Necessary Repairing Tools - Makita 8391D Technical Information

R
epair
CAUTION: Remove the battery and the bit from the machine for safety before repair/
maintenance in accordance with the instruction manual!

[1] NECESSARY REPAIRING TOOLS

Description
Hex wrench 8 Removing / Installing Drill chuck
Plastic hammer Removing Drill chuck
[2] LUBRICATIONS
The components of Gear ass'y has been lubricated in Makita plant and assembled under strict quality control. Therefore,
it is recommended to replace Gear ass'y without disassembling in repair.
[3] DISASSEMBLY/ASSEMBLY
[3]-1. Keyless Drill Chuck
Note: When replacing Gear ass'y, begin by removing Keyless drill chuck.
As long as the repairing does not concern Gear ass'y, it is not necessary to remove Keyless drill chuck.
DISASSEMBLING
(1) Remove M6x22 Flat head screw. (Fig. 1)
(2) Preset the machine as illustrated in Fig.2.
(3) Hold the machine firmly and pull the switch trigger slowly and carefully.
Note: 1) Pay attention that the machine except Keyless drill chuck starts revolving with strong force. Do not pinch your
hand between the moved machine and Vise in this step.
2) If it is impossible to remove Keyless drill chuck, use 1R359 (Chuck removing tool) to remove it. Refer to Makita
repair tool list.
Fig. 1
M6x22 Flat head screw
with adhesive
Note: Pay attention to the
turning direction.
Open the jaws of Keyless drill chuck fully
and remove M6x22 Flat head screw by
turning clockwise.
If it is difficult to remove the screw with
slotted screwdriver, use cordless impact
driver.
ASSEMBLING
1) Turn Keyless drill chuck clockwise until it sits on the end of the threaded portion of Spindle.
2) Fix the short portion of Hex wrench 8 to Drill chuck, and clamp the long portion of Hex wrench 8 in Vise.
3) Set Speed change lever in the low speed mode and F/R change lever in the Forward (clockwise) rotation mode. Then
Install Battery.
4) Hold the machine firmly and pull the switch trigger to rotate Spindle until the motor is locked.
Note: Pull the switch trigger so that Spindle reaches full speed in one second.
Important: Be sure to release the switch trigger just after Spindle is locked.
5) Secure Keyless drill chuck with M6x22 Flat head screw by turning counterclockwise with impact driver.
Note: If you reuse the removed M6x22 Flat head screw, apply adhesive (ThreeBond 1321B/ 1342, Loctite 242) to
the threaded portion. Makita genuine M6x22 Flat head screw for securing Keyless drill chuck is threadlocker
screw.
Use for
Fig. 2
Set Speed change lever
in the low speed mode.
Set Change ring
in the drill mode.
Hold Hex wrench 8
by tightening the jaws
of Keyless drill chuck.
Vise
Note: Hold the flat surface
Hex wrench 8
of Hex wrench 8.
P 2/ 7
Set F/R Change lever in
the reverse mode.
Install Battery.
Clamp the long portion
of Hex wrench 8 in Vise.
Vise