Airlocker RD212 User manual

RD212
MITSUBISHI 9”, REAR,
28 SPLINE
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 & 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
Marking the Bearing Caps
6
2.5
Checking the Current Backlash Amount
7
2.6
Removing the Differential Carrier
8
2.7
Use of the Thrust Block
9
3 Installing the Air Locker
10
3.1
Mounting the Ring Gear
10
3.2
Installing the Carrier Bearings
12
3.3
Drilling and Tapping the Bulkhead Port
13
3.4
Final Air Locker Assembly
14
3.5
Checking the Backlash
14
3.6
Installing the Seal Housing
16
3.7
Setting up the Bulkhead Fitting
18
3.8
Profiling the Seal Housing Tube
20
3.9
Bench Testing the Air Locker
22
3.10
Reinstalling the Differential & Axles
23
4 Installing the Air System
24
4.1
Mounting the Solenoid
24
4.2
Running & Securing the Air Line
26
4.3
Connection to the Bulkhead Fitting
27
5 Mounting & Connecting the Electrical System
29
5.1
Mounting the Actuator Switch(es)
29
5.2
Wiring the Actuator System
30
6 Testing & Final Assembly
33
6.1
Leak Testing
33
6.2
Testing the Air Locker Actuation
33
6.3
Filling the Differential
34
6.4
Post-Installation Check List
35
7 Parts List
37
7.1
Exploded Assembly Diagram
37
7.2
Specifications
37
7.3
Itemized Parts List
38

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.
A dial indicator or other suitable measuring tool for checking ring &
pinion backlash.
An adjuster-nut wrench (e.g., ARB Adjuster Nut Pliers #0770002)
A razor knife suitable for cutting nylon tubing.
A torque wrench (See your vehicle service manual for the required
torque range).
A lubricant drain reservoir.
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 soft hammer (e.g., copper or nylon).
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)
A gasket sealant or replacement gasket for your third member.
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.

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 differential drain plug to prevent dirt from entering
the differential.
Position a fluid drain reservoir under the differential and loosen the
differential drain plug.
Completely drain all differential fluid.
Once drained, reinstall the drain plug finger tight to prevent drips
coming out of the housing and dust getting in.
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 Removal of the Axles and Differential
Remove the axles according to your vehicle’s service manual.
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.
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 Removing the Existing Differential
6
2.4 Marking the Bearing Caps
Using a small 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.)
Mark the right hand cap in a similar way.
HINT : Many installers choose to make one punch mark on
the left hand side of the left hand bearing cap and a
similar 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.

2 Removing the Existing Differential
7
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 dial indicator on one of the ring gear teeth. (Fig.2.)
Figure
2.
While supporting the pinion gear by holding the pinion 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.
Record the average of all measurements.

2 Removing the Existing Differential
8
2.6 Removing the differential carrier
Remove the adjuster nut locking tabs.
Remove the bearing caps.
Loosen the adjuster nuts.
Carefully remove the differential carrier from the housing.
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.

2 Removing the Existing Differential
9
2.7 Use of the Thrust Block
This Air Locker has been designed to replace both drum and disc
brake Mitsubishi diffs. As such, a thrust block used to maintain axle
end float has been supplied for some drum brake equipped models.
NOTE : Not all drum brake equipped models require use of a
thrust block. Look down the splines of the OE
differential to see if a thrust block is present (e.g. look
for any evidence of axle shaft contact marks).
With the Air Locker case side facing down, remove the two
countersunk screws and remove the flange cap from the assembly.
Remove the splined side gear from the assembly.
Insert the thrust block (ARB Part #110504) through the hole in the
center of the spider block, until it sits on the plain side gear (Fig. 4.).
HINT : A wad of thick grease will help to hold the thrust block
in place during installation.
Figure
4.
Re-install the splined side gear and flange cap.
NOTE : When re-installing the flange cap, ensure all the
springs sit upright; Also, ensure there is no gap
between the case and flange cap after fully tightening
both parts.

3 Installing the Air Locker
10
3.1 Mounting the Ring Gear
Remove the bolts that hold the ring gear in place.
Using a soft mallet or copper hammer, tap in a circle around the
ring gear to separate it from the differential carrier.
Thoroughly clean any thread locking compound or other foreign
matter from the holes of the ring gear, the threads of the ring gear
bolts, the mating surfaces of the ring gear and the Air Locker
flange.
HINT : 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 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 tapped holes with compressed air (if wet).
Apply a thin film of high-pressure grease to the ring gear shoulder
of the Air Locker to prevent seizing.
Install the ring gear onto the Air Locker by aligning the tapped holes
and then gently tapping it around in a circle with a soft mallet or
hammer. Avoid using the bolts to pull the ring gear down 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 locking compound directly into
the threaded hole as this could prevent the bolt from reaching its
full depth.
NOTE : On some models, the crown wheel bolts cannot be
reused and should therefore be replaced. Refer to
your vehicle manufacturer’s service manual for
details.
Tighten the ring gear bolts in a star pattern with a torque wrench
(Fig.5.) set to your vehicle manufacturer’s specified torque.

3 Installing the Air Locker
11
Figure
5.

3 Installing the Air Locker
12
3.2 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.
Identify the bearings according to where each was removed from
the OE diff, and allocate them to the correct sides of the Air Locker
respectively.
Press one of the tapered roller bearing cones onto one of the
bearing journals of the Air Locker until the bearing seats firmly
against the bearing journal shoulder (Fig. 6.).
NOTE : Never re-use any bearings which are damaged or
worn.
Invert the Air Locker and press the second bearing cone onto the
opposite bearing journal until the bearing seats firmly against the
bearing journal shoulder.
Figure
6.
NOTE : Do not add any shims between the seal housing
bearing and the bearing seat.

3 Installing the Air Locker
13
3.3 Drilling and Tapping the Bulkhead Port
An air line port must be drilled and tapped through the differential
housing to mount the bulkhead fitting into.
Mark a spot on the seal housing side of the differential, on the flat
between the third member mounting face and the bearing seat, as
shown. (Fig. 7.)
NOTE : Find a spot where there is a minimum of 12mm
between the bearing seat wall and mounting face edge
(Fig. 7.). Take your time to measure carefully, because
being too near to the bearing centre, the copper tube
may interfere with the axle; being too far, the hole will
break into the mounting face.
Figure
7.
Cover the drive pinion and axle tube areas with a rag to protect
them from metal filings.
Pilot drill a through hole from the inside, then drill an 11.2mm
[7/16”] hole from the outside.
Tap the hole from the outside using ¼”NPT thread tap.
Remove any sharp edges that may chip off from around the hole
and fall into the housing.
Very carefully, remove the rags and inspect with a service light
inside the housing to ensure no metal filings are left behind.
12mm

3 Installing the Air Locker
14
3.4 Final Air Locker Assembly
Clean all parts of the differential assembly making sure the O-ring
grooves are free from any contaminants (e.g., dirt, water, metal
fillings, etc.)
Place the Air Locker into the differential housing and install the
bearing caps.
NOTE : Be sure to check that the bearing caps are on the
correct sides of the third member and are correctly
aligned.
Insert the bearing cap bolts and hand tighten.
NOTE : Before attempting to install the adjuster nuts, make
sure the threads on the inside of the bearing caps and
differential housing are perfectly aligned. If they are
not, the threads could be stripped.
Insert and lightly hand tighten the supplied adjuster nut with the Air
Locker kit into the ring gear side bearing cap.
NOTE : You should feel no backlash between the ring and
pinion gears once the adjuster nut tightens.
Reverse the adjuster nut (counterclockwise) ¼ turn.
Insert the original adjuster nut on the case side of the differential
and tighten with 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. Re-check the
clearance.

3 Installing the Air Locker
15
3.5 Checking the Backlash
Set a depth indicator on one of the ring gear teeth (Fig.8.).
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.
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 the bearing cap bolts with a torque wrench to the torque
specified in your vehicle manufacturer’s service manual.
Figure
8.

3 Installing the Air Locker
16
3.6 Installing 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
cause excessive wear and leakage.
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
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.
Rotate the seal housing until the square cutout lines up with the
locking tab position at the center of the bearing cap. (Fig.9.)
Figure
9.

3 Installing the Air Locker
17
NOTE : The locking tab needs to be modified to suit the
supplied adjuster nut and seal housing.
Position the tab where it will be assembled, and re-determine the
bending line for the end tip.
Linish the tab width and tail length as necessary to ensure it does
not come in contact with the bearing or seal housing. The modified
locking tab should look as per Fig. 10.
Figure 10.
Tighten the modified locking tab into the bearing cap.
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.11.)
Figure 11.
Check that the seal housing is now secured from rotating and that it
is still sitting flat against the adjuster nut.

3 Installing the Air Locker
18
3.7 Setting up the Bulkhead Fitting
Apply thread sealant to the outside threads of the bulkhead body.
Screw the bulkhead body into the tapped hole, and lightly tighten
using a 14mm [9/16”] spanner.
Wipe the area clean of any excess thread sealant (inside and
outside of the housing).
Without using sharp, jagged tools such as pliers (your hands are
the best tool for this job), bend the seal housing tube on the outside
of the housing to approximate the finished profile. This will allow the
tube to be trimmed to a length that would allow it to protrude from
the bulkhead fitting. (See Fig. 12.).
IMPORTANT:
The seal housing must still be able to freely float after the tube
is connected to the bulkhead fitting. 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 hook shape can be
formed between the seal housing and the bulkhead.
NOTE : Use an automotive brake line tubing cutter to cut the
seal housing tube, never a hacksaw as this will leave
metal filings in the air system.
Figure 12.