ARB RD121 Operating and maintenance instructions

INSTALLATION GUIDE
RD121
TOYOYA 8” IFS,53mm BRNG
Part No. 2102121
Revision 20/09/05
Copyright © 2005 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 [email protected]
North & South American enquiries [email protected]
Other international enquiries [email protected]
www.arb.com.au

Table of Contents:
1
1Introduction 3
1.1
Pre-Installation Preparation 3
1.2
Tool-Kit Recommendations 4
2Removing the Existing Differential 5
2.1
Vehicle Support 5
2.2
Differential Fluid Drain 5
2.3
Removing the Differential Assembly 5
2.4
Checking the Current Backlash Amount 6
2.5
Removing the Differential Center 7
3Installing the Air Locker 8
3.1
Approximate Backlash Shimming 8
3.2
Calculation & Selection of Backlash Shims 10
3.3
Mounting the Ring Gear 11
3.4
Installing the Carrier Bearings 12
3.5
Preload Shim Measurement 13
3.6
Calculation & Selection of Preload Shims 15
3.7
Drilling & Tapping the Bulkhead Port 15
3.8
Installing the Seal Housing 17
3.9
Installing the Bulkhead Fitting 19
3.10
Setting Up the Bulkhead Fitting 19
3.11
Final Assembly 20
3.12
Checking the Backlash 21
3.13
Bench Testing the Air Locker 23
3.14
Reinstalling the Differential Assembly 24
4Installing the Air System 25
4.1
Mounting the Solenoid 25
4.2
Running & Securing the Air Line 27
4.3
Connection to the Bulkhead Fitting 28
5Mounting & Connecting the Electrical System 29
5.1
Mounting the Actuator Switch(es) 29
5.2
Wiring the Actuator System 30
6Testing & Final Assembly 33
6.1
Leak Testing 33
6.2
Testing the Air Locker Actuation 33
6.3
Re-Sealing & Filling the Differential 34
6.4
Post-Installation Check List 35
7Parts List 37
7.1
Exploded Assembly Diagram 37
7.2
Itemized Parts List 38

2

2 Removing the Existing Differential
3
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 csymbols as
you complete each step. It is very important NOT to
miss any of the steps!

2 Removing the Existing Differential
4
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
cStandard automotive sizes (metric and/or imperial) of sockets,
wrenches, Allan keys, and drills.
cA dial indicator or other suitable measuring tool for checking ring &
pinion backlash.
NOTE :Split ‘clamshell’ type Toyota differential housings
require a long series dial indicator to check backlash.
cA razor knife for nylon tubing.
cA torque wrench (See vehicle service manual for required torque
range)
cA lubricant drain reservoir.
cA slide hammer for removing CV axles.
cSuitable measuring tools to measure a differential for preload
shimming. (e.g., an automotive feeler gauge)
cA 11.2mm [7/16”] drill and ¼”NPT tap for bulkhead fitting
installation.
cAn automotive bearing puller (2 jawed) or a differential carrier
bearing puller.
cA bearing press or arbor press.
1.2.2 Supplies
cThread lubricant/sealant compound (e.g., LOCTITE #567)
cThread locking compound (e.g., LOCTITE #272)
cA gasket sealant or replacement gasket for your differential.
cA sufficient volume of differential oil to completely refill your
housing. (see the ARB Air Locker Operating and Service Manual
for recommended lubricants)
cA soap and water mixture to test for air leaks.
cA selection of differential bearing shims to set-up preload and
backlash.

2 Removing the Existing Differential
5
2.1 Vehicle Support
cSafely 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.
cOnce supported in the air, chock the wheels (if necessary) and
leave the vehicle in neutral.
2.2 Differential Fluid Drain
cPosition a fluid drain reservoir under the differential.
cRemove the drain plug and drain all of the oil from the housing.
HINT :This is a good time to check for metal particles in
your oil and on the end of the magnetic drain plug which
may indicate a worn bearing or differential component.
cOnce drained, reinstall the drain plug.
2.3 Removing the Differential Assembly
cRemove the stub axles from the differential housing according to
your vehicle manufacturer’s service manual.
NOTE :Rubber oil seals can be easily damaged. Support the
weight of the axle when extracting it across the edges
of the seals.
NOTE :Some Toyota IFS axles can be removed easier by
disconnecting the lower ball joint bracket.
HINT :Toyota IFS axle stubs are retained with a snap ring
which is considered to be a one-use part. Keep two of
these clips on-hand in case the clip(s) are damaged or
sheared off while removing the stub axle. Make sure all
of the remains of the clips are accounted for so that
they cannot damage differential components and seals.
cDisconnect the drive shaft from the drive pinion flange.
cCompletely remove the entire differential assembly.

2 Removing the Existing Differential
6
2.4 Checking the Current Backlash Amount
IMPORTANT:
This step is a precautionary measure recommended by ARB due
to the fact that some aftermarket 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.
cSet a long series lever type dial indicator on one of the ring gear
teeth. Access to the ring gear teeth is gained through the oil filler
hole. (Refer to Figure 1.)
Figure 1.
cInsert a large flat screwdriver or pry-bar through one of the axle
stub holes so that it wedges between the cross shaft and the carrier
body so that the differential center can be rotated by the cross
shaft, and not by the spline of one of the differential gears.
cWhile supporting the pinion gear by holding the drive shaft flange,
rotate the differential in both directions (with the screwdriver or pry-
bar) 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.
cRotate the differential center 90°and measure again for accuracy.
cRecord the average of all measurements.

2 Removing the Existing Differential
7
2.5 Removing the Differential Center
cRemove the floating shaft (or ADD unit if present) from the side of
the differential housing.
NOTE :The floating shaft or stub axle is retained by the same
type of clip that was used to retain the outer stub axle.
A slide hammer may be required for safe removal.
Refer to your vehicle manufacturer’s service manual.
cRemove all bolts from around the outside of the clamshell.
cGently pry the clamshell apart and remove the differential center.
cUsing an arbor press, remove both bearing cups and preload shims
by pressing on the face of the shims through the housing from the
outside.
NOTE :Be sure not to mix up the left and right hand tapered
roller bearing cups or preload shims. Later it will be
necessary to know which cup came from which
bearing and which shim came from which side of the
differential.

3 Installing the Air Locker
8
3.1 Approximate Backlash Shimming
In order to reproduce a similar preload and ring and pinion backlash in
your Air Locker to that of your existing differential, measurements
need to be taken so that a shim thickness can be calculated.
cSecure the differential to a work bench.
cRemove the bolts that hold the ring gear in place.
NOTE :Ring gear bolt locking tabs used on some models will
not be required on the Air Locker and may be
discarded.
cUsing a plastic or copper hammer, gently tap in a circle around the
outside of the ring gear to separate it from the differential carrier.
cRemove the original bearings from the differential center using a
bearing puller.
NOTE :Keep the bearings separated so that they can be
identified as to which end of the differential they came
from.
cExamine the bearing cups and cones for damage or wear and, if
necessary, discard them and replace with the same size and type
of bearings.
Figure 2.
FACTORY DIFFERENTIAL

3 Installing the Air Locker
9
cUsing a caliper or similarly accurate measurement method
(i.e., able to take accurate measurements within 0.04mm [0.0015”]),
measure the distance from the shoulder of the bearing journal to
the ring gear mounting face (shown as ‘A’ in Figure 2.) and record
this measurement as ‘A’.
cMeasure the thickness of the factory shim removed from the end of
the differential carrier (shown as ‘B’ in Figure 2.) and record this
measurement as ‘B’.
Figure 3.
cMeasure the distance from the Air Locker bearing shoulder to the
ring gear mounting face (shown as ‘C’ in Figure 3.) and record this
measurement as ‘C’.
RING GEAR
FLANGE
AIR LOCKER DIFFERENTIAL

3 Installing the Air Locker
10
3.2 Calculation & Selection of Backlash Shims
Ideally, the measurement you recorded as ‘C’ from the Air Locker
differential will closely match ‘A’ on the existing differential (within
0.1mm [0.004”] ) and then the factory shim can be reused, however,
quite often these measurements will vary slightly between one factory
differential and the next.
If this is the case you must create a new shim pack thickness by using
the measurements you recorded earlier to find a desired measurement
for ‘D’ in Figure 3.
Use the following calculation:
A + B –C = D (Replacement Shim Pack)
HINT :If your calculations are correct then the following
calculation will also be true:
A + B –C –D = ZERO
cCreate a shim pack to match the thickness calculated as ‘D’.
To achieve the desired shim thickness you can:
•Machine down the factory shim thickness.
•Add shims between the factory shim and the bearing cup.
HINT :A selection of shims of this size have been supplied
with your Air Locker kit.
•Purchase new factory shims at the desired thickness.
•Use a universal shim kit available from most drive train
specialists.
•Add small amounts of shim between the bearing cone and the
bearing seat.
NOTE :NEVER machine the Air Locker.

3 Installing the Air Locker
11
3.3 Mounting the Ring Gear
cApply a thin film of high pressure grease to the ring gear shoulder
of the Air Locker to prevent seizing.
cThoroughly 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.
cHeat 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.
cDry the gear and bolt holes with compressed air (if wet).
cInstall 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.
cApply a thread locking compound to the thread of each ring gear
bolt before inserting it. Do not apply threading compound directly
into the threaded hole as this could prevent the bolt from reaching
its full depth.
cTighten the ring gear bolts in a star pattern with a torque wrench
according to your vehicle manufacturer’s specified torque.

3 Installing the Air Locker
12
3.4 Installing the Carrier Bearings
cApply a thin film of high pressure grease to both bearing journals of
the Air Locker.
cUsing a bearing press or arbor press, press one of the original
tapered roller bearing cones onto the bearing journal opposite to
the ring gear flange of the differential carrier (As shown in Figure 4.)
until the bearing seats firmly against the bearing journal shoulder.
Figure 4.
cInvert the Air Locker and press the second bearing cone onto the
bearing journal on the ring gear flange side of the differential (the
seal housing side) until the bearing seats firmly against the bearing
journal shoulder.
NOTE :Never re-use any bearings which are damaged or
worn. Do not add any shims between the seal
housing bearing and the bearing seat.

3 Installing the Air Locker
13
3.5 Preload Shim Measurement
In order to preload the tapered roller bearings in your Air Locker,
measurements need to be taken so that a value can be calculated for
the total shim thickness ‘E’ in Figure 5.
Figure 5.
cAssemble the shim pack determined earlier as ‘D’ (Fig.3.) into the
bearing bore of the deep half of the clamshell.
cUsing a bearing press or arbor press, press the appropriate bearing
cup into the bottom of the same bearing bore (i.e., until it stops
against the shim pack).
HINT :You should not be able to rotate the shim pack
underneath the bearing cup if it has been pressed in
far enough.
cWith the deep half of the clamshell sitting firmly on a horizontal
surface, set the Air Locker into the bearing cup inside the clamshell.
cBend the seal housing tube so that it points straight away from the
seal housing flange.
cAssemble any remaining shims from the Air Locker shim kit
(supplied) together into one shim pack and measure the total
thickness.

3 Installing the Air Locker
14
cAssemble the shim pack onto the seal housing flange on the same
side as the seal housing tube’s solder joint.
cAssemble the seal housing into the bearing bore in the shallow half
of the clamshell (shims against the clamshell).
cUsing a bearing press or arbor press, press the remaining bearing
cup into the bottom of the same bearing bore (until it stops against
the seal housing).
cCarefully assemble the shallow half of the clamshell over the top of
the Air Locker.
cMeasure the preload gap that exists between the two halves of the
clamshell housing with a feeler gauge. (Refer to Fig.6.)
Figure 6.
NOTE :The preload gap should be the same when measured
all the way around the housing. If this is not true, then
reposition the shallow clamshell half and re-measure.
cSubtract the amount measured at the preload gap from the
thickness of the shim pack placed onto the seal housing flange.
cRecord the result as this is your true ‘end float’ amount.

3 Installing the Air Locker
15
3.6 Calculation & Selection of Preload Shims
cConsult your vehicle manufacturer’s service manual to determine
the carrier bearing preload amount specified for your vehicle.
NOTE :If your service manual specifies preload in terms of a
torque value measured off the drive pinion flange,
then assume a preload amount of 0.25mm [0.01”] for
the following calculations. Once you have assembled
the housing to check the final backlash (Refer to
Section 3.12 Checking the Backlash) you should verify
that your preload is correct using a torque wrench and
your service manual’s table of values.
cAdd the specified preload amount to the end float measurement
determined with the feeler gauge to determine a shim amount for
‘E’ (Refer to Figure 5.).
PRELOAD + END FLOAT = SHIM PACK
cCreate a shim pack ‘E’ to closely match the measured amount.
NOTE :Do not add shims between the bearing cone and the
bearing seat and NEVER machine the Air Locker.
3.7 Drilling & Tapping the Bulkhead Port
A port must be drilled and tapped through the shallow half of the
clamshell to allow the seal housing tube through the housing to
connect with the air line from the air compressor.
cRemove the Air Locker from the housing.
cPress the shims, seal housing and bearing cup out of the bearing
bore of the shallow half of the clamshell.
cMark a spot on the shallow half of the clamshell in the same
position shown in the photograph in Figure 7. and Figure 8.

3 Installing the Air Locker
16
Figure 7.
Figure 8.
NOTE :To best determine the correct vertical position of the
drilled hole, measure down from the machined face
(shown at the top of the picture in Figure 8.) a
distance of 13.5mm [17/32”] and mark the horizontal
line which the hole is centered on. Then refer to
Figure 9. for the correct position on that line to start
drilling.

3 Installing the Air Locker
17
Figure 9.
cCover the bearing seat area with a rag to protect the inside of the
clamshell from metal filings.
cDrill through the housing square to the outside surface using an
11.2mm [7/16”] drill.
cTap the hole from the outside using a ¼” NPT pipe tap.
cRemove any sharp edges from the hole that may chip-off and fall.
Carefully remove the rag and inspect with a service light inside the
clamshell to insure no metal filings are left behind.
3.8 Installing the Seal Housing
cSit the seal housing on top of the shallow clamshell half.
cWithout 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 lines up with the bulk head fitting hole as shown in
Figure 10.
cMark the tube approximately 8mm [5/16”] out from the end of the
hole, and cut with an automotive brake line tubing cutter.
Figure 10.

3 Installing the Air Locker
18
cMake sure the seal housing tube and the grooves of the seal
housing are clean and free from any contaminants (e.g., water, dirt,
metal filings, etc.).
cInspect the seal housing O-rings (supplied) for dirt, damage or
other conditions which might cause leaks.
NOTE :Be careful not to bend the seal housing tube or
damage the O-ring grooves.
cGenerously 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
cause excessive wear and leakage.
cAssemble the shim pack and seal housing (‘E’ in Figure 5.) into the
bearing bore of the shallow half of the clamshell.
cPosition the seal housing so that the end of the seal housing tube
goes through the center of the bulkhead port hole
(Refer to Figure 11.).
Figure 11.
cUsing a bearing press or arbor press, press the bearing cup into the
bottom of the bearing bore until it stops against the seal housing.
NOTE :Do not use excessive force when pressing as this may
damage the seal housing assembly.
NOTE :You should not be able to rotate the shim pack
underneath the bearing cup if it has been pressed in
far enough.