ARB RD99 User Manual

INSTALLATION GUIDE

RD99

FORD 9”, 35 SPLINE

Part No. 210299

Revision Date 07/06/2006

Copyright © 2003 by ARB Corporation Limited

No liability is assumed for damages resulting in the use of the information contained herein.
ARB Air Locker Air Operated 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 Central and South American enquiries [e-mail]
Other international enquiries [e-mail]

www.arb.com.au

Table of Contents:

1 Introduction 3

Pre-Installation Preparation 3

1.1

Tool-Kit Recommendations 4

1.2

Assembly Type Identification 5

1.3

2 Removing the Existing Differential 6

Vehicle Support 6

2.1

Differential Fluid Drain 6

2.2

Removing the Axles 7

2.3

Marking the Bearing Caps 7

2.4

Checking the Current Backlash Amount 8

2.5

Removing the Differential Carrier 9

2.6

3 Installing the Air Locker 10

Installing the Carrier Bearings 10

3.1

Re-Mounting the Ring Gear 11

3.2

Drilling and Tapping the Bulkhead Port 12

3.3

Checking for Assembly Clearance 13

3.4

Checking the Backlash 15

3.5

Assembling the Seal Housing 16

3.6

Profiling the Seal Housing Tube 18

3.7

Setting Up the Bulkhead Fitting 19

3.8

Bench Testing the Air Locker 21

3.9

3.10

4 Installing the Air System 23

5 Mounting & Connecting the Electrical System 28

6 Testing & Final Assembly 33

Reinstalling the Differential and Axles 22

Mounting the Solenoid 23

4.1

Running & Securing the Air Line 25

4.2

Connection to the Bulkhead Fitting 26

4.3

Mounting the Actuator Switch(es) 28

5.1

Wiring the Actuator System 29

5.2

Leak Testing 33

6.1

Testing the Air Locker Actuation 34

6.2

Re-Sealing & Filling the Differential 34

6.3

Post-Installation Check List 35

6.4

7 Parts List 37

Exploded Assembly Diagram 37

7.1

Itemized Parts List 38

7.2

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. Please 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.
 A razor knife to cut the nylon tubing.
 An adjuster-nut wrench. (See your vehicle service manual)
 A torque wrench. (See vehicle service manual for required torque

range.)

 A lubricant drain reservoir.
 A 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 for pressure fittings

(e.g., LOCTITE #567 Teflon paste)

 Thread locking compound (e.g., LOCTITE #272)
 Either a replacement gasket, or gasket sealant for sealing the third

member to the axle housing.

 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

1 Introduction

1.3

Assembly Type Identification

IMPORTANT:

ARB’s RD99 Air Locker differential was not designed for use with the
factory standard Ford third member assembly (i.e., the original third
member produced by the Ford Motor Company to accept either 28 or
31 spline axle shafts).

Before proceeding with installation of this Air Locker it is highly
recommended that you ensure you have a third member assembly
which accepts tapered roller bearings of the dimensions shown in
Figure 1.

Figure 1.

Contact ARB or your local ARB distributor if you cannot determine
which Air Locker was designed for your application.

Also note that this document was written in reference to a standard
factory Ford type of axle assembly, and therefore, special installation
considerations due to any variations that might exist such as front
applications or high pinion and independent suspension models of
third member will have to be accounted for by the individual installer.

5

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

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

your oil, on your drain plug, or in the bottom of the
housing which may indicate a worn bearing or
differential component.

 Clean any loose dirt from around the differential third member

flange area, the filler plug area, and the drain plug to avoid
contaminating the differential cavity with abrasive particles.

 Position a fluid drain reservoir under the differential.
 Remove the drain plug and completely drain all differential oil from

the housing.

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 HOUSING. 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.

6

2 Removing the Existing Differential

2.3

Removing the Third Member

 Disconnect the drive shaft from the pinion flange.
 Remove both of the rear wheels and brake drums/rotors according

to your vehicle manufacturer’s service manual.

 Slide the axle shafts outward until they are completely disengaged

from the splines of the differential side gears.

NOTE : The oil seals are delicate and can be easily damaged.

Support the weight of the axle shafts when drawing
them out of their sockets in the housing.

 Remove the third member flange bolts.
 Completely remove the third member from the axle housing.
 Support the third member firmly in a vice or on a work bench.

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.2.)

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 2.

7

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 3.

Figure 3.

 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 carrier 90° and measure again for accuracy.
 Record the average of all measurements.

8

2 Removing the Existing Differential

2.6

Removing the Differential Carrier

 Remove both adjuster nut locking tabs.
 Loosen both bearing caps.
 Using the appropriate adjuster nut wrench, loosen the adjuster

nuts at least half a turn.

 Remove the bearing caps, adjuster nuts, and tapered roller bearing

cups.

 Carefully remove the differential carrier.

NOTE : The differential carrier is heavy and quite difficult to

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

9

3 Installing the Air Locker

3.1

Installing the Carrier Bearings

 If the tapered roller bearings from the original differential carrier are

to be reused, then remove them with an automotive bearing puller
and inspect them for damage and/or wear and replace them if
necessary.

 Apply a thin film of high pressure grease to both bearing journals of

the Air Locker to prevent seizing.

 Using a bearing press or arbor press, press one of the bearing

cones (supplied with the Air Locker kit) onto one bearing journal of
the Air Locker until the bearing seats firmly against the bearing
journal shoulder.

 Invert the Air Locker and press the other tapered roller bearing

cone onto the opposite bearing journal of the differential carrier until
the bearing seats firmly against the bearing journal shoulder.

Figure 4.

10

3 Installing the Air Locker

3.2

Re-Mounting the Ring Gear

 Remove the bolts that hold the ring gear in place.
 Using a plastic or copper hammer, tap in a circle around the ring

gear to separate it from the original differential carrier.

NOTE : Some aftermarket ring gears use 1/2” diameter bolt

threads instead of 7/16”. If this is the case then the

bolt holes of the Air Locker will require enlargement
to 13mm [0.512”]. This operation should be
performed by a qualified machinist.

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

of the Air Locker to prevent seizing.

 Thoroughly clean any thread locking compound or other foreign

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

HINT : Stoning the ring gear mounting face before

installation will remove any high spots around the
threads.

 Heat the ring gear to between 80 and 100°C [175 - 212°F] in hot

water or in an oven 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 gear and bolt holes with compressed air (if wet).
 Install the ring gear onto the Air Locker by aligning the bolt holes

and then gently tapping it around in a circle with a soft mallet.
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. Do not apply the 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

.

11

3 Installing the Air Locker

3.3

Drilling and Tapping the Bulkhead Port

An airline port must be drilled and tapped through the third member
casting to mount the bulkhead fitting into.

 Mark a spot on the third member casting in the position shown in

the completed assembly in Figure 5.

Figure 5.

 Remove the pinion shaft assembly from the third member.
 Press the pinion support bearing out of the third member.
 Drill through the housing square to the outside surface using a

11.2mm [7/16”] drill.

 Tap the hole from the outside using a ¼” NPT pipe tap.
 Remove any sharp edges from the hole that may chip-off and fall

into the housing.

12

3 Installing the Air Locker

3.4

Checking for Assembly Clearance

IMPORTANT:

Some third member castings will require modification for

correct Air Locker installation. A properly installed

Air Locker will have no less than 2mm [1/16”] between any

part of the differential carrier and the third member casting.

 Reassemble the pinion shaft assembly using only 2 bolts finger

tight. (The pinion shaft assembly will be fully assembled later)

 Hold the tapered roller bearing cups onto the cones on the carrier.
 Carefully insert the carrier assembly into the third member so that

the ring gear is in mesh with the drive pinion.

 Using an automotive feeler gauge, check for adequate clearance

between the body of the Air Locker and the third member casting
around the pinion support bearing and behind the flange cap.

 If necessary, remove the pinion shaft assembly and grind or file the

third member casting to gain clearance. An example of relief
grinding areas are shown in Figure 6.

Figure 6.

13

3 Installing the Air Locker

HINT : Applying a machinists marking compound to the third

member casting surfaces will show any points of
contact after the Air Locker has been removed.

 Once the required clearance has been achieved, remove the Air

Locker and the pinion shaft assembly and thoroughly clean the third
member of any grinding dust or other foreign particles.

 Reinstall the Air Locker into the third member.
 Install the bearing caps oriented as they were marked before they

were removed, and finger tighten the bearing cap bolts. It is not
necessary to torque them down at this time.

 Insert and lightly hand tighten the adjuster nut supplied with the Air

Locker kit into the flange side bearing cap.

NOTE : You should feel no backlash between the ring and

 Reverse the adjuster nut (counterclockwise) ¼ turn.

pinion gears once the adjuster nut tightens.

 Insert one of the original adjuster nuts into the bearing cap on the

opposite side and hand tighten using the appropriate adjuster nut
wrench.

NOTE : You should now feel some backlash between the

ring and pinion gears. If not, there might be a
clearance problem which is binding the carrier. Re­check the clearance.

14

3 Installing the Air Locker

3.5

 Set a depth indicator on one of the ring gear teeth (Fig.7.).
 While supporting the pinion gear by holding the drive shaft flange,

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

increased stresses in the differential carrier, increased running

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

Checking the Backlash

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.

and minimum amounts of backlash.

IMPORTANT:

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

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

noise, and ultimately, ring and pinion gear damage.

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 the bearing cap bolts with a torque wrench to the torque

specified in your vehicle manufacturer’s service manual.

Figure 7.

15

3 Installing the Air Locker

3.6

Assembling the Seal Housing

 Make sure the grooves and airway of the seal housing are clean

and free from any contaminants (e.g. water, dirt, metal filings, etc.).

 Inspect the seal housing O-rings (supplied) for dirt, damage or

other conditions which might cause leaks.

 Generously lubricate the O-rings with oil prior to assembly, then

insert them into the grooves of the seal housing.

NOTE : When assembling the O-rings, be careful not to leave

them twisted when seated in the grooves as this could

 Lubricate the seal housing running surface on the Air Locker carrier

with oil.

 Carefully install the seal housing by sliding it all of the way onto the

bearing journal with a gentle twisting motion until it sits flat against
the adjuster nut.

NOTE : A twisting motion (i.e., a slight rotation while pressing

 Rotate the seal housing until the square cutout lines up with the

locking tab position at the center of the bearing cap, and then
assemble the locking tab. (Fig.8.)

cause excessive wear and leakage.

the seal housing on) will allow the O-rings to engage
gently and prevent them from twisting. Twisted
O-rings will result in pre-mature O-ring wear and oil
contamination in the air system due to the helical
shape formed by the O-ring mould line.

Figure 8.

16

3 Installing the Air Locker

 Install the spring clip by first hooking both ends of the clip into the

small aligned cutouts of the seal housing and the adjuster nut, and
then snapping the clip into the groove of the seal housing using a
screwdriver. (Fig.9.)

Figure 9.

 Check that the seal housing is now secured from rotating and that it

is still sitting flat against the adjuster nut.

IMPORTANT:

Check that the tail of the adjuster nut locking tab does not

push on the seal housing. Bend it up away from the seal

housing with a screw driver if necessary.

17

3 Installing the Air Locker

3.7

Profiling the Seal Housing Tube

Without using sharp, jagged tools such as pliers (usually your hands
are the best tool for this job), gently bend the seal housing tube so that
it runs closely around the outside of the differential carrier and ring
gear and through the bulkhead port hole as shown in Figure 10.

NOTE : It is also a good idea to keep the tube away from the

bearing caps or any other part of the differential
casting as any contact due to vibration or shock may
wear the tube and eventually cause a leak.

IMPORTANT:

In order for the seal housing to float and self center on the

bearing journal after the tube is connected to the bulkhead

fitting, the seal housing tube must not be left pulling against

the seal housing. Therefore, it is critical to ensure that the

tube is not under any tension. To avoid this always leave

the tube long enough so that a loose hook shape can be

formed between the seal housing and the bulkhead.

Figure 10.

18

3 Installing the Air Locker

3.8

Setting Up the Bulkhead Fitting

 Trim the seal housing tube that is extended through the bulkhead

port to approximately 8mm [5/16”] long using an automotive brake
line tubing cutter.

NOTE : Never use a hacksaw to cut the seal housing tube as

this will leave metal filings 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).

 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.11.), 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.11.)

Figure 11.

19

3 Installing the Air Locker

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

3.9

Bench Testing the Air Locker

 To test the Air Locker, when 620kPa [90 PSI] shop air is applied to

the seal housing tube, the Air Locker should engage.

 Check all fittings and the seal housing for air leaks.
 Rotate the differential carrier by turning the pinion flange whilst

applying air pressure.

NOTE : An accurate way to test for air leaks is to fit a shut-off

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

onto the bulkhead air fitting. Bubbles should appear at any leak
points.

valve to an air pressure gauge, once 620 KPA [90 PSI]
is reached shut the valve off, disconnect the air hose,
and watch to see if there is any drop in pressure.
Any pressure drop will indicate an air leak. (Fig.12.)

Figure 12.

NOTE : Do not spray this soapy mixture inside the differential.

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

persists.

 If a leak is found at the seal housing, carefully remove and refit. Be

very careful with the O-rings and check they have not been
damaged during installation.

21

3 Installing the Air Locker

3.10

Reinstalling the Differential and Axles

 Reinstall the third member to the differential housing according to

your vehicle service manual.

 Reconnect the drive shaft.
 Inspect the condition of the axle seals and replace if necessary.
 Insert both axles fully into the housing, engaging splines, and then

gently tap them inward.

NOTE : Be careful not to damage the axle shaft oil seals when

installing the axle. Support the axle’s entire weight
where possible.

 Torque down the axle bolts to manufactures specifications.

22

4 Installing the Air System

4.1

Mounting the Solenoid

4.1.1

Connection to an ARB Air Compressor

(Fig.13.)

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

tank.

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

the port and tighten.

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

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

NOTE : The solenoid exhausts compressed air through the

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

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

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

ARB

Air Compressor

Figure 13.

23

4 Installing the Air System

4.1.2

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:

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

Connection to an Alternate Air Source

Air Locker(s), ARB strongly recommends use

Air Locker air system

 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.

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.

 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.

24

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.
(Not necessary on IFS installations)

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, always trim the line to length with

a sharp knife to avoid distorting the tube where it plugs into the
push-in fitting.

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.

25

4 Installing the Air System

 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.

4.3

Connection to the Bulkhead Fitting

 In the case of an IFS axle assembly or in the case that the axle

assembly has been completely removed from the vehicle, the
assembly will have to be remounted in order to position the
bulkhead fitting in its correct location for air line access.

 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.14.)

 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 14.

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

26

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.

27

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. 15.) may be purchased from your ARB Air Locker
distributor to suit 1, 2, or 3 switches.

28

5 Mounting & Connecting the Electrical System

Figure 15.

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. 16.)

NOTE : Refer to your ARB Air Compressor Installation Guide

for details on configuring your installation.

29

5 Mounting & Connecting the Electrical System

ARB AIR COMPRESSOR WIRING LOOM

SWITCH

IDENTIFICATION

TERMINAL

Figure 17.

Figure 16.

UP

30

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 18. and 19., 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 18. 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 17. for the correct switch terminal

identification and switch orientation.

SINGLE Air Locker SYSTEM

Figure 18.

31

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 19. 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 17. 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 19.

32

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

 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

 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.

compressor tank O-ring seal.

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.

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

persists.

33

6 Testing & Final Assembly

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’.

 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.

 While supporting the drive shaft flange, 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 carrier 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.

34

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.

 Axle breather has been checked and found to be clear and free

flowing, and located where it will not be susceptible to water or mud
contamination.

 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 properly and illuminate to indicate that Air

Locker(s) are 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:

___________________________
___________________________

35

6 Testing & Final Assembly

36

7 Parts List

7.1

Exploded Assembly Diagram

(See itemized parts list overleaf)

Figure 20.

37

7 Parts List

7.2

* Not illustrated in exploded view.

Itemized Parts List

(See exploded diagram figure 20.)

AIR LOCKER MODEL No. :

ITEM # QTY DESCRIPTION PART #

01 1 TAPERED ROLLER BEARING
02 1 FLANGE CAP ASSEMBLY 027303
03 1 SPLINED SIDE GEAR 131403H
04 1 SPIDER BLOCK 070201
05 1 LONG CROSS SHAFT 060204
06 1 SIDE GEAR 131303H
07 2 COUNTERSUNK SCREW 200213
08 3 CROSS SHAFT RETAINING PIN 120701
09 1 TAPERED ROLLER BEARING
10 1 SEAL HOUSING RETAINING CLIP 150601
11 1 SEAL HOUSING ASSEMBLY 081901
12 2 SEAL HOUSING O-RING 160207
13 1 ADJUSTER NUT 100105
14 1 BONDED SEAL 160703
15 1 CLUTCH GEAR 050804
16 12 RETURN SPRING 150113
17 2 SIDE GEAR THRUST WASHER 151010
18 2 SHORT CROSS SHAFT 060403
19 4 PINION GEAR 140701R
20 4 PINION THRUST WASHER 151110
21 1 DIFFERENTIAL CASE 012205

* 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 (FRONT) 180210
* 1 SWITCH COVER (REAR) 180211
* 10 CABLE TIE 180301
* 1 WARNING LABEL 210101
* 1 BUMPER STICKER 210102
* 1 OPERATION & SERVICE MANUAL 210200

* 1 INSTALLATION GUIDE 210299

RD99

NOT SUPPLIED

NOT SUPPLIED

38