Alfa Romeo Suspension Adjustments


Alfa Romeo Suspension Guide DiagramIn stock form the 105 and 115 chassis cars (65-74 GTV and Berlinas, 66-94 Spiders) have more weight over the front tires and tend to understeer. The 116 Alfettas, 119 GTV/6s, and 119 Milanos have their weight equally distributed over the front and rear tires resulting in neutral handling. The accompanying table lists adjustments you can make to fine tune your car’s handling. One change at a time will give insight to your car’s behavior, and allow you to safely evaluate the changes.

A condition in which the vehicle does not make the directional change that steering input would indicate. More steering correction is needed to negotiate a given radius turn. The front of the car loses traction first causing the car to plow straight ahead.

A condition in which the vehicle makes a greater directional change than the steering input would indicate. Less steering correction is needed to negotiate a turn. The rear of the car loses traction first and the rear end may spin out.

Steering action matches car reaction.

Suspension Adjustments

Tire Pressure
The amount of air pressure in a tire. During hard cornering a tire tries to shift sideways from the wheel, reducing its contact area and traction on the road. Increasing the pressure in a tire reduces the tendency to shift. (Never inflate a tire to a pressure greater than the maximum allowed by the manufacturer.)

Tire Section
The width of tire in relation to its height. A tire with a label of “195-60 14” has a width of 195 mm, a height of 117 mm (195 mm x 60%), and fits on a 14 inch rim. Increasing tire width increases the contact area of a tire, providing more traction. Reducing height decreases sidewall flex under load, also improving traction.

Wheel Width
The distance between the outside and inside wheel rims. Increasing wheel width reduces the tendency of a tire to shift sideways from the wheel, and maintains greater tire contact patch on the road.

The inward or outward tilt of the tire at the top, measured in degrees; the amount the tire is tilted from “true vertical.” Incorrect camber causes the front tires to wear unevenly. Positive camber is when the top of the tire tilts away from car; negative camber is when the top of the tire tilts towards the car. During cornering the outside wheels should be near vertical to maintain the greatest contact area and traction. As a car corners, body roll forces the outside wheel away from true vertical towards positive camber. This can reduce the contact area causing a loss of cornering traction. More negative camber will increase grip in turns, to a point.

The forward or rearward tilt of the steering spindle and the amount the center line of the spindle is tilted from the vertical, measured in degrees. Caster provides “trailing effect” for positive steering control, ease of steering, and ease of straight line tracking. Correct caster causes the tires and steering wheel to return to center after a turn and causes the tires to track straight on level roads. Uneven caster causes the car to drift or pull. More positive caster will give less camber change as the front wheels turn. More positive caster , to a point, improves straight line tracking.

The difference in distance between the front of the wheels and the rear of the wheels, measured in inches, millimeters, or degrees of angle. Toe-in is when both front wheels are angled slightly with the leading edges closer together. On most rear wheel drive cars, this compensates for the tendency of the wheels to angle out slightly under power, allowing the tires to track straight and wear evenly. Too much toe-in will scrub the outer edges of both tires causing wear while too little toe-in will wear the inside edges of both tires. If wandering on straight roads is a problem, a little more toe-in will help.

Springs support and control the motion of a car. Stiffer springs reduce roll and dive, but can reduce ride quality if too stiff. If too stiff, a car can bounce over road irregularities, losing traction as the wheels leave the road.

Anti-Roll Bars
Anti-roll bars (or sway bars) reduce roll and camber changes without creating a harsh ride when both wheels hit a bump, as stiffer springs might. When only one wheel hits the bump, steering kickback is increased with larger front anti-roll bars. The ends of an anti-roll bar are attached to the left and right suspension members and the center of the bar is attached to the chassis. While the car is traveling in a straight direction the sway bar does nothing. During cornering sway bars reduce roll by pushing against the chassis as roll begins. Increasing the diameter of the anti-roll bar reduces body roll, keeping the tires more vertical to maintain a better contact area for more traction. Replacing rubber anti-roll bar bushings with urethane bushings can improve the effectiveness of the stock anti-roll bar.

Weight Distribution
Weight distribution is the amount of weight (car and driver) being carried by the tires and is given as a ratio, such as 60/40. The ratio can be for the weight carried by the front compared with rear tires or one side of the car compared with the other side. (For example, the front and rear weight distribution of a GTV/6 is almost 50/50, which means that 50 percent of the weight is carried on the front tires and 50 percent is carried on the rear tires.) A car maintains its highest traction when all the tires are working equally.

Aerodynamic Devices
Aerodynamic devices channel air flow around and over a car body creating areas of high or low pressure, which will load or unload the tires as required. A nose spoiler keeps the front of a car from lifting at speed by blocking some of the air flow beneath the car, increasing traction at the front. A rear spoiler increases downforce at the rear of a car, increasing traction at the rear.

Adjustable Shocks
Shock absorbers dampen the oscillation of a spring. Adjustable shocks can be used to balance under/over steer; stiffen front shocks for less oversteer, stiffen rear for more oversteer and visa-versa. Be careful not to over-stiffen the shocks as the car will bounce over road irregularities losing traction as the wheels leave the road.