Liftmaster 041A7278 Sprocket Kit
The LiftMaster 041A7278 sprocket kit is a service part for select LiftMaster and Chamberlain opener drive assemblies that use this specific sprocket style. In the field, this part is usually replaced when the chain no longer tracks properly, the sprocket teeth are worn, the sprocket is loose on the shaft, or the opener makes a grinding or jumping sound under load. A worn sprocket can also create uneven chain movement that looks like a travel, force, or door-balance issue, so the door and drive system should be inspected before the part is replaced. This kit is commonly associated with LiftMaster 3950 and LJ8950W style applications and other units only when the parts diagram identifies 041A7278 or 41A7278. Do not confuse this sprocket kit with 041A7279 live shaft, 041A7280 dead shaft, chain kits, or rail trolley kits.
Compatible With
- Select LiftMaster 3950 wall mount / light commercial style opener applications when the parts diagram calls for 041A7278
- Select LiftMaster LJ8950W applications when the original sprocket reference matches 041A7278 or 41A7278
- Various LiftMaster and Chamberlain garage door openers that specifically list 041A7278 in the replacement parts diagram
- Chain drive or jackshaft style assemblies using the matching sprocket, shaft bore, set screw location, and chain size
- Not a universal replacement for 041A7279, 041A7280, 041A7314, 041A3489, or standard rail trolley kits
Features and Specifications
| Manufacturer | LiftMaster |
| Product Type | Sprocket replacement kit |
| Part Number | 041A7278 |
| Application | Garage door opener drive sprocket service |
| Compatible Operator Type | Select LiftMaster / Chamberlain operators by parts diagram |
| Drive Type | Chain / sprocket drive applications where specified |
| Included Components | Sprocket and replacement hardware |
| Notes | Match original part number and parts diagram before ordering |
Also Known As / Related Part Numbers
- 041A7278
- 41A7278
- LiftMaster 041A7278
- Chamberlain 041A7278
- Sprocket kit for select 3950 / LJ8950W references
- Related but different: 041A7279 live shaft sprocket kit
- Related but different: 041A7280 dead shaft sprocket kit
- Related but different: 041A7314 #48x73 chain kit
Technician Note
When a sprocket fails, check chain tension, shaft play, set screw condition, door balance, and the condition of the related chain before replacing the sprocket alone. A tight, binding, or unbalanced door can damage the new sprocket quickly.
Before Ordering Checklist
- Confirm the opener model number and full parts diagram reference
- Match the original sprocket part number to 041A7278 or 41A7278
- Inspect the chain for stretched links, rust, or damaged master links
- Verify this is not a live shaft or dead shaft sprocket kit before ordering
- Do not reuse damaged set screws or worn mounting hardware
Professional Advisory
Garage door opener drive parts should be serviced with power disconnected and with the door properly supported. If the door is heavy, unbalanced, or the drive assembly is damaged beyond the sprocket, have a qualified garage door technician inspect the system.
Product Questions and Answers
Is 041A7278 the same as 41A7278?
Yes. 41A7278 is a common shorter reference for the LiftMaster 041A7278 sprocket kit.
Does this fit every LiftMaster chain drive opener?
No. It fits only select LiftMaster and Chamberlain applications where the parts diagram calls for 041A7278 or 41A7278.
Is this the same as the 041A7279 live shaft kit?
No. 041A7279 is a different live shaft sprocket kit. Do not substitute it unless the opener parts diagram confirms that part.
What symptoms point to a worn sprocket?
Common signs include chain jumping, grinding, worn sprocket teeth, loose set screws, uneven chain travel, or visible damage at the drive sprocket.
Should the chain be replaced at the same time?
Inspect the chain before reusing it. A stretched or damaged chain can shorten the life of the replacement sprocket.
