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Welcome to ‘Tuning: In a Nutshell’.

This tuning guide has been written to make tuning easy to understand.  By knowing what each tuneable part of the car does, gives you the knowledge of how to correctly adjust them to suit your requirements.  Before continuing, there is one very important thing you should always remember - The tyres are the only part of the car that make any contact with the track’s surface (at least that’s the plan)!  Plus, only a small area of the tyre, the ‘contact patch’, is in contact with the track’s surface at any given moment.  Maximising the size of the contact patch across all four tyres is the primary focus while tuning.  Every tuneable part does something that influences the tyres and their contact patches in one way or another.  This is something you should never forget.
  
Part one starts us off with tyre pressures.

We’re starting with tire pressure, as this is the only part of the car that can be tuned without making any upgrades.

So, let’s touch on a few important details first. 

​As you drive, friction between your tyres and the track will cause your tyres to heat up.  As the tyre compound heats up, it becomes softer and more pliable, helping it to mould into small cracks in the track's surface, therefore increasing grip.  This could lead us to believe that the hotter the tire gets, the more grip it produces.  But there’s more to consider.

As the tyre gets hot, the air inside the tire begins to expand.  This causes the pressure inside the tyre to rise.  If the pressure rises excessively, the tyre may 'Balloon’.  Ballooning is when the edges of the tyre lift off the ground, significantly reducing the size of the contact patch, and available grip is drastically reduced!
 
Tyres need pressures that suit a maximum contact patch, but the temperatures need to suit the compound.
 
In most cases, 'road' compound tyres reach their optimum grip with temperatures ranging somewhere between 140-170 degrees Fahrenheit (F).  Sport compound tyres will perform best between 160 - 200 degrees F, while race compound tyres can run much hotter, often performing best between 170 - 220 degrees F.

Remember: Tyres will not be at these optimum temperatures straight from the pits!  You’ve got to run a few corners first (or maybe even an entire lap), to bring the tyres up to race temperature before you start making any adjustments.  Once race temperatures are achieved, re-check tyre pressures to ensure they have not climbed too high.  Race temperature tyres should ideally have pressures between 32-33 PSI or 2.20-2.27 BAR.  This will result in a good shape, maintaining a large contact patch.
You can check tyre information by using the in-game telemetry.  While on the track, press ‘down’ on the d-pad on your Xbox controller to bring up the Telemetry.  Using the 'right' button on the d-pad, tab across to the 'Heat' page.  Here you can see the temperature of the tyres.  They are divided into 3 areas for each tyre: Inside, Middle, and Outer.   If the centre of the tyre is hotter than the edges, then the pressure is set too high - The tyre is ballooning!  If the edges are hotter than the centre, the pressure is set too low.  Should the inside edges of the tyre remain hotter than the outside edges (or vice-versa), this is not a pressure issue.  This is a camber problem and is discussed in the very next section.

Adjusting tyre pressures also affects the response of the car.  Increasing tyre pressure increases response, while decreasing pressure reduces response. Personally however, I recommend you focus on contact patch and temperatures when adjusting tyre pressures, and use suspension adjustments to tune response, which is all covered in this guide.

  
Section one covered tyre pressures, and the importance of a large contact patch.  In part two, I’m discussing how camber angles can be used to help maximise the size of the contact patch by keeping it centred across the tyre.
 
So, what is camber, and how can adjusting it be useful?
 
As you look at the front of the car, camber is the angle of the wheel relative to true vertical.  By increasing negative camber, wheels lean into the car, and tyres sit on their inside edges.  Positive camber causes the opposite effect.  Wheels lean away from the car, with tyres sitting on their outside edges. 
 
To maximise grip at any given point, tyres must be parallel with the ground, ensuring a large, centred contact patch, with the load on the tyre being spread evenly across its width.  With this in mind, why not just leave the camber angle at zero, where it’s parallel with the track?  Makes sense, right!?
 
Well, during a turn, all supported weight gets transferred to the outside wheels.  More specifically, by leaving the camber angle at zero, most of the weight ends up on just the outside edges of the tyres on the outside wheels.  With most of the weight focused on the edges, we’re not maximising the size of the contact patch, and therefore not using anywhere near the total amount of available grip.  But by using the correct amount of negative camber, this weight transfer can be accounted for, and through a corner, tyres are parallel with the ground, receiving an even weight distribution and a large centred contact patch, providing maximum grip.
 
This noticeably huge benefit of using camber adjustments to maximise grip in the corners doesn't come without compromise. 
 
On the straights, little-to-no weight transfer takes place, so any negative camber used to maximise cornering grip reduces the size of the contact patch on the straights. If straight line grip is reduced, performance in acceleration and braking suffer.  By fixing one problem, we’ve created another, and as is so often the case when tuning cars, there’s a ‘balance’ to find.  A happy medium.  In the case of camber alignment, you should tune to find the 'ideal' angle.  A compromise which allows for the best possible cornering grip, without impairing performance too much on the straights.
 
To find the ‘ideal’ angle, first get the tyres up to race temperature.  As discussed in the previous section, you can monitor tyre information by using the in-game telemetry.  While on the track, press ‘down’ on the d-pad, followed by a few clicks 'right' until you find the 'Heat' page.  From here, you can attempt to develop one of sim-racing’s toughest skills - monitoring tyre temperatures while you drive!  It’s not easy but here’s what you’re looking for;
 
Firstly, bear this in mind… The more weight there is pressing down on a tyre, the hotter it gets. This handy little fact means you can monitor the location of the contact patch by looking for the hottest area of the tyres. 
 
To ensure the size of the contact patch is maximised, it needs to be positioned in the centre of the tyre.  Tyres with a correctly centred contact patch have even temperatures across their widths and are making the most out of available grip.  You should aim to achieve even temperature distribution at the point of corner exit, but as temperature distribution results will vary from one corner to another (after all, every corner is different), focus tuning for corners which carry the most speed.
 
If the inside edges of the tyre are hotter than the outside edges, there is too much weight pressing down on the inside edges.  By reducing negative camber, we can shift the weight more into the centre of the tyre, and the temperatures will even out.
 
If the outside edges are hotter than the inside edges, there’s too much weight on the outside edges.  Simple.  Increase negative camber.  This centralises the weight across the tyre, and once again the temperatures will even out.
 
While making these changes, make sure to only adjust in amounts of +/- 0.1° or +/- 0.2°, and re-check.  Even small changes to camber alignment can make a noticeable difference.
 
TIP: Aim for tyres to be a fraction warmer on the outside edges at corner exit.  This uses slightly less negative camber compared to that which would produce an even distribution of heat, but by doing so you’ll help keep the contact patches a little bigger on the straights, minimising any loss of performance in acceleration and braking.  It’s a happy medium.
 
Remember, through a turn, weight is transferred to the outside wheels, meaning they’re doing most of the work.  These are the tyre temperatures you need to focus on.  Don’t worry about the tyres on the inside wheels while tuning camber.
 
And that’s camber. Get tuning and centralise those contact patches!​​

In sections one and two we looked at the importance of correct tyre pressures and camber angles to maximise the size of the contact patches. Here in part three, we’ll be discussing how your tyres will benefit from correctly tuned toe.  
 
So, what is toe?
 
Well, let me explain.  Toe is the angle of the wheels as you look down on them from above.  To illustrate this, stand up straight, with your feet parallel and pointing precisely forwards.  If the direction you are facing represents the front of the car, looking down, your feet resemble wheels with a toe angle of zero.  Now, point your feet slightly towards each other.  This is toe in - Easily remembered because your toes are pointing in!  Pointing your feet slightly away from each other illustrates toe out - Your toes are pointing out.  It’s almost too easy!
 
So why is an adjustment like this useful?
 
Picture slowly driving a car in a small circle with maximum steering lock applied.  The inside wheels trace a smaller circle than the outside wheels.  A smaller circle means a tighter turn, which means the inside wheels need to turn at a tighter angle than the outside wheels.  While I agree this is a strange concept, it should not be overlooked, especially as we can easily do something about it.
 
By increasing toe out, inside wheels turn at the required tighter angle compared to the outside wheels.  This encourages steering, and promotes oversteer characteristics, as the inside and outside wheels independently point at the angles they require. 
 
By increasing toe in, the inside wheels turn with less angle than the outside wheels. This discourages steering, promoting understeer characteristics, as the toe angle causes the inside wheels to fight against the outside wheels, resisting the turn.
 
Now we already know that during a turn, weight is transferred to the outside wheels.  We also know that the effects of tuning toe require influences from both the inside and outside wheels.  For this reason, toe adjustments effect handling during corner entry and corner exit where less weight transfer is taking place but have very little effect during the middle-section of a corner.
 
We can summarise tuning toe very easily;
 
Increase turn in oversteer                       -               Increase front toe out
Increase turn in understeer                    -               Increase front toe in
 
Increase corner exit oversteer              -               Increase rear toe out
Increase corner exit understeer           -               Increase rear toe in
 
 
Toe adjustments are incredibly effective, with even the slightest of angles producing noticeable handling changes, however adjusting toe in any amount or direction will cause tyres to scrub.  This will negatively impact top speed and acceleration. Once again, you’ll need to find a suitable balance – A sweet spot, where both cornering and straight-line speeds are maximised.
 
TIP: Oversteer and understeer can often be tuned using other areas, such as anti-roll bars, spring rates, or dampers. Leaving toe angles at zero for front and rear wheels, means you won’t have to worry about the tyres scrubbing.  Should you still adjust toe, angles must stay particularly small, and should never need to be more than +/- 0.5°.

In section 4 we’ll be covering the final section of wheel alignment, with tuning caster.
 
So far, we know that camber is the angle of the wheels looking at the car from the front, and toe is the angle of the wheels looking at the car from above.  Caster refers to the angle between true vertical and the steering axis while looking at the car from the side.

This angle should never be negative, but what are the benefits from using a positive caster angle?

Just for a moment, consider this.

While riding a bicycle, the slower you move, the harder it is to stay upright, but the faster you ride, the easier it is to stay upright.  This is inertia in action.  Inertia is the resistance to a change in motion, so in the case of our bicycle, the spinning wheels try to remain upright.  The faster the wheels spin, the more force is created, which is why it’s easier to stay upright while riding faster.  Now, if we include a positive caster angle, the effects of inertia are considerably magnified.  The larger the angle, and the faster the wheels spin, the stronger the force becomes.  Transferring this information over to our car setup illustrates that the faster you drive, or the larger the caster angle, the more the wheels try to remain upright, making it harder to turn the steering wheel and the more it will try to self-centre.

This brings us to the main advantage of using a large caster angle - Increased stability, particularly at high speeds.  For these reasons, higher caster angles tend to suit faster tracks, with less off-throttle steering during corner entry, and more on-throttle steering during corner exit.

While these benefits are not to go unnoticed, low caster angles also have their advantages.  Firstly, there is far less effort required to steer, making steering feel much sharper and more direct, with self-centering effects reduced.  Lower caster angles consequently suit tighter tracks, with more off-power steering during corner entry, and less on-power steering during corner exit.

Taking all of this into account, once again forces us to find an optimum setting.  The happy medium.   
Set the caster angle as low as possible, maximising a sharp, direct steering effect, without the car suffering from decreased stability at speed.

If during long straights you feel instability and are constantly having to correct your line, or the car feels too responsive to any steering input, increase the caster angle.

If the car feels too stable, not responding enough to any steering input, decrease the angle.

Remember, find a setting that suits the kind of “feel” you are trying to create.  While this may fluctuate slightly from one car to another, it’s not uncommon for people to use the same caster angle across many different cars.

So, in the usual way, let’s first look at what anti-roll bars are.  You must have figured out by now that I like to chat a bit!

Anti-roll bars (or Sway bars) can be installed at the front and rear of the car.  Their purpose is to essentially connect the inside and outside wheels together at a point below the suspension.  But why would a connection like this be necessary, and how can it be used to our advantage?

Let’s look at a few important points.

By this stage in the guide, you should be familiar with the concept of weight transfer.  Due to flex in the springs, and weight moving from side-to-side as you drive in and out of corners, your car will roll or lean to one side or the other.  The rolling of the car causes the springs on the outside wheels to compress, while the springs on the inside wheels extend.  

Through a turn, as the springs on the outside wheels compress, the wheels are forced up into the arches of the car.  By connecting the inside and outside wheels together with an anti-roll bar, the inside wheels are forced to mimic the movements of the outside wheels and are also forced up into the wheel arches by a similar amount, compressing the springs more evenly across the car, and naturally causing the car to remain flatter through a turn.  It’s fair to highlight at this point, the effects of anti-roll bars are largely noticed during cornering but have little-to-no influence while driving in a straight line.  The stiffer the anti-roll bar, the closer the inside and outside wheels are forced to mimic each other, resulting in less body-roll. 

But is less body-roll a good thing?

Absolutely!  By reducing the amount of body-roll, a car’s centre-of-gravity remains more centred across it’s width.  This doesn’t reduce the amount of weight transferred through a corner, but stiff anti-roll bars mean weight has less distance to move.  With less distance to move, weight transfer is completed faster, and fast weight transfer makes a car’s handling far more precise and predictable.  Predictable cars are easier to drive!
Secondly, because stiff anti-roll bars help keep the weight more centralised across a car’s width through a turn, we can make far better use of the grip available from the tyres on the inside wheels.  On top of that, less body-roll means you can set your ride-height far lower, and a lower ride-height means more grip!

Here we have three very strong reasons to use stiff anti-roll bars, and while I absolutely recommend you install anti-roll bars in every one of your builds, consideration should still be taken regarding how stiff to set them.   Less body-roll is your absolute goal, so you should set your anti-roll bars at whatever stiffness is required to achieve this.

Honestly, there are not any situations where more body-roll would be preferable.  What needs to be considered are the bumpy tracks.  The irregular surfaces.  If body-roll is to be minimised on these types of surfaces, inside and outside wheels are going to need to move independently from one another, and stiff anti-roll bars are going to prevent that from happening.  To reduce body-roll on these surfaces, anti-roll bars will need to be much softer. Equally, on smooth surfaces where vertical movement of inside and outside wheels need little independence, we can crank the stiffness right back up.

As mentioned before, stiff anti-roll bars cause weight to transfer quickly, and while this improves a car’s predictability, fast weight transfer requires lots of available grip to exploit the benefits.  Not having enough grip to respond with any sudden changes in weight transfer may easily cause the car to slide.  For this reason, cars with race compound tyres installed will cope far better with stiff anti-roll bars, while tyres which produce less grip will have to settle for a softer setup.  Looking at this from another angle, we can manipulate grip depending on the stiffness of the anti-roll bar. 

Softer anti-roll bars slow down the transfer of weight, providing tyres with more opportunity to react. 
Too stiff, and tyres may not react in time.

This brings us to the next consideration when tuning anti-roll bars.  Do we set the front and rear stiffness the same?  Well, it’s very rare.  Front and rear anti-roll bars are almost always set at different strengths. 

Let’s suggest, while cornering, you experience understeer.  Understeer is when a car turns less than intended. This is because the weight at the front of the car is being transferred too quickly, and the front tyres have lost grip.  By reducing the stiffness of the front anti-roll bar, we can slow weight transfer down independently from the rear, providing more cornering grip at the front, helping the car to rotate and get around the corner faster.
Likewise, if while cornering you experience oversteer (when a car turns more than intended), the weight at the rear of the car is being transferred too quickly, and the rear tyres lose grip.  By reducing the stiffness of the rear anti-roll bar, weight transfer is slowed down independently from that at the front, preventing the car from rotating too much, and keeping it more stable in the corner.

I cannot express just how incredibly effective anti-roll bars are at tuning out oversteer and understeer problems and should absolutely be your first point of call for curing these matters.
 
To conclude;

Reduce body-roll on flat, smooth surfaces by increasing overall anti-roll bar stiffness.
Reduce body-roll on bumpy, uneven surfaces by reducing overall anti-roll bar stiffness.
 
Reduce understeer by reducing front anti-roll bar stiffness independently from the rear.
Reduce oversteer by reducing rear anti-roll bar stiffness independently from the front.


TIP:  It is important not to forget that understeer is controlled by making front anti-roll bar adjustments, and oversteer is controlled by making rear anti-roll bar adjustments.  Do not try to reduce oversteer by influencing more understeer or vice-versa.  Just focus on the end of the car with the problem.

And as a final note, spend some time while setting anti-roll bar stiffness.  They can be awkward to get right, but once adjusted correctly will increase handling predictability and control through corners.

It’s not like I’ve not mentioned it, but just to confirm, everything we’ve covered so far enables us to extract as much available grip from our tyres as possible.  It’s all about providing the tyres with every opportunity to work effectively.  This section is no different, and by correctly tuning spring setups, we can ensure that tyres are kept in contact with the track’s surface for as much time as possible.  Incorrect spring setups can drastically reduce tyre compliance and will seriously harm your car’s handling.

So, let’s look at the springs.  Each spring has a ‘spring rate’, which tells us how easy it is to compress.  Spring rates are measured by a unit of force over a given distance, often in the form of Pounds per Inch, or Kilograms per centimetre.

Spring rates determine the length of suspension travel and should be tuned with only this in mind!

The softer the spring rate, the less force is required to compress the spring.  This means, when you go over a bump or onto a steep curb, the spring compresses easily, keeping the tyres in contact with the road, instead of causing them to skip over small bumps where tyres momentarily leave the track’s surface.  Set the spring rates too soft however, and bottoming-out is much more likely.  Bottoming-out is when the spring becomes fully compressed.  A fully compressed spring acts in the same way as if you were to remove the spring all together. We go from a soft spring rate, to an infinitely stiff one.  Sudden changes like this will cause serious, unpredictable handling issues, making the car incredibly difficult to drive. 

By increasing the spring rate, more force is required to compress the spring. A car using springs with high spring rates, although now far less likely to bottom-out, becomes more likely to skip over the bumps.
So, what do we do?  Any guesses? Once again, we compromise.  We need to go soft enough for the bumps, but we can’t go so soft that the car bottoms-out.  Could we use a soft spring rate and just raise the ride-height?  Surely a car that sits higher will have far less chance of bottoming-out?  It certainly would, but a car with a high centre-of-gravity produces substantially less grip than the same car with a low centre-of-gravity.  In fact, the increase in grip created by lowering a vehicle’s ride-height is tremendous.  Pure and simple, a low centre-of-gravity means more grip. 

This gives us an excellent, methodical way of tuning spring setups.  Firstly, set the ride-height as low as sensibly possible. While smooth tracks may allow for the ride-height to be lowered all the way, you will need to allow for some additional suspension travel on the bumpier tracks, which will require softer spring rates to absorb the bumps.  Then set the spring rates high enough to just about prevent bottoming-out.  Heavier cars will obviously need stiffer spring rates than lighter cars, and cars with an uneven weight distribution will require setting different spring rates at the front and rear, but the numbers here really aren’t the focus.  Just aim for maximum grip by using a low ride-height and maximise tyre compliance by setting the springs as soft as the ride-height will allow.  Use this method for tuning the front and rear separately.

You can check spring information by once again using the in-game telemetry.  While on the track, press ‘down’ on the d-pad on your Xbox controller to bring up the Telemetry.  Using the 'right' button on the d-pad, tab across to the 'Suspension' page.  Here you can see how much each spring is compressing.  A spring has bottomed-out when the figure alongside it reads ‘1.00’.  Set your spring rates at the required stiffness to achieve maximum figures between 0.95 to 0.99, ensuring they never fully compress.  This will ensure you are making the absolute most out of your available spring travel without encouraging any unexpected handling problems. 
 
There is one more thing to consider when setting your spring rates.  Softening spring rates too much, may very well lead to excessive squatting and diving.  Squatting is when the rear springs are too soft and the car rolls back onto the rear wheels during acceleration.  Diving is when the front springs are set too soft and the car rolls forward onto the front wheels during braking.  To ensure you don’t induce these additional handling problems, keep springs stiff enough to maintain a reasonably flat car while accelerating and braking.
To conclude, we find ourselves in a vicious circle;

Low ride-heights increase grip but require stiffer spring rates to prevent bottoming-out.
Stiffer spring rates prevent bottoming-out, and prevent excessive squatting and diving, but can lead to less tyre compliance on bumpy surfaces.


Soft spring rates help maximise tyre compliance, but can encourage excessive diving and squatting, requiring higher ride-heights to prevent bottoming-out.

A three-way compromise!  Even so, I still recommend you set the ride-height as low as possible, set the spring rates stiff enough to just keep the springs from bottoming-out, and only increase the spring rates any further if you experience too much squatting or diving.

And that’s spring rates.

We’ve just covered springs, but luckily for us that’s not the only part of the suspension.  In this section I’ll be covering how to tune dampers (sometimes referred to as ‘Shocks’ or ‘Shock Absorbers’).
 
So, what are dampers?
 
Although not quite as simple as this, dampers basically combine a cylinder full of pressurised oil, and an internal piston.  The piston is allowed to move up and down through the oil at a rate controlled by internal valves.  Small valves restrict the flow of oil passing through them, limiting the movement of the piston.  Large valves allow far more oil to pass through, allowing the piston more movement. But why do we need to be concerned with any of this?
 
For a moment, consider taking the dampers out of your suspension setup altogether.  With nothing to dissipate the energy stored in your springs, your car would bounce up and down, over and over, and while you were driving it would be doubtful the suspension would ever settle.  Although you can’t remove the dampers from the suspension assembly in Forza 7, you could experience something similar by setting all your damper stiffnesses as low as possible. You’ll soon see what I mean. Dampers are essential to stop springs oscillating!

So, we’re agreed you need dampers, but how stiff do we need to set them to maximise control and grip? 
The stiffer you set the dampers, the smaller you’re making the valves inside them, and therefore the more resistance they have to movement.  This enables the damper to rapidly dissipate the energy stored from the spring, and the spring stops oscillating.  This promptly stabilises the car’s sprung weight, and can help reduce or eliminate that bouncy, floating characteristic you get in typically older cars which use much softer dampers. This huge reduction in body roll produces stable, predictable handling, and makes the car easier to drive, all while maximising tyre compliance. 

So, is a stiffer setup better?

Well, while off-road tracks would certainly benefit from soft suspension setups combined with high ride-heights, for the flatter, asphalt-covered wonders we race on in Forza 7, firmer setups with low ride-heights are more suited.

Although you will primarily be using firm-to-stiff damper setups in Forza 7, lowering the stiffness of dampers slows weight transfer and generally aids traction by giving tyres more opportunity to react.  This is particularly useful when using tyres with low levels of grip which struggle to handle abrupt changes in loads.  Firmer setups will require the tyres to match!

We should at this point also consider how adjusting front and rear damper stiffnesses in relation to each other effects handling. 

By lowering the stiffness of the front dampers, the front tyres are given more time to react to changes.  They can make more controlled and effective use of available grip, also useful to fix understeer issues.  The same is true for the rear suspension.  By lowering the stiffness of the rear dampers, the rear tyres have more time to react, making better use of available grip and oversteer problems can be resolved.
 
This leads us into the next part of dampers. 

We can control the rate of oil-flow through the valves in both directions. These are referred to as Bump and Rebound.

Bump refers to the suspension during a state of compression.
Rebound refers to the suspension during a state of extension.

Being able to accurately control how fast the suspension moves (or reacts) in these two directions independently offers potentially great handling.
 
Bump Damping

If bump damping isn’t stiff enough, the suspension will react too slowly. Bumps in the road will be soaked up beautifully, but the car is going to roll around, with lots of diving and squatting taking place.  If you haven’t already read the section on Springs and Ride-Height, diving occurs when you brake hard and the car leans forwards as weight is transferred, and squatting is the reverse effect experienced during hard acceleration, and weight transfer causes the car to lean back. 
Set the bump damping too high and you could experience what it would be like to have no suspension at all.  Any bumps or irregularities in the track could be harsh enough to cause the car to bounce into the air!  Not ideal, really.

Rebound Damping

Set your rebound damping too soft and the car will continue to oscillate after dealing with any bumps or surface changes.  With the car bouncing like this, it can make it particularly difficult in getting the power down. 
Set the rebound too high, and the wheels may be held back in the wheel arches after hitting any bumps or kerbs and in extreme situations could even cause the inside wheels to be pulled off the track’s surface during cornering.
 
Once again, while setting dampers, there are compromises to be made to achieve your desired requirements.  Find the balance.

Unfortunately, there’s no interesting introduction to this section. Pure and simple, we’re talking about the brakes.
 
There are only two things to consider when tuning brakes.  Balance, and Pressure.
 
Balance
 
The brake balance refers to how the braking force is divided between the front and rear brakes.  Successful tuning will depend on your preferred style of braking.  Do you like to get all your braking done on approach to a corner while moving in a straight line, or do you trail brake?  Trail braking is when you continue to brake way past corner entry and sometimes even as deep as the apex.  This technique means you are braking while steering, a combination that will heavily influence your most suitable setting.  While trail braking, if you suffer from vehicle understeer, send the brake balance towards the rear.  This will help with vehicle rotation but be careful not to go too far.  Excessive rear brake bias could result in the rear wheels locking up before the front.  If you’ve ever imagined what it may be like to pull the handbrake while entering a corner, this one is for you! As you can imagine, the results are going to be less than spectacular.  Likewise, if the car rotates too much as you enter a turn, sending the brake balance forward will help to stabilise the front of the car and help to induce understeer.  As the heading suggests, balance is the key.
 
I’ve got to say at this point that braking in a straight line has one huge potential over trail braking, but before going any further into detail, here’s a quick reminder to not forget about your tyres!  We can only slow down as quickly as our tyres will allow, irrespective of how good the brakes are.  If your tyres are using 100% of their available grip, they’re slowing the car down as fast as is physically possible.  If your tyres ever try to use 101% of their available grip, they fail and ‘let go’ of the road, entering a skid.  Another benefit is that because we’re doing all our braking in a straight line, tyres don’t have to use any grip to aid cornering forces.  Basically, every ounce of grip the tyre can offer, we can use for braking.  Once the car is slow enough for the corner, we can stop braking and begin to steer, now utilising the tyre’s potential to get us around the corner as fast as possible.  To maximise braking efficiency, we need to adjust the braking balance so that both the front and the rear tyres are using 100% of their available grip at the same time.  This is easier than you may think.  Simply adjust the brake balance so that the front and rear brakes lock together.  After all, if front and rear tyres reach 101% of their maximum potential at the same time, it’s fair to assume they do the same at 100%.
 
Pressure
 
I used to think that adjusting braking pressure was simply a matter of preference, not really a case of what produces the best results.  By “preference”, I mean setting the pressure to an amount that was manageable and wasn’t resulting in regular locking of the wheels.  After trying several variations of brake pressure, I found that brakes are far more effective when pressures are set at their highest.  This makes regulating brake application extremely difficult and is certainly considered a ‘skill’.  It is one worth learning though, as you’ll be slowing your car far quicker with good control of a high pressure setting.
 
I absolutely recommend you use 200% brake pressure on every on of your tunes, and if you find it difficult to control, practice more.  You’ll reap the benefits!

Aero, or Aerodynamics, is “The study of air in motion, particularly as it interacts with solid objects.”.

By making cars silky-smooth and streamlined, air flows easily over their surfaces reducing their aerodynamic drag.  This means they have less resistance to the surrounding air as they pass through it, aiding in both acceleration and top speed.  Being able to control and manipulate the flow of air over the body of a car offers huge benefits.

Installing a wing at either end of a car allows us to exploit the airflow and generate additional grip.  In a similar way to the wings of an aircraft which provide lift, we use wings on a car to create the reverse effect, pressing the car down onto the track’s surface.  The effects of aerodynamic downforce are governed by two important factors. 

The speed of air passing over the wing.
The angle of the wing.

Firstly, the car needs to be travelling fast enough for any installed wings to generate noticeable effects.
Secondly, the angle of the wing needs to be steep enough.  A wing with an angle set parallel (or close to parallel) with the direction of travel, is going to glide through the surrounding air, creating little-to-no downforce irrespective of vehicle speed.

So, the car needs to be going fast enough, and the wing angle needs to be steep enough.  Using this knowledge, we can create large amounts of downforce, seriously improving handling at high speed.  But of course, it’s not without compromise.  The installed wing increases the aerodynamic drag of the vehicle, reducing its top speed, and to some extent it’s acceleration. 

Therefore, one of the most important things to determine before installing any aerodynamic upgrades, is the track you are racing on.  Short winding tracks will certainly benefit from increased grip, but if there are no straights long enough to get the car up to a speed that profits from the wing's effects, is the wing beneficial?  So, are wings more suitable for tracks compromising of long straights?  By using less downforce, we can reduce the aerodynamic drag, and maximise a vehicle’s top speed.  As you can see, there seem to be contradicting reasons surrounding the installation of aerodynamic upgrades.

Another important consideration is the overall performance of the car to which you are potentially installing these upgrades.  Slow cars with poor power-to-weight ratios can take a long time to accelerate up to speeds where wings begin to function effectively.  These types of cars may never really benefit from additional downforce.  However, high-powered cars with rapid acceleration very quickly reach speeds where wings begin to work effectively.  The additional grip provided by wings, especially during fast-paced cornering, builds exit speeds quickly, and will almost certainly negate the reduction in top speed caused by additional drag.

Analyse each track and determine if your car can quickly reach ideal speeds before installing aerodynamic wings.  Sometimes they help.  Sometimes they don’t.  You can always try your chosen track without aerodynamic upgrades installed, and again with them fitted, just to see which works best.  For the record, they more-than-often are worth installing, unless you’re driving (something) particularly slow.  There are very few car and track combinations which I don’t use aerodynamic upgrades, but every car and track combination should be considered.

By tuning front and rear wings independently, can also keep the car balanced through turns.  If the front of the car doesn’t turn enough, increase the front downforce.  This pushes the front tyres down into the track with more force than the rear and will encourage oversteer.  Likewise, by increasing the rear downforce independently from the front, presses the rear tyres down into the track, preventing the rear from losing grip, and encourages understeer.

Tune aero to keep the car balanced but remember to ensure the car can out-accelerate the additional drag!

Possibly one of the most misunderstood areas of tuning are differentials.  In fact, this is an area I struggled to get my head around at first, but upon reflection, they’re actually very easy to tune.  To fully understand how to effectively tune them, you need to understand how they work.
 
So, in the usual way, before I explain what differentials do, let’s first take a moment to consider some important details.
 
While driving round corners, the outside wheels of the car travel further than the inside wheels.  If the outside wheels travel further, but complete the turn in the same time, they must have to travel faster than the inside wheels.  The differential allows the inside and outside wheels to rotate at different speeds, vital if both inside and outside tyres are to maintain traction during cornering.  If both inside and outside wheels were driven at the same rate, the outside wheel would be dragging or skidding across the ground.

Differentials are only found at sets of wheels that are being driven.  So, a front wheel drive car has a differential at the front, and rear wheel drive cars have a differential at the rear.  All wheel drive cars have differentials at both the front and the rear, with an additional differential controlling torque split between the front and rear wheels.

To allow independent rotation of both inside and outside wheels, differentials need to be open, but the trouble with having a differential completely open (a setting of 0%), is that due to the mechanical nature of a differential, the torque gets sent to the wheel with less grip.  But why is this a problem?  Well, during a turn, we know that weight gets transferred to the outside tyre, reducing the load on the inside tyre. Now with less grip, the inside wheel receives all the torque from the engine.  If you apply too much power, the inside wheel suffers from high levels of wheelspin. This results in all our acceleration essentially ‘leaking’ out of that wheel, as it saps any acceleration we had through and out of the turn.
 
By using Limited Slip Differentials, we can limit the difference in wheel speed between the inside and outside wheels.  This helps prevent any dragging or skidding taking place at the outside wheel, while providing us with the ability to accelerate harder out of a turn.
 
When tuning differentials, remember;
 
High differential settings mean more locking of the inside and outside wheels (rotating at similar speeds).
Low differential settings mean less lock of the inside and outside wheels (rotating more independently).
 
Differentials are tuneable for two separate situations; Acceleration and Deceleration.
 
Acceleration

When tuning the acceleration setting, the effects are only present while the throttle is being applied.  
 
With the acceleration set to 0%, the differential is open and therefore has no lock!  Think of zero as “O”, for “Open”.  As mentioned, this setup restricts acceleration through and out of the corner, but control is far greater.  This is because an open differential is less likely to lead to power-on oversteer, caused by both driven tyres losing traction and you accelerate out of the turn.
 
With the acceleration set to 100%, the differential is locked, forcing inside and outside wheels to rotate at the same speed. Oversteer will be typically inevitable, particularly in high-powered cars, and gentle throttle control will be essential to tame the power-on oversteer.

No surprises here, but the trick is to once again find a balance.  For a rear-wheel drive car, high acceleration settings increase oversteer, and low acceleration settings reduce oversteer. The less traction you have available, the lower you need the setting, so tyre compound should also be considered. 

Deceleration
 
When tuning the deceleration setting, the effects are only present while off the throttle.

With the deceleration set to 0%, the differential is fully open and has no lock while slowing down.  This allows the wheels to rotate independently, getting the car around the corner earlier for sooner throttle application.  Be aware, as a setting of 0% may cause one of the driven wheels to lock during abrupt downshifting, resulting in instability.


With the deceleration set to 100%, while off the throttle, inside and outside wheels are forced to rotate at the same speed.  As you lift off the throttle, both wheels grip the track equally, and the car refuses to rotate.  Once again, be aware, as setting of 100% may cause both driven wheels to lock during abrupt downshifting creating an effect similar to applying the handbrake!  This will be hugely detrimental to corner entry stability.

Again, you need to find a balance.  For a rear-wheel drive car, lowering the deceleration setting will reduce corner-entry understeer, and high differential settings increase corner-entry understeer.

 
As a short summary;
 
High acceleration settings increase power-on oversteer.
Low acceleration settings reduce power-on oversteer

High deceleration settings increase power-off understeer.
Low deceleration settings reduce power-off understeer. ​

To finish this tuning guide, below are two troubleshooting flowcharts.  You can follow these to quickly help you identify the  most likely cause for common problems experienced in both oversteer and understeer.  
Both troubleshooters were sourced online, and I take no credit for them.

UNDERSTEER TROUBLESHOOTING

​​​Corner Entry

​Mid Corner

​​​Corner Exit

​​​Does The Front
Bottom out?

​​​Reduce Front
​Rebound Damping

​​​High Speed

​​​Mid-Low Speed​

​​​Yes

​​​No

​​​Increase Front
​Toe-Out

​​​Increase Front
​Downforce

​​​Stiffen Front
Anti-Roll Bar

Soften Front
Anti-Roll Bar

​​​Reduce Front
Ride Height

​​​Increase Front
Bump Damping

​​​Reduce Front
Spring Rate

​​​Increase Front
Spring Rate

​​​Increase Front
Caster Angle

​​​Increase Front
Bump Damping

​​Reduce Front
Shocks (Overall)

​​​Reduce Front
Ride Height

​​​Increase Negative Front Camber

​​​Reduce Front
Ride Height

OVERSTEER TROUBLESHOOTING

​​​Corner Exit

​Mid Corner​

​​​Increase Rear
Toe-In

​​​High Speed

​​​Mid-Low Speed

​​​Increase Rear
Downforce

​​​Reduce Rear
Bump Damping

​​​Does The Rear
​Bottom Out?

​​​Yes

​​​No

​​​Increase Rear
​Rebound Damping

​​​Increase Rear
​Spring Rate

​​Soften Rear
​Anti-Roll Bar

​​​Reduce Rear
Ride Height
If Higher Than The Front

​​​Reduce Rear
Ride Height
If Higher Than The Front

​​​Reduce Rear
Spring Rate

​​​Soften Rear
Shocks (Overall)

​​​Increase Negative Rear ​Wheel Camber

​​​Reduce Rear
Ride Height
If Higher Than The Front

I hope you have found 'Tuning: In a Nutshell' both informative and easy-to-follow!  Maybe you haven't?  Either way, your feedback is incredibly important to me, so please spend just two minutes commenting via the link provided here.  

Many thanks.

Dave Lacey 
FACR DLTuning

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