not engineer and I don't care enough of correct terms, for me it is enough to understand how thing works so I can re-create it or use information to make a good setup