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Handling Problems
from "Performance Handling" by Don Alexander (Motorbooks Intl. Publishers)

The key to setting up your suspension is in diagnosing what the handling problems are and resolving how to fix them.
There is always a cause and an effect.

Problem

Manifestation

 Solutions

  Steady state understeer All turns or low-speed turns only If front tire temps are optimum and rears are low, stiffen rear antiroll bar; if front temps are too hot, soften front (most likely).
If front tire pressures are optimum, decrease rear tire pressure. Increase if chunking occurs.
Improper front camber.
Too much body roll at front, causing excessive camber change.
 Steady state understeer  High-speed turns only If front tire temps are OK, increase front downforce.
If front tire temps are too hot, reduce rear downforce.
 Steady state oversteer All turns or low-speed turns only If rear tire temps are optimum, with fronts too low, stiffen front antiroll bar; if rear temps are too hot, soften rear antiroll bar (most likely).
If rear tire pressures are optimum, decrease front tire pressure. Increase if chunking occurs.
Improper rear camber.
 Steady state oversteer High-speed turns only If rear tire temps are OK, increase rear downforce.
If rear tire temps are too hot, reduce front downforce.
 Corner entry understeer   Front shocks are too soft in bump resistance.
Too much front toe-in; use a small amount of front toe-out. 
 Corner exit understeer   Rear shocks are too soft in bump.
Front shocks are too stiff in rebound.
 Corner entry oversteer   Rear shocks are too soft in rebound.
Rear ride height is too high (too much rake) compared to front.
 Corner exit oversteer   Rear shocks are too soft in rebound.
Too much rear toe-in or any rear toe-out.
 Straight-line instability   Tire pressure is too low in one or more tires.
Too little positive front caster.
Too much front toe-in or any toe-out in rear.
 Straight-line speed too slow   Too much overall downforce.
Too much toe-in or toe-out.
Ride height is too hight.
 Excessive steering effort All turns Too much positive caster.
Front tire pressures are too low.
 Chassis or suspension bottoms   Spring rates are too soft.
Shock absorber bump rates are too soft.
Inadequate suspension travel.
Inadequate ride height.

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Effect of Suspension Changes
from "Performance Handling" by Don Alexander (Motorbooks Intl. Publishers)

Before making changes to suspension components and settings,
it is good to know how the changes will effect performance and ride.
The following chart will give you a general idea of the effect a specific change will make to handling and ride.

Spring Rate Changes

Modification

 Effect on Suspension

 Increase front and rear rate  Ride harshness increases; tires may not follow bumps causing reduced traction. Roll resistance increases.
 Increase front rate only  Front ride rate increases. Front roll resistance increases, increasing understeer or reducing oversteer.
 Increase rear rate only  Rear ride rate increases. Rear roll resistance increases, increasing oversteer or reducing understeer.
 Decrease front and rear rate  Ride harshness decreases; tires follow bumps more effectively, possibly improving traction. Roll resistance decreases.
 Decrease front rate only  Front ride rate decreases. Front roll resistance decreases, decreasing understeer or increasing oversteer.
 Decrease rear rate only  Rear ride rate decreases. Rear roll resistance decreases, decreasing oversteer or increasing understeer.
   
 Antiroll Bar Changes  

 Modification

 Effect on Suspension

 Increase front rate  Front roll resistance increases, increasing understeer or decreasing oversteer. May also reduce camber change, allowing better tire contact patch compliance with the road surface, reducing understeer.
 Increase rear rate  Rear roll resistance increases, increasing oversteer or decreasing understeer. On independent rear suspensions, may also reduce camber change, allowing better contact patch compliance with road surface, reducing oversteer.
 Decrease front rate  Front roll resistance decreases, decreasing understeer or increasing oversteer. More body roll could reduce tire contact patch area, causing understeer.
 Decrease rear rate  Rear roll resistance decreases, decreasing oversteer or increasing understeer. On independent rear suspensions, more body roll could reduce tire contact patch area, causing oversteer.
   
 Shock Absorber Changes  

 Modification

 Effect on Suspension

 Increase rebound and bump rates  Ride harshness increases.
 Increase rebound rates only  On bumps, tires may leave track surface.
 Increase bump rates only  Body roll resisted; outside tire loaded too quickly; car won't stabilize into a turn.
 Decrease rebound and bump rates  Ride harshness decreases; car may float over bumps.
 Decrease rebound rates only  On bumps, tires follow track surface more effectively; car may continue to oscillate after bumps.
 Decrease bump rates only  Body rolls quickly; car is slower to respond to turn-in.

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Tire Temperatures
from "Performance Handling" by Don Alexander (Motorbooks Intl. Publishers)

In the course of testing the handling of a car, use tire temperatures and driver feel to make adjustments.
It is critical to monitor tire temperatures often. They offer valuable clues to the setup of the car.
The areas of adjustment that tire temperatures are used for include: tire pressure, camber, body roll,
shock settings, wheel width and transient handling response.

 Reading

 Handling Problem

Reason

All tires too hot    Compound too soft for track and ambient temperature conditions.
Front tires too hot  Understeer  Front tire pressures too low.
Rear tires too hot  Oversteer  Rear tire pressures too low.
Inside edges too hot  Too much body roll Too much negative camber or too much toe-out.
Outside edges too hot  Too much body roll Too little negative camber, too little toe-out or too much toe-in or wheel width too narrow for tire width.
Center of tread too hot   Tire pressure too high.
Edges too hot   Tire pressure too low.
All tires too cold    Compound too hard for track and ambient temperature conditions or car not being driven to limit.
Front tires too cold    Inadequate load on front tires.
Rear tires too cold    Inadequate load on rear tires.

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