I confirmed the input values are correct (+1 and -1 for steering), and the model seems placing bones symmetrically. I’m using UE5.7, and I think you can check it on your end too with importing the vehicle templates. Set the Max RPM to 1000, so the vehicle stay at low gear low speed and the speed difference is significant.
Does anyone know a solution for this? Is this a known issue?
Edit: A new observation is the rear wheel forces are leaning to the right side in both left turn and right turn.
Please leave a comment if you see this issue too. It’s always good to have more details/conditions of the issue
Here’s the bug: Inside the engine code UChaosWheeledVehicleSimulation::ProcessMechanicalSimulation has a for loop to set RPM to 0 when RPM exceeds the max RPM, but it always takes the last entry, which is the last wheel. If the vehicle has 4 wheels, it will be the BR wheel. And when doing right turn, it will take the inner wheel’s RPM to compare to the MAX RPM, so the vehicle will have higher RPM compared to the left turn case.
The solution is saving the MAX RPM to the wheelRPM in that for loop.
float WheelRPM = 0;
for (int I = 0; I < PVehicle->Wheels.Num(); I++)
{
if (PVehicle->Wheels[I].EngineEnabled)
{
WheelRPM = FMath::Max(WheelRPM, FMath::Abs(PVehicle->Wheels[I].GetWheelRPM()));
}
}