Tuning in a Nutshell is a tuning guide which has been specifically written in a way to make tuning easy to understand.  Learning how each tuneable component of the car works gives you the knowledge to correctly tune to suit your requirements.

Before continuing, there is one obvious yet highly important thing you should always remember. The tyres are the only part of the car that make any contact with the track’s surface, with only a small area of the tyre known as the ‘contact patch’, being in contact with the track at any given moment.  Maximising the size of the contact patch across each of the four tyres is the primary focus while tuning.  Every tuneable component 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 tyre pressure, as this is the only part of the car that can be tuned without making any vehicle upgrades.

 

Let’s touch on a few important details first.

 

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

 

As a tyre gets hot, the air inside 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 between 140-170 degrees Fahrenheit (F).  Sport compound tyres 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 lap or two 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 using the in-game telemetry.  While on 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, pressure is set too high - The tyre is ballooning!  If the edges are hotter than the centre, 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 tyre tuning based on maximising the size of the contact patch and maintaining suitable temperatures, 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, we’re looking at how camber angles can also 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 a 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.  This ensures a large, centralised 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 it would do if we never had to turn, but during cornering, some of the supported weight is transferred to the outside wheels. The sharper the turn or the faster the turn is taken, more of the weight ends up on 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 amount of available grip.  But, by using the correct amount of negative camber, we can shift the weight distribution away from the edges to a more centred position, increasing the size of the contact patch and maximising 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 unfortunately large negative camber angles force the tyres to roll with more weight on their inside edges reducing the size of the contact patch once again. If straight line grip is reduced, performance in acceleration and braking will suffer.

 

By fixing one problem, we’ve created another!  This is often the case when tuning cars and so there’s generally a ‘balance’ to find.  A happy medium.  In the case of camber alignment, you should tune to find 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 explained in the previous section, you can monitor tyre information by using the in-game telemetry.  From here, you can attempt to develop one of sim-racing’s toughest skills - monitoring tyre temperatures while you drive! It’s not as easy as you'd think, 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.  You should aim to achieve an even temperature distribution across the width of the outside tyres at the point of corner exit, but as temperature distribution results will vary from one corner to another (after all, every corner is different), primarily tune for corners which carry the fastest exit speeds leading onto long straights.

 

If during corner exit the inside edges of the tyre are hotter than the outside edges, too much weight is pressing down on the inside edges.  By reducing negative camber, we can shift the weight into the centre of the tyre, and the temperatures will even out.

 

Likewise, if the outside edges are hotter than the inside edges, there’s too much weight there.  No problem.  Just increase negative camber.  This once again centralises the weight distribution across the tyre, and 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 noticeable differences.

 

TIP: Aim for tyres to be a fraction warmer on the outside edges at corner exit.  This approach uses slightly less negative camber compared to that which would produce a perfect even distribution of heat, but by doing so will help keep the contact patches a little bigger on the straights, minimising any loss of performance in acceleration and braking.  It’s the 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 heat distribution on the tyres on the inside wheels while tuning camber.

 

Now, 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 cover how your tyres will benefit from correctly tuned toe alignment. 

 

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!

 

But 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, meaning 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 causes the inside wheels to fight against the outside wheels, resisting the turn. discouraging steering and promotes understeer.

 

We already know that during a turn, weight is transferred to the outside wheels.  We also now know that for the effects of tuning toe to be appreciated, we require influences from both the inside and outside wheels.  For this reason, toe adjustments will affect 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 as the weight is primarily on the outside wheels.

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 changes to handling, however adjusting toe in any amount or direction will cause tyres to scrub.  This will negatively impact top speed and acceleration, so once again you’ll need to find a suitable balance – A sweet spot, where both cornering and straight-line speeds are both maximised.

 

TIP:  Toe adjustment angles must stay particularly small and should never need to be more than +/- 0.6°.

In section 4 we’ll be covering the final section of wheel alignment; 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.  A “Chopper” motorcycle is a great illustration of an extreme caster angle where the front wheel is way out in front of the bike.

 

This angle should never be negative, but what are the benefits of using a positive caster angle and how much angle is required?

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 becomes.  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 and the more upright the wheel wants to be.  Therefore, it’s easier to stay upright while riding faster.  By adding a positive caster angle, the effects of inertia are considerably magnified.  The larger the caster angle, and the faster the wheel spins, the stronger the force becomes.

 

This brings us to the main advantage of using a large caster angle in our car’s setup - 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 be ignored, 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.  

 

If during long straights you feel instabilities and are constantly having to correct your driving 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.

 

TIP: Generally, in Forza Motorsport, I’d recommend setting the caster to its maximum angle of 7°, however remember to 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 preferred caster angle across many, if not all their cars.

Following the general flow of this guide, let’s first look at what anti-roll bars are.  You must have figured out by now that I like to chat a bit first!

Anti-roll bars (or Sway bars) can be installed at the front and rear of the car.  They essentially connect the inside and outside wheels together at a point below the suspension assembly.  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 caused by weight transfer makes the springs on the outside wheels 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 at a point below the suspension 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 during cornering 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 the cornering stages 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 centralised across it’s width.  This doesn’t reduce the amount of weight transferred through a particular corner, but stiff anti-roll bars mean weight isn’t transferred as far.  With less distance to move, weight transfer is completed faster, and fast weight transfer makes a car’s handling more precise and predictable, and 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.  And on top of that, less body-roll means you can set your ride-height far lower, and a lower ride-height means more grip!

 

Wow! 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.

 

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 more 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 very 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 grip to have any chance of exploiting 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, it is possible 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, except in cars which already have a very balanced front-to-back weight distribution.

 

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 have lost 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 they 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 setting and testing anti-roll bar stiffnesses.  They can be awkward to get right, but once adjusted correctly, will hugely increase handling predictability and control through corners.

It’s not like I haven't mentioned it, but just to confirm, everything we’ve covered so far enables us to extract as much available grip from the 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.

 

Each spring has a ‘spring rate’.  This 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 how far the suspension can 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 springs compress easily, keeping the tyres in contact with the road, instead of skipping over them and having tyres momentarily leaving 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 will act 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, is much more likely to skip over the bumps.

 

So, what do we do?  Once again, we compromise.  We need to go soft enough for the bumps, but not so soft that the car bottoms-out.  Well… Couldn't 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 all 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 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 spring rates 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 which has bottomed-out displays a figure alongside it of ‘1.00’.  Set your spring rates to achieve maximum compression figures ranging between 0.95 to 0.98, ensuring they never actually 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 however one more thing to consider.  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 its rear wheels during acceleration.  Diving is when the front springs are set too soft and the car rolls forward onto its front wheels during braking.  To ensure you don’t induce these additional handling problems, keep springs stiff enough to maintain a generally flat car while accelerating and braking.

 

To conclude, we find ourselves in a vicious circle;

 

1. Low ride-heights increase grip but require stiffer spring rates to prevent bottoming-out.

2. Stiffer spring rates prevent bottoming-out, and prevent excessive squatting and diving, but can lead to less tyre compliance on bumpy surfaces.

3. 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 further if you experience too much squatting or diving.  The real control of suspension is found in the dampers, and that's up next.

We’ve just covered springs, but luckily for us that’s not the only part of the suspension assembly.  In this section we’ll be covering how to tune Dampers, sometimes referred to as ‘Shocks’ or ‘Shock Absorbers’.

So, what exactly are Dampers?

 

Although it's not quite as simple as this, Dampers are made of 2 things.  A cylinder full of pressurised oil, and an internal piston.  The piston can move up and down through the oil at a rate controlled by internal valves.  Small valves restrict the flow of oil passing through them, slowing the movement of the piston.  Large valves allow far more oil to pass through, allowing the piston to move quicker. 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 the springs, the car would bounce up and down, over and over.  While driving it would be doubtful the suspension would ever settle!  Although you can’t completely remove the dampers from the suspension assembly in Forza Motorsport, you can experience what it may feel like by setting all your damper stiffnesses as low as possible. I'd encourage you to do this!  You’ll soon see what I mean.   If you went ahead and tried that, we’re absolutely agreed you need dampers to stop springs oscillating, 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 slower they can move.  This enables the damper to quickly dissipate the energy stored from the spring, and the spring stops oscillating.  This will promptly stabilise the car’s sprung weight, and can help reduce or eliminate that bouncy, floating characteristic you get in cars which use much softer damping. This huge reduction in spring oscillation produces stable, predictable handling, making the car easier to drive, all while maximising tyre compliance!

 

So, is a stiffer setup better?

 

While off-road surfaces require softer damping - allowing suspension to move more freely over bumps and gravel - for the flatter, asphalt-covered wonders we race on in Forza Motorsport, firmer setups are generally more suited.  Lowering the stiffness of dampers can however aid traction by giving tyres more ‘opportunity’ or time to react.  This is particularly useful to know, as cars that use tyres with low levels of grip will struggle to handle abrupt changes in load. 

 

Firmer setups, while more suited to racing, will require high-performance 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 controllable and effective use of available grip, also very useful to help dial out 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 helping to resolve oversteer issues.

 

This leads us into the next part of dampers.

 

We can control the rate of oil-flow through the valves in both directions – when the springs compress and extend. These are referred to as Bump and Rebound respectively.

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 during weight transfer, and squatting is the reverse effect, experienced during hard acceleration as 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 to get any power down, and the car will feel somewhat like a boat!

 

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 but finding the correct balance with your dampers will lead to magnificent performance gains!

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

Brake balance refers to how the total 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 itself.  This technique means you are braking while steering, a combination that will heavily influence a setting suited for you.  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 reduce any over-rotation.  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 for this you must remember that all tyres have their limits!  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 will fail and ‘let go’ of the road.  Now you’re entering a skid, and almost certainly hurting you’re lap time.  Not to mention you’ve now got to stabilise the car. 

 

So, while braking in a straight line, tyres don’t have to use any grip to aid cornering loads.  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%.  Adjust the balance to achieve this result, and you can’t go wrong.

 

Pressure

 

I used to think that adjusting braking pressure was simply a matter of preference, and not really a case of what produces the best results.  By “preference”, I mean setting the pressure to an amount that was manageable.  Something which just felt good 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 setting of 200%.  This makes regulating brake application much harder, but it is a skill worth learning!  You’ll be slowing your car far quicker with good control of a high pressure setting, than with less control on a lower pressure.

 

I absolutely recommend you use 200% brake pressure on every one of your tunes, and if you find it difficult to control, just practice more.  You’ll reap the benefits!

Aero, or Aerodynamics; “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 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 how the flow of air passes over the body of a car offers huge benefits!

 

Let’s look at the wings of an aircraft.  The shape of the wing (combined with the speed of the plane) causes the air pressure above the wing to be lower than the air pressure below it.  The laws of physics mean the air pressure is constantly trying to stabilise.  The high air pressure below the wing tries to take the place of the low pressure above the wing, and the wing moves up.  Planes are literally sucked off the ground!  We use wings on a car to create the reverse effect, forcing the car down onto the track’s surface. 

 

As mentioned above, the effects of aerodynamic downforce are governed by two important factors;

 

The speed of air passing over the wing. i.e. The car needs to be travelling fast enough for any installed wings to generate noticeable effects.

 

The angle of the wing - The angle of the wing needs to be steep enough.  A wing set at an angle 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 potential top speed and high-speed acceleration.

 

Therefore, one of the most important things to consider 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?

 

OK. So, are wings more suitable for tracks compromising of long straights? Surely by using more downforce we’re going to reduce a vehicle’s top speed!?  As you can see, there seems to be contradicting reasons surrounding the installation of aerodynamic upgrades.

A final but 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 can quickly reach speeds where wings begin to work effectively. 

 

So, analyse each track and determine if your car can quickly reach effective 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 still be individually considered.

 

The additional grip provided by wings, especially during fast-paced cornering, builds fast exit speeds quickly.  Getting out of corner faster could easily negate or even out-way the lower top speed caused by additional drag.

 

By tuning front and rear wings independently, can also keep the car balanced through high-speed turns.  If (at speed) the front of the car doesn’t turn enough, increase the front downforce.  This forces the front tyres down into the track more than the rears and will reduce high-speed understeer.  Likewise, by increasing the rear downforce independently from the front, forces the rear tyres down into the track more than the fronts and will reduce high-speed oversteer.

 

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 around 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.

 

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, but with the inclusion of an additional centre differential controlling torque split between the front and rear wheels.

To allow fully independent rotation of both inside and outside wheels, differentials need to be fully open (a setting of 0%).  The trouble with this setting is that due to the mechanical nature of a differential, engine torque gets sent to the wheel with less grip.  But why is this trouble?  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 much more the torque from the engine than the outside wheel.  Should you apply too much power during this cornering stage, the inside wheel suffers from high levels of wheelspin. This results in all our power essentially ‘leaking’ out of that wheel, sapping any acceleration power we could be using to get out of the corner quicker.

 

By using Limited Slip Differentials, we can control the difference in wheel speed between the inside and outside wheels, meaning we can reduce or even eliminate the unwanted wheelspin of the inside wheel and take back 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: 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 RWD cars, and gentle throttle control will be essential to tame the power-on oversteer.

 

Deceleration: 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, but be aware! A completely open differential (0%) could easily cause the inside wheel to lock during abrupt downshifting, resulting in sudden and unpredictable 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! A setting of 100% may cause both driven wheels to lock during abrupt downshifting creating an effect like you’d just pulled the handbrake!  This will be hugely detrimental to corner entry stability.

Again, you need to find a balance. 

 

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. ​

 

Thanks! I hope you’ve found this guide useful.  Maybe you can implement what you now know to make any final tweaks to your setups, just for that truly personalised touch!

 

Enjoy Tuning It Yourself!

Dave Lacey 

© Fast And Clean Racing 2015