Forza 3 tuning guide

written by Gary Weeks on 8.11.09


A lot of people look at the tuning options but not really understand what is going on with the different elements of a tune.  Tunes, in general are an art form and one that has brought about a number of dedicated tuners to the Forza mix.  With your own storefront now available in Forza 3 people can sell their tunes for credits.  There are positives and minuses to this way of getting your car to perform better.  Some people complain about having to pay for things but with all of the deeper parts of the Forza package, these elements can take hours to get right so to complain about it is a little unfair.  Also, these tunes are locked and while they may work for the tuner and his driving style, it may not work for you.  If you find a tune that works with your style then please fave them and buy them for support as they can really help with your online quest.

Alternatively, you can work on your own tunes which, although may take time will be beneficial to you as you can keep adjusting them to your style based on upgrades and tracks, save them and even sell them on too to up your credit rate and buy those vinyl groups, designs and cars that you always wanted.  Maturegaming will now try and break down the options available to you to better understand what each element does and how it works.

Tyres

Adjusting your tire pressure is a good, simple way to improve the cornering performance of your vehicle. Stock tire pressure is generally tuned for comfort rather than raw conering ability. When you take a new vehicle to the track, you should always make some adjustments to the tire pressure, usually increasing the pressure to all four tires to improve responsiveness and reduce tire roll in the corners.

However, take note that too much inflation can give you the opposite effect. An over-inflated tire will bow out in the center, reducing the contact surface. This effect is maximized as the tires heat up and the air inside expands, increasing the psi level. If you’ve reached the effectiveness limit of inflation, try reducing tire pressure to similarly affect the grip levels of your tires. If your FWD car is understeering, especially as the race wears on and the tires heat up, lower the front tire pressure to keep the contact surface flat.

Lowering tire pressure gives the tire more pliability, allowing it to conform to the ground and increase the overall contact patch with the asphalt. Accordingly, lowering tire pressure can help straight acceleration. But low pressure comes with negative side effects that become evident during cornering, as the more pliable tire rolls under lateral acceleration and gives you sloppy handling.

One thing to remember is that a little adjustment goes a long way. Differences of just a few psi between wheels can have a big effect, so don’t get extreme with the adjustments.

Gearing

Gearing ratios determine how many turns of the driveshaft result in a single turn of the wheels (the car’s wheels, not your steering wheel). A higher ratio (e.g. 3:1) makes it easier for the engine to rev high and reach max horsepower output quickly, but minimizes the top end speed of the gear. The effect of high gear ratios is quick acceleration with a sacrifice to top speed. A low gear ratio (e.g. 0.8:1) is harder for the engine to turn but improves top-end speed in that gear. The effect of a low ratio is slow acceleration with high top speed.

Lower gears should have higher ratios, while higher gears should gradually move to lower ratios. Sudden drops in the ratios between gears (e.g. having a first gear ratio of 3:1 and a second gear ratio of 1:1) will make it difficult to keep your engine revving within its peak power band. Most engines make the most power in the upper limits of their rev range (like between 4,000 RPM and 6,500 RPM). If the jump between two gear ratios is too large, your engine will drop too many revs on the upshift, dropping below the optimal powerband. This drop in revs will make for slow acceleration until you can muscle the revs back to their peak power.

Imagine a curved line on the gearing graph that connects the right edges of the ratios for each gear. A gradual curve will make it easier to keep your engine revving within its optimal RPM range. However, a curve too dull will restrict the range of your gear ratios. A sharper turn will naturally give you more range between gear ratios, but as we mentioned earlier it may also cause the engine RPMs to drop too much between upshifts. Experiment with your car to find its peak power band and adjust the gears to keep your revs within that RPM range while giving you the acceleration or top speed you need for a given track.

Many tracks will not allow you to reach the maximum speed of your vehicle. In these cases, it’s a good idea to increase your gear ratios to improve your acceleration. Other tracks, however, are all about top speed. On these tracks, it’s worth sacrificing some acceleration by lowering your gear ratios to make for better top-end speed.

Alignment

There are three categories of alignment you can adjust: camber, toe and front caster. Each setting should be adjusted only slightly between testings to avoid dramatic changes to handling. As well, these settings can negatively affect tire wear, so consider running different setups on longer races where tire wear is a factor.

Camber

Camber deals with the tilt of the wheels when viewed from the face of the car. Wheels with the tops tilted inward have negative camber, while wheels with the tops tilted outward have positive camber. There’s generally no racing application for positive camber, though some degree of negative camber can help cornering. As the car hits hard into a corner, centrifugal force will naturally roll the weight of the vehicle outwards. Negative camber helps keep the tire flat on the asphalt during this weight transfer. However, too much negative camber will prevent the tires from sitting flat during straight acceleration and braking, reducing grip in those situations.

Toe

Toe is the tilted angle of the wheels when viewed from above the car. Positive toe moves the fronts of the wheels inward together, while negative toe has the fronts of the wheels pointed outward, away from each other. The effects of toe are limited, other than affecting tire wear, though a little positive toe can give the characteristic of understeer, while a little negative toe can give the characteristic of oversteer.

Caster

Caster is the angle of the steering relative to the wheels. Imagine the front forks on a bicycle wheel. Typically, the front forks point forwards from the handle bars (the steering). This angle of the steering, in both bicycles and cars, is known as positive caster.

Positive caster will naturally center the direction of the wheels, lending some stability to straight-line driving. As well, some degree of positive caster can help in cornering. During hard cornering, the suspension of the front wheels compresses and the wheels naturally take on a negative camber which, as we described earlier, helps grip in the corners. This effect is enhanced by positive caster.

However, too much positive caster will make the car fight cornering. Because of the natural tendency of wheels with positive caster to center themselves, too much positive caster will make a fight of turning the wheels into corners.

Anti Roll Bars

Anti-roll bars increase the vehicle’s rigidity and stability under hard cornering by effectively tying together the left and right sides of the vehicle. Hard corners will cause the body of a car to roll away from the turn. You can adjust the stiffness of anti-roll bars to counter the body roll and tweak the cornering characteristics of your vehicle.

Generally, increasing front anti-roll bar stiffness will also increase the tendency to understeer. Conversely, increasing the stiffness of the rear anti-roll bars will increase the tendency to oversteer. It’s a good idea to tweak the stiffness to an even level that suits the vehicle before adjusting for understeer or oversteer. When it comes time for the fine-tuning, it’s often better to soften the anti-roll bars to correct understeer and oversteer rather than stiffen. If the anti-roll bars are too stiff, you’ll get some instability on rough roads and hairiness in tight corners where the inside tires may lift off the ground.

Springs

Most vehicles come from the factory with fairly soft springs made to deal with rough public roads. On the track, however, the range of lumpy road surfaces is much narrower. The generally smoother track surfaces make suspension stiffening a very helpful adjustment in the corners. However, like all things in tuning, too much of anything will negatively impact your lap times.

Stiffer suspension will better control suspension travel and the always-changing nature of your wheel camber. By holding wheel camber more constant, you can effectively keep the tires flat against the pavement for improved grip. Too much suspension travel will cause the camber angle to change—since suspension does not travel straight upward, but rather in an arc—which will result in vastly different levels of grip depending on the weight balance of the vehicle at any given moment.

Though as we mentioned, too much suspension stiffness can be a bad thing. Too-stiff suspension will not have the travel necessary to properly deal with imperfections in the road surface. Slight bumps in the road will then cause the tires to skip and lose traction. As such, stiffening the front suspension too much can cause understeer, while stiffening the rear suspension too much can cause oversteer. Conversely, you can reduce understeer and oversteer by softening the front and rear suspension, respectively.

Ride Height

Ride height is another adjustment you can make to the suspension. Generally, you want as low a ride height as possible without bottoming out the suspension on rough roads and under heavy weight transfer. However, balancing the front and rear ride height can let you play with your vehicle’s center of gravity. A higher ride height in the rear will shift the car’s center of gravity forward, which may help front tire grip.

Damping

While spring stiffness determines how much travel is in the suspension, dampers, also known as shocks, control the rate at which a vehicle’s springs oscillate. Picture hitting a large bump at high speed in a standard road-going vehicle. After the bump, the car’s suspension will continue to oscillate, bouncing up and down as the springs settle back down to their normal state. While this oscillation is good for driver comfort on public roads, it’s not so desirable on the race track. The fluctuating weight balance during such oscillation can make tire grip unsteady, fluctuating with the suspension travel.

Stiffer shocks will control the oscillation of the suspension for a steadier weight balance. As well, stiffer springs will increase the speed of weight transfer, letting you more quickly and predictably redistribute the weight of the car with acceleration and braking. However, too-stiff shocks can overpower the springs, reducing their effectiveness at dealing with imperfections in the road and contributing to a loss of traction on uneven road surfaces, including bumps, dips and rumble strips.

Suspension in general can be an absolute pain in the ass but can be made simpler by using calculators which will detect decent settings to work from based on the weight of the car, what drive the car has and a couple of other details.  The best calculator, created by Feuerdog, can be found here and has been used by tuners since Forza 2 to get some base settings to work from.  It’s easy to use and simple to get.  Follow the link and go to file/save as/excel or open office seem to be best.

Once done, simply enter:-

  • In the yellow fields you will select a drivetype(FF,FR, FA, MR, MA, RR, RA), and enter the vehicles weight(lbs) and front weight distribution. This info is availiable in the upgrade and car selection areas.
  • FF = Front engine, Front wheel drive.
  • MR = Mid engine, Rear wheel drive.
  • RA = Rear engine, All wheel drive.
  • The blue fields will then give you all the setting calculations automatically which you can enter into your tune on Forza 3.
  • The orange fields are optional, but will add small compensations into the values to compensate for aerodynamic downforce and differing tire widths. Tire widths are the first three digit number in the tire size located in the tire width upgrade screen. If you do not want to compensate for aero or tires then leave these cells blank.

Aero

Aerodynamic downforce acts as added weight, pushing down on either end of the vehicle to enhance the traction of the tires. Note that the effect of downforce increases with speed, and at low speeds downforce has little if any effect. Add downforce to the front of the car and you’ll effectively give the front tires some added traction at speed. Add downforce to the rear of the car and you’ll boost the grip of the rear tires at speed.

However, the benefits of downforce come at a cost. As we said, downforce effectively adds weight to the vehicle, which limits top-end speed and acceleration. Increase downforce sparingly to correct for understeer and oversteer tendencies, especially in powerful rear-wheel-driven vehicles that tend to break loose over sweeping high-speed turns.

Braking

Generally, you want braking to be even between the front and rear wheels. However, as you make changes via upgrades and other tuning, you may offset the balance of braking. If you find that the vehicle tends to understeer or oversteer under braking, you may have a braking imbalance.

You can correct for some amount of braking oversteer by moving the braking balance forward. Conversely, you can correct some understeer by moving the braking balance rearward. Too much braking balance to the rear, however, will upset stability under braking, while too much forward braking will contribute to understeer. Look for a neutral balance in the braking so that you feel neither understeer nor unsteady oversteer under hard braking conditions.

Differential

A differential splits power between the left and right halves of a car’s driven axle(s) and allows either half of the axle to rotate at a different speed than the other. Letting both axle halves rotate independently—thus rotating the two wheels at different speeds—is necessary for maintaining traction in a turn. In corners, the wheel on the inside will naturally rotate less than the wheel on the outside as the inside wheel travels a shorter distance. Without the allowed slip of a differential, the wheels would be locked into the same rotational speed and either the inside or the outside wheel would skip and lose traction.

Performance vehicles have a special type of differential, called limited-slip. A limited-slip differential (LSD) does what it says—it limits the slip allowed by the differential. Remember, the slip of the differential is what allows the wheels to rotate at different speeds. However, there is a limit to this benefit, and an LSD helps by locking the rotation of both wheels at a certain level of slip. Slip is good for cornering, but not for acceleration and braking.

When traveling in a straight line, as in under hard acceleration or braking, you want both wheels rotating at the same speed. A limited-slip differential makes this happen. Increasing the acceleration and deceleration rates of the differential will make the LSD lock the wheels together sooner. Decreasing the rates will allow for more differential slip before the LSD kicks in.

Increasing the acceleration rate of the differential in a rear-wheel-drive vehicle will tend to make more oversteer as you exit a corner, hard on the accelerator. Increasing the acceleration rate of the differential in a front-wheel-drive vehicle will, conversely, contribute to added understeer as you accelerate out of a corner, as the wheels lock together and begin to lose traction under acceleration. Too low a setting in either drivetrain configuration will result in decreased acceleration and braking efficiency. Keep the LSD settings relatively high without adding to your vehicle’s natural tendency to oversteer or understeer. If you find the car tends to lose traction to the powered wheels as you accelerate out of a corner, consider lowering the setting of the LSD.

Well, there you have it.  I hope it has not been too confusing and hope you will at least give it a little go and see what you can produce.  The guide itself has taken its references from a few other sites but is, hopefully condensed into a helpful analysis of what goes on and how it works.  I would also suggest that you work a little bit at a time too.  Too much of one thing, can throw other settings out so work one bit at a time until you feel it is right.  You wouldn’t want to put a couple of hours work in to have it all go wrong from over compensating!

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