Posi-Traction or locked/welded differential on A-Chassis vehicle

  1. What do you want to achieve? Keep it simple and clear!
    I want to know if there is anyway I can get Posi-Traction or a locked/welded differential on my A-Chassis vehicle so the wheels don’t spin as soon as they come off the ground.

  2. What is the issue? Include screenshots / videos if possible!
    https://streamable.com/u45y4e
    That video shows what I’m taking about. Going up a ramp and then the wheels that are not touching a surface just spins causing me to get stuck, versus if i had a Posi-Trac, welded, or locked differential it would make me not get stuck.

  3. What solutions have you tried so far? Did you look for solutions on the Developer Hub?
    I tried to mess around with different sections of the A-Chassis script but nothing seems to work for me. I looked high and low for an answer to this but no one seemed to have asked before

After that, you should include more details if you have any. Try to make your topic as descriptive as possible, so that it’s easier for people to help you!

--[[
		___      _______                _     
	   / _ |____/ ___/ /  ___ ____ ___ (_)__ 
	  / __ /___/ /__/ _ \/ _ `(_-<(_-</ (_-<
	 /_/ |_|   \___/_//_/\_,_/___/___/_/___/
 						SecondLogic @ Inspare
]]

local Tune = {}

--[[Misc]]
	Tune.LoadDelay		= .1		-- Delay before initializing chassis (in seconds)
	Tune.AutoStart		= true		-- Set to false if using manual ignition plugin
	Tune.AutoFlip		= true		-- Set to false if using manual flip plugin
	
--[[Wheel Alignment]]
	--[Don't physically apply alignment to wheels]
	--[Values are in degrees]
	Tune.FCamber		= -1
	Tune.RCamber		= -1
	Tune.FToe			= 0
	Tune.RToe			= 0
	
--[[Weight and CG]]
	Tune.Weight			= 3000		-- Total weight (in pounds)
	Tune.WeightBSize	= {			-- Size of weight brick (dimmensions in studs ; larger = more stable)
	 --[[Width]]		6		,
	 --[[Height]]		3.5		,
	 --[[Length]]		14		}
	Tune.WeightDist		= 50		-- Weight distribution (0 - on rear wheels, 100 - on front wheels, can be <0 or >100)
	Tune.CGHeight		= .8		-- Center of gravity height (studs relative to median of all wheels)
	Tune.WBVisible		= false		-- Makes the weight brick visible
	
	--Unsprung Weight
	Tune.FWheelDensity	= .1		-- Front Wheel Density
	Tune.RWheelDensity	= .1		-- Rear Wheel Density
	Tune.FWLgcyDensity	= 1			-- Front Wheel Density [PGS OFF]
	Tune.RWLgcyDensity	= 1			-- Rear Wheel Density [PGS OFF]
	
	Tune.AxleSize		= 2			-- Size of structural members (larger = more stable/carry more weight)
	Tune.AxleDensity	= .1		-- Density of structural members
	
--[[Susupension]]
	Tune.SusEnabled		= true		-- works only in with PGSPhysicsSolverEnabled, defaults to false when PGS is disabled
	
	--Front Suspension
	Tune.FSusDamping	= 200		-- Spring Dampening
	Tune.FSusStiffness	= 9000		-- Spring Force
	Tune.FAntiRoll 		= 50		-- Anti-Roll (Gyro Dampening)
	
	Tune.FSusLength		= 2			-- Suspension length (in studs)
	Tune.FPreCompress	= .3		-- Pre-compression adds resting length force
	Tune.FExtensionLim	= .3		-- Max Extension Travel (in studs)
	Tune.FCompressLim	= .1		-- Max Compression Travel (in studs)
	Tune.FSusAngle		= 80		-- Suspension Angle (degrees from horizontal)
		
	Tune.FWsBoneLen		= 5			-- Wishbone Length
	Tune.FWsBoneAngle	= 0			-- Wishbone angle (degrees from horizontal)
	Tune.FAnchorOffset	= {			-- Suspension anchor point offset (relative to center of wheel)
	 --[[Lateral]]		-.4		,	-- positive = outward
	 --[[Vertical]]		-.5		,	-- positive = upward
	 --[[Forward]]		0		}	-- positive = forward
	
	--Rear Suspension
	Tune.RSusDamping	= 500		-- Spring Dampening
	Tune.RSusStiffness	= 9000		-- Spring Force
	Tune.FAntiRoll 		= 50		-- Anti-Roll (Gyro Dampening)

	Tune.RSusLength		= 2			-- Suspension length (in studs)
	Tune.RPreCompress	= .3		-- Pre-compression adds resting length force
	Tune.RExtensionLim	= .3		-- Max Extension Travel (in studs)
	Tune.RCompressLim	= .1		-- Max Compression Travel (in studs)
	Tune.RSusAngle		= 80		-- Suspension Angle (degrees from horizontal)
		
	Tune.RWsBoneLen		= 5			-- Wishbone Length
	Tune.RWsBoneAngle	= 0			-- Wishbone angle (degrees from horizontal)
	Tune.RAnchorOffset	= {			-- Suspension anchor point offset (relative to center of wheel)
	 --[[Lateral]]		-.4		,	-- positive = outward
	 --[[Vertical]]		-.5		,	-- positive = upward
	 --[[Forward]]		0		}	-- positive = forward

	--Aesthetics	
	Tune.SusVisible		= true			-- Spring Visible
	Tune.WsBVisible		= false			-- Wishbone Visible
	Tune.SusRadius		= .2			-- Suspension Coil Radius
	Tune.SusThickness	= .1			-- Suspension Coil Thickness
	Tune.SusColor		= "Bright red"	-- Suspension Color [BrickColor]
	Tune.SusCoilCount	= 6				-- Suspension Coil Count
	Tune.WsColor		= "Black"		-- Wishbone Color [BrickColor]
	Tune.WsThickness	= .1			-- Wishbone Rod Thickness
	
--[[Wheel Stabilizer Gyro]]
	Tune.FGyroDamp		= 100		-- Front Wheel Non-Axial Dampening
	Tune.RGyroDamp		= 100		-- Rear Wheel Non-Axial Dampening
	
--[[Steering]]
	Tune.SteerInner		= 36		-- Inner wheel steering angle (in degrees)
	Tune.SteerOuter		= 37		-- Outer wheel steering angle (in degrees)
	Tune.SteerSpeed		= .05		-- Steering increment per tick (in degrees)
	Tune.ReturnSpeed	= .1		-- Steering increment per tick (in degrees)
	Tune.SteerDecay		= 320		-- Speed of gradient cutoff (in SPS)
	Tune.MinSteer		= 10		-- Minimum steering at max steer decay (in percent)
	Tune.MSteerExp		= 1			-- Mouse steering exponential degree
	
	--Steer Gyro Tuning
	Tune.SteerD			= 1000		-- Steering Dampening
	Tune.SteerMaxTorque	= 50000		-- Steering Force
	Tune.SteerP			= 100000	-- Steering Aggressiveness
	
--[[Engine]]
	--Torque Curve
	Tune.Horsepower		= 180		--	[TORQUE CURVE VISUAL]
	Tune.IdleRPM		= 700		--		https://www.desmos.com/calculator/2uo3hqwdhf
	Tune.PeakRPM		= 6000		--		Use sliders to manipulate values
	Tune.Redline		= 6700		--		Copy and paste slider values into the respective tune values
	Tune.EqPoint		= 5500
	Tune.PeakSharpness	= 7.5
	Tune.CurveMult		= 0.16
	
	--Incline Compensation
	Tune.InclineComp	= 2.7			-- Torque compensation multiplier for inclines (applies gradient from 0-90 degrees)
	
	--Misc
	Tune.RevAccel		= 150		-- RPM acceleration when clutch is off
	Tune.RevDecay		= 75		-- RPM decay when clutch is off
	Tune.RevBounce		= 500		-- RPM kickback from redline
	Tune.IdleThrottle	= 3			-- Percent throttle at idle
	Tune.ClutchTol		= 500		-- Clutch engagement threshold (higher = faster response)
	
--[[Drivetrain]]	
	Tune.Config			= "AWD"		--"FWD" , "RWD" , "AWD"
	
	--Differential Settings	
	Tune.FDiffSlipThres	= 50		-- 1 - 100%				(Max threshold of applying full lock determined by deviation from avg speed)
	Tune.FDiffLockThres	= 50		-- 0 - 100%				(0 - Bias toward slower wheel, 100 - Bias toward faster wheel)
	Tune.RDiffSlipThres	= 50		-- 1 - 100%
	Tune.RDiffLockThres	= 50		-- 0 - 100%
	Tune.CDiffSlipThres	= 50		-- 1 - 100%				[AWD Only]
	Tune.CDiffLockThres	= 50		-- 0 - 100%				[AWD Only]
	
	--Traction Control Settings
	Tune.TCSEnabled		= true		-- Implements TCS
	Tune.TCSThreshold	= 20		-- Slip speed allowed before TCS starts working (in SPS)
	Tune.TCSGradient	= 20		-- Slip speed gradient between 0 to max reduction (in SPS)
	Tune.TCSLimit		= 10		-- Minimum amount of torque at max reduction (in percent)
	
--[[Transmission]]
	Tune.TransModes		= {"Auto", "Semi"}								--[[
	[Modes]
		"Auto"		: Automatic shifting
		"Semi"		: Clutchless manual shifting, dual clutch transmission
		"Manual"	: Manual shifting with clutch
		
		>Include within brackets
			eg: {"Semi"} or {"Auto", "Manual"}								
		>First mode is default mode													]]
	
	--Automatic Settings
	Tune.AutoShiftMode	= "RPM"												--[[
	[Modes]
		"Speed"		: Shifts based on wheel speed
		"RPM"		: Shifts based on RPM											]]	
	Tune.AutoUpThresh	= -200		--Automatic upshift point 	(relative to peak RPM, positive = Over-rev)
	Tune.AutoDownThresh = 1400		--Automatic downshift point (relative to peak RPM, positive = Under-rev)
	
	--Gear Ratios
	Tune.FinalDrive		= 4.06			-- Gearing determines top speed and wheel torque
	Tune.Ratios			= {				-- Higher ratio = more torque, Lower ratio = higher top speed
		--[[Reverse]]	5.23		,	-- Copy and paste a ratio to add a gear
		--[[Neutral]]	0			,	-- Ratios can also be deleted
		--[[ 1 ]]		2.71		,	-- Reverse, Neutral, and 1st gear are required
		--[[ 2 ]]		1.54		,
		--[[ 3 ]]		1.00		,
		--[[ 4 ]]		0.71		,
		--[[ 5 ]]		0.52		,
	}
	Tune.FDMult			= 3.5			-- Ratio multiplier (Change this value instead of FinalDrive if car is struggling with torque ; Default = 1)
	
--[[Brakes]]
	Tune.ABSEnabled		= true		-- Implements ABS
	Tune.ABSThreshold	= 20		-- Slip speed allowed before ABS starts working (in SPS) 

	Tune.FBrakeForce	= 1500		-- Front brake force
	Tune.RBrakeForce	= 1000		-- Rear brake force
	Tune.PBrakeForce	= 5000		-- Handbrake force
	
	Tune.FLgcyBForce	= 15000		-- Front brake force [PGS OFF]
	Tune.RLgcyBForce	= 10000		-- Rear brake force [PGS OFF]
	Tune.LgcyPBForce	= 25000		-- Handbrake force [PGS OFF]
	
--[[[Default Controls]]
	--Peripheral Deadzones
	Tune.Peripherals = {
		MSteerWidth				= 67		,	-- Mouse steering control width	(0 - 100% of screen width)
		MSteerDZone				= 10		,	-- Mouse steering deadzone (0 - 100%)
		
		ControlLDZone			= 5			,	-- Controller steering L-deadzone (0 - 100%)
		ControlRDZone			= 5			,	-- Controller steering R-deadzone (0 - 100%)
	}
	
	--Control Mapping
	Tune.Controls = {
		
	--Keyboard Controls
		--Mode Toggles
		ToggleTCS				= Enum.KeyCode.T					,
		ToggleABS				= Enum.KeyCode.Y					,
		ToggleTransMode			= Enum.KeyCode.M					,
		ToggleMouseDrive		= Enum.KeyCode.R					,
		
		--Primary Controls
		Throttle				= Enum.KeyCode.Up					,
		Brake					= Enum.KeyCode.Down					,
		SteerLeft				= Enum.KeyCode.Left					,
		SteerRight				= Enum.KeyCode.Right				,
		
		--Secondary Controls
		Throttle2				= Enum.KeyCode.W					,
		Brake2					= Enum.KeyCode.S					,
		SteerLeft2				= Enum.KeyCode.A					,
		SteerRight2				= Enum.KeyCode.D					,
		
		--Manual Transmission
		ShiftUp					= Enum.KeyCode.E					,
		ShiftDown				= Enum.KeyCode.Q					,
		Clutch					= Enum.KeyCode.LeftShift			,
		
		--Handbrake
		PBrake					= Enum.KeyCode.P					,
		
	--Mouse Controls
		MouseThrottle			= Enum.UserInputType.MouseButton1	,
		MouseBrake				= Enum.UserInputType.MouseButton2	,
		MouseClutch				= Enum.KeyCode.W					,
		MouseShiftUp			= Enum.KeyCode.E					,
		MouseShiftDown			= Enum.KeyCode.Q					,
		MousePBrake				= Enum.KeyCode.LeftShift			,
		
	--Controller Mapping
		ContlrThrottle			= Enum.KeyCode.ButtonR2				,
		ContlrBrake				= Enum.KeyCode.ButtonL2				,
		ContlrSteer				= Enum.KeyCode.Thumbstick1			,
		ContlrShiftUp			= Enum.KeyCode.ButtonY				,
		ContlrShiftDown			= Enum.KeyCode.ButtonX				,
		ContlrClutch			= Enum.KeyCode.ButtonR1				,
		ContlrPBrake			= Enum.KeyCode.ButtonL1				,
		ContlrToggleTMode		= nil				,
		ContlrToggleTCS			= nil				,
		ContlrToggleABS			= nil		,
	}
	
--[[Weight Scaling]]
	--[Cubic stud : pounds ratio]
	--[STANDARDIZED: Don't touch unless needed]
	Tune.WeightScaling = 1/50	--Default = 1/50 (1 cubic stud = 50 lbs)
	Tune.LegacyScaling = 1/10	--Default = 1/10 (1 cubic stud = 10 lbs) [PGS OFF]
	
return Tune

That script is the entire A-Chassis tune script I have. Can anyone help?

1 Like

Since this isn’t a real world physics thing your car may be losing traction simply because your wheels don’t have enough Friction, or the wheel Density isn’t high enough to push down to create traction.

In the video it appears your truck is getting hung up and high centered. No amount of torque or traction will help if the weight of a vehicle is supported on the frame or differential housing. The wheels aren’t sitting on the ground so there’s no traction.

Also look at tuning items in the AChassis script like Incline Compensation for hills.
The Differential settings for which you have all of the diff settings at 50%.
Traction Control Settings, where the wheel spin is controlled.