ARB RD40 User Manual

INSTALLATION GUIDE

RD40

GM, 9½”, 14 BOLT, 33 SPLINE

Part No. 210240

Revision Date 06/02/07

Copyright © 2001 by ARB Corporation Limited

No liability is assumed for damages resulting in the use of the information contained herein.
ARB Air Locker Locking Differentials and Air Locker are trademarks of ARB Corporation Limited.
Other product names used herein are for identification purposes only and may be trademarks of their respective owners.

ARB 4x4 ACCESSORIES

Corporate Head Office

42-44 Garden St Tel: [phone]
Kilsyth, Victoria Fax: [phone]
AUSTRALIA
3137

Australian enquiries [e-mail]
North and South American enquiries [e-mail]
Other international enquiries [e-mail]

www.arb.com.au

Table of Contents:

1 Introduction 3

1.1 Pre-Installation Preparation 1.2

1.3 Tool-Kit Recommendations 1.4

2 Removing the Existing Differential 5

2.1

2.2

2.3

2.4

2.5

2.6

3 Installing the Air Locker

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

3.10

3.11

3.12

4 Installing the Air System

4.1

4.2

4.3

5 Mounting & Connecting the Electrical System

5.1

5.2

6 Testing & Final Assembly

6.1

6.2

6.3

6.4

7 Parts List

7.1

7.2

Vehicle Support 5
Differential Fluid Drain 5
Removing the Axles 5
Marking the Bearing Caps 6
Checking the Current Backlash Amount 7
Removing the Differential Carrier 8

9

Installing the Carrier Bearings 9
Mounting the Ring Gear 10
Drilling & Tapping the Bulkhead Port 11
Assembling the Differential Carrier 12
Approximating the Backlash for Tube Position 12
Marking the Bearing Cap for Tube Clearance 13
Modifying the Bearing Cap 15
Final Air Locker Assembly 17
Checking the Backlash 17
Profiling the Seal Housing Tube 19
Setting up the Bulkhead Fitting 19
Reinstalling the Axles 21

22

Mounting the Solenoid 22
Running & Securing the Air Line 24
Connection to the Bulkhead Fitting 25

27

Mounting the Actuator Switch(es) 27
Wiring the Actuator System 28

32

Leak Testing 32
Testing the Air Locker Actuation 32
Re-Sealing & Filling the Differential 33
Post-Installation Check List 34

35

Exploded Assembly Diagram 35
Itemized Parts List 36

1

2

1 Introduction

IMPORTANT :

BEFORE ATTEMPTING TO DISMANTLE YOUR VEHICLE FOR THIS

INSTALLATION, PLEASE READ THIS INSTALLATION GUIDE IN ITS

ENTIRETY, AS WELL AS ALL APPLICABLE SECTIONS OF YOUR

VEHICLE MANUFACTURER’S SERVICE MANUAL.

1.1 Pre-Installation Preparation

This booklet is to be used in conjunction with your vehicle
manufacturer’s service manual. ARB endeavors to account for every
possible variation in vehicle model when publishing its installation
guides, and guides are updated regularly as new model information
becomes available, however, the rapid and globally varied release of
some vehicles makes it difficult to insure that your vehicle model has
been accurately accounted for. In the case of any technical
discrepancies between this guide and your service manual, we
strongly advise that you adhere to the specifications and techniques
as documented in your service manual.

Although your ARB Air Locker comes complete with all the step by
step instructions you will need to supplement your vehicle
manufacturer’s service manual and install your new differential, ARB
recommends that you have your Air Locker installed by a trained
professional. Many ARB distributors around the world have been fully
instructed in Air Locker installations by ARB, and have gained a wealth
of experience and skill from years of performing similar installations.

Once you begin this installation your vehicle will be immobile until all
steps of the installation are complete. Make sure your Air Locker kit is
the correct model for your vehicle and that it contains all of the parts
listed on back cover of this booklet. Also be sure you have
appropriately equipped yourself with all the necessary tools, parts, and
materials to complete this installation (see section 1.2 Tool-Kit
Recommendations), and that you have allowed for an appropriate
amount of vehicle down time.

HINT : Place a mark inside each of the  symbols as

you complete each step. It is very important NOT to
miss any of the steps!

3

1 Introduction

1.2 Tool-Kit Recommendations

Below is a list of tools and supplies you may need to complete this
installation. Requirements for your vehicle may vary. Plea se consult your
vehicle service manual for additional recommendations.

1.2.1 Tools

 Standard automotive sizes (metric and/or imperial) of sockets,

wrenches, Alan keys, and drills.

 A dial indicator or other suitable measuring tool for checking ring &

pinion backlash.

 A standard automotive feeler gauge.
 Automotive brake tubing cutters to cut the steel tubing.
 A razor knife to cut the nylon tubing.
 An adjuster nut wrench.
 A torque wrench. (See vehicle service manual for required torque

range.)

 A lubricant drain reservoir.
 Suitable measuring tools to measure a differential for pre-load

and/or backlash.

 An 11.2mm [7/16”] drill and ¼” NPT tap for bulkhead fitting

installation.

 An automotive bearing puller (2 jawed is recommended) or a

differential carrier bearing puller.

 A bearing press or arbor press.

1.2.2 Supplies

 Thread lubricant/sealant compound (e.g., LOCTITE #567)
 Thread locking compound (e.g., LOCTITE #272)
 Either a replacement gasket, or gasket sealant, for your differential

cover.

 A sufficient volume of differential oil to completely refill your

housing. (see the ARB Air Locker Operating and Service Manual
for recommended lubricants)

 A soap and water mixture to test for air leaks.
 Teflon paste.

4

2 Removing the Existing Differential

2.1 Vehicle Support

 Safely secure the vehicle on a hoist. We recommend supporting the

vehicle on a chassis hoist to keep the differential area at a
convenient working height and to leave the wheels and axles free to
be rotated and removed.

 Once supported off the ground, release the parking brake and leave

the vehicle in neutral. Chock the wheels if necessary.

2.2 Differential Fluid Drain

 Clean around the differential cover plate seal to prevent dirt from

entering the differential.

 Position a fluid drain reservoir under the differential and loosen all

differential cover plate retaining bolts.

 Gently pry the cover plate away from the differential housing to

completely drain all differential fluid.

 Once drained, remove differential cover plate.

HINT : This is a good time to check for metal particles in

your oil and in the bottom of the housing which may
indicate a worn bearing or differential component.

2.3 Removing the Axles

IMPORTANT:

Collision damage or heavy off-road use of your vehicle in the past may

have resulted in some degree of bending in the axle. Any misalignment of

the axle tubes may result in excessive wear and/or failure of your

differential and axle shafts. ARB strongly recommends that you have your

axle assembly inspected for concentricity and straightness before

installing your Air Locker.

NOTE : If the Air Locker is being installed into a non-‘C’ clip

housing then the cross shaft may not need to be
removed, however, the cross shaft pin retaining pin will
need to be installed and the retaining screw will still need
to have a thread locking compound applied and be
installed into the Air Locker and tightened before final
assembly (see Section 4.12 Reinstalling the Axles).

5

2 Removing the Existing Differential

 Remove the wheels and brake assembly according to your vehicle’s

service manual.

 Remove the cross shaft retaining pin and cross shaft (Refer to your

vehicle service manual.).

 Rotate the differential until the ‘C’ clip access window is accessible.
 Gently tap the axle ends inward to release the ‘C’ clips.
 Remove ‘C’ clips with needle nose pliers.
 Gently tap axles outward and remove them from the differential

center.

NOTE : Rubber oil seals can be easily damaged. Support the

weight of the axle when extracting it across the edges of
the seals.

2.4 Marking the Bearing Caps

 Using a pointed center punch, gently mark the bearing caps in a way

that will enable you to know which cap is ‘LEFT’ and which cap is
‘RIGHT’, which way is ‘UP’ and which way is ‘DOWN’. (Fig.1.)

HINT : Many installers choose to make one punch mark on

the left hand side of the left hand bearing cap and one
similar punch mark on the housing at close proximity to
the cap mark. The right hand side is then designated
with two punch marks on the right hand side of the cap
and two similar punch marks on the housing.

Figure 1.

6

2 Removing the Existing Differential

2.5 Checking the Current Backlash Amount

IMPORTANT:

This step is a precautionary measure recommended by ARB due to

the fact that some after market ring and pinion sets have been

manufactured to run with different backlash settings than those

specified by your vehicle manufacturer. Although ARB must

recommend you set backlash according to your service manual

guidelines, we also advise that you compare the backlash

measurements taken here to the recommended backlash settings

in your vehicle service manual. Measurements found to be outside

of your service manual recommendations may indicate the need to

deviate from those settings in order to achieve quiet running with a

good contact mark.

Refer to your vehicle service manual or your local authorized ARB

installer for more information.

 Set a depth indicator on one of the ring gear teeth as in Figure 2.

Figure 2.

 While supporting the pinion gear by holding the drive shaft, rotate the

differential in both directions while observing the maximum variation
in depth from the indicator (i.e., the highest value minus the lowest
value). This value is referred to as the ring and pinion backlash.

 Rotate the differential center 90° and measure again for accuracy.
 Record the average of all measurements.

7

2 Removing the Existing Differential

2.6 Removing the Differential Carrier

 Loosen the adjuster nuts.
 Remove the bearing caps from the third member.
 Carefully remove the differential carrier from the third member.

NOTE : The differential center is heavy and quite difficult to

handle when covered in oil. Take care not to drop it.

 Remove the tapered roller bearings from the differential carrier with a

bearing puller. (Fig.3.)

HINT : Check the condition of the bearing for wear and replace

if necessary.

Figure 3.

 Secure the original differential to a work bench.
 Remove the bolts that hold the ring gear in place.

NOTE : GM 9.5” ring gear bolts are usually left hand threaded.

 Using a plastic or copper hammer, tap in a circle around the ring

gear to separate it from the differential carrier.

8

3 Installing the Air Locker

3.1 Installing the Carrier Bearings

 With the Air Locker well supported in an arbor press, apply a thin

film of high pressure grease to the ring gear side bearing journal.

 Press the tapered roller bearing cone onto the bearing journal of

the differential carrier until the bearing seats firmly against the
shoulder of the Air Locker.

NOTE : Never re-use any bearings which are damaged or

worn.

 Invert the Air Locker and apply a thin film of high pressure grease

to the seal housing side bearing journal.

 Press the bearing cone which was supplied with the Air Locker kit

onto the bearing journal, taking care not to damage the o-ring
grooves. (Figure 4.)

Figure 4.

9

3 Installing the Air Locker

3.2 Mounting the Ring Gear

 Apply a thin film of high-pressure grease to the ring gear shoulder

 Thoroughly clean any thread locking compound or other foreign

HINT : Rubbing the ring gear mounting face with a flat oil

 Heat the ring gear to between 80 and 100°C (175 - 212°F) in an

of the Air Locker to prevent seizing.

matter from the holes of the ring gear, the threads of the ring gear
bolts, and the mating surfaces of the ring gear and the Air Locker
flange.

stone before installation will remove any high spots
around the threads

.

oven or in hot water to slightly expand the gear and facilitate
assembly.

NOTE : NEVER HEAT GEARS WITH A FLAME! This could

damage the hardened surface of the gear and result in
premature wear or failure.

 Dry the ring gear with compressed air (if wet), paying particular

attention to the threaded holes.

 Install the ring gear onto the Air Locker by aligning the holes in the

flange with the tapped holes in the ring gear, then gently tapping it
around in a circle with a plastic or copper hammer.

NOTE : Avoid using the bolts to pull down the ring gear as

this puts excess strain on the bolts and the differential
flange.

 Apply a thread locking compound to the thread of each ring gear

bolt before inserting it.

NOTE : Do not apply threading compound directly into the

threaded hole as this could prevent the bolt from
reaching its full depth.

 Tighten the ring gear bolts in a star pattern with a torque wrench

according to your vehicle manufacturer’s specified torque.

10

3 Installing the Air Locker

3.3 Drilling and Tapping the Bulkhead Port

A port must be drilled and tapped through the differential housing to
allow the seal housing tube through the housing to connect with the air
line from the air compressor.

 Mark a spot for the bulkhead port on the right hand (seal housing)

side toward the top of the differential housing that is in an area that
will be well clear of the ring gear, the differential, and any other
obstructions that may snag the seal housing tube.

 Cover the drive pinion and axle tube areas with a rag to protect

them from metal filings.

Figure 5.

 Drill through the housing square to the outside surface using an

11.2mm [7/16”] drill. (Fig.5.)

 Tap the hole from the outside using a ¼’’ NPT tapered pipe thread

tap.

 Remove any sharp edges from the hole that may chip-off and fall

into the housing.

 Very carefully remove rags and inspect with a service light inside

the housing to insure no metal filings are left behind.

11

3 Installing the Air Locker

3.4 Assembling the Differential Carrier

 Place the bearing cups over the bearing cones.
 Slide the seal housing into place against the bearing cup (stepped

side out).

NOTE : The grooves in the bearing journal under the seal

housing, will house the O-rings in the final assembly
but they will not be installed now to avoid damage to
the O-rings.

 Insert and hold the Air Locker into the differential housing with the

seal housing tube pointing straight out of the housing.

 Install one bearing cap on the ring gear side. The bearing cap on

the seal housing side will need to be drilled or slotted as clearance
for the seal housing tube.

 Install the bearing cap bolts finger tight.

3.5 Approximating the Backlash for Tube Position

If the backlash is not close enough to the specified amount, the seal
housing tube position cannot be accurately measured to modify the
bearing cap for tube clearance. This must be checked before hand.

 Set a depth indicator on one of the ring gear teeth as in figure 6.

Figure 6.

12

3 Installing the Air Locker

 While supporting the pinion gear by holding the drive shaft, rotate

the differential in both directions while observing the maximum
variation in depth from the indicator (i.e., the highest value minus
the lowest value).

 Set the backlash to a value less than 0.5mm [0.02”] by rotating the

adjuster nuts.

NOTE : This backlash value is for the tube position only and

will not be used for final assembly.

3.6 Marking the Bearing Cap for Tube Clearance

With the Air Locker in place and less than 0.5mm of backlash, an
accurate measurement for the seal housing tube clearance can be
made.

NOTE : Take time and double check when taking your

measurements, as bearing caps are custom fitted to
the axle housing and cannot be replaced.

 With the seal housing tube pointing straight out, measure the

distance from a fixed position inside the differential housing to the
center of the seal housing tube. (Fig.7.)

Figure 7.

 Record your findings and recheck for accuracy.
 Remove the bearing cap from the ring gear side of the differential.
 Remove the Air Locker from the differential housing.

13

3 Installing the Air Locker

 Install the seal housing side bearing cap and hand-tighten the

bearing cap bolts.

NOTE : It is very important to make sure the punch marks

made on the differential housing while removing the
differential are matched to the punch marks on the
bearing cap. The bearing cap must be replaced
exactly as it was removed. (Refer to section 2.4)

 Measure to the bearing cap from exactly the same position on the

differential housing that you took the previous measurements from.
(Fig.8.)

 Mark the tube position with a center punch where the clearance is

to be made for the seal housing tube.

Figure 8.

 Remove the bearing cap from the differential housing.
 Measure the distance from the center punch mark made on the

bearing cap to the closest edge of the bearing cap.

 If the center punch mark is greater than 6.35mm [¼’’] from the

closest edge of the bearing cap, it is recommended that a small
hole be drilled through the bearing cap (Section 4.7.1). If less than

6.35mm [¼’’] from the edge it is recommended that a notch is filed
into the side of the bearing cap to avoid break-through while drilling
(Section 4.7.2).

14

3 Installing the Air Locker

3.7 Modifying the Bearing Cap

3.7.1 Drilling the Bearing Cap

 Hold the bearing cap steady for drilling in a soft jawed vise clamp.

NOTE : Do not apply too much clamping pressure with the

 Using a pedestal drill, drill a 6.35mm [¼’’] hole through the bearing

cap where the seal housing tube hole has been marked.
(Fig.9.)

 Remove the bearing cap from the vise, turn it upside down, and

re-clamp it in the vise.

vise. The bearing cap may be damaged.

Figure 9.

 The drilled hole must be chamfered approximately 3mm [1/8”] to

remove any sharp edges that may chip-off and fall into the housing.
(Fig. 10.)

15

3 Installing the Air Locker

Figure 10.

3.7.2 Notching the Bearing Cap

 Use a soft jawed vise clamp to hold the bearing cap steady.
 Using a 6.35mm [¼’’] rat-tailed file. File out a notch in the bearing

cap from the closest edge until an adequate notch has been cut
around the position of the punch mark. (Fig. 11.).

Figure 11.

 File a chamfer around the inside edge of the notch to remove any

sharp edges from the notch that may chip-off and fall into the
housing.

16

3 Installing the Air Locker

3.8 Final Air Locker Assembly

 Remove the seal housing and clean all parts of the differential

assembly. It is very important to make sure the bearing journal
grooves are free from any contaminants (eg: water, dirt, metal
fillings, etc.)

 Lubricate the O-rings with oil (prior to assembly), then stretch them

over the bearing journal and release them into the grooves.

NOTE : Do not roll the O-rings onto the seal housing as this

will damage them.

 Place the bearing cups onto their respective bearing cones.
 Install the seal housing over the O-rings by gently applying a

downward twisting motion. This will allow the O-rings to gently
engage.

 Point the seal housing tube straight out of the housing, hold the

tapered roller bearing cups in place, and insert and hold the Air
Locker into the differential housing.

 Install the bearing cap on the ring gear side.
 Check to see if the bearing cap on the seal housing side fits over

the tube without fouling.

NOTE : Do not forget to check the bearing caps are turned the

correct way around.

 Install all bearing cap bolts and hand tighten.

3.9 Checking the Backlash

 Set a depth indicator on one of the ring gear teeth (Fig.12.).
 While supporting the pinion gear by holding the drive shaft flange,

rotate the differential in both directions while observing the
maximum variation in depth from the indicator (i.e., the highest
value minus the lowest value). This value is referred to as the ring
and pinion backlash.

 Rotate the differential center 90° and measure again for accuracy.
 Refer to your vehicle service manual for the specified maximum

and minimum amounts of backlash.

17

3 Installing the Air Locker

IMPORTANT:

It is critical to set up bearing pre-load when a differential is

installed. Improper pre-load will result in undue bearing wear,

increased stresses in the differential center, increased running

noise, and ultimately, ring and pinion gear damage.

 Adjust the backlash and pre-load using an adjuster nut wrench to

tighten or loosen the adjuster nuts as required. (Refer to your
vehicle service manual.)

 Recheck backlash as before, repeating this procedure until

backlash is within the specified amount.

 Tighten all bearing cap bolts with a torque wrench to the torque

specified in your vehicle manufacturer’s service manual.

Figure 12.

18

3 Installing the Air Locker

3.10 Profiling the Seal Housing Tube

 Without using sharp, jagged tools such as pliers (usually your

hands are the best tool for this job), bend the seal housing tube so
that it closely follows the profile of the differential housing and
protrudes through the bulkhead port in the differential housing.

(Fig. 13.)

Figure 13.

 Check that the contour of the tube will not interfere with the ring

gear, differential, or the cover plate.

4.11 Setting up the Bulkhead Fitting

 Trim the seal housing tube that is extended outside the differential

housing to approximately 20-25mm [0.8-1.0”] of extension using an
automotive brake line tubing cutter.

NOTE : Never use a hacksaw for trimming the steel tube as

this will leave metal fillings in the air system.

 Apply thread sealant to the threads of the bulkhead body.
 Screw the bulkhead body into the tapped hole, and tighten.
 Wipe the area clean of any excess thread sealant (inside and

outside of the housing).

19

3 Installing the Air Locker

 From the outside of the housing, assemble the small O-ring over

the top of the short length of seal housing tube protruding through
the bulkhead fitting.

 While holding the seal housing tube into the bulkhead fitting, insert

the small drilled end of the center compression nut over the
extended tube as shown in the assembly diagram (Fig.14.), and
screw it into the bulkhead body, and lightly tighten.

NOTE : Be sure to insert the correct end of the center

compression nut into the bulkhead body. The thread
has been partially relieved on the bulkhead side of the
center compression nut to visually identify its
orientation. (Fig.14.)

Figure 14.

NOTE : Excessive tightening of the center compression nut is

not necessary to form a good seal around the tube
and may damage the O-ring, the seal housing tube, or
the threads of the compression nut.

NOTE : Make sure the seal housing tube is all of the way into

the center compression nut while you are tightening
it.

20

3 Installing the Air Locker

 Again check that no part of the seal housing tube comes in contact

with the moving differential components. Less than 8mm [5/16”]
should be considered too little clearance. Gently bend the tube
away from moving parts if necessary.

3.12 Reinstalling the Axles

 Rotate the differential center until the circular access window in the

differential is in view and accessible.

 Insert both axles fully into the housing and gently tap them inward.
NOTE : Be careful not to damage oil seals with the axle.

 Install the ‘C’ clips on to the ends of the axles.
 Gently tap the axles outward until both ‘C’ clips are fully seated.
 Insert the cross shaft maintaining alignment between the cross

shaft retaining pin hole in the differential and its corresponding hole
in the cross shaft.

 Ensure that some degree of axle end float exists (i.e., some

clearance exists between the end of the axle and the cross shaft or
thrust block). ‘C’ clips may need to be substituted with others of a
different thickness to achieve correct end float if too tight or too
loose.

 Insert the cross shaft retaining pin (threaded end out) to its

maximum depth.

 Apply thread locking compound to the threads of the button head

screw (supplied).

 Assemble the locking washer onto the screw, and insert and tighten

the screw into the retaining pin hole.

 Torque the button head screw to 24Nm [17.7 ft.lbs].
 Reassemble brakes and wheels according to your vehicle’s service

manual.

21

4 Installing the Air System

4.1 Mounting the Solenoid

4.1.1

 Remove one of the 1/8” BSP plugs from its port in the compressor

 Apply Teflon paste to the nipple (1/8” X 1/8” BSP) and insert it into

 Apply Teflon paste to the free end of the nipple.
 Assemble the inlet port side of the solenoid (stamped with a ‘1’)

NOTE : The solenoid exhausts compressed air through the

 Apply Teflon paste to the threads of the 5mm push-in fitting and

Connection to an ARB Air Compressor (Fig.15.)

tank.

the port and tighten.

onto the nipple and tighten. The solenoid should be rotated into a
position that does not obstruct any other ports on the compressor
tank.

center of the black retaining cap when the Air Locker
is disengaged. Make sure this orifice cannot be
obstructed.

assemble it into the solenoid outlet port (stamped “2”) and hand
tighten.

ARB

Air Compressor

Figure 15.

22

4 Installing the Air System

4.1.2 Connection to an Alternate Air Source

For ease of installation, quality of air supply, and a high level of
dependability from your
of a genuine ARB Air Compressor, however, the
can be operated on any alternate air source that meets each of the
following guidelines:

 Must supply a minimum of 85PSI [586kPa].
 The supply must never exceed 105PSI [724kPa].
 The Air source should have a tank capacity that enables it to

actuate the Air Locker(s) in one charge so that no hesitation
is experienced when locking one or two differentials.

HINT : A good way to insure that you have the necessary

capacity is to make sure you can engage, disengage,
and then reengage your Air Locker(s) without the air
source having to regenerate (e.g., without the
compressor turning on to refill the tank).

 Must supply clean air, free of rust, dirt, water, or other foreign

matter.

Air Locker(s), ARB strongly recommends use

Air Locker air system

 Must match the 1/8” BSP porting of the Air Locker solenoid.

 Mount solenoid within close proximity of the air supply and secure it

from the effects of vibration and shock.

 Connect the air supply to the 1/8” BSP inlet port of the solenoid

(stamped “1” on the solenoid body) using thread sealant.

IMPORTANT :

ARB cannot warrant your Air Locker(s) against damage caused

as a result of using an alternate air supply. If you have any

doubts as to the suitability of your air system to use in an Air

Locker system, consult your ARB distributor.

23

4 Installing the Air System

4.2 Running and Securing the Air Line

The path taken by the air line from your air source (i.e., compressor) to
your
source. Plan ahead carefully when running the air line and always
follow these guidelines:

 Account for axle travel when running the line from the axle to a

 Avoid leaving large lengths of air line hanging underneath the

HINT : Cable tying the air line to one of your flexible brake

 Run the air line all the way from the compressor to the differential

Air Locker is unique to your vehicle and the position of your air

fixed point on the vehicle. Leave enough slack in the air line to
allow for maximum suspension travel in both directions.

vehicle where they may get tangled on rocks, sticks, etc.

lines will account for axle travel and should help keep
your line from getting snagged.

before trimming either end of the line to length. This will save
complications that may arise if the air line has to be removed.

 Make sure the line does not contact sharp edges or abrasive

surfaces that may damage the air line over time.

 Do not run the air line around tight bends which may kink the air

line and restrict or block the air flow.

 Keep the air line well away from your vehicle’s exhaust

components. Air lines will melt if subjected to extreme heat.

 Do not run more air line than necessary. Excess line volume

created when coiling the left over hose, using unusually large
diameter hose, etc., will increase drain on the compressor tank
resulting in the compressor running more often than needed.

 Support the air line by tying it back with cable ties wherever

possible.

 At the solenoid end of the air line, trim the line to length with a

sharp knife.

 To attach the air line to the push-in fitting of the solenoid; insert the

line firmly into the fitting, pull outward on the flange of the fitting
while holding the line as far into the fitting as possible, and then
gently pull outward on the air line to clamp the line in place.

24

4 Installing the Air System

NOTE : To remove the air line from the push-in fitting; while

holding the flange of the fitting out, push the air line
into the fitting as far as possible, then press the flange
inward, then pull the air line free of the fitting.

4.3 Connection to the Bulkhead Fitting

 Trim the air line to length using a sharp knife.
 Insert the support spring over the end of the air line - small end first.

(Fig.16.)

 Insert the outer compression nut over the air line.
 Insert the 5mm [0.197”] ferrule over the end of the air line. Leave

approx. 5mm of tubing between the ferrule and the end of the tube.

Figure 16.

 Insert the support tube all the way into the end of the air line.

25

4 Installing the Air System

HINT : If the support tube is too difficult to insert, place the

end of the air line into a cup of boiled water to soften
the tubing.

 Insert the tube end all the way into the center compression nut.
 Screw on the outer compression nut and tighten. The ferrule and

support tube are now permanently attached.

 Assemble the support spring over the outside of the outer

compression nut.

 Secure any loose sections of tube with a cable tie.

26

5 Mounting & Connecting the Electrical System

5.1 Mounting the Actuator Switch(es)

Air Locker actuator switch(es) can be easily panel mounted inside the
vehicle in a 21mm x 36.5mm [0.83” x 1.44”] rectangular cutout.

NOTE : Only attach the cover plate to the face of the switch

once the switch has been mounted and wired correctly
as the cover plates are designed to be difficult to
remove.

For reasons of safety and for ease of operation, the Air Locker
actuator switch(es) should be mounted in a location picked to best suit
the operator. Make sure you have taken the following points into
consideration:

 Switch(es) MUST be mounted and should never be allowed to

simply dangle from the wiring loom during vehicle use.

 Switch(es) should be within easy reach of the driver. Ideally, any

Air Locker switch should be able to be operated without physical
effort or distraction to the driver.

 Switch(es) should be mounted within the line of sight of the driver

so that switch position (‘ON’ or ‘OFF’) can be visually determined
by the rocker position and the illumination state.

 The position of the switch(es) should best eliminate any possibility

of accidental operation by the driver or one of the passengers.

 Switch cutout position(s) must be located in an area with a

minimum of 50mm [2”] of clearance behind the face of the cutout.

 Switch(es) should not be mounted where they will be exposed to

water (e.g., in the lower section of an inner door panel).

 ARB recommends that you apply the Air Locker Warning Sticker

(ARB part # 210101) within close visual proximity of the switch
location.

NOTE : If no adequate position can be found on existing

dashboard panels, a surface mounted bracket
(Fig. 17.) may be purchased from your ARB Air Locker
distributor to suit 1, 2, or 3 switches.

27

5 Mounting & Connecting the Electrical System

Figure 17.

5.2 Wiring the Actuator System

5.2.1

Connection to an ARB Air Compressor

When wiring the Air Locker actuator switch(es) and solenoid(s) to an
ARB Air Compressor, all connections can easily be set up directly from
the supplied wiring loom. (Fig. 18.)

NOTE : Refer to your ARB Air Compressor Installation Guide

for details on configuring your installation.

28

5 Mounting & Connecting the Electrical System

ARB AIR COMPRESSOR WIRING LOOM

SWITCH

IDENTIFICATION

TERMINAL

Figure 19.

Figure 18.

UP

29

5 Mounting & Connecting the Electrical System

5.2.2 Connection to an Alternate Air Source

When connecting the actuation switch to an alternate air source, the
switch(es) should be wired according to figures 20. and 21., depending
on whether one or two Air Lockers will be installed in the vehicle.

5.2.2.1 Single Air Locker System

 If only one Air Locker is to be installed in the system, the switch and

solenoid should be wired according to figure 20. regardless of
whether the Air Locker has been installed in the front or rear axle of
the vehicle.

 Attach the appropriate switch cover (i.e., ‘FRONT’ or ‘REAR’) to

the switch.

NOTE : Refer to Figure 19. for the correct switch terminal

identification and switch orientation.

SINGLE Air Locker SYSTEM

Figure 20.

30

5 Mounting & Connecting the Electrical System

5.2.2.2 Dual Air Locker System

 If two Air Lockers are to be installed in the system, ARB

recommends that the switches and solenoids be wired according to
figure 21. For safety reasons, this configuration allows SOLENOID
2 to be actuated only if SOLENOID 1 is already on.

 Attach the “REAR Air Locker” switch cover to SWITCH 1, and the

“FRONT Air Locker” switch cover to SWITCH 2.

NOTE : Refer to Figure 19. for the correct switch terminal

identification and switch orientation.

 Configure SOLENOID 1 as the air line leading to the rear axle Air

Locker, and SOLENOID 2 as the air line leading to the front axle Air
Locker.

DUAL Air Locker SYSTEM

Figure 21.

31

6 Testing & Final Assembly

6.1 Leak Testing

 With the vehicle parked and the engine off, turn the compressor on

and wait until the air system is fully charged.

NOTE : With the Air Locker(s) disengaged, the air source (i.e.,

compressor) should not have to recharge over time.
Intermittent recharging without Air Locker use usually
indicates a leak at the solenoid fittings or at the
compressor tank O-ring seal.

 Actuate the Air Locker(s).
 The compressor should not come on again for a period of at least

15min. Air system recharging within that time period would indicate
that a leak is present in the system.

NOTE : If an alternate air source (e.g., an air cylinder or a belt

driven air pump) is used instead of a compressor, the
air system will have to be leak tested with a pressure
gauge and a shut-off valve in series before the
solenoid input.

 If a leak is found to be present, spray a soap and water mixture

onto all air fittings in the system while the compressor is fully
charged. Bubbles should appear at any leak points.

 Check that leaky fittings have been adequately tightened.
 Disassemble, clean threads, and reapply thread sealant if leaking

persists.

6.2 Testing the Air Locker Actuation

To test that your air system, electrical system, and your Air Locker
differential is functioning correctly:

 Support the vehicle such that the wheels are free to rotate (e.g., on

axle stands, a chassis hoist, etc.)

 Leave the parking brake off, the transmission in neutral, and the Air

Locker switch ‘OFF’.

32

6 Testing & Final Assembly

 Turn the ignition to the ‘ON’ position (leaving the motor off). The

large illuminating symbol on the Air Locker switch cover should be
‘OFF’.

 Turn the compressor (or alternate air source) on to charge the air

supply up to its maximum pressure.

 Rotate one wheel by hand.
 The wheel should rotate freely and the opposite wheel should be

turning in the opposite direction without any resistance or
mechanical noise from within the differential.

 Turn the Air Locker switch to the ‘ON’ position. The illuminated

symbol on the switch cover should light up.

 Rotate the same wheel again.
 Both wheels should rotate together.
 Turn the switch off again.
 Rotate the same wheel.
 The wheels should again rotate in opposite directions.

6.3 Re-Sealing & Filling the Differential

NOTE : Consult the ARB Air Locker Operating & Service

Manual for recommendations on differential lubricant
specifications.

 Replace the differential cover using gasket sealant or a new

standard differential cover gasket for your make of vehicle.

 Refill the differential until level with the filler hole.
 Rotate the differential center 2 full turns.
 Check the oil level and add oil if necessary.
 Replace filler plug (apply thread sealant to filler plug before

inserting if it is a threaded type plug).

 Wipe differential housing clean of any oil or grease which may

collect dirt or other abrasive particles.

33

6 Testing & Final Assembly

6.4 Post-Installation Check List

Now that the Air Locker installation has been completed, ARB
recommends that you take the time to complete the following check list
just to insure that you haven’t missed any of the vital steps.

 The air system has been leak tested.
 Thread locking compound was used on the ring gear bolts.
 All torque settings comply with the vehicle manufacturer’s specs

and were set with an accurate torque wrench.

 Differential fluid complies with ARB recommendations and has

been filled to the correct level.

 All air lines and wiring have been securely cable tied to resist

snagging.

 Switch(es) have been securely mounted within operator reach, yet

well away from danger of accidental engagement.

 Switch(es) function correctly and illuminate to indicate that Air

Locker(s) have been engaged.

 All operators who are to use the Air Locker have read, and fully

understand the ARB Air Locker Operating & Service Manual.

 The Air Locker Warning Sticker has been located within close

proximity of the actuator switch(es).

INSTALLATION PERFORMED BY:

DATE OF INSTALLATION:

ODOMETER READING:

ARB AIR LOCKER SERIAL No:

___________________________
___________________________
___________________________
___________________________

34

7 Parts List

7.1 Exploded Assembly Diagram

(See itemized parts list overleaf)

Figure 22.

35

7 Parts List

7.2 Itemized Parts List

(See exploded diagram figure 22.)

AIR LOCKER MODEL No. : RD40

ITEM # QTY DESCRIPTION PART #

01 1 FLANGE CAP 022001
02 1 CLUTCH GEAR 050402
03 1 DIFFERENTIAL CASE 012101
04 4 PISTON SPRING 150101
05 1 CROSS SHAFT RETAINING PIN 120401

* 1 HEX HEAD SCREW 6151172
* 1 LOCK WASHER 4581059

* 1 PIN WITHDRAWAL TOOL 1201T
06 1 LONG CROSS SHAFT 060901
07 1 PISTON (Polyamide) 040501
08 1 BONDED SEAL 160703
09 1 CYLINDER CAP 031001
10 2 SEAL HOUSING O-RING 160211
11 8 CYLINDER CAP RETAINING BOLT 200204
12 1 TAPERED ROLLER BEARING 160110
13 1 SEAL HOUSING ASSEMBLY 080901
14 1 SPLINED SIDE GEAR 130802
15 2 PINION GEAR 140402
16 2 PINION THRUST WASHER 151104
17 1 SIDE GEAR 130702
18 2 SIDE GEAR THRUST WASHER 151004

* 1 ‘C’ CLIP KIT CCK002

* 1 BULKHEAD KIT, O-RING TYPE, 3.5-5mm 170105

* 1 PUSH-IN FITTING,5mm (R1 5 1/8”) 170201

* 1 AIR LINE (5mm DIA X 6m LONG) 170301

* 1 NIPPLE, 1/8” BSP,MALE TO MALE 170501

* 1 SOLENOID VALVE 180103

* 1 ACTUATOR SWITCH 180209

* 1 SWITCH COVER (REAR) 180211

* 10 CABLE TIE 180301

* 1 WARNING LABEL 210101

* 1 BUMPER STICKER 210102

* 1 OPERATING & SERVICE MANUAL 210200

* 1 INSTALLATION GUIDE 210240

* Not illustrated in exploded view.

36