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Old 01/24/2009, 12:35 AM   #1 (permalink)
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Exclamation Everything about handling that you need to know

I have spent alot of time on this and hoping that it will become a sticky so read on there is alot of information so enjoy and if you would like me to make anything more clear send me a p.m and I will do what I can thanks


What is handling?
How often have you heard the phrase "good handling" ? Just what is that? For many drivers, good handling is a feeling. Some describe it as improved responsiveness. While that is part of the equation, good handling encompasses much more than just feel or responsiveness. Good handling means more traction during braking, cornering , and acceleration , quicker response to driver inputs , good balance at the limit, and, in competition , lower elapsed times or faster lap times.
A car that handles well has three primary characteristics. First , it makes the best possible use the tires traction capacity. Second, it has a god balance of traction front to rear. Third , is it instantly responsive to the drivers steering , throttle and throttle inputs.

Maximum traction implies sticky tires, but sticky tires only aid traction when they have good contact with the road. What keeps the four tire contact patches on the road is a combination of tire sidewall stiffness, suspension geometry, the ability of the springs and shocks to control the tires over bumps, the degree or roll resistance offered by the anti roll bars and springs and the compliance of the suspension bushings. Thus, good traction requires far more than wider rims and a set of new tires.
Superior handling incorporates balance, a problem that confronts even top racers. Most everyone has heard the term push or loose on T.V race coverage. A push, or understeer, means the front tires are loosing traction before the rear. The car will not turn as much as it should as the limits of the tires are reached. A loose condition, or oversteer , means the rear tires lose traction before the front tires. Thus the car will turn more than it should, as the tires reach the limits of traction. The biggest influence on handling balance is the balance in roll resistance of the front springs and anti roll bar compared to the rear springs and anti roll bar. If you take a car with neutral handling and stiffen the rear anti roll bar or springs, the car may become loose or understeer. If you stiffen the front springs or bars instead the car may push or understeer. The job of the aftermarket spring and anti roll bar is to control body roll and create the optimum balance between front and rear resistance so that the handling balance is near neutral.
Responsiveness to driver control inputs is the third characteristic of good handling. While stiffer springs and antiroll bars, stiffer suspension bushings and stiffer short tire sidewall all improve a cars responsiveness, the biggest influence here is the shock absorber. Stiffer shocks improve responsiveness, to a point. Shocks that are to stiff will make the car twitchy to drive and cause it to skate over bumps, actually hurting traction and over all handling performance

A well conceived suspension system address all of the factors and uses suspension components that are compatable with the car, the driving and road conditions and the degree of desired handling performance. Ill conceived systems can hurt cornering and overall handling performance and deteriorate ride quality as well. Lets take a look at the factors and components that must be right to achieve good handling.

TIRE LOADS
When a car is at a rest, a certain amount of weight rests on each tire contact patch. This static weight distribution influences the traction at each corner of the car. The traction of the tire is proportional to the weight , or load, on the tire contact patch. If the load increases, the traction increases, If the load decreases, the traction decreases. The relationship is non linear, however this means that if the load is doubled on a tire, the traction is something less than double.

WEIGHT TRANSFER
When a car accelerates brakes or corners, some proportion of the weight or vertical load will effectively transfer from front to rear , rear to front, or inside to outside. This changes the traction at each of the tire contact patch. For a givin car and rate of acceleration, slowing, or cornering, a givin amount of weight will transfer from one set of tires to the opposite set of tires. What effect this has on handling depends on where the weight is transferred, when its transferred, and how fast it gets there.
Weight moves from the front to the rear under acceleration, from the rear to the from under braking, and from the inside to the outside while cornering. But while cornering , some of the weight moves to the front outside and some moves to the rear outside. The comparative stiffness of the springs and antiroll bars between the front and the rear determines how much weight moves to the outside front verses the outside rear. If a spring or antiroll bar is stiffer at one end of the car, that end of the car will get more of a sideways weight transfer during conering. That end of the car will also have less traction relative to the other end of the car. For example stiffening the front springs or anti roll bars will caise more weight to transfer to the outside front and cause more understeer or push. Antiroll bars and spring rates are used to control this handling balance.

When the weight transfer occurs depends on when the driver uses the controls and how quickly those controls are moved. Abrupt use of the controls can cause abrupt weight transfer , upsetting the handling balance and deteriorating handling quality.

Compliance in the suspension system determines how quickly weight in transferred. The major component here is the shock absorber, though suspension bushings play a small roll. Stiffer shocks cause weight to move faster. Softer shocks cause weight to move slower. As mentioned above, increasing shock stiffness improves handling to a point, after which the tires will lose contact with the road surface on bumpy surfaces. Stiffer shocks also reduce ride comfort.

TIRE PRESSURE

Tire pressure effects the shape of the tire contact patch, which effects the load across the tread of the tire. If the tire is overinflated, the center of the contact patch is loaded more than the edge of the patch. Under inflation has the opposite effect. Finding the optimum tire pressure for the car, tires, wheels, and suspension system ensures that each contact patch is evenly loaded and maximum traction is available.


CAMBER

Camber is the tilt of a tire when viewed from the front of the car. Camber is positive if the top of the tire is tilted to the outside and negative if the tile is to the inside. Since most suspension systems gain positive camber during bump travel, and the outside tire goes into bump during cornering, some amount of negative camber is need to off set the camber gain and keep the tire contact patch flat on the road surface during cornering.

Camber gain is caused by suspension geometry changes caused by body roll. During body roll the outside front tire usually gains camber. This tilts the tire contact patch and changes the loading across the tread, reducing traction. Some static negative camber can compensate for this, but too much negative camber causes accelerated tire ware and hurts straight line braking performance. Stiffer front springs and antiroll bars, which reduced bump travel and camber gain. This reduces the amount of static negative camber needed to keep the tire contact patch flat on the road surface in a corner.

TOE

Toe is the angle of the front tires when viewed from above. Toe in means the front of the tires are closer together than the rear of the tires, toe out is the opposite. Cars will turn into a coner better with a small amount of toe out. Toe in offers more stability in a straight line, so for highway and daily street driving, a small amount of toe in is preferred. To much toe in or toe out will increase tire wear. Rear suspensions can also have toe in or toe out. Some cars actually work better with a small amount of toe out at the rear, but most cars need some toe in at the rear to ensure straight line stability, especially drag racing or high speed road courses.

CASTER

Caster is the angle of the steering axis at the front of the car when viewed from the side. More caster increases the self centering effect of the steering, but also increases scrub lightly while cornering. Different caster angles on the left and right side cause the steering to pull in one direction. Using the factory recommended caster angle is preferred.

RIDE HEIGHT

Lowering a car reduces weight transfer and improves cornering performance by lowering the center of gravity. It also reduces suspension travel so stiffer springs are needed to keep the car from bottoming out over bumps over bottoming on the suspension which can cause damage, especially to shock absorbers.

SPRINGS

The job of springs is first to keep the car from bottoming , second to allow the tire contact patches to stay on the road surface over bumps, and finally to partially to control body roll. Stiffer springs allow a car to have a lower ride height and also reduce body roll, both important for improved handling. On the other hand, stiffer springs reduce the ability of the tire contact patch to stay on the road surface over bumps, hurting traction on bumpy roads as well as increasing ride harshness. Any spring choice represents a compromised based on a drivers ride and handling priorities.

ANTIROLL BARS

Antiroll bars serve two purposes. First as a name suggests they control body roll so that camber gain is not excessive. Second, they bars are convenient way to balance the roll resistant front to rear to achieve the best handling balance. Stiffer springs play a roll in these functions but could not replace antiroll bars without being to stiff for comfort and control on bumpy surfaces.

SHOCKS

Shocks are designed to control spring movements over bumps. Without shocks, the springs would continue to oscillate, causing the car to bob down the road. In a performance application, shocks are used to control how fast weight is transferred and thus influence the responsiveness of the car to driver inputs. Shocks can be tuned in both bump and rebound travel and can operate at various shaft speeds to achieve a variety of handling characteristics under many road or track conditions. Shocks must be designed to work in a specific application to achieve good handling characteristics.

BUSHINGS

Suspension bushings are intended to reduce and insulate the car’s occupants from road noise and vibration. Bushings also permit the suspension to move through its arc of travel. Stock bushings are usually made of rubber. The soft rubber insulates well but allows a high degree of compliance in the suspension. This hinders responsiveness to drivers inputs and increases suspension deflection, hurting over all handling performance. Solid metal bushings reduce compliance to nearly zero, but they are noisy and harsh. Urethane bushings reduce compliance considerably but maintain some comfort and noise control. Just adding performance bushings to your car will improve handling noticeably.

CHASSIS BRACING
A variety of chassis stiffeners and strut tower braces are available for many street and motor sport applications. By limiting chassis flex, such bracing reduces suspension movement, making the car more responsive and reducing handling issues such as camber change. When a chassis flexes, it acts like an undamped spring, which can be very difficult to control and tune. Chassis bracing improves handling but also makes the ride harsher.

TUNING

Even after installing a fully integrated suspension system consisting of springs, antiroll bars, shocks, bushings, wheels, and tires, the system needs to be tuned for optimum performance. At a minimum, the proper tire pressures and suspension alignment settings must be found. Tuning can make big improvements in handling performance once you have the best components on your car. Its also a broad subject, which is why a major part of this book is devoted to alignment and tuning. Even for the street, tuning pays significant dividends in improves performance and better tire wear. And the best handling car is also the safest, since good handling and braking mean you have a better chance to avoid as impending accident.

DRIVE SYSETEM CHARACTERISTICS

While each type of drive system has its individual characteristics, the tire contact patches do not know what type of drive system they are trying to control. We do exactly the same things to a front driver that we do to a rear or all wheel drive vehicle to get the handling balanced and maximum traction from the entire vehicle. Over all, the differences are more significant to driving technique than to drive system adjustments. There are a couple of exceptions.

First, the higher suspension frequency (determined by spring rate among other factors) will go at the driven end of the vehicle with an all wheel drive being treated as a front driver if the weight bias is to the front. Second, on a front drive vehicle with about 59% of the weight on the front end, the roll stiffness should be high enough to un weight the rear tire contact patch considerably in a corner. On the track or auto cross course, this usually means that the tire contact patch is just off the track surface. This is usually what is needed to counteract under steer, and it is accomplished with a stiffer antiroll bar. On the highway, a slightly softer setup is needed for stability. Beyond these specifics, we engineer and tune the chassis in the exact same way regardless of the drive system.

THE ISSUES
There are two decisions that you must make when you begin the quest for improved handling. First, how will you use the car?
• Street or highway only?
• Combination of highway and motor sports?
• Competition only?
Second, what compromises must you make, or are you willing to make, to achieve improved handling? These will be different for each individual and for each of the above categories.

STREET AND HIGHWAY APPLICATIONS
If you will use your car only on the street or highway, consider the following factors and their relative importance to you.
• Type of daily driving
• Fun driving (mountain roads, canyons, interstate ramps)
• Importance of ride quality
• Desire and practical ground clearance
• Vehicle appearance
• Product availability for your vehicle
• Driving skills
• Mechanical skills

COMBINED STREET AND MOTOR SPORTS APPLICATIONS
If you plan to compete with your daily driver, consider the following factors.
• Type of event (drag race, auto cross, rally, track days)
• Category of competition
• Rules
• Budget
• Product availability for your vehicle
• Ease of conversion from road to track specs (tires/wheels, ride height, alignment)
• Ride quality
• Ground clearance

COMPETITON ONLY
This one is much easier. The compromises are geared toward making your vehicle as fast as possible. But you should still consider the following.
• Type of competition
• Suitability of your vehicle
• Class
• Budget
• Availability of parts for your vehicle
• Mechanical skills
• Driving skills
Your goals and desires, along with your budget, will settle most of your decisions. The rest is combining you parts and goals to achieve optimum performance.



don alexander 2002 h.p.h.h.
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Old 01/24/2009, 01:11 PM   #2 (permalink)
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Here is the original source of what he posted.
High-Performance Handling - Google Book Search

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Old 01/24/2009, 06:15 PM   #3 (permalink)
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Originally Posted by BlackWidow View Post
Here is the original source of what he posted.
High-Performance Handling - Google Book Search
yep and I made sure that I put his name at the end of that and the year. I thought that we should have a thread that was nothing about opinoin and all about time tested truth
didnt think that it was a bad thing I was thinking about taking time and writing up most of it so that people that dont have that book would be able to get all the great information that is in it. I would of course give all credit to don for it though. if anyone can find that book I would suggest that you buy it, its terrific
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Old 01/24/2009, 11:39 PM   #4 (permalink)
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Nice post, but it doesn't seem to cover the importance of corner weighting your vehicle for more optimal handling and load distribution under hard or extreme conditions. Not every corner will require the same damperner settings or even ride height. That is very specific and in many cases why some teams are successful and some aren't.

I suspect it maybe in that book that is referenced though, but again great post.
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Old 01/25/2009, 01:38 PM   #5 (permalink)
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Originally Posted by RedGalant2k1 View Post
Nice post, but it doesn't seem to cover the importance of corner weighting your vehicle for more optimal handling and load distribution under hard or extreme conditions. Not every corner will require the same damperner settings or even ride height. That is very specific and in many cases why some teams are successful and some aren't.

I suspect it maybe in that book that is referenced though, but again great post.

thank you ... again this was intended as a more general knowledge post for those that dont have a good undersdtanding, I will get into another post soon for more race ready setups and more involved understanding of different types of setups and how they are used
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Old 03/19/2009, 06:20 PM   #6 (permalink)
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I agree with your post!

I've been trying to instill in those who installed CO's to have the car professionally balanced but know for a fact very few have done so!

And of course that brings up the point as to what one is using the car for, ( as described above). For the street may not be too critcal but for any type of Autocrossing/ road race quit so. IMHO
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