ARB AIRLOCKER RD216 User manual

RD216
GM 12 BOLT, 8.9”,
30 SPL, 3.73&UP
AIR OPERATED
LOCKING DIFFERENTIAL
INSTALLATION GUIDE

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 [email protected]
North Central 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
6
2.4
Marking the Bearing Caps
7
2.5
Checking the Current Backlash Amount
8
2.6
Removing the Differential Center
9
3 Installing the Air Locker
10
3.1
Insuring Adequate Oil Drainage
10
3.2
Approximate Backlash Shimming
13
3.3
Installing the Carrier Bearings
15
3.4
Mounting the Ring Gear
16
3.5
Drilling and Tapping the Bulkhead Port
17
3.6
Assembling the Seal Housing
18
3.7
Pre-Load Shimming
19
3.8
Reinstalling the Bearing Caps
21
3.9
Checking the Backlash
22
3.10
Setting Up the Bulkhead Fitting
23
3.11
Profiling the Seal Housing Tube
25
3.12
Bench Testing the Air Locker
26
4 Installing the Air System
27
4.1
Mounting the Solenoid
27
4.2
Running & Securing the Air Line
29
4.3
Connection to the Bulkhead Fitting
30
5 Mounting & Connecting the Electrical System
32
5.1
Mounting the Actuator Switch(es)
32
5.2
Wiring the Actuator System
33
6 Testing & Final Assembly
37
6.1
Leak Testing
37
6.2
Reinstalling the Axles
38
6.3
Testing the Air Locker Actuation
40
6.4
Re-Sealing & Filling the Differential
40
6.5
Post-Installation Check List
41
7 Parts List
43
7.1
Exploded Assembly Diagram
43
7.2
Specifications
43
7.3
Itemized Parts List
44

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 automotive brake tubing cutter to cut the copper tubing.
A razor knife to cut the nylon tubing.
A differential housing spreader, to facilitate removal, installation and
preloading of the carrier (e.g. ARB Spreader #0770003).
A torque wrench (See vehicle manual for required torque range).
A lubricant drain reservoir.
Suitable measuring tools to measure a differential for pre-load
and/or backlash shimming (e.g. automotive feeler gauge)
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.
A suitable shim driver (e.g. ARB Shim Driver #0770004).
A soft hammer (e.g. raw hide or nylon).
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 your differential
cover.
A sufficient volume of differential oil to completely refill your
housing. (see the ARB Air Locker Operating and Service Manual
for recommended lubricants)
A soap and water mixture to test for air leaks.

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
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 cover flange area,
the filler plug area, and the drain plug (if any) to avoid
contaminating the differential cavity with abrasive particles.
Position a fluid drain reservoir under the differential.
If a drain plug exists, remove it and completely drain all differential
oil from the housing.
If no drain plug exists then the oil can be drained by loosening the
cover bolts and gently prying the cover away at the bottom until oil
runs out.
HINT : If a drain plug does not exist then it would be a good
idea to drill and tap for a tapered oil drain plug to assist
with future oil changes.
Once drained, remove the differential cover plate.

2 Removing the Existing Differential
6
2.3 Removing the Axles
IMPORTANT :
Collision damage or heavy off-road use of your vehicle in the past may
have resulted in some degree of bending in the axle. Any misalignment
of the axle tubes may result in excessive wear and/or failure of your
differential and axle shafts. ARB strongly recommends that you have
your axle assembly inspected for concentricity and straightness before
installing your Air Locker.
Remove both of the rear wheels and brake drums/rotors according
to you vehicle manufacturer’s service manual.
Rotate the differential carrier using the drive shaft until you have
clear access to the cross shaft retaining pin.
Completely remove the retaining pin from the differential carrier.
Rotate the differential carrier again until you can completely remove
the cross shaft.
Tap the axle shafts inward to unseat the ‘C’ clips from their pockets
in the center of the differential side gears.
Using needle nosed pliers, remove both ‘C’ clips from the
differential.
Tap the axle shafts outward until the splines are disengaged from
the differential side gears.
Gently slide the axle shafts out of the axle tubes until they can be
completely removed from the vehicle.
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.

2 Removing the Existing Differential
7
2.4 Marking the Bearing Caps
Using a pointed center punch, gently mark the bearing caps in a
way that will enable you to know which cap is ‘LEFT’ and which cap
is ‘RIGHT’, which way is ‘UP’ and which way is ‘DOWN’. (Fig.1.)
HINT : Many installers choose to make one punch mark on
the left hand side of the left hand bearing cap and one
similar punch mark on the housing at close proximity to
the cap mark. The right hand side is then designated
with two punch marks on the right hand side of the cap
and two similar punch marks on the housing.
Figure
1.

2 Removing the Existing Differential
8
2.5 Checking the Current Backlash Amount
IMPORTANT:
This step is a precautionary measure recommended by ARB due
to the fact that some after market ring and pinion sets have been
manufactured to run with different backlash settings than those
specified by your vehicle manufacturer. Although ARB must
recommend you set backlash according to your service manual
guidelines, we also advise that you compare the backlash
measurements taken here to the recommended backlash settings
in your vehicle service manual. Measurements found to be
outside of your service manual recommendations may indicate
the need to deviate from those settings in order to achieve quiet
running with a good contact mark.
Refer to your vehicle service manual or your local authorized
ARB installer for more information.
Set a depth indicator on one of the ring gear teeth as in figure 2.
Figure
2.
While supporting the pinion gear by holding the drive shaft 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
9
2.6 Removing the Differential Center
IMPORTANT:
YOU MUST SPREAD THE HOUSING ON GM 8.9” MODELS
Spreading the differential housing with a differential case
spreader is a step which is critical to set up bearing pre-load on
GM 8.9” differential housings. 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.
Remove both bearing caps.
Carefully spread the housing (Fig.3.) enough to remove the
differential center. (Refer to your vehicle’s service manual).
NOTE : Do not spread the housing more than 0.50mm [0.020”].
NOTE : Be sure not to mix up the left and right hand bearing
cups and master shims. Later it will be necessary to
know which cup and shim came from which side.
Once the housing has been adequately spread, the differential may
be removed by pulling forward on the differential carrier.
Figure
3.
NOTE : The differential center is heavy and quite difficult to
handle when covered in oil. Take care not to drop it.
Relieve any tension on the spreader immediately after the
differential has been removed.

3 Installing the Air Locker
10
3.1 Insuring Adequate Oil Drainage
IMPORTANT:
Some axles were manufactured with poor oil drainage between
the axle tubes and the differential housing. This can often result
in one of the axle tubes filling up with differential oil while
running. In most cases this will result in a blocked air vent which
will cause the differential housing to pressurize and expel oil
from the axle seals at the wheels or force oil into the air system
of the Air Locker, eventually expelling oil at the solenoid valve.
This is a design flaw which was corrected by most automakers in
the later releases of their axle assemblies. If no lower drainage
points are present in the differential housing then it is critical
that you modify the housing to include them.
Inspect the differential housing for the presence of adequate
drainage in both axle tubes (refer to Fig.4.).
Figure
4.
If no drainage exists at all then slots or holes should be created in
the bearing seat face of both axle tubes; one on the upper side of
the tube, and one on the lower side.
If drainage exists but is inadequate (Refer to Figure 5. where only
one drainage position is present.) then slots or holes should be cut
into the housing on the upper and lower side of the tubes where
required.

3 Installing the Air Locker
11
Figure
5.
Figure
6.
NOTE : Cover the differential housing cavity and the axle tube
openings with a rag to protect them from metal filings.
(Fig. 6.)

3 Installing the Air Locker
12
NOTE : Figure 7. shows a completed drainage hole cut into a
bearing seat.
Figure
7.
Remove any sharp edges left behind by the modifications that
could break off and fall into the cavity.
Make sure any grinding dust, filings or drill chips left behind by
cutting the drainage slots are completely cleaned out of the
housing.
Check that the axle air vents are clear and working correctly.
HINT : Position the seal housing against the bearing seat
face of the diff housing, then place the bearing cap
over the seal housing. If no clearance exists for
running the copper tube later (refer Fig. 18.), a
drainage slot, instead of hole, should be cut to suit
this purpose.

3 Installing the Air Locker
13
3.2Approximate 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 differential to a work bench.
Remove the bolts that hold the ring gear in
place.
NOTE : GM 8.9” ring gear bolts are
usually left-hand threaded.
Using a plastic or copper hammer, tap in a
circle around the ring gear to separate it
from the differential carrier.
Remove the original bearings from the
differential center using a bearing puller
(Fig. 8.)
NOTE : Keep the bearings and shims
separated so that they can be
identified as to which end of
the differential they came from. Figure 8.
Examine the bearing cups and cones from Figure 9. for damage or
wear and, if necessary, discard them and replace with the same
size and type of bearings.
Figure 9.
ORIGINAL
DIFFERENTIAL

3 Installing the Air Locker
14
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 bearing shoulder to the ring gear
mounting face and record this measurement as ‘A’ (Figure 9.).
Measure the thickness of the original master shim that was
removed from the right-hand side of the original differential carrier
and record this measurement as ‘B’(Figure 9.).
Measure the distance from the Air Locker bearing shoulder to the
ring gear mounting face and record this measurement as ‘C’
(Figure 10.).
Figure 10.
The thickness of the shim pack ‘D’ must be calculated to position the
ring gear seat of the Air Locker the same as the original differential
(within 0.1mm [0.004”] ).
Use the following calculation to find the desired thickness of ‘D’:
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
AIR LOCKER DIFFERENTIAL

3 Installing the Air Locker
15
Create a shim pack to match ‘D’.
To achieve this desired shim thickness you can:
•Use the shim from the other side of the differential if it is closer to
the desired thickness (only 1 original shim is required to be reused).
•Machine down the original shim thickness.
•Add shims between the original shim and the bearing cup.
•Purchase new factory original shims at the desired thickness.
•Use a universal shim kit available from most drive train specialists.
NOTE : NEVER machine the Air Locker.
3.3Installing the Carrier Bearings
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 the case side bearing
cone (supplied with the Air Locker kit) onto the case side journal of
the Air Locker (refer to Figure 11.) until the bearing seats firmly
against the bearing journal shoulder.
Figure 11.

3 Installing the Air Locker
16
Invert the Air Locker and press the flange cap side bearing cone
onto the opposite bearing journal of the differential carrier until the
bearing seats firmly against the bearing journal shoulder.
NOTE : Do not add any shims between the bearings and the
bearing seat. Shimming of the Air Locker will be
performed with the supplied shim kits and/or the
original master shims (if any) on the outside of the
carrier bearings.
3.4 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 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 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.

3 Installing the Air Locker
17
3.5 Drilling and Tapping the Bulkhead Port
An airline port must be drilled and tapped through the differential
housing to mount the bulkhead fitting into.
Mark a spot on the top of the outside shell of the differential
housing approximately at the position shown in Figure 12.
Figure 12.
Cover the drive pinion and axle tube areas with a rag to protect
them from metal filings.
Drill through the housing square to the outside surface using an
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.
Carefully remove the rags and inspect with a service light inside the
housing to insure no metal filings are left behind.

3 Installing the Air Locker
18
3.6 Assembling the Seal Housing
Figure 13.
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.
Assemble the ARB master shim onto the stepped face of the seal
housing with the rounded edge of the shim facing out.
NOTE : Shim pack ‘E’ should not be assembled at this time.
Carefully install the seal housing by sliding it all of the way onto the
bearing journal with a gentle twisting motion. This will allow the O-
rings to engage gently.
E