An Unsettling and Disturbing Guide to Handling, Modifying and Enjoying Your Car...

Handling 102 – let's get technical

Rules of thumb! This is all interesting and useful stuff, but you'll have to bear with me whilst I go through the list...

• Lowering the center of gravity of your car is good for handling; you have to be aware of all the variables, though, or you will create an ill-handling monster. The suspension of a car is designed with caster, camber, trail and roll centre values in mind, plus spring rates and damper values; just going in and cutting the springs to make the car sit lower isn't scientific. And it can be dangerous as well as illegal. So don't do it! (At least get an engineer's advice first if you are tempted an dwish to remain roadworthy.)
• Cornering force declines at slip angles above the limit of adhesion - which is why the steering "goes light" when the front end 'lets go'. Obvious in the wet. Ahhhh, so that's why that happens!
• Large slip angles create resistance which scubs off speed - this may seem the opposite to the previous dot point, but there you go! On a wet road it won't happen like this - you'll just slip and possibly gain speed as you slide sideways to oblivion (or the gutter). But on a dry road the friction of rubber against road will slow you down. The slip angle may be described as being the amount of steering input less the actual effective angle of turn. So a big slip angle means lots of wheel angle for little result. Therefore, if you reduce your slip angles you can go faster! This fact is handy also when your brakes aren't up to the job and some reduction in speed is warranted - just wind on some more lock! (Remembering to steer away from obstacles of course!)
  

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• Grip, expressed (for example) in the form "0.7" means that grip equals 700kg for every 1000kg of vertical force. This will make more sense when you get to a corner and run out of grip! Remembering that road surfaces and slip angles will affect your total grip 'budget'.
• At the limit of adhesion there is no room for additional forces. For example, braking or accelerating mid-corner will rob the tyres of some grip, and if by so doing you exceed the total grip (like the 700kg above), you will lose adhesion. If you habitally brake or accelerate mid-corner (or anywhere in the corner) and have not experienced this fact, then you can safely assume that you were nowhere near the limit of adhesion!
• If you don't 'get it' - slow down. The physics is important. Sure you can skill up by experience but knowing how and why things happen allows you to learn faster and to logically work through solutions - otherwise you'll be stuck with trial and error.
• So what about four-wheel drive? So what? Indeed, so what. Effective 4wd will distribute the forces more evenly, redistributing drive to balance traction thoughout a turn. This is especially noticeable when exiting a corner - the 4wd allows you to get more of the power down, earlier. However 4wd doesn't endow your car with mystical powers. Grip is still grip and you can only use what you have. Indeed your total grip budget will be no more than a 2wd car's, all things being equal (which they never are). However taking advantage of the available grip is made easier by the 4wd, especially so when it automatically redistributes torque between wheels. The downside is extra weight, of course. A lighter 2wd with good weight distribution and a throttle-sensitive, skilled driver will in all probability have the advantage. Especially in the dry.