Project Motor Racing Car Setup Guide: Tuning GT3, GT4 & Handling

Dialing in a handling profile in Straight4 Studios' Project Motor Racing (built on GIANTS Engine 10) comes down to isolating corner entry, mid-corner balance, and corner exit. Rather than overcomplicating every spring rate and damper valve across the game's garage, focusing on brake bias, anti-roll bars (ARBs), differential preload, and target tire pressures solves the vast majority of balance issues.

Official updates such as Patch 1.6.0.0 directly overhauled the physics baseline by shifting default brake bias closer to a 50/50 split alongside revised rear brake sizing across LMDh, GT3, GT4, and 992 Cup cars. As a result, older custom setups require specific adjustments to keep cars stable under hard braking.

The Core Handling Triangle: Entry, Apex, and Exit

A clean setup workflow isolates vehicle behavior into three distinct phases across every turn:

1. Corner Entry: Dialing in Brake Bias

Brake bias determines the distribution of braking force between the front and rear axles. A lower, more rearward bias shortens total braking distance by utilizing rear tire grip, but shifting too much brake force to the rear causes the back end to step out during trail braking.

Test braking zones incrementally:

1. Start at your baseline bias (often 53%–54% in GT3 baselines).
2. Move the bias rearward in small steps on practice laps.
3. Stop lowering the bias the moment you sense the rear stepping out on turn-in.
4. Add back one or two clicks forward to maintain trail-braking stability.

Note for Update 1.6.0.0 and newer versions: The developers re-engineered brake balance and rear rotor sizes toward a 50/50 default split. Custom legacy setups built before this update will feel unstable on entry until bias is pulled forward toward the mid-50s.

2. Mid-Corner Balance: Anti-Roll Bar Adjustments

Anti-roll bars control lateral load transfer across an axle. When adjusting ARBs in Project Motor Racing, players have noted that the numeric scale differs substantially from other titles—ranging on arbitrary values like 40 to 110 or 22 to 113 depending on the vehicle class.

• ARBs work in relation to each other. Stiffening the front bar increases front understeer; stiffening the rear bar promotes oversteer and rotation.
• When tuning balance, adjust the bars in opposing directions. If your car understeers heavily through mid-corner, reduce the front ARB value while increasing the rear ARB value.
• When fine-tuning in-car on flyable sessions, softening bars during initial out-laps allows tires to move independently and generate heat, after which stiffer bars stabilize the aerodynamic platform.

3. Corner Exit: Differential Preload

Preload dictates the static locking torque between the rear wheels.

• Higher Preload: Locks the differential more consistently across acceleration and deceleration. If your GT3, GTE, or Supercar suffers from violent snap oversteer while accelerating out of a corner, raising preload (community drivers have pushed values as high as 80, 100, or even 300 depending on the vehicle class) forces the rear to understeer, keeping the car tracking straight down the road. High preload is also beneficial on bumpy circuits like Sebring, preventing differential chatter and sudden wheelspin disparity over pavement seams.
• Lower Preload: Keeps the differential more open, demanding less torque to allow wheels to spin at differing speeds. On exceptionally smooth circuits like Monza, lower preload aids off-throttle rotation into low-speed corners.

Suspension, Camber, and Ride Height Setup Steps

When altering geometry, the order of operations matters inside the garage menus because adjusting certain parameters changes others dynamically:

1. Set Ride Height and Spring Perch First: Always adjust your ride height before setting camber, as ride height alterations directly alter suspension geometry and camber readouts.
2. Platform Split (Rake): Many GT and touring cars in the game benefit from a split rake—such as a 10 mm difference between front and rear (for example, 60 mm front, 70 mm rear).
3. Camber & Contact Patch:
   • Maximizing negative camber increases lateral grip and turn-in aggression for short time-trial runs (such as Factory Driver challenges).
   • However, extreme negative camber shrinks the straight-line braking contact patch and escalates inner-shoulder tire wear. In longer endurance stints (like GT endurance races at Sebring), drivers reduce negative camber to preserve front tire life and prevent premature lockups.
4. Toe Settings:
   • Rear toe-in (positive values like +0.10) provides straight-line stability, but too much introduces heavy understeer.
   • Front toe near neutral or slightly outward promotes sharp turn-in response, whereas heavy toe angles generate excess tire friction and heat.

Managing Dynamic Tire Pressures

Tire pressure directly influences mechanical grip, contact patch dimensions, and carcass temperatures:

• Lowering cold pressure increases the physical contact patch of the tire once up to temperature.
• In Project Motor Racing, cars exiting the pit lane on cold tires often display warning readouts on digital dashboards (e.g., flashing red at 1.44 bar).
• Your tuning target is active running pressure: set cold pressures so that after 2–3 warmup turns, the tires expand just enough to stabilize within their optimal operating window (green/yellow display status).
• Brake duct sizing works hand-in-hand with tire temperatures. For example, tightening ducts (lowering from 6 to 3) allows the brakes to retain heat, which assists cold stopping power.

Three Universal GT3 Setup Presets

For players seeking reliable presets without re-engineering chassis parameters for every track, community testing on the GT3 platform (such as the BMW GT3) has identified three distinct configurations:

1. Balanced Preset (All-Rounder)

Best for: Spa-Francorchamps, Sebring, Kyalami, Road Atlanta, Imola, Zolder.

• Tire Pressure: Front 22.9 PSI, Rear 21.7 PSI (Brake Ducts: 6 Front / 6 Rear)
• Aero: Rear Wing Angle 4
• Front Suspension: Springs 223, Slow Bump 10, Slow Rebound 11, Fast Bump 9, Fast Rebound 12, Bump Stop Length 40, Bump Stop Rate 600, Camber -3.7°, Toe -0.03°, Ride Height 12 mm, Anti-Roll Bar 113
• Rear Suspension: Springs 156, Slow Bump 12, Slow Rebound 8, Fast Bump 8, Fast Rebound 10, Bump Stop Length 0, Bump Stop Rate 200, Camber -2.96°, Toe +0.10°, Ride Height 10 mm, Anti-Roll Bar 22
• Drivetrain & Electronics: Preload 100, Clutches 6, Brake Bias 54%, Brake Pressure 100%, Traction Control 5, ABS 6, Final Drive 2.765

2. Low-Drag Preset (High-Speed Circuits)

Best for: Monza, Mount Panorama (Bathurst), Le Mans layouts.

• Tire Pressure: Front 22.6 PSI, Rear 22.2 PSI (Brake Ducts: 5 Front / 5 Rear)
• Aero: Rear Wing Angle 3
• Front Suspension: Springs 194, Slow Bump 9, Slow Rebound 10, Fast Bump 8, Fast Rebound 11, Bump Stop Length 40, Bump Stop Rate 500, Camber -3.43°, Toe -.08°, Ride Height 14 mm, Anti-Roll Bar 93
• Rear Suspension: Springs 156, Slow Bump 10, Slow Rebound 9, Fast Bump 7, Fast Rebound 10, Bump Stop Length 0, Bump Stop Rate 200, Camber -2.65°, Toe +0.10°, Ride Height 12 mm, Anti-Roll Bar 22
• Drivetrain & Electronics: Preload 80, Clutches 6, Brake Bias 53.4%, Brake Pressure 100%, Traction Control 4, ABS 6, Final Drive 2.765

3. High-Grip Preset (Technical & Tight Circuits)

Best for: Lime Rock Park, Nürburgring GP, Lexington.

• Tire Pressure: Front 23.6 PSI, Rear 22.2 PSI (Brake Ducts: 6 Front / 6 Rear)
• Aero: Rear Wing Angle 5
• Front Suspension: Springs 223, Slow Bump 10, Slow Rebound 11, Fast Bump 9, Fast Rebound 12, Bump Stop Length 40, Bump Stop Rate 600, Camber -3.3°, Toe -0.03°, Ride Height 12 mm, Anti-Roll Bar 93
• Rear Suspension: Springs 156, Slow Bump 12, Slow Rebound 8, Fast Bump 8, Fast Rebound 10, Bump Stop Length 0, Bump Stop Rate 200, Camber -2.66°, Toe +0.10°, Ride Height 10 mm, Anti-Roll Bar 22
• Drivetrain & Electronics: Preload 80, Clutches 6, Brake Bias 53.6%, Brake Pressure 100%, Traction Control 5, ABS 6, Final Drive 2.765

Per-Car Wheel and Controller Steering Tweaks

Project Motor Racing allows individual steering wheel and force feedback (FFB) tuning within each vehicle's setup screen under the "Steering Wheel" tab:

• Direct Drive Wheelbases (e.g., Moza, Fanatec, Simagic): If the wheel feels disconnected or light around center, players configure the Steering Wheel sub-menu with higher Steering Force (up to 2.0), Steering Wheel Feel around 1.0, and reduce Friction (such as -0.100) for smoother on-center transitions. Setting the "High" frequency slider near 0 removes unwanted digital noise.
• Logitech G29 Users: Drivers often increase overall software smoothing up to 80 to eliminate harsh gear-chatter effects.
• Controller Responsiveness: If you struggle to catch oversteer on a gamepad, sensitivity alone will not resolve it. Adjust the Steering Rack Rate / Steering Ratio inside the car setup menu (increasing rack rates between 1.2 and 1.5 increases input speed), or set the input method to "Wheel" via Steam Input to bypass standard gamepad dampening filters.

Frequently Asked Questions

Why does my car spin out under braking on older setups?

In Patch 1.6.0.0, Straight4 Studios shifted the baseline brake balance toward a true 50/50 split and modified rear brake sizes for LMDh, GT3, GT4, and 992 Cup classes. Setups saved prior to this patch have too much rearward stopping bias; move your brake bias forward into the 53%–55% range to stop the rear axle from stepping out.

How do I stop snap oversteer when exiting corners on throttle?

Raise your differential preload. A higher preload setting locks the axle earlier under acceleration, adding understeer and preventing the inside wheel from spinning abruptly, which keeps the car pointing straight as you apply full power.

What order should I follow when tuning suspension in the garage?

Always adjust ride height and spring perch offsets first. Changing ride height alters dynamic suspension angles and camber readouts; adjusting height first ensures your subsequent camber and toe settings remain accurate.