Bulletin No.:

Service Bulletin

Date:

18-NA-108
September, 2019

TECHNICAL
Subject:

Body Structure and/or Suspension Leans to the Left

Attention: This bulletin does not apply to ZR2 models.
Brand:

Model:

Chevrolet

Colorado

GMC

Canyon

Model Year:

VIN:

from

to

from

2015

2020

to

Engine:

Transmission:

Involved Region or Country

North America and NA Export vehicles

Condition

Some customers may comment on their vehicle leaning left.
Note: The same steps are followed whether the lean appears in the front, rear or both.

Cause

This condition may be caused by architectural corner mass distribution.

Correction

Perform one of the following to correct this condition:
• Install a shim on the rear left side between the rear axle and the left side leaf spring.
OR
• Install a shim on the rear left side between the rear axle and the left side leaf spring
and replace the front coil spring.

P Height and R Height Measurements

4957635

Copyright 2019 General Motors LLC. All Rights Reserved.

Measure fender wheel-opening heights, front and rear,
to quantify vehicle lean. Fender wheel-opening heights
are related to, but distinct from, trim height (a.k.a. Z and
D height). The front wheel-opening height is known as
P height, and the rear wheel-opening height is known
as R height. These are the most direct and repeatable
measurement of what a customer would perceive as a
leaning condition.
Perform the following before measuring the fender
wheel-opening heights:
• Set the tire pressures to the pressure shown on
the certification label. Refer to Label - Vehicle
Certification in SI.
• The vehicle MUST have a full tank of fuel.
Important: GM will NOT cover the cost of fuel.
• Ensure proper weight distribution.
• Make sure the vehicle is on a level surface, such
as an alignment rack.
If the P and R difference left to right, measurement is
12 mm (0.47 in) or less DO NOT perform any repairs.
If the P and/or R difference left to right measurement is
13 mm (1/2 in) or more, follow the steps listed below.
Note: Measurments must be attached to the Warranty
claim.

Page 2

September, 2019

Bulletin No.: 18-NA-108

Refer to Trim Height Specifications in SI.
LEFT
FRONT COIL
SPRING RPO:

6____

RIGHT
7____

NOMINAL
“P”

mm ±12

CROSS “P”
(LEFT “P” RIGHT “P”) =

mm

FRONT
LEFT “P1”

mm

X1 (NOMINAL
“P”- LEFT
“P1”) =

mm

FRONT
RIGHT
“P2”

mm

X2 (RIGHT
“P2” NOMINAL
“P” =

mm

REAR
LEFT “R1”

mm

NOMINAL “R”

mm ±12

REAR
RIGHT
“R2”

mm

CROSS “R”
(LEFT “R” RIGHT “R”) =

mm

Service Procedure for Shim
Installment (ONLY)
1. Raise the vehicle. Refer to Lifting and Jacking the
Vehicle in SI.
2. Using a hydraulic jack stand, support the rear axle.

4958046

6. Lower the hydraulic jack stand just enough to be
able to slide the shim under the spring and the bolt
up through the hole of the spring.
Important: DO NOT disassemble or remove the right
rear leaf spring, also, the removal of the left leaf spring
or the fuel tank is NOT required.

4956756

4992651

3. Put a C-clamp on each end of the leaf spring and
tighten so that tension is applied.
4. Remove the lower shock absorber nut. Refer to
Shock Absorber Replacement in SI.
5. Remove the rear spring anchor plate. Refer to
Rear Spring Anchor Plate Replacement in SI.

Important: Make sure to line up the shim with the leaf
spring.

Tighten
Torque the nut to 100 N.m (74 lb ft) +130°.

Service Procedure for Shim Installment
and Front Coil Spring Replacement
1. Raise the vehicle. Refer to Lifting and Jacking the
Vehicle in SI.
2. Using a hydraulic jack stand, support the rear axle.

Bulletin No.: 18-NA-108

September, 2019

Page 3

4992651

3. Put a C-clamp on each end of the leaf spring and
tighten so that tension is applied.
4. Remove the lower shock absorber nut. Refer to
Shock Absorber Replacement in SI.
5. Remove the rear spring anchor plate. Refer to
Rear Spring Anchor Plate Replacement in SI.

4956756

Important: The shim MUST be lined up with the leaf
spring.

Tighten
Torque the nut to 100 N.m (74 lb ft) +130°.
7. Install the front coil spring. Refer to Shock
Absorber and Spring Removal/Installation in SI.
Important: The vehicle MUST be driven 3 to 5 miles
(5 to 8 kms) to settle the suspension after the repair has
been made.

Parts Information
Causal
Part

Description

Part
Number

SHIM KIT-RR
AUX SPR

84421341

Qty

23426900
23426901
23426902
23426903
N/A*

23426904
SPRINGFRT COIL

1

23426905
23141685

4958046

6. Lower the hydraulic jack stand just enough to be
able to slide the shim under the spring and the bolt
up through the hole of the spring.
Important: DO NOT disassemble or remove the right
rear leaf spring, also, the removal of the left leaf spring
or the fuel tank is NOT required.

23141684
23141686
23426898
23426899

*For warranty transactions, DO NOT mark this/these
parts as the Causal Part. Enter the word “Bulletin” in the
Causal Part Description free-flow text field.

Page 4

September, 2019

Bulletin No.: 18-NA-108

Follow the steps below for PN chart selection:
1. If the front spring RPO is the same between left/
right (example: 6XU & 7XU, 6 = Left, 7 = Right, the
last two letters are the spring check load) go to
step 2, otherwise go to step 6 (not required to
change any of the front coil spring).
2. If X1 (Left Spring) is greater than X2 (Right Spring)
go to step 3, otherwise go to step 4.
3. From the Front Spring Chart find the Left Spring
RPO and look for the next highest check load RPO
available and go to step 5, if the current spring is at
the highest check load go to step 4.
Note: Before and After measurements must be
attached to the Warranty claim.
4. From the Front Spring Chart find the Right Spring
RPO and look for the next lowest check load RPO
available and go to step 5, if the current spring is at
the lowest check load go to step 3.
Note: Before and After measurements must be
attached to the Warranty claim.
5. Depending on the selection, replace the front left or
front right spring (DO NOT change both springs).
6. Install the Shim Kit on the rear left leaf spring.
Note: The technician will need to add the comments to
the Warranty Claim when the spring RPO is NOT the
same and the vehicle needs the Shim ONLY.
Front Coil Spring Selection Chart (2WD)
GASOLINE LFX / LGZ
Front Left RPO

Front Right RPO

SWB / LWB
Check LOAD

Spring RATE

Part Number

&6B4.

&7B4.

9339

23426901

&6B1..

&7B1.

8680

23426900

&6A9.

&7A9.

8022

&6A8.

&7A8.

7363

78.3

23426899
23426898

GASOLINE LCV / LFX

SWB / LWB

Front Left RPO

Front Right RPO

Check LOAD

&6D5.

&7D5.

9339