Suspension Negative Camber Info - Sport Compact Car Magazine

Front Toe-In
Just Right
Generally helps make the car feel more stable

Too Much
Wandering under braking Refusal to turn in or rapid turn-in followed by understeer

Rear Toe-Out
Just Right
Easy midturn rotation. Less front tire load

Too Much
Violent on-throttle oversteer on RWD cars. Can help drift cars
Violent lift-throttle or trail-braking rotation

Rear Toe-In
Just Right
Easily controlled power oversteer in rear-wheel-drive cars

Too Much
Sluggish response. Midcorner understeer Instability at turn-in

Every car is adjustable for front toe through the steering tie rod ends. All multilink and some strut cars are adjustable for toe front and rear. Cars that use a live or beam rear axle must have the axle or axle housing bent to adjust toe by an experienced chassis shop.

Below are some typical toe adjustments for different cars, tire wear expectations and styles of driving.

Aggressive Street Driver
Front
FWD/AWD: 0 RWD: 1/16" In

Rear
FWD/AWD: 0 RWD: 1/8" In

Weekend Hot Lapper
Front
FWD/AWD: 0-1/8" OutRWD: 0

Rear
FWD/AWD: 0-1/8" OutRWD: 1/8" In

Racer Only or serious drifter
Front
FWD/AWD: 1/8-1/4" out RWD: 0

Rear
FWD/AWD: 0-1/4" out RWD: 0-1/8" in

Kingpin
Kingpin Inclination Angle is the angle of the line drawn through the same pivots as caster but viewed from the front of the car. Kingpin inclination angle always slopes toward the center of the car and is measured in degrees relative to vertical
Vertical
Kingpin inclination angle

Kingpin Kingpin Inclination Angle is the angle of the line drawn through the same pivots a

Step Seven: Make It Stiffer
Chassis stiffness is a critical element in suspension tuning. A flexible chassis doesn't allow the suspension to keep the tires in contact with the road and is less responsive to critical suspension changes like increased spring and anti-roll bar rates.

The best way to combat chassis flex is by seam welding every spot-welded panel in the unibody and installing a welded-in roll cage. Unfortunately, these are also the least practical ways to solve the problem. Chassis braces are better.

The most common brace is the strut tower brace, which connects the strut towers in the engine compartment. Triangulated strut tower braces are the most effective and tie both shock towers to the firewall. There are also lower crossmember braces and subframe braces available for most cars. Harness bars, which are stout bars that connect to the upper shoulder harness bolts and the floor, also significantly stiffen the chassis. Hinge braces tie the shock towers to the sturdy base of the A-pillar via the door hinges. These make a huge difference.

Any chassis bracing has the potential to bump your car up several classes in virtually any competition series (especially autocross), so be sure you read the rules if you plan to add braces to a car you race.

Caster
Caster is the angle of an imaginary line drawn through a car's steering pivots. On a car using upper and lower control arms (as pictured here), those pivots are the ball joints on the control arms. On a car with a strut suspension, the pivots are at the lower control arm ball joint and the upper strut mount at the body. Caster is measured in degrees relative to verticalThe torque reaction between the Dave Point and the tire's contact patch causes the steering to self-align-an effect drivers perceive as on-center feel. More caster and longer caster trail increase that feelingPositive caster angle
Dave Point
Caster Trail

Caster Caster is the angle of an imaginary line drawn through a car's steering pivots. On

Another way to stiffen a chassis is to inject Foamseal-brand two-part catalyzed polyurethane structural foam into the hollow structural members of the unibody. Although it's time consuming and messy, it can produce significant gains in chassis stiffness without resorting to a roll cage. Some manufacturers use this treatment to increase chassis stiffness from the factory.

Beware of the all-too-common inferior chassis brace. These are usually spindly-looking devices with small tubes and no gussets.

Contrary to popular Internet wisdom, it's impossible to make a chassis too stiff. Fortunately, chassis braces are rarely expensive and have few negative side effects. Certain chassis braces in combination with aggressive suspension tuning will cause handling problems, which should be tuned out through suspension adjustment. You paid good money for your adjustable suspension, so be sure you adjust it correctly.

Step Eight: Adjust Caster
Every car's front wheels turn on pivots attached to the suspension. Caster is the angle of the imaginary line drawn through the pivots. It's measured in degrees relative to vertical.

If the top pivot point is behind the lower pivot point so the caster angle slopes backward like on a bicycle (as viewed from the side), the caster is positive. If the angle slopes forward (which it never does), the caster is negative.

Kingpin Inclination Angle (KIA) is the angle of the line drawn through the same pivots as caster but viewed from the front of the car. KIA always slopes toward the center of the car and is expressed as degrees from the vertical plane. KIA is a design constraint and is not adjustable. Caster and KIA together affect straight-line stability and camber while the wheel is turned.