--- name: SpringConstraint last_updated: 2026-06-11T23:11:57Z inherits: - Constraint - Instance - Object type: class memory_category: BaseParts summary: "Simulates spring and damper behavior between two attachments." --- # Class: SpringConstraint > Simulates spring and damper behavior between two attachments. ## Description A **SpringConstraint** applies a force to its [Attachments](/docs/reference/engine/classes/Attachment.md) based on spring and damper behavior. This constraint, along with a [CylindricalConstraint](/docs/reference/engine/classes/CylindricalConstraint.md), is ideal for building vehicle suspension. Note that if this constraint attaches one part (**A**) to another part (**B**) that is anchored or connected to an anchored part (**Z**), part **A** will not be locally simulated when interacting with a player. When configuring this constraint, it may be helpful to study [Roblox Units](/docs/en-us/physics/units.md) to understand how Roblox units compare to metric units. #### Free Length [FreeLength](/docs/reference/engine/classes/SpringConstraint.md) defines the natural resting length of the spring. If the attachments are further apart than the free length, they are forced together; if the attachments are closer together than the free length, they are forced apart. #### Damping The [Damping](/docs/reference/engine/classes/SpringConstraint.md) value controls how fast the spring's oscillation dies down. A value of 0 allows the spring to oscillate endlessly, while higher values bring the spring to a rest more quickly. #### Stiffness [Stiffness](/docs/reference/engine/classes/SpringConstraint.md) sets the strength of the spring. Higher values create a spring that responds with more force when its attachments are closer together or further apart than [FreeLength](/docs/reference/engine/classes/SpringConstraint.md). #### Limits Enabling the [LimitsEnabled](/docs/reference/engine/classes/SpringConstraint.md) property exposes the [MinLength](/docs/reference/engine/classes/SpringConstraint.md) and [MaxLength](/docs/reference/engine/classes/SpringConstraint.md) values for setting the minimum and maximum length of the spring. If the spring's attachments reach these limits, they stop moving apart from one another without restitution. ## Properties ### Property: SpringConstraint.Coils ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Appearance", "capabilities": [ "Physics" ], "simulationAccess": true } ``` The number of coils visualized on the [SpringConstraint](/docs/reference/engine/classes/SpringConstraint.md). This can only be set between 0 and 8. ### Property: SpringConstraint.CurrentLength ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": false, "can_save": true }, "thread_safety": "ReadSafe", "category": "Derived", "capabilities": [ "Physics" ], "simulationAccess": true } ``` The current distance between the constraint's [Attachments](/docs/reference/engine/classes/Attachment.md). ### Property: SpringConstraint.Damping ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Spring", "capabilities": [ "Physics" ], "simulationAccess": true } ``` Damping constant for the [SpringConstraint](/docs/reference/engine/classes/SpringConstraint.md). Multiplied to the velocity of the constraint's [Attachments](/docs/reference/engine/classes/Attachment.md) to reduce the spring force applied. ### Property: SpringConstraint.FreeLength ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Spring", "capabilities": [ "Physics" ], "simulationAccess": true } ``` Natural resting length of the spring. ### Property: SpringConstraint.LimitsEnabled ```json { "type": "boolean", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Spring", "capabilities": [ "Physics" ], "simulationAccess": true } ``` Sets whether the [SpringConstraint](/docs/reference/engine/classes/SpringConstraint.md) enforces a minimum and maximum length. If the constraint's [Attachments](/docs/reference/engine/classes/Attachment.md) reach these limits, they will simply stop moving apart from one another without restitution. If you need restitution or elasticity at the ends of the range of motion, you can combine a [SpringConstraint](/docs/reference/engine/classes/SpringConstraint.md) with another constraint that allows restitution at the end of its range, such as a [PrismaticConstraint](/docs/reference/engine/classes/PrismaticConstraint.md) or [RopeConstraint](/docs/reference/engine/classes/RopeConstraint.md). ### Property: SpringConstraint.MaxForce ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Spring", "capabilities": [ "Physics" ], "simulationAccess": true } ``` The maximum force the [SpringConstraint](/docs/reference/engine/classes/SpringConstraint.md) can apply on its [Attachments](/docs/reference/engine/classes/Attachment.md). Some spring systems can give rise to forces that grow fast leading to instability. In such cases it is recommended to set MaxForce to a reasonable value. ### Property: SpringConstraint.MaxLength ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Limits", "capabilities": [ "Physics" ], "simulationAccess": true } ``` The maximum separation the [SpringConstraint](/docs/reference/engine/classes/SpringConstraint.md) will allow if [LimitsEnabled](/docs/reference/engine/classes/SpringConstraint.md) is true. ### Property: SpringConstraint.MinLength ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Limits", "capabilities": [ "Physics" ], "simulationAccess": true } ``` The minimum separation the [SpringConstraint](/docs/reference/engine/classes/SpringConstraint.md) will allow if [LimitsEnabled](/docs/reference/engine/classes/SpringConstraint.md) is true. ### Property: SpringConstraint.Radius ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Appearance", "capabilities": [ "Physics" ], "simulationAccess": true } ``` The visualized radius of the spring's coils. ### Property: SpringConstraint.Stiffness ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Spring", "capabilities": [ "Physics" ], "simulationAccess": true } ``` The strength of the spring. The higher this value the more force will be applied when the attachments are separated a different length than the [FreeLength](/docs/reference/engine/classes/SpringConstraint.md). ### Property: SpringConstraint.Thickness ```json { "type": "float", "access": "ReadWrite", "security": { "read": "None", "write": "None" }, "serialization": { "can_load": true, "can_save": true }, "thread_safety": "ReadSafe", "category": "Appearance", "capabilities": [ "Physics" ], "simulationAccess": true } ``` The visualized thickness of the spring's coils. ## Inherited Members ### From [Constraint](/docs/reference/engine/classes/Constraint.md) - **Property `Active`** (`boolean`): Indicates if the constraint is currently active in the world. - **Property `Attachment0`** (`Attachment`): The Attachment that is connected to - **Property `Attachment1`** (`Attachment`): The Attachment that is connected to - **Property `Color`** (`BrickColor`): The color of the constraint. - **Property `Enabled`** (`boolean`): Toggles whether or not the constraint is enabled. - **Property `Visible`** (`boolean`): Toggles the constraint's visibility. - **Method `GetDebugAppliedForce(bodyId: int): Vector3`**: *(deprecated)* - **Method `GetDebugAppliedTorque(bodyId: int): Vector3`**: *(deprecated)* ### From [Instance](/docs/reference/engine/classes/Instance.md) - **Property `Archivable`** (`boolean`): Determines if an Instance and its descendants can be cloned using - **Property `archivable`** (`boolean`): *(deprecated, hidden)* - **Property `Capabilities`** (`SecurityCapabilities`): The set of capabilities allowed to be used for scripts inside this - **Property `Name`** (`string`): A non-unique identifier of the Instance. - **Property `Parent`** (`Instance`): Determines the hierarchical parent of the Instance. - **Property `PredictionMode`** (`PredictionMode`): - **Property `RobloxLocked`** (`boolean`): A deprecated property that used to protect CoreGui objects. *(hidden)* - **Property `Sandboxed`** (`boolean`): When enabled, the instance can only access abilities in its `Capabilities` - **Property `UniqueId`** (`UniqueId`): A unique identifier for the instance. - **Method `AddTag(tag: string): ()`**: Applies a tag to the instance. - **Method `children(): Instances`**: Returns an array of the object's children. *(deprecated)* - **Method `ClearAllChildren(): ()`**: This method destroys all of an instance's children. - **Method `Clone(): Instance`**: Create a copy of an instance and all its descendants, ignoring instances - **Method `clone(): Instance`**: *(deprecated)* - **Method `Destroy(): ()`**: Sets the Instance.Parent property to `nil`, locks the - **Method `destroy(): ()`**: *(deprecated)* - **Method `FindFirstAncestor(name: string): Instance?`**: Returns the first ancestor of the Instance whose - **Method `FindFirstAncestorOfClass(className: string): Instance?`**: Returns the first ancestor of the Instance whose - **Method `FindFirstAncestorWhichIsA(className: string): Instance?`**: Returns the first ancestor of the Instance for whom - **Method `FindFirstChild(name: string, recursive?: boolean): Instance?`**: Returns the first child of the Instance found with the given name. - **Method `findFirstChild(name: string, recursive?: boolean): Instance`**: *(deprecated)* - **Method `FindFirstChildOfClass(className: string): Instance?`**: Returns the first child of the Instance whose - **Method `FindFirstChildWhichIsA(className: string, recursive?: boolean): Instance?`**: Returns the first child of the Instance for whom - **Method `FindFirstDescendant(name: string): Instance?`**: Returns the first descendant found with the given Instance.Name. - **Method `GetActor(): Actor?`**: Returns the Actor associated with the Instance, if any. - **Method `GetAttribute(attribute: string): Variant`**: Returns the value which has been assigned to the given attribute name. - **Method `GetAttributeChangedSignal(attribute: string): RBXScriptSignal`**: Returns an event that fires when the given attribute changes. - **Method `GetAttributes(): Dictionary`**: Returns a dictionary of the instance's attributes. - **Method `GetChildren(): Instances`**: Returns an array containing all of the instance's children. - **Method `getChildren(): Instances`**: *(deprecated)* - **Method `GetDebugId(scopeLength?: int): string`**: Returns a coded string of the debug ID used internally by Roblox. - **Method `GetDescendants(): Instances`**: Returns an array containing all of the descendants of the instance. - **Method `GetFullName(): string`**: Returns a string describing the instance's ancestry. - **Method `GetStyled(name: string, selector: string?): Variant`**: Returns the styled or explicitly modified value of the specified property, - **Method `GetStyledPropertyChangedSignal(property: string): RBXScriptSignal`**: - **Method `GetTags(): Array`**: Gets an array of all tags applied to the instance. - **Method `HasTag(tag: string): boolean`**: Check whether the instance has a given tag. - **Method `IsAncestorOf(descendant: Instance): boolean`**: Returns true if an Instance is an ancestor of the given - **Method `IsDescendantOf(ancestor: Instance): boolean`**: Returns `true` if an Instance is a descendant of the given - **Method `isDescendantOf(ancestor: Instance): boolean`**: *(deprecated)* - **Method `IsPropertyModified(property: string): boolean`**: Returns `true` if the value stored in the specified property is not equal - **Method `QueryDescendants(selector: string): Instances`**: Returns an array containing all descendants of the instance that match the - **Method `Remove(): ()`**: Sets the object's `Parent` to `nil`, and does the same for all its *(deprecated)* - **Method `remove(): ()`**: *(deprecated)* - **Method `RemoveTag(tag: string): ()`**: Removes a tag from the instance. - **Method `ResetPropertyToDefault(property: string): ()`**: Resets a property to its default value. - **Method `SetAttribute(attribute: string, value: Variant): ()`**: Sets the attribute with the given name to the given value. - **Method `WaitForChild(childName: string, timeOut: double): Instance`**: Returns the child of the Instance with the given name. If the - **Event `AncestryChanged`**: Fires when the Instance.Parent property of this object or one of - **Event `AttributeChanged`**: Fires whenever an attribute is changed on the Instance. - **Event `ChildAdded`**: Fires after an object is parented to this Instance. - **Event `childAdded`**: *(deprecated)* - **Event `ChildRemoved`**: Fires after a child is removed from this Instance. - **Event `DescendantAdded`**: Fires after a descendant is added to the Instance. - **Event `DescendantRemoving`**: Fires immediately before a descendant of the Instance is removed. - **Event `Destroying`**: Fires immediately before (or is deferred until after) the instance is - **Event `StyledPropertiesChanged`**: Fires whenever any style property is changed on the instance, including ### From [Object](/docs/reference/engine/classes/Object.md) - **Property `ClassName`** (`string`): A read-only string representing the class this Object belongs to. - **Property `className`** (`string`): *(deprecated)* - **Method `GetPropertyChangedSignal(property: string): RBXScriptSignal`**: Get an event that fires when a given property of the object changes. - **Method `IsA(className: string): boolean`**: Returns true if an object's class matches or inherits from a given class. - **Method `isA(className: string): boolean`**: *(deprecated)* - **Event `Changed`**: Fires immediately after a property of the object changes, with some