Makita GA4042C Manual

P 1/ 12
Model No. GA4040C/GA4042C, GA4540C/GA4542C,
GA5040C/GA5042C, GA6040C/ GA6042C
Dimensions: mm (")
Width (W)
Height (H)
Length (L)
Model No.
303 (11-7/8)
GA4040C/GA4042C, GA4540C/GA4542C,
GA5040C/GA5042C, GA6040C/ GA6042C
117 (4-5/8), 130 (5-1/8),
140 (5-1/2), 171 (6-3/4)
111 (4-3/8), 116 (4-9/16),
116 (4-9/16), 116 (4-9/16)
*1 Anti-restart function is available for the following models only:
GA4040C, GA4540C, GA5040C, GA6040C
PRODUCT
Description Angle Grinders 100mm (4"), 115mm (4-1/2"),
125mm (5"), 150mm (6")
L
H
W
CONCEPT AND MAIN APPLICATIONS
Standard equipment
Note: The standard equipment for the tool shown above may vary by country.
1,400W Angle grinder series models; GA4040C/ GA4042C,
GA4540C/ GA4542C, GA5040C/ GA5042C and GA6040C/
GA6042C are successor models of 9560 series models, featuring:
•"Super Joint System II"developed for effective vibration
absorption
• Electronic current limiter, speed control and soft start
• Anti-restart function*1
• Re-designed durable gear housing
• Ergonomically best possible barrel grip
Side grip ............................................... 1 (normal type or anti-vibration type)
Lock nut wrench ................................... 1
Depressed center wheel ........................ 1 (100mm for GA4040C/ GA4042C, 115mm for GA4540C/ GA4542C,
125mm for GA5040C/ GA5042C, 150mm for GA6040C/ GA6042C)
Optional accessories
Depressed center wheels
Rubber pads
Dust collecting wheel guards
Abrasive discs
Wire brushes
Wheel covers for wire brushes
Diamond wheels
Abrasive cut off wheels
Wheel covers
Sanding lock nut
etc.
Specification
Continuous Rating (W)
Voltage (V) Cycle (Hz) Input Output
840
Max. Output (W)
110
120
220
230
240
13
12
6.7
6.4
6.1
50/60
50/60
50/60
50/60
50/60
1,400
1,400
1,400
1,400
1,400
2,100
2,100
1,800
2,000
2,100
Current (A)
840
127 12 50/60
---
2,000840
840
840
840
*2 with Side grip, Wheel cover, Inner flange, Lock nut
Model No.
No load speed: min.ˉ¹=rpm
Diameter
Hole diameter
Wheel size:
mm (")
Protection against electric shock
Power supply cord: m (ft)
Weight according to
EPTA-Procedure 01/2003*2: kg (")
GA4040C/ GA4042C GA6040C/ GA6042C
100 (4) 115 (4-1/2)
European countries except UK: 4.0 (13.2), Brazil, Australia: 2.0 (6.6)
Other countries including UK: 2.5 (8.2)
2,800 - 11,000
150 (6)
Double insulation
22.23 (7/8)16 (5/8)
Max. thickness 6 (1/4)
Shock absorbing System
Mechanical brake
Super Joint System II
Yes
Yes
Yes
GA4040C, GA4540C, GA5040C, GA6040C: Yes/ GA4042C, GA4542C, GA5042C, GA6042C: No
Constant speed control
Variable speed control by dial
Soft start
Electronic current limiter
Anti-restart function
Electronic
control
Yes
No
GA4540C/ GA4542C
125 (5)
2.3 (5.2) 2.5 (5.4) 2.6 (5.6)
GA5040C/ GA5042C
4,000 - 9,000
TECHNICAL INFORMATION

P 2/ 12
Repair
Apply Makita grease to the following portions designated with the black triangle and gray triangle to protect parts and
product from unusual abrasion.
[1] NECESSARY REPAIRING TOOLS
CAUTION: Repair the machine in accordance with “Instruction manual” or “Safety instructions”.
Code No. Description Use for
1R045 Gear extractor (Large) separate Armature from Gear housing cover
1R049 Drill chuck remover 15 fixing large Spiral bevel gear when removing Spindle
1R050 Drill chuck remover 22
1R232 Pipe 30 removing Cup ring and Ball bearing 6903ZZ from large Spiral bevel gear
1R258 V block supporting Bearing box
1R268 Spring pin extractor M3 disassembling Shaft lock mechanism
1R269 Bearing extractor removing Ball bearings 627DDW/ 696ZZ from Armature
1R281 Round bar for Arbor 7-50 removing Switch knob from Switch lever
1R286 Round bar for Arbor 12-50 removing large Spiral bevel gear section from Bearing box
1R291 Retaining ring S & R pliers removing Retaining ring S-9
1R340 Bearing retainer wrench removing Bearing retainer 20-33 from Bearing box
1R350 Ring 60 supporting Gear housing when disassembling Shaft lock mechanism
[2] LUBRICATION
Fig. 1
Item No. Description
Gear housing
C-type plate
Lubricant AmountPortion to lubricate
Coupling
Spindle
Model No.
GA4040 GA4540C
GA4540 GA5040C
GA5040 GA4542C
GA4040C GA5042C
GA6040 GA6042C
GA6040C
Smaller spiral bevel gear
(on armature shaft)
Larger spiral bevel gear
(on spindle)
10 teeth 38 teeth
9 teeth 41 teeth
Gear room 15 g
a little
a little
a little
70
56
1
Joint sleeve
Note: As listed below, the grinders use different spiral bevel gears, and they are not interchangeable.
Referring to this list, therefore, be sure to use correct gears for replacement.
Spiral bevel gear (large)
Ball bearing 6903ZZ
56
58
58
Outer surface where 58 Coupling contacts
Drum portion where 58 Coupling contacts
Cylindrical portion where 56 C-type plate contacts
Makita Grease FA No. 2:
Makita Grease FA No. 2:
Makita Grease FA No. 2:
Makita Grease SG No. 0:
1
70
[3] DISASSEMBLY/ASSEMBLY
[3] -1. Note in Disassemble (general)
No load
speed: min.ˉ¹
11,000
9,000

P 3/ 12
Repair
[3] DISASSEMBLY/ASSEMBLY
[3] -2. Armature, Spiral bevel gear [small one]
DISASSEMBLING
1. Remove Rear cover by unscrewing
one 4x18 Tapping screw.
(1) Remove Spiral bevel gear (small) from the drive end of Armature as drawn in Fig. 2.
4x18 Tapping screw
4. Unscrew four Tapping screws. Then separate Gear housing cover from Motor housing
while applying a slotted screwdriver to the groove on Gear housing cover.
Rear cover
2. Shift Spiral spring from
Carbon brush top.
3. Disconnect Carbon brush from
commutator by pulling up.
Note: No need to remove in this step.
Fig. 2
Groove on
Gear housing cover
Gear housing cover
Armature
Wrench 10
Flat washer 12
Gear housing
cover
Ball bearing
6001LLB
5. Remove M6 Hex nut to turn it with Wrench 10
counterclockwise. Then, remove Flat washer 6
and small Spiral bevel gear from Armature.
6. Remove Gear housing cover with 1R045.
Then, remove Flat washer 12.
Flat washer 6
Spiral bevel
gear (small)
M6 Hex nut
Armature
1R045

P 4/ 12
Repair
DISASSEMBLING
ASSEMBLING
(2) Disassemble the commutator end of Armature as drawn in Fig. 3.
Note: This step is required for the models with electronic control system of GA4040C, GA4540C, GA5040C,
GA6040C, GA4542C, GA5042C, GA6042C.
Fig. 3
1. Pick up three tabs of
Self lock 6 with tweezers
to remove it from Armature.
2. Remove Magnet sleeve,
Wave washer 6 and
Labyrinth rubber ring 22.
3. Remove Ball bearing 627DDW with 1R269. 4. Remove Flat washer 7 and
Insulation washer.
Self lock 6
Tabs
Tweezers
Wave washer 6
Magnet sleeve
Labyrinth rubber ring 22
Ball bearing 627DDW
1R269 Flat washer 7
Insulation washer
(1) Assemble small Spiral bevel gear to Armature end by reversing the disassembly procedure. (Refer to Fig. 2)
(2) Assemble the commutator end of Armature as drawn in Fig. 4.
Note: This step is required for the models with electronic control system of GA4040C, GA4540C, GA5040C,
GA6040C, GA4542C, GA5042C, GA6042C.
Fig. 4
2. Press down Self lock 6 until
Wave washer 6 gets flat.
3. Magnet sleeve is stabilized
between Self lock 6 and
Wave washer 6 by the reaction
force of Wave washer 6.
1. Return tabs of Self lock 6 to their
normal shape before assembling.
Then, mount Wave washer 6 to
the commutator end of Armature.
Note: Be careful to their directions.
Refer to the drawings in Fig. 4.
Wave washer 6
Magnet sleeve
Self lock 6
Wave washer 6
Magnet sleeve
Self lock 6
[3] DISASSEMBLY/ASSEMBLY
[3] -2. Armature, Spiral bevel gear [small one] (cont.)

P 5/ 12
Repair
[3] -3. Spiral bevel gear [large one], Ball bearings 696ZZ/ 6201DDW
ASSEMBLING
DISASSEMBLING
(3) Assemble Gear housing cover with Armature and Gear housing to Motor housing as drawn in Fig. 5.
Note: The gear and the ball bearings can be replaced without disassembling the motor section.
(1) Remove Ball bearing 696ZZ, Retaining ring S-9, Flat washer 10 and C-type plate from Spindle as drawn in Fig. 6.
Fig. 5
Fig. 6
Armature
Notch on Gear housing cover Name plate
1. Removing four M4x16 Hex socket head bolts, then separate Bearing box section from Gear housing.
1. Assemble Gear housing cover together with Armature
while facing its notch to the same side as Name plate.
2. Assemble Gear housing while facing Spindle
to the same side as the notch and Name plate.
Name plate
Gear housing
Spindle
Bearing box
section
2. Remove Ball bearing 696ZZ
with 1R269.
3. Remove Retaining ring S-9
with 1R291.
4. Remove Flat washer 10.
Then, remove C-type plate.
Ball bearing
696ZZ Retaining
ring S-9
Flat washer 10
C-type plate.
[3] DISASSEMBLY/ASSEMBLY
[3] -2. Armature, Spiral bevel gear [small one] (cont.)

P 6/ 12
Repair
DISASSEMBLING
(2) Disassemble large Spiral bevel gear from Spindle and Separate Coupling from the gear as drawn in Fig. 7.
Fig. 7
1. Put Bearing box on the turn base of Arbor press. Then, inert 1R049
and 1R050 into the gap between Bearing box and large Spiral bevel
gear. And then, remove Spindle by pressing it with Arbor press.
3. Tap Bearing box to shift Flat washer 12
so that the surface reveals as large as
possible.
Then, put Bearing box on 1R258.
1R049
Spindle
1R050
Spindle
Joint sleeve
Bearing retainer
Bearing box Flat washer 12
Flat washer 12
4. While applying 1R286 to Flat washer 12 through Bearing
retainer, press it carefully to remove large Spiral bevel gear
section (including Coupling and Ball bearing 6903ZZ)
from Bearing box.
1R286
large
Spiral bevel gear
Ball bearing
6903ZZ
Coupling
Flat washer 12
1R232
Coupling
Ball bearing 6903ZZ
large Spiral bevel gear
5. While applying 1R232 to Coupling, press it to remove Coupling together with Ball bearing 6903ZZ
from large Spiral bevel gear.
[3] DISASSEMBLY/ASSEMBLY
[3] -3. Spiral bevel gear [large one], Ball bearings 696ZZ/ 6201DDW (cont.)
2. Joint sleeve can be removed.

P 7/ 12
Repair
DISASSEMBLING
ASSEMBLING
(3) Disassemble Ball bearing 6201DDW from Bearing box as drawn in Fig. 8.
Fig. 8
1. Clamp Bearing box with Vise. Then, while fitting the claw of 1R340 to the notch of Bearing retainer 20-33,
turn 1R340 clockwise to remove the retainer.
2. Take out Felt ring 17 and Flat washer 21
from Bearing box.
3. Remove Ball bearing 6201DDW with Arbor press.
1R340
Bearing
retainer 20-33
Bearing
retainer 20-33
Felt ring 17
Felt ring 17
Flat washer 21
Assemble by reversing the disassembly procedure. (Refer to Figs. 8, 7 and 6)
Note: •Do not re-use the removed Joint sleeve. New Joint sleeve has to be mounted.
(Refer to the upper right illustration in Fig. 7)
• Apply the following thread locker to the thread of M4x16 Hex socket head bolts, if the unscrewed bolts are used.
* ThreeBond 1342
* Loctite 242
(Refer to the upper left illustration in Fig. 6)
Ball bearing
6201DDW
Ball bearing
6201DDW
[3] DISASSEMBLY/ASSEMBLY
[3] -3. Spiral bevel gear [large one], Ball bearings 696ZZ/ 6201DDW (cont.)

P 8/ 12
Repair
[3] DISASSEMBLY/ASSEMBLY
[3] -4. Switch Lever
DISASSEMBLING
(1) Remove Rear cover from Motor housing by removing 4x18 Tapping screw. (Fig. 2)
(2) Disassemble Switch lever and Switch knob from the machine as drawn in Fig. 9.
Assembled Switch lever and Switch knob as drawn in Fig. 10.
Note: Make sure that Compression spring 4 is assembled to Switch lever in advance.
Fig. 9
3. Bend Switch lever to make it
free from the wall of Switch
box. Then, Pull out Switch
lever from Motor housing.
1. While locking Switch knob with 1R281,
strongly push Switch lever in a direction
designated with black arrow.
2. Switch lever is disconnected
from the locking claw of
Switch knob.
Then, remove Switch knob.
Switch lever
Tumbler
Switch lever
1R284
Switch knob
Switch Switch
Switch knob
Tumbler of
Switch
Tumbler of
Switch Switch lever
Fig. 10
Switch knob
2. Fit the hook of Switch knob to the hole of Switch lever.
Then, release Switch lever. (The hook of Switch knob
interlocks with the hole of Switch lever when Switch
lever is pushed back to OFF position by Compression
spring 4.)
Switch lever
Switch knob
1. Push Switch lever into Motor housing
until the hole of Switch lever comes into
sight through Switch knob assembling hole
on Motor housing. And keep the position.
ASSEMBLING

P 9/ 12
Repair
[3] DISASSEMBLY/ASSEMBLY
[3] -5. Switch Block
[3] -6. Switch
DISASSEMBLING
After removing Switch Lever (Refer to Fig. 9), separate Switch block from Motor housing as drawn in Fig. 11.
After removing Switch lever (Refer to Fig. 9), remove Switch from Switch block as drawn in Fig. 12.
Fig. 11
Insert Slotted screwdriver into the gap between
Switch block and Motor housing, remove
Switch block from Motor housing.
Fig. 12
Fig. 13
Switch block
Controller
ASSEMBLING
Connect Switch block as drawn in Fig. D-3.
DISASSEMBLING
[3] -7. Brush Holder
DISASSEMBLING
Insert Slotted screwdriver into the gap between Switch and Switch block.
While fitting the tip of the screwdriver to the side groove of Switch,
remove Switch by levering it up.
Remove 3x10 Tapping screw. Then, insert Slotted screwdrivers into the gap between Motor housing
and Brush holder’s plastic portion. And then, disassemble Brush holder by levering them up.
Brush holders can be disassembled as drawn in Fig. 13.
Brush holder
Slotted screwdriver
Switch
Slotted screwdrivers
Slotted screwdriver

P 10/ 12
Repair
[3] DISASSEMBLY/ASSEMBLY
[3] -8. Shaft Lock
DISASSEMBLING
While applying 1R268 to Shoulder pin 6 through the small hole
on Pin cap, tap 1R268 with a hammer.
Now, Shoulder pin 6 comes out from Gear housing complete.
Release 1R268 from Pin cap carefully
so that Pin cap is not slung by
Compression spring 8.
Shoulder pin 6
Pin cap
Note: Do not re-use removed Pin cap
because removal one damages
the inside surface of the cap,
producing plastic dust.
Pin cap
Pin cap
Compression
spring 8
1R268
1R350
Fig. 14 Fig. 15
(1) Disassemble Bearing box section from Gear housing. (Refer to Fig. 6)
(2) Disassemble Shaft lock mechanism as drawn in Figs. 14 and 15.
Fig. 16 Fig. 17
(1) Be sure to use a new Pin cap for replacement and to remove all the plastic dust on Shoulder pin 6. (Fig. 16)
(2) Assemble the Parts for Shaft lock mechanism as drawn in Fig. 17.
Plastic dust
O Ring 7
Shoulder pin 5 Shoulder
pin 6
Pin cap
Compression
spring 8
ASSEMBLING
2. Assemble new Pin cap by pressing
it to Shoulder pin 6.
Note: Do not forget to assemble
Compression spring 8.
1. Insert Shoulder pin 6 through
the hole of Gear housing
complete.

P 11/ 12
Circuit diagram
Color index of lead wires' sheath
with Controller
GA4040C, GA4540C, GA4542C, GA5040C, GA5042C, GA6040C, GA6042C
without Controller
Field Brush holder
Blue
Fig. D-1A
Brown
57
Switch
Noise
suppressor
GA4040, GA4540, GA5040, GA6040
Fig. D-1B
Color index of lead wires' sheath
Blue Brown
Switch
Controller
Noise suppressor* is installed
in Switch block.
*Noise suppressor is not used
for some countries.
Field Brush holder
Noise
suppressor
7
Black lead wire is used
for some countries.
White lead wire is used
for some countries.
8
6
1
45
2
3
Switch block
Switch block
Noise suppressor* is installed
in Switch block.
*Noise suppressor is not used
for some countries.
Black lead wire is used
for some countries.
White lead wire is used
for some countries.
8
6
1
4
2
3

P 12/ 12
Wiring diagram
Fig. D-2
Fig. D-3
Wiring of Lead wires of Power supply cord
Connecting of Switch block to Motor housing
Brush holder
Connecting terminal
1. Before mounting Switch block to Motor housing,
make sure that these three Connecting terminals
of Switch block are not deformed or broken.
Put Lead wires of Power supply cord
into this place designated with gray color.
2. Make sure that these connecting terminals
of Switch block fit to Brush holders’
connecting terminals, push Switch block
to Motor housing until it stops.