AUTOMOBILE
ISSUE NO. : N-Q-G-045
DATE

: Nov. 20, 2018

PAGE

: 1 OF 5

SUBJECT

: Important inspection of suspension lower arm ball joint

REFERENCE

:

1. APPLICABLE MODEL
All models
2. CONDITION / DESCRIPTION
The suspension lower arm ball joint may gradually deteriorate and wear due to a long time use.
Therefore, if the vehicle is used continuously without proper inspection, it may become unsafe if the
ball stud becomes separated from suspension lower arm. [Fig.1]
[Section of ball joint part]

Suspension
lower arm

Ball joint part

Ball stud

Dust boot

Fig.1 Suspension lower arm ball joint part

3. REPAIR PROCEDURE
Perform the following inspection from (1) to (4) in order and change the suspension lower arm
assembly with new one as required.
(1) Backlash of ball joint
(2) Water intrusion into dust boot
(3) Rust of ball joint
(4) Crack of dust boot

AUTOMOBILE
ISSUE NO. : N-Q-G-045
DATE

: Nov. 20, 2018

PAGE

: 2 OF 5

(1) Inspect backlash of ball joint
1)

Lift up the vehicle. Remove the tire and wheel. [Fig.2]
Washer

2)

3)

Bolt the front brake disc to wheel hub using washer and
nut to prevent it from rattling.
Note : Place them to two points on a diagonal line. [Fig.2]

Nut

Attach the magnet stand with dial indicator attached to front
brake disc and set the dial gauge.
Note: The pointer of the dial gauge needs to be set on
the center of the bottom face of the suspension lower
arm ball joint.

It must also be placed at a right angle

Fig.2 Brake disc fixture

to the bottom face. [Fig.3]

Front brake disc
Magnet stand

Backlash

Dial gauge

Fig.3 Dial gauge setting
4)

Rotate the scale plate to the zero-position without loading to the suspension lower arm. [Fig.3]

5)

Push near the ball joint part of suspension arm to up direction of the vehicle by hand (with
approximately 20 – 30N), and hold it for 2-3 seconds while measuring the value of the dial gauge.
It shows the amount of backlash in the upward direction. [Fig.3]

6)

Pull near the ball joint part of suspension arm to down direction of the vehicle by hand (with
approximately 20 – 30N), and hold it for 2-3 seconds while measuring the value of the dial gauge.
It shows the amount of backlash of downward direction. [Fig.3]

7)

The total measurements of step 5) and 6) are the total amount of backlash. Based on the value,
take action according to the decision criteria described in table 1.

AUTOMOBILE
ISSUE NO. : N-Q-G-045
DATE

: Nov. 20, 2018

PAGE

: 3 OF 5

Table1 Judgement criteria for backlash of suspension lower arm
Judgement criteria

Action

Less than 0.2mm

Go to (2) “Inspect water intrusion into dust boot “

More than 0.2mm

Replace the suspension lower arm.

(2) Inspect water intrusion into dust boot
Press lightly the dust boot by thumb to see if there is any water intrusion into the dust boot. [Fig.4]
Based on the observation, take action according to the judgement criteria described in
table 2.
,

Dust boot
Fig.4 Dust boot pressing

Table2 Judgement criteria for the water intrusion into the dust boot
Judgement criteria
No water leaking from dust
boot
Water leaking from dust
boot

Action
Go to (3) “Inspect rust of ball joint”
Replace the suspension lower arm.

(3) Inspect rust of ball joint
Separate the ball joint on the control arm from the lower spindle so you can inspect the
ball joint. Move the upper sealing area of the dust boot, and inspect the ball joint for rust in
the contact area between the ball joint and the dust boot. [Fig.5]
Based on the inspection, take action according to the judgement criteria described in
table 3.

AUTOMOBILE
ISSUE NO. : N-Q-G-045
DATE

: Nov. 20, 2018

PAGE

: 4 OF 5

Contact area between the ball

Inspect the ball joint for rust in the contact

joint and the dust boot

area between the ball joint and the dust
boot.

Mouth of the ball joint facing hole
Move the upper sealing

area of the dust boot to
inspect the surface.
Fig.5 Inspection area for the rust of the ball joint
Table3 Judgement criteria for the rust of the ball joint
Judgement criteria

Action

No rust visible

Go to (4) “Inspect the damage of dust boot”

Rust visible

Replace the suspension lower arm.

(4) Inspect the damage of dust boot
1) Inspect the dust boot if there is damage such as chap, crack or fracture on it. Based on the
inspection, take action according to the judgement criteria described in table 4. [Fig.7]

Dust boot
Fig.6 Dust boot

AUTOMOBILE
ISSUE NO. : N-Q-G-045

Crack

DATE

: Nov. 20, 2018

PAGE

: 5 OF 5

Chap

Fracture

Fig.7 Example of chap, crack or fracture

Table4 Judgement criteria for the damage of the dust boot
Judgement criteria
No occurrence of chap, crack or
fracture
Occurrence of chap, crack or
fracture [Note]

Action
Finish the inspection and reassemble (see note below).
Replace the suspension lower arm

Note : If the chap, crack or fracture is already reaching inside, the water may intrude into
the dust boot and the rust may be generated by it. In this case, change the
suspension lower arm with the new one.
If the chap, crack or fracture is not reaching inside, change the dust boot
with new one.