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    Tuning FAQ by BChmilnitzky

    Updated: 06/15/98 | Printable Version | Search Guide | Bookmark Guide

    Subject: GT Tuning FAQ (long)
    From: chmilnirtooth@worldtoothnet.att.toothnet (Jet Jaguar)
    Date: Mon, 15 Jun 1998 06:15:36 GMT
    Newsgroups: rec.games.video.sony, alt.games.video.sony-playstation
    Gran Turismo Tuning FAQ
    By:  Bob Chmilnitzky  a.k.a. "Jet Jaguar"
    	The reason I'm writing this FAQ is to help others make
    intelligent, informed decisions concerning car setup.  I've found this
    area of the otherwise excellent Gran Turismo manual is sorely
    deficient.  This FAQ is based on real-life car physics.  This may or
    may not apply to the game, depending on how accurately the game
    depicts car physics.  Any areas that I feel I have found to be
    different are noted in brackets, though the real-world effect is still
    listed for the sake of completeness, since I haven't sat down and
    tried everything out to see if it works (or in case I'm wrong :-) ).
    It should also be noted that my real-world experience is limited to
    rear-wheel drive cars, so any special considerations that need to be
    made for front- and four-wheel drive vehicles is not mentioned, but,
    from what I understand, the basic principles of setup are the same.
    	Feel free to use this FAQ on a web page, as long as you let me
    know first.  Also, I don't feel it is quite finished yet.  I would
    have liked to have talked about dynamic camber changes caused by
    suspension movements (a.k.a. double wishbone suspensions:  why you
    need them, and why everything else is junk :-) ), expanded the section
    on gearing, and added a troubleshooting section (i.e.  if your car
    understeers while exiting corners then do this... type of thing), but
    that's not gonna happen any time soon, as I'm just too busy at the
    moment.  In fact, I've been sitting on what I've got here for the
    better part of a week already.  *sigh*    :-(
    [Tip:  Make one adjustment at a time and test it.  If you make several
    adjustments at once, it can be difficult to isolate the effects of
    each adjustment, as one adjustment can cancel out another.]
    	The purpose of the springs is to control wheel movement and
    keep the tyre in contact with the road over bumps and undulations.
    Stiffening the springs front and rear will reduce body roll and make
    handling more responsive, but cause a loss of traction over bumpy
    surfaces.  Likewise, softening all of the springs will give more grip
    on bumpy tracks, but increase roll and reduce responsiveness.  You can
    also use the springs to affect the car balance.  You can reduce
    oversteer by stiffening the front springs or softening the rear.
    Likewise, you can reduce understeer by softening the front springs or
    stiffening the rear.  However, be advised that changing just one end
    also affects fore/aft weight transfer.  By softening the front
    springs, you'll also get more dive under braking.  Softening the rear
    will give you more rear weight transfer under acceleration, which can
    give you more traction on the rear wheels in straight-line
    acceleration.  [Tip:  I generally do not use the springs to adjust
    balance, because of its effects on fore/aft weight transfer.  I
    reserve the stabilizers for this purpose.]
    Ride Height:
    	A lower ride height lowers the center of gravity, which
    reduces weight transfer during cornering, acceleration, and braking.
    The reduced weight transfer improves cornering.  A lower ride height
    also lowers drag at high speed because you are presenting a smaller
    frontal profile to the airstream.  Also, by lowering the front end and
    raising the rear, you can improve high speed stability and increase
    downforce by preventing high-pressure air from building up underneath
    the nose of the car.  [Note:  I have not noticed ride height affecting
    aerodynamics at all in the game]  If the car is too low, it can bottom
    out, though this can be eliminated by stiffening the springs.  For
    rear-wheel drive cars, you can improve rear traction under
    acceleration by increasing ride height, since maximum traction can be
    obtained with the maximum amount of weight on the rear tyres.
    Generally, you'll only want to do this in the acceleration tests,
    since it will hurt cornering performance, and never with front-wheel
    drive cars, since the driving wheels will be losing grip.
    	The purpose of the dampers (also called shock absorbers) is to
    dampen the oscillation of the springs.  The shocks not only dampen
    spring oscillations, but they also affect handling during transient
    conditions (such as the entry and exit of turns), but not steady-state
    conditions.  Softening the dampers reduces responsiveness, and
    likewise stiffening the dampers will increase responsiveness.
    However, if they are too stiff, they can lead to a loss of suspension
    sensitivity and increase the harshness and bumpiness of the ride.  If
    they are too soft, it will cause the handling to feel mushy.  You can
    reduce understeer during corner entry and exit by softening the front
    dampers or stiffening the rear.  Conversely, you can reduce oversteer
    in the entries and exits by stiffening the fronts and softening the
    rear dampers.
    	Camber is the angle the tyres make with the road and is
    measured in degrees.  Tyre grip varies with the camber angle, and
    ideally is maximum when the angle is zero.  However, the maximum grip
    is found with a small amount of negative camber because of tyre
    sidewall deflection (when the top of the tyre is tilted inward it is
    called negative camber.  The game does not allow positive camber, and
    in real life it is never used).  Also, as the body rolls in a turn,
    the suspension movements themselves causes some adverse camber change.
    These combined effects mean that for maximum cornering power you need
    to have some amount of negative camber.  [Note:  Unfortunately, I have
    not found a reliable way in the game to determine the optimum camber
    settings.  In real life, camber is generally determined by measuring
    tyre temperatures at different points across the tread surface, or by
    monitoring tyre wear.  Generally, I just play around with the settings
    until I come across a setting I think feels best.]
    	The purpose of the stabilizer (also known as the anti-roll
    bar, or anti-sway bar, although I prefer anti-roll bar because it can
    very well destabilize a car and has nothing to do with sway) is to
    resist body roll in a turn, much like a spring.  However, unlike the
    springs, they do not come into play on two-wheel bumps or on fore/aft
    weight transfer.  Stiffening the stabilizers front and back gives more
    responsive handling and less body roll, but can upset stability on a
    bumpy track by transmitting loads from one-wheel bumps to the opposite
    wheel.  Likewise, softening the bars all around can increase body roll
    and reduce responsiveness, but make the car more stable on bumpy
    tracks.  Because the anti-roll bars are fairly independent of other
    chassis settings, they are ideal for fine-tuning car balance.  You can
    reduce understeer by softening the front bar, or stiffening the rear.
    You can reduce oversteer by stiffening the front bar or by softening
    the rear.
    	The brake balance allows you to adjust the proportion of
    braking power distributed between the front and rear brakes, which
    affects the balance under the car under braking.  Oversteer under
    braking (i.e. the back wants to jump out while braking) can be reduced
    by increasing front brake balance, or reducing rear balance.
    Understeer under braking (the car doesn't turn in) can be reduced by
    decreasing front brakes, or increasing rear.  [Tip:  generally, you
    always want higher front brakes than rear.  This is because of forward
    weight transfer under braking.  As the weight is transferred forward
    off of the rear tyres, they are unloaded and lose grip, which causes
    them to lock up before the front tyres.]
    Gear Ratio:
    	The purpose of the gearbox is to keep the engine within it's
    optimum rpm range over a range of road speeds.  Shorter gear ratios
    (bigger ratio numbers) give you more acceleration and rpms.  Taller
    ratios (smaller ratio numbers) give you higher speed before the engine
    redlines, but less acceleration.  The final drive ratio can be thought
    of a sort of "multiplier" that affects all of the gear ratios
    simultaneously, which makes it convenient to fine tune your
    transmission to different tracks.  
    	[Tip:  The way I generally set up the gears is to first set
    1st gear so the engine rpm is in the meaty part of the torque curve
    for the exits of the slowest turns on the track.  I then set top gear
    for top speed and space out the rest of the gears evenly between the
    two, except for the top couple gears, which I space a little closer
    together than the lower gears since acceleration is slower at high
    speed due to increased air resistance.  I don't normally change gear
    ratios from one track to the next, I just set a good compromise and
    stick with it.  The only exception is I'll sometimes adjust the final
    drive ratio at certain tracks.  For example, at the Autumn Ring I'll
    bump the final drive to a shorter ratio to get more acceleration since
    you won't be hitting top speed anywhere on the track anyway, and on
    the oval track I'll change to a taller ratio to get more top end
    	Downforce is the aerodynamic force pressing the car down on
    the track and improves cornering grip.  This downforce is dependent on
    forward speed, and increases as you go faster.  Increasing the
    downforce all around increases cornering speed, but also increases
    drag, which gives you slower straightaway speed, and you may also need
    to increase ride height and/or spring stiffness to prevent bottoming.
    Likewise, decreasing downforce gives you lower cornering speeds but
    higher straigtaway speeds, and allows you to run softer springs and/or
    a lower ride height.  [Note:  I find downforce has only a small effect
    on drag.  For example, in the Viper GTS on the top speed test, the
    difference between maximum and minimum downforce top speeds is only
    about 5 mph (8 km/h).]  Also, you can also use downforce to fine-tune
    balance at high speeds.  To reduce understeer, increase front
    downforce or reduce rear.  To reduce oversteer, decrease front
    downforce or increase rear.  Keep in mind that these adjustments are
    dependent on forward speeds and has less effect as speeds drop, so you
    can use this to give the car different handling characteristics for
    different speed ranges.
    Bob Chmilnitzky, a.k.a. Jet Jaguar
    To reply, do dental work on my address and pull all of the teeth.
    MSTie #54297
    The Face on Mars issue is dead.  Deal with it, and move on.