Airlocker RD253 User manual

RD253
TOYOTA 9.5” RR, 32 SPL,
OE LOCKER REPLACEMENT
AIR OPERATED
LOCKING DIFFERENTIAL
INSTALLATION GUIDE

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 and South American enquiries [email protected]
Other international enquiries [email protected]
www.arb.com.au

Table of Contents:
1
1 Introduction
3
1.1
Pre-Installation Preparation
3
1.2
Tool-Kit Recommendations
4
2 Removing the Existing Differential
5
2.1
Vehicle Support
5
2.2
Differential Fluid Drain
5
2.3
Removing the Axles and Differential
5
2.4
Removing OE Locker Mechanism
5
2.5
Marking the Bearing Caps
8
2.6
Checking the Current Backlash Amount
8
2.7
Spreading the Differential Housing
10
3 Bench Measurement
11
3.1
Approximate Backlash Shimming
11
3.2
Calculation & Selection of Shims
13
4 Installing the Air Locker
14
4.1
Installing the Carrier Bearings
14
4.2
Mounting the Ring Gear
15
4.3
Assembling the Seal Housing
16
4.4
Calculation & Selection of Pre-Load Shims
17
4.5
Final Air Locker Assembly
18
4.6
Final Backlash Checking
18
4.7
Profiling the Seal Housing Tube
20
4.8
Setting up the Bulkhead Fitting
23
4.9
Bench Testing the Air Locker
24
4.10
Reinstalling the Differential and Axles
25
5 Installing the Air System
26
5.1
Mounting the Solenoid
26
5.2
Running & Securing the Air Line
28
5.3
Connection to the Bulkhead Fitting
29
6 Mounting & Connecting the Electrical System
30
6.1
Rear Differential Lock Sensor Replacement
30
6.2
Wiring Modifications
31
7 Testing & Final Assembly
37
7.1
Leak Testing
37
7.2
Testing the Air Locker Actuation
37
7.3
Filling the Differential
38
7.4
Post-Installation Check List
39
8 Parts List
41
8.1
Exploded Assembly Diagram
41
8.2
Specifications
41
8.3
Itemized Parts List
42

2

1 Introduction
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 symbols as
you complete each step. It is very important NOT to
miss any of the steps!

1 Introduction
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
Standard automotive sizes (metric and/or imperial) of sockets,
wrenches, Allen keys, and drills. Automotive wiring tools.
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 copper tubing.
A razor knife to cut the nylon tubing.
A differential housing spreader, to facilitate removal of the carrier.
(e.g., ARB Differential Spreader #0770003)
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 shimming. (See Section 3 Bench Measurement)
An 11.2mm [7/16”] drill and ¼” NPT tap for bulkhead fitting
installation.
An automotive bearing puller (e.g., ARB Bearing Puller #0770001)
or a differential carrier bearing puller.
A bearing press or arbor press.
Shim driver (e.g., ARB Shim Driver #0770004).
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.
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.
A selection of differential bearing shims to set-up pre-load and
backlash. (See section 3 Bench Measurement)

2 Removing the Existing Differential
5
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 third member flange seal to prevent dirt from
entering the differential.
Position a fluid drain reservoir under the differential.
Remove fluid drain plug to empty all differential oil.
HINT : This is a good time to check for metal particles in
your oil which may indicate a worn bearing or
differential component.

2 Removing the Existing Differential
6
2.3 Removing the Axles and Differential
Remove the axles according to your vehicle’s service manual.
NOTE : Toyota OE Diff Lock must be engaged (rotate
dashboard switch to lock rear diff, and rotate wheel to
ensure diff is locked) before removing short axle
shaft. Failure to do this will result in OE locking collar
becoming jammed.
Disconnect the drive shaft from the flange of the differential.
Remove the third member from the differential housing. (Refer to
your vehicle’s service manual)
NOTE : Keep OE Diff locked to aid removal of third member.
Unlock once diff has been removed.
NOTE : The differential housing is heavy and quite difficult to
handle when covered in oil. Do not drop it!
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.
2.4Removing OE Locker Mechanism
The OE Diff Lock motor and limit switch will need to be removed to
enable fitment of the Air Locker. They will be replaced by supplied
blanking plates. (Fig. 1.)
Figure
1.

2 Removing the Existing Differential
7
Undo the 3 bolts that hold the limit switch bracket in position.
Remove the bracket and switch from the diff.
Unbolt the screw that is retaining the engagement fork to the motor
shaft (Fig. 2.).
Figure
2.
Undo the 4 bolts holding the motor onto the housing and remove
the motor. The locking gear engagement fork can be removed once
it is clear of the motor shaft.

2 Removing the Existing Differential
8
2.5Marking the Bearing Caps
Using a pointed center punch, gently mark the differential housing
and the bearing caps in a way that will enable you to correctly
position the cap during reassembly. (Fig.3.)
Figure
3.
2.6Checking 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.

2 Removing the Existing Differential
9
Set a depth indicator on one of the ring gear teeth as in Figure 4.
Figure
4.
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.

2 Removing the Existing Differential
10
2.7Spreading the Differential Housing
IMPORTANT:
Spreading the differential housing with a differential case
spreader is a step which 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.
Unbolt and remove the bearing caps.
Setup the differential spreader and a dial indicator and carefully
spread the differential housing (Fig.5.) just enough to remove the
differential carrier (Refer to your vehicle’s service manual).
NOTE : Never spread the housing more than 0.5mm [0.020”].
Once the housing has been adequately spread, the differential may
be removed by pulling forward on the differential center.
Remove spreader tension.
Figure
5.

3 Bench Measurement
11
3.1 Approximate Backlash Shimming
In order to reproduce a similar pre-load and ring and pinion backlash
in your Air Locker to that of your original differential, measurements
need to be taken so that a shim thickness can be calculated.
Secure the original differential to a work bench.
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 differential carrier.
Remove the original bearings and shims from the differential center
using a bearing puller.
NOTE : Keep the bearings and shims separated so that they
can be identified as to which end of the differential
they came from.
Examine the bearing cups and cones from Figure 6. for damage or
wear and, if necessary, discard them and replace with the same
size and type of bearings.
Figure
6.

3 Bench Measurement
12
Using 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 Fig.6.) and record this
measurement as ‘A’.
Measure the thickness of the factory shim removed from the end of
the differential carrier (shown as ‘B’ in Fig.6.) and record this
measurement as ‘B’.
Figure
7.
Measure the distance from the Air Locker bearing shoulder to the
ring gear mounting face (shown as ‘C’ in Fig.7.) and record this
measurement as ‘C’.

3 Bench Measurement
13
3.2 Calculation & Selection of 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 7.
Use the following calculation:
A + B –C = D (Replacement Shim Pack)
HINT : If your calculations are correct then the following
equation will also be true:
A + B –C –D = ZERO
Create 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.
NOTE : NEVER machine the Air Locker.

4 Installing the Air Locker
14
4.1 Installing the Carrier Bearings
With the Air Locker well supported in an arbor press, apply a thin
film of high pressure grease to both bearing journals.
Press one of the tapered roller bearing cones onto the ring gear
side bearing journal first until the bearing seats firmly against the
bearing journal shoulder.
Invert the Air Locker and press the second bearing cone onto the
diff case side bearing journal until the bearing seats firmly against
the bearing journal shoulder (Fig. 8.).
Figure
8.
NOTE : Never re-use any bearings which are damaged or
worn.

4 Installing the Air Locker
15
4.2 Mounting the Ring Gear
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 of the ring gear and the Air Locker
flange.
NOTE : Rubbing the ring gear mounting face with a flat oil
stone before installation will remove any high spots
around the threads.
Heat the ring gear to between 80 and 100C (175 - 212F) in an
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 (e.g. Loctite 272) 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.

4 Installing the Air Locker
16
4.3 Assembling the Seal Housing
Figure
9.
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
cause excessive wear and leakage.
Lubricate the seal housing running surface on the Air Locker carrier
with oil. Assemble the bearing cup onto the left-hand side of the Air
Locker.
Carefully install the seal housing by sliding it all of the way onto the
bearing journal with a gentle twisting motion (Fig. 9.). This will allow
the O-rings to engage gently.

4 Installing the Air Locker
17
4.4 Calculation & Selection of Pre-Load Shims
In order to pre-load the tapered roller bearings in your Air Locker,
measurements need to be taken so that a value can be calculated for
the shim thickness ‘E’ in Figure 10.
Hold the bearing cup and shim pack ‘D’ (Fig.5.) in place, and insert
the Air Locker into the housing.
Push the Air Locker hard across against the bearing and shim pack
‘D’, and measure the gap between the end of the seal housing
assembly and the bearing seat of the differential housing with a
feeler gauge.
Consult your vehicle manufacturer’s service manual to determine
the carrier bearing pre-load amount specified for your vehicle.
Add the specified pre-load amount to the measurement taken with
the feeler gauge to determine a shim amount for ‘E’ in Figure 10.
Figure
10.
PRE-LOAD + END FLOAT = SHIM PACK
Select suitable shims from the shim kit supplied with your Air
Locker to make up a shim pack of this thickness. (Refer to section
3.2 for methods of shim adjustment).

4 Installing the Air Locker
18
4.5Final Air Locker Assembly
Spread the differential housing again (Refer to section 2.6).
Hold shim pack ‘E’ (Refer to section 4.4) in position on the Air
Locker.
Reinstall the Air Locker into the differential housing.
Place the seal housing bearing cap in place to align the seal
housing.
Using a Shim Driver, lightly tap shim pack ‘D’ into place on the
right-hand side between the bearing cup and the bearing seat of
the axle assembly.
NOTE : If the carrier is too difficult to install with the added
shim pack then the spreader tension may need to be
increased. Do not spread the housing more than
0.50mm [0.020”].
Relieve all tension on the housing spreader.
Place the remaining bearing cap in place, and tighten all bearing
cap bolts with a torque wrench to the torque specified in your
vehicle manufacturer’s service manual.
4.6Final Backlash Checking
Set a depth indicator on one of the ring gear teeth as in Figure 11.
While supporting the pinion gear by holding the drive 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.
Figure
11.