Forza Motorsport 4 Tuning Guide and Car Upgrades

By   /   4 years ago


Brake Bias maintains the balance between the front and rear brakes. It is represented by a percentage such as, a brake bias of 65/35 means that the front brakes get 65% of the braking power, and the rear brakes get 35% of the braking power. It’s an important setting that you would need to adjust subjected to how you go into the corner and get out of it.

Now to the tuning part – When you move brake bias toward the front brakes, the car is tight and more stable while braking and entering a turn. When you move the brake bias toward the rear, the car is loose while braking and entering a turn.

Be careful though, excessive front braking can lock up the tires and decrease overall effectiveness of your brakes since you are not slowing down the car by using the rear brakes.

It is recommended that your car always have more front braking power than the rear because the weight transfer during braking loads the front tires only. If you set brake bias toward rear, the rear tires will lock as weight transfers forward and makes the rear of the car lighter.

Set the brake bias between 70/30 and move from there to fine tune your car. Don’t forget to ‘Turn ABS OFF’. How would you fine tune the brake bias ? Replay and Telemetry combo… read the telemetry for friction.

How Should You Read Telemetry For Friction ?
Red Circles is a visual of the grip available at each tire, and the blue lines inside them are the amount of grip you are actually asking the tire to produce. This displays a more detailed brake down of the “Friction Circle” type telemetry from the “Body Acceleration” telemetry screen.

If you watch the red circles off the start line, the front ones will get slightly smaller and the back ones will grow. That is because a tire’s grip is related to the amount of weight on that tire more weight = more grip, to an extent. So as you jump on the gas, weight shifts backward, and the rear circles grow because your rear tires have more grip.

When you go into a corner, you will also see the circles change size as weight shifts side-to-side. jump over a curb, and the circles disappear if the tire leaves the ground! The blue line shows how much you are asking of the tire – if it is outside the red circle, it means you are pushing that tire too hard and it has lost grip, so it is sliding. If you look at the telemetry during a spin, the blue lines will be well outside the red circles.

If the blue line is inside the circle, it means that there is more grip available, since the circle is the limit. You are using your tires most effectively when the blue line is touching the red circle.

Notice while Braking which circles are getting bigger, usually the front will get bigger than the rear with the bias > that 50% Front. Keep moving 1% Front till you have lost grip completely skidded out as a result of understeer when braking. Move back 1% to be in the safe zone.

Tuning Brake Pressure
Once you have found the ideal setting for brake bias, the brake pressure will increase your stopping power. To fine tune brake pressure, look at the brake indicator and notice if you are at 100% or 70%.

Subjected to your braking style, you may do one of these:

  • On Demand (Pull the trigger all the way back)
  • On Power (Pull the trigger all the way back with acceleration)
  • Off Throttle Down Shift Half Brake (Pull the trigger half way)

On Demand
Go for less brake pressure as you want the tires to skid only when the trigger is pulled all the way back. Start at 100% and keep going down 5% till you have the perfect brake. Using the Telemetry, make sure you have 4 big red circles when skidding to show good brake bias.

On Power
Similar to On Demand but make sure you get into a race-brake situation you are locking the front tires and burning the rear tires.

Off Throttle
Squeezing the brakes coming out of the corner is similar to squeezing the throttle, you will learn it over time and it comes natural afterwards.


Differential controls how your car transfers its power and torque to the road. Differential sends the power to the wheels with least grip and because of the way your car transfers power to the wheels, it is prone to wasting it and losing traction.

Similarly, when the differential sends the uneven amount of torque to the wheels, the limited slip kicks in, and locks the wheel together. Though, it evenly locks both wheels still one wheel is receiving more torque.

Differential has two settings, Acceleration and Deceleration. Acceleration controls at what point the differential locks while on gas. Having a higher percentage of acceleration will prevent each wheel from slipping, which will allow you to harness more power when exiting a corner but if you are driving an RWD car, it is easier to spin out a drift.

Having a lower percentage will make it easier for each wheel to slip, resulting in power loss when exiting a corner but if you are driving a RWD car, it is hard to spin out and drift.

Use the high-slip rate, even in front wheels because it usually creates a less sloppy feeling when you exit a corner and it allows you to leave the corner with higher speeds but if back-end of your car slides out more than you should stick to lower rate.

Deceleration controls at what point the differential locks when you let off the gas, usually when entering the corner. The high the rate, the more stable your car will be.

It will make your car less agile, and can cause under steer. Having the higher rate while accelerating, makes it harder to stop the skid, so be careful with whatever setting you choose. Use the low-slip rate here, because it will make your car more agile. If your car tends to over steer, increase the slip-rate a bit.

The central differential of AWD cars control how the torque is divided between the front and back wheels. It sends more power to wherever there is least amount of grip, just like any other differential. Rear biased central differential gets the most performance out of AWD, so give it a try.


It controls the suspension’s stiffness and compression between wheel and wheel-well. Rebound and Bump work in ‘reverse-way’ like having the Front Rebound higher than rear increases grip on rear, because more weight is concentrated in the front tires under spring compression, so rear wheel con work more freely.

Rebound Stiffness

Increasing Front Rebound

  • More grip in the rear.

Decreasing Front Rebound

  • Reduces transitional under steer.

Increasing Rear Rebound

  • More grip in the front.

Decreasing Rear Rebound

  • Reduces transitional over steer.

Front biased Rebound

  • Increases under steer & increases grip in RWD cars, sacrificing turn-in slightly.

Rear biased Rebound

  • Increases over steer & highly recommended for FWD & AWD cars.

How high rebound setups you can have depends on the Bump stiffness that you have set. If you are using high Rebound with low Bump, your car may get upset by curbs etc. This is modified by ride height and suspension stiffness.

Higher Rebound than Bump is must but the Bump Stiffness should be 75% of the Rebound’s stiffness at maximum. Low Bump Stiffness goes great so don’t limit yourself with officially given tip that 50% of the Rebound’s stiffness should be a minimum.

Bump Stiffness
It fine tunes damping and suspension.

Increasing Front Bump

  • Increases under steer and slightly increases rear grip + modifies the effectiveness of Damping and Spring setups.

Increasing Rear Bump

  • Increases over steer and slightly increases front grip + modifies the effectiveness of Damping and Spring setups.

Decreasing Front Bump

  • Improves bump absorption + modifies the effectiveness of Damping & Springs.

Decreasing Rear Bump

  • Improves bump absorption + modifies the effectiveness of Damping & Springs.

Front biased Bump

  • Increases under steer + slightly increases grip in RWD cars.

Rear biased Bump

  • Increases over steer & highly recommended for FWD & AWD cars.

To test the excessive Bump Stiffness, let your car take a mild curb aggressively and then see if your car rolls. If it rolls, your setup is too stiff. If you already had your bump

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Zawad is the lead editor of SegmentNext. He primarily manages what gets published on the site. He is a finance student and PC games enthusiast.
  • DJ-Kemical

    Could sum1 PLEASE tell me how 2 upgrade my cars in Forza 4 please? I DONT want to automatically upgrade. Any help will be very much appreciated! My email is -Thanks in advance!!

  • Wright

    hi my name is Selby, I’m a new player to fotza 4. I completed everything on gt5. I don’t know how to save the races on forza 4, and when you download the car packs I don’t know how to get them to come up I read your article on tuning and I found it to be very helpful.

  • NC Bubba

    I purchased ForzaTune also. Waste of money and time. After some real research, I have found set-ups that work much, much better. The keys to remember are that every car is different, and that for every different car, there are innumerable combinations of upgrades, etc. that will alter how the tires, suspension, gearing and brakes need to be tuned to acheive maximum grip, acceleration, etc. The long and short is: be willing to spend a lot of time with it if you consistently want a spot on the podium.

    A good place to start is this equation for setting front and rear spring weights:

    Front spring weight = car weight / 2 x front/rear weight distribution ratio (in decimal form)

    Rear spring weight = car weight / 2 – front spring weight

    For example: Let’s say you have a Charger Daytona that you’ve upgraded…its current weight is 3189 lbs and the front/rear weight distribution is 62%. Divide the car’s weight by 2 and you get 1594.4, then multiply by 0.62 (62%), and you get 988.59. This is your front spring weight. Then subtract this from 1594.4 to get your rear spring weight of 605.81.

    Lots of other points are also important, but if you have been struggling to get a good basic tune, I GUARANTEE you will smile from ear to ear while driving a freshly tuned car using the above equation (I was laughing aloud and flashing all kinds of teeth on my first lap at Hockenheim after discovering this formula).

    Like I said before, the finer points take a lot of time, so if you’re not a big fan or don’t have the spare tick-tock on your clock, don’t bother with all that…just settle for the middle of the pack and have fun.

  • Craig Borysowich

    the end of this page says “If you already had your bump” and then ends abruptly – did part of this post get lost?

  • Chris

    Hi, just thought Id add that ForzaTune ‘DisAgrees’ with your ‘Rules’ on Front/Rear Biased items, like Damping, Anti Roll Bars, Rebound and Bump.. On my FWD 97 Civic TypeR it was telling me to have everything Front Biased except the AntiRoll Bars.. But you say that Rear Biased is Highly Recommended for FWD cars.. Im not saying your wrong at all, I used the ForzaTune to get a ‘Base’ then tweaked it using your info and found it to have better results thanks to you.. Its just a warning to anyone that blindly follows ForzaTune..

  • Adam D

    I currently own a Lamborghini Countach LP5000 and have tuned it so it has the following stats:

    Speed – 9.5
    Handling – 6.4
    Acceleration – 10
    Launch – 10
    Braking 6.8

    It falls into the R2 class with a rating of 818, i need help with the handling/braking and how to get it to the top of R1. Thankyou!

    Gamertag : AdamD x

  • Paulo Hirata

    How to unlock tuning configuration? At this moment I can only configure tire pressure. Need I buy anything to unlock other configurations?

    • Jason


      You need to upgrade to Race suspension/transmission, etc… To be able to adjust those for tuning for most cars. The stock transmission and suspension are non adjustable. If you don’t have a rear spoiler, you can’t adjust it. Look in the description under the parts in the upgrade shop and they will tell which upgrades are adjustable.

  • F4g

    I recommend iphone app Forza 4 gear
    Any car setup same taste

  • john

    i found iphone app “Forza 4 Gear”.
    tuning calculator app.

  • Samuel Tylstedt

    First of all, nice guide!
    But i’m not a native english speaker so I don’t know what you mean with biased under Dampening section. Do you mean to have front and rear set to the same value, or?

    Thx again for a nice guide 😉

    • Zawad Iftikhar

      Front Biased would mean amount of weight on front compared to rear. It is reverse for Rear Biased Rebound. Explanation of how they work is already in the description of the specific section of the guide.

      Biased generally means more inclined towards…

      I hope I have cleared few clouds :)

      • Samuel Tylstedt

        Yes, thank you very much!
        It’s much clearer now :)

        Then i’ll see what good i can make this new knowledge. Watch out in the game 😉

  • arnie

    in the Anti-Roll Bars section, there are sub-sections:

    Stiffer Front Anti-Roll Bar
    Stiffer Front Anti-Roll Bar
    Softer Rear Anti-Roll Bar
    Stiffer Rear Anti-Roll Bar

    one should be Softer Front Anti-Roll Bar.
    thanks for correction.

    • Zawad Iftikhar

      Thanks for the heads up =)

      • arnie

        You are welcome 😉 im glad you wrote this article .. because im not familiar in tuning. Im making my own notes so the next weekend will be only about tuning and testing :)) And this article is really long and full of useful info .. so its ok, there are a few mistypes 😉

        I found another misunderstanding – maybe it is correct, maybe not:

        Driveline –> Differential

        If you are driving a FWD Car, stiffen up the front different acceleration to force more power to the outside wheel but it can result in understeer

        If you have RWD car – stiffen up your front differential acceleration to force more power to the outside wheel but it can result in oversteer if you put too much power.

        is it ok, that in both cases you need to stiffen up the front diff.accel ?

        • Zawad Iftikhar

          It’s correct. The difference is that you will get oversteer in RWD and understeer in FWD.

  • arnie

    hi, please make a review of this part in tire pressure section:

    If rear tires are hotter than front tires, your car will over steer. This is because, too much rear spring/sway bar, not enough front spring/sway bar, front pressure is too high, rear pressure is too low, rear tires are too narrow or front tires are too wide. In this case, soften up rear springs and sway bar, stiffen up front spring and sway bar, decrease rear pressure or increase front pressure.

    is it correct ? if too high front pressure i need to increase the front pressure ? the same for rear tires ..

    thanks 😉

    • Zawad Iftikhar

      My bad. At that point, rear pressure is too high and front pressure is too low that’s why increasing front pressure is the suggested tuning.