Extension Spring Conversion Kit for 8' High Doors
Genuine Clopay replacement hardware for rebuilding or converting the extension spring system on compatible residential garage doors up to 8 feet high.
The Extension Spring Conversion Kit includes the pulleys, lift cables, safety containment cables, and fasteners commonly needed to rebuild the extension spring hardware on a compatible residential sectional garage door.
Designed for garage doors measuring 8 feet high or less, this kit is useful for replacing worn pulleys and cables or supplying the hardware needed for an eligible extension spring installation. The extension springs are selected and purchased separately according to the actual weight of the door.
Sized for 8' Doors Includes lift and safety cables suitable for compatible residential garage doors up to 8 feet high.
3" Pulley System Includes the stationary and traveling pulleys needed for both sides of a typical extension spring system.
Safety Cables Included Containment cables run through the extension springs to help control them if a spring or attachment point fails.
How This Kit Benefits Your Garage Door
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Replaces worn hardware: Useful when existing pulleys, lift cables, safety cables, or fasteners are rusted, frayed, damaged, or missing.
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Supports smoother movement: Properly operating pulleys allow the cables and extension springs to move more freely as the door opens and closes.
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Helps maintain balanced lifting: Matching hardware on both sides supports consistent cable travel and controlled door movement.
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Adds spring containment: Safety cables help contain an extension spring if the spring or an attachment point breaks.
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Simplifies parts selection: Common extension spring hardware is packaged together rather than ordered individually.
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Allows separate spring selection: The appropriate extension springs can be matched to the actual weight of the garage door.
Package Includes
| Component |
Quantity |
Purpose |
| 3" Extension Spring Pulleys |
4 |
Guides the lift cables and allows the extension springs to stretch and retract during operation. |
| 1/8" Lift Cables |
1 pair |
Connects the lower portion of the garage door to the extension spring and pulley system. |
| 1/8" Safety Containment Cables |
1 pair |
Runs through the extension springs to help contain them if a spring or attachment point fails. |
| Fasteners and Attachment Hardware |
1 package |
Provides applicable hardware for connecting the included pulleys and cables. |
Key Features
- Genuine Clopay replacement hardware kit
- Clopay model number 4147350
- Designed for residential sectional garage doors
- Suitable for compatible doors up to 8 feet high
- Includes four 3-inch extension spring pulleys
- Includes one pair of 1/8-inch lift cables
- Includes one pair of 1/8-inch safety containment cables
- Includes applicable fasteners and attachment hardware
- Provides hardware for both sides of the garage door
- Suitable for repair or eligible conversion applications
- Extension springs are not included
Product Specifications
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Manufacturer: Clopay
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Model Number: 4147350
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Product Type: Extension spring hardware conversion kit
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Door Application: Residential sectional garage doors
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Maximum Door Height: 8 feet
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Pulley Diameter: 3"
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Pulley Quantity: 4
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Lift Cable Diameter: 1/8"
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Safety Cable Diameter: 1/8"
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Springs Included: No
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Hardware for Both Sides: Yes
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Package Quantity: One hardware kit
Lift Cables and Safety Cables
The lift cables connect the garage door to the extension spring and pulley system. The separate safety containment cables run through the center of each extension spring to help control the spring if it breaks or becomes disconnected.
Extension Springs Are Not Included: The correct extension springs must be purchased separately. Springs must be selected according to the actual weight of the garage door, not by door height alone. Both springs should have matching weight ratings and specifications.
Replace Extension Springs in Pairs: When one extension spring breaks or becomes worn, replacing both springs together is generally recommended. Springs of the same age have typically completed a similar number of operating cycles and should remain evenly matched.
8' Door Application: The supplied cables are intended for compatible residential garage doors measuring 8 feet high or less. Confirm the door height, track layout, cable routing, and extension spring arrangement before ordering.
Clearance Notice: The included pulleys measure approximately 3 inches in diameter. Verify adequate clearance between the pulleys, wall, track, rear hangers, and surrounding framing.
Compatibility Notice: Verify the garage door height, actual door weight, spring rating, pulley diameter, cable routing, horizontal track supports, rear hanger location, existing hardware, and mounting clearances before ordering.
Additional Parts May Be Required: Extension springs, spring-adjusting clips, rear track hangers, angle iron, bottom brackets, rollers, track, additional fasteners, and installation tools are not included unless specifically stated.
High-Tension Safety Warning: Extension springs, lift cables, bottom brackets, and related garage door hardware can be under substantial tension. A broken or improperly secured spring can release suddenly and cause severe injury or property damage. Safety containment cables must be installed through both springs. Professional installation is strongly recommended.
