This gear assembly is an authentic OEM component. It is designed for use with Makita driver-drills. The assembly contains gears and it is the part that drives the chuck. Over time components may wear out or get damaged eventually requiring a replacement assembly. It is made of high-quality materials and is sold as an individual item. Check the owners manual and the diagrams of your model for the exact location and the correct installation of this part. You will need a screwdriver to take the drill apart and perform this repair.
Gear Assembly 126459-4
OEM part for: Makita
Part Number: 126459-4
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Compatibility
This Gear Assembly will fit the following 8 machines. Confirm this part works with your model, and view the detailed model diagrams and repair help we have to offer.
Makita
Show More Compatible ModelsThis item works with the following types of products:
- Cordless Drill Parts
- Drill Parts
This part replaces obsolete part #: 125831-7
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Customer Part Reviews ?
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Customer Repair Instructions ?
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Gear assembly needed replaced
Tool Type
Cordless Drill
Difficulty
Medium
Time
30-60 minutes
Tools Used
Screwdriver, dead blow hammer, needle nose pliers, large allen wrench
Parts Used
2. Turned out reverse thread screw inside the chuck.
3. Removed chuck using a large allen wrench which proved to be a bit of a challenge. It took a number of tries to finally get the chuck to break loose.
4. Removed 2 rear housing screws. This allowed access to hidden screw holding rest of housing together shown in video.
5. Separated rear housing from rest of drill.
6. Removed all housing screws using magnetic Phillips head #2 screwdriver.
7. Separated housing being careful not to let springs on either side of speed control go flying as shown in the video.
8. Removed heat sink by pulling straight up with needle nose pliers.
9. Carefully removed gear box assembly after raising assembly and armature just enough to get the gear box out.
10. Put new gear box onto spindle making sure to line up the large notch with the large tab still connected to the armature. (Don't turn off the top part of gear assembly as the ball bearings inside will come out.)
11. Seated armature and gear assembly into housing making sure to seat all portions of both just like they were originally situated. Re-installed heat sink.
12. Re-installed the speed control switch being careful not to lose the springs on either side and inserting the little tab on the speed control into the proper gap.
13. With one side of the housing and parts fully assembled inside and laying on the bench, lined up the other half making sure all components were seated in the correct grooves, etc. I had a problem getting the housing to come together at the rear part and kept trying without forcing anything until I got the unit fully seated together. A little patience was called for to get this done since it didn't seem to matter that everything was lined up, but it just wouldn't come together as it should have. This step took the most time of the whole process.
14. Re-installed all housing screws including hidden one inside rear housing.
15. Used a dental pick to move springs holding brushes in place and pried off the snap on brush attachments with the same tool.
16. Carefully pulled out old brushes and replaced with new, realigned springs holding brushes in place and snapped on brush brackets onto top of brush housing.
17. Put rear housing back on and screwed back into place.
Clutch slipped when drilling.
Tool Type
Cordless Drill
Difficulty
Easy
Time
15-30 minutes
Tools Used
Screwdriver, Allen wrench, hammer
Parts Used
Removed chuck from gear assembly using allen wrench and hammer.
Removed screws from housing.
Separated housing halves.
Removed old gear assembly.
Installed new gear assembly.
Reassembled housing, installed chuck, installed screw in chuck and tested.
High spend gear stripped
Tool Type
Cordless Drill
Difficulty
Easy
Time
Less than 15 minutes
Tools Used
Screwdriver
Parts Used
Failed keyless chuck that was unable to remove. So elected to replace the gear assembly also.
Tool Type
Cordless Drill
Difficulty
Easy
Time
15-30 minutes
Tools Used
Screwdriver, flashlight
Parts Used
Removed the old gear and chuck assembly.
Installed the new gear assembly.
Threaded the new chuck onto the gear assembly output shaft, then installed the new machine screw.
Reassembled the drilled housing, installed the housing screws, snugged the screws with a Phillips screwdriver.
Clutch slipping when driving screws
Tool Type
Cordless Drill
Difficulty
Easy
Time
15-30 minutes
Tools Used
Screwdriver, Large Allen Wrench and hammer
Parts Used
Drill chuck was worn and gearbox was not working as it should
Tool Type
Cordless Drill
Difficulty
Medium
Time
1-2 hours
Tools Used
Screwdriver, Allen wrench
Gears were slipping
Tool Type
Cordless Drill
Difficulty
Medium
Time
15-30 minutes
Tools Used
Screwdriver
Parts Used
Cordless drill was not turning
Tool Type
Cordless Drill
Difficulty
Easy
Time
15-30 minutes
Tools Used
Screwdriver
Parts Used
Gears were stripped out.
Tool Type
Cordless Drill
Difficulty
Easy
Time
30-60 minutes
Tools Used
Screwdriver, Impact driver
Parts Used
2. Tightened a medium size allen wrench in the chuck.
3. Held the drill tight on the workbench.
4. Hit the allen wrench with a rubber mallet to loosen the chuck from the gear assembly.
5. Unscrewed the chuck completely from the gear assembly.
6. Took all screws out so could take one half of the drill housing off.
7. Slowly lifted up the gear assembly and armature. Be careful not to lose the spring from the speed switch.
8. Carefully pull the gear assembly off.
9. Push the new gear assembly on, attach the speed switch, and push everything back into place.
10. Reassemble in reverse order of taking apart.
Drill clutch gears wore out, no longer functioning
Tool Type
Cordless Drill
Difficulty
Medium
Time
30-60 minutes
Tools Used
Screwdriver, Pliers, Large hex wrench
Parts Used
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All our customer repair instructions are solicited directly from other customers just like you who have purchased and replaced this exact part. While we moderate these reviews for profanity, offensive language or personally identifiable information, these reviews are posted exactly as submitted and no alterations are made by our team.
Based on data from past customer purchasing behaviors, these parts are most commonly purchased together along with the part you are viewing. These parts may be necessary or helpful to replace to complete your current repair.
All our installation videos are created and produced in collaboration with our in-house repair technician, Mark Sodja, who has helped millions of eReplacementParts customers over the last 13 years repair their products. Mark has years of experience in selling and repairing both commercial and residential products with a specialty in gas-powered equipment.
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