v7 Reactive Suspension (BETA)

v7 beta documentation in progress. v7 beta documentation may be incomplete or inaccurate.
v7 functions and features may be significantly different from previous ACS versions.
These instructions are not valid for current v6+ ACS!

This is currently an experimental unsupported beta feature

The v7 Reactive Suspension repositions your wheel prims while driving to create a suspension effect.

Reactive Suspension has two main operational functions. Both work together but you do not need to use both:

  • Wheels can react to bumps in the road surface or ground
  • Wheels reposition to react to inclines on the vehicle X & Y axis.

The Reactive Suspension system works in combination with v7 Pivoting & Fixed Wheel Scripts.

The system is separate from the Wheel Vibration function, though they both can operate together.

Limitations & Things to Know

  • The v7 Reactive Suspension system is designed primarily for standard-sized four-wheel automobiles, though it can generate usable results for motorcycles and other vehicles.
  • Reactive Suspension works only with single prim wheels. It is not set up to function with multi-prim wheels (separate rim & tire etc). The visible wheel prims must be scripted with Pivoting or Fixed Wheel Scripts.
  • Wheels prims can be solid/Convex Hull or non-solid style used in conjunction with invisible solid guide wheel prims.
  • For best results, wheel prims should not be included in any prims repositioned with TurnSystem.
  • Reactive Suspension requires no root prim scripts, only the Suspension Sensor scripts placed/injected in the appropriately placed suspension sensor prims.
  • Enabling either Wheel Vibration or installing Reactive Suspension (or both) adds a Suspension switch to the vehicle menu system. You can then disable the associated effects by accessing the + Suspns button in the vehicle's >Options, >Advanced, >Extras menu.
  • Strut repositioning is not yet implemented. Currently only the wheel prims reposition as part of the suspension. The system will be expanded to extend to support struts/disk brakes/multi-prim wheels and other prims as time permits.

Installation Overview

The main components of the system are the suspension sensor prims that each contain the Suspension Sensor script.

For a standard four-wheel vehicle, you will be adding four sensor prims, one for each wheel. These prims must be solid/convex hull, as one of their functions is collision detection which requires them to be solid. After completing setup, these prims can be set to transparent so they are not visible.

The suggested prim to use as a sensor prim is a plain standard cylinder prim, probably best to make it the same width and diameter as your wheel prims. The best place to put this to start is just to the inside of your actual wheel prim, slightly forward from it (0.25 or so) and slightly higher than it (0.15-0.25ish). It is fine if it intersects with other vehicle prims as long as its forward lower portion is clear of other prims in order to detect obstacles. The prim position is so that the prim can detect obstacles just before they reach the tire prim, and the sensor prim should be high enough off the ground that it is not dragging on the ground. A rounded prim is suggested to avoid sharp corners from catching on obstacles, however it is not required.

You will place one of these sensor prims for each wheel. The sensor prims, like your wheel prims, should be at the same Z/height coordinate as each other when the vehicle is at zero rotation. This is important, as the sensors monitor the positions of each other in order to operate the suspension incline effect.

Include the solid keyword in the prim name (or set it to convex hull by hand if manualprimshapes is enabled), and place inside it a copy of the Suspension Sensor script. After all four sensors have been linked in, reboot the vehicle.

Step by Step Setup

  • Set your vehicle to 0 rotation.
  • Make sure your wheels are properly vertically aligned and share the same Z/height coordinate
  • Make sure your visible vehicle wheels are scripted and operational.
  • Rez a plain cylinder prim, name it solid.
  • Place inside the prim a copy of the Suspension Sensor script.
  • Make three more copies of this prim
  • Set each prim in place on your vehicle, recommended to be slightly forward and higher than each wheel prim.
  • Double check each of the sensor prims is at the same Z/height coordinate, and link them in.
  • Drive the vehicle around and observe if the wheels are reacting to objects like road edges. You may want to rez some flat low prims to drive over for testing purposes. Also, observe wheel behavior on steep hills and inclines.

After repositioning wheels or sensors that are linked to the vehicle, you should unlink/relink them to reset their default positions or they will snap back to the older position once the vehicle starts operating.

When you are finished, set your suspension sensor prims to be invisible/100% transparent.


  • If your wheels bump too often, your sensors are too low, raise the sensors.
  • If you see no affect on driving over small bumps, lower the sensor positions.

In the Root Settings are two variables you can adjust and experiment with for the reactive suspension:

SuspensionBounce - this effects how much the tires pop up when encountering a bump/obstacle, specifically the 3rd/Z value of the vector. (Default value <0.0, 0.0, 0.15>)

SuspensionSway - this affects how much the wheels shift in relation to each other on hills and inclines. (Default value -0.1)


  • You can disable the bump effect and just keep the incline effect by raising your sensor away from the ground, and removing the solid keyword.
  • You can keep the bump effect and disable the incline repositioning by setting SuspensionSway to 0.0 in the Root Settings.
  • You can trigger a sound on bump collisions by placing a sound file inside each sensor prim. This is a good way to help test how much your sensors are actually triggering. The sound file does not react to wheel positioning for inclines/hills.

[v7 Main]