This guide is intended to help you understand the basic ideas involved in tuning a car. Please note that this is only a general guide and should not be taken as gospel, there are many aspects that can change a cars characteristics and I cannot account for all of them. I just want to give people who are new to tuning a sense of what all the parts do and how they can be potentially improved.
(My Race tuning garage - https://www.gtplanet.net/forum/threads/haus-of-flying-daggers-accepting-requests.301978/
Drift tuning Garage - https://www.gtplanet.net/forum/threads/drift-haus-tuning-garage.302396/ )
Printable Version (thanks to @aboe)- https://docs.google.com/document/d/1AcEzaJxvkD0lXa_WnwOygw404oLRWjidaxbjY42EGcg/edit
Begginers Guide to the Data Logger by @F1Racer68 - https://www.gtplanet.net/forum/threads/gt6-data-logger-a-beginners-guide.318832/
(Picture and editing by @FussyFez)
Spring Rates -
Springs are one of the major components of the suspension in any vehicle. Their purpose is to support the weight of the car and absorb bumps. Simple but effective, the spring can be set at various strengths which are measured by how much weight the spring can take before compressing (higher weight = stiffer spring).
Pros: Allows wheels to stay in contact with the road surface over imperfections which helps to maintain grip.
Cons: Allows body roll in vehicles and encourages weight transfer which can lead to instability during quick or violent directional changes.
Pros: Minimises body roll therefore making the car more stable and predictable during cornering. It also allows a lower ride height to be used because of the reduced likelihood of bottoming out the suspension.
Cons: Causes car to skip over bumps which can cause a loss of grip and twitchy, unpredictable handling.
Spring tuning guide:
Front Springs -
Stiff Springs = Increase understeer
Soft Springs = Decrease understeer
Rear Springs -
Stiff Springs = Increase oversteer
Soft Springs = Decrease oversteer
Controlling weight shift is very important in GT6, the new physics engine puts much more focus on how the weight moving around the car affects things during the various stages of cornering/accelerating/braking.
The overall stiffness of springs should always be adjusted to suit the different grip levels of tyres. A car running on Comfort Hard tyres (Less grip = Tyre can handle less load before slipping) will need to run softer overall spring rates compared to a car running on Comfort Soft (More grip = Tyre can handle more load before slipping) to work at optimum efficiency. Its always a compromise between controlling body roll and not transferring too much force (load) to the tyres.
Road cars usually have a certain level of softness to the springs to cope with real world problems such as poor road surfaces/potholes/speed humps/curbs etc., on a race track this is much less of an issue. When tuning these it is important to first remove this extra body roll by stiffening the springs, put simply the less body roll there is the more speed you can hold through a corner without encountering lateral slip.