Solutions to the most common problems when rigging and simulating with RBC. For installation problems, see RBC Installation.

The simulation skips frames or plays back differently each time

Blender's rigid body simulation has to calculate every frame in order.

• In the Timeline, open the Playback menu and set Sync to Play Every Frame.
• With Frame Dropping or Sync to Audio, Blender skips frames while playing, so the vehicle can jump or behave differently on every playback.

The simulation resets when I go back to the first frame

This is expected. The rigid body simulation always starts from the first frame of the cache (the scene's Start frame when Sync with Timeline is enabled in RBC Animation). Going back to that frame resets the physics and puts the rig back at its starting position.

• To keep a result, record it with Record Cache or Record KeyFrames in RBC Animation.

I can't move the rig, or it snaps back

The rig can only be moved on the first frame of the simulation. On every other frame the physics controls the rig's position, so your changes are overwritten.

• Go to the first frame (the Reset button in RBC Animation, or Shift+Left Arrow), move the rig, then play.
• If a cache has been recorded, delete it first. A recorded cache also keeps the rig where it was.

Preparing your vehicle model

A clean model makes rigging much more reliable:

• Make each wheel its own object, with its origin at the center of the wheel (Object > Set Origin > Origin to Geometry).
• Apply rotation and scale before rigging (Ctrl+A > Rotation & Scale), so the sizes RBC reads are correct.
• If several wheels share one mesh (linked duplicates made with Alt+D), make them single user first (Object > Relations > Make Single User > Object & Data). Blender can't apply transforms to shared data.
• Use a single mesh object for the body where possible. Empty hierarchies and Collections are supported but have limitations (see Set Up).
• Build the vehicle at real-world scale (see below).
• For Quick Rig, the front of the vehicle should point toward −Y.