FS25 Realistic 4×4 Traction System V1.3.0.0

FS25 Realistic 4×4 Traction System V1.3.0.0

This mod adds a fully switchable 4×4 traction system to compatible vehicles, including tractors, trucks, harvesters and cars. Multiplayer is in development; it is playable but may contain bugs.

Features

• Real rear-wheel slip detection: automatic modes react to actual wheel-slip physics, not just speed.
• Four driving modes, assigned to each vehicle by default:
  • Manual: always in control.
  • Semi-automatic: engages with actual wheel slip, while manual control is always available.
  • Automatic: the same logic, adjusted for vehicles with factory-fitted automatic 4WD (CVT/IVT transmissions).
  • Intelligent: continuous, proportional engagement in the Fendt style, without abrupt switching on/off.
• Native tyre-pressure simulation during engagement, with no dependency on any other mod.
• On-screen HUD with real-time status and adjustable position in the game Settings menu.
• Zero XML changes to any vehicle; the system integrates automatically into all compatible vehicles.

Changelog

V1.3.0.0
Multiplayer is in development, playable but may contain bugs.
Compatibility tested with the MudSystemPhysics and Tractor Terrain Dynamics mods.

Behaviour fixes:

• Continuous-track tractors with only 2 tracks, such as John Deere 8RT and Fendt Vario MT, are no longer affected by the 2WD/4WD system; it makes no mechanical sense for them.
• Fixed the actual difference between “semiauto” and “auto” modes: semiauto now only engages automatically and never disengages automatically; this is always left to the player.
• Terrain anticipation GPS now always reads, even above road speed. Previously, it always stayed at 0% in this situation.
• Fixed implement mass reading. It was reading tonnes as if they were kg, underestimating the actual weight by 1000x.
• Fixed false triggering of “smart” mode when braking and shifting into reverse.
• Fixed being “stuck to the ground” when lowering a heavy implement; the differential lock reacted too quickly to the initial spike.
• The automatic system (semiauto/auto) now reacts much faster to real and sustained wheel slip. Previously, it could take dozens of seconds.
• Fixed rapidly switching between 2WD/4WD when stopped in the field.
• Fixed false triggering of semiauto when starting from a standstill, caused by a normal and brief wheel-slip spike at the moment of take-off.
• The “smart” mode (Fendt) has been isolated from the binary engagement logic, preventing interference between the smart mode’s own hysteresis and the new detections.

New features:

• Detection of “fieldwork in progress” via the game’s native GPS and automatic “arming”: when stationary/almost stationary in a field with the implement lowered for more than 2 seconds, 4WD engages directly.
• Experimental support for engine load as an additional signal, disabled by default and available in DriveModeConfig.lua.

Features from previous versions, already included in this version:

• Proprietary GPS/terrain-elevation anticipation system without depending on another mod, only on each brand’s top-of-the-range tractors: Fendt VarioGuide, John Deere JDLink, Case AFS Connect, New Holland IntelliSteer, Deutz-Fahr Agrosky and CLAAS EASY.
• Proper 4WD terminal (Ctrl+Shift+G) with Status, Telemetry and Settings tabs, with wheel-slip thresholds and anticipation strength adjustable live, per vehicle.
• Per-tractor telemetry: total hours, hours in 4WD, hours with differential locked, number of engagements, distance in 4WD and GPS anticipations. This is saved in the savegame and includes a reset button.
• Savegame persistence of the 4WD state, including engaged/differential locked, and adjusted Settings.
• Renewed HUD with capsule-style bars, glow and a pulsing halo on active elements, without text overlap.
• Fix for the tyre-pressure conflict with FS25_MudSystemPhysics.
• Extended support for brands/models: John Deere 6R/8R/9RX, New Holland T8/T8000, Deutz-Fahr Series 7/8, CLAAS Xerion and McCormick X8 VT-Drive.

V1.2.0.0

MULTIPLAYER (tested on a real dedicated server):

• Differential detection on dedicated servers fixed; it previously always failed on the client side.
• Toggling 4×4 (Ctrl+J) now synchronizes correctly between the server and clients.
• Manual differential lock (Ctrl+K) now synchronizes correctly between the server and clients.
• Automatic modes (auto/semiauto/smart) are calculated by the server and synchronized with all clients.
• A player joining in the middle of a session immediately receives the correct state of every vehicle.

REALISM:

• Ctrl+K manual differential lock respects a speed limit for engagement; it only locks when stationary or moving slowly, just like in a real transfer case.

GENERAL:

• Internal diagnostic code removed.
• Documentation and store description reorganized.

V1.1.0.0
Fendt Vario Grip Smart unchanged for now. Looking for more details on how it works.

New Features

• Automatic differential lock: in “Auto” and “Smart” drive modes, the center differential lock now engages and disengages by itself under severe wheel slip, at low speed only and never on the road. “Semi-Automatic” and “Manual” modes still require Ctrl+K.
• Shop upgrade: Semi-Automatic → Automatic. Tractors configured as “Semi-Automatic” now show a new configuration option in the store’s Customize screen, letting you pay to upgrade that specific unit to full “Automatic” behavior, including automatic diff lock.
• The option was added because many players did not realize Semi-Automatic and Automatic tractors behave differently. It is now labeled clearly:
  • Semi-Automatic (Diff Lock Manual) — free, default.
  • Automatic (Diff Lock Automatic) — paid upgrade.

Known Issues

• There are several things that may need a tweak or fix.
• Not all vehicles have real or near real specs.
• This was not tested in depth with other mods, including mod tractors or maintenance scripts, except my maintenance mod, so compatibility is not fully confirmed with other mods yet.

Fixes

• Excluded 3 grape harvesters with independent hydraulic wheel motors: ERO Grapeliner Series 7000, New Holland Braud 9070L and Gregoire GL. These vehicles are always all-wheel-drive by design, with four independent hydraulic motors and no mechanical differential to switch, so the mod no longer applies to them.
• Crawlers and tracked vehicles no longer get the 4×4 system.

Documentation clarified the real difference between “Semi-Automatic” and “Automatic” modes in the in-game HUD hints, configuration comments and readme: both engage/disengage the 4×4 itself automatically based on real wheel slip; the actual difference is that only “Automatic” and “Smart” also lock the differential automatically.

Compatibility

• Singleplayer only.
• No changes to save-game compatibility; existing installs can update directly.