Airlocker RD103 User manual

RD103
DANA 35, 27 SPLINE,
3.31 & DOWN
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 [e-mail]
North Central and South American enquiries [e-mail]
Other international enquiries [e-mail]
www.arb.com.au

Table of Contents:
1
1 Introduction
3
1.1
Pre-Installation Preparation
3
1.2
Tool-Kit Recommendations
4
1.3
Assembly Type Identification
5
2 Removing the Existing Differential
6
2.1
Vehicle Support
6
2.2
Differential Fluid Drain
6
2.3
Removing the Axles
7
2.4
Marking the Bearing Caps
8
2.5
Checking the Current Backlash Amount
9
2.6
Removing the Differential Center
10
3 Installing the Air Locker
12
3.1
Insuring Adequate Oil Drainage
12
3.2
Installing the Carrier Bearings
14
3.3
Approximate Backlash Shimming
15
3.4
Mounting the Ring Gear
17
3.5
Drilling and Tapping the Bulkhead Port
18
3.6
Assembling the Seal Housing
19
3.7
Pre-Load Shimming
20
3.8
Reinstalling the Bearing Caps
23
3.9
Checking the Backlash
24
3.10
Setting Up the Bulkhead Fitting
25
3.11
Profiling the Seal Housing Tube
27
4 Installing the Air System
28
4.1
Mounting the Solenoid
28
4.2
Running & Securing the Air Line
30
4.3
Connection to the Bulkhead Fitting
31
5 Mounting & Connecting the Electrical System
33
5.1
Mounting the Actuator Switch(es)
33
5.2
Wiring the Actuator System
34
6 Testing & Final Assembly
38
6.1
Leak Testing
38
6.2
Reinstalling the Axles
38
6.3
Testing the Air Locker Actuation
41
6.4
Re-Sealing & Filling the Differential
41
6.5
Post-Installation Check List
42
7 Parts List
43
7.1
Exploded Assembly Diagram
43
7.2
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, 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.

A differential housing spreader, to facilitate removal of the carrier.

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 3.3)

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 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.

Teflon paste.

1 Introduction
5
1.3 Assembly Type Identification
IMPORTANT:
Sections 2 and 6 of this installation guide have been written to
accommodate two different Dana 35 applications:
AThe ‘C’ clip retained axle shaft (Refer to Fig.1.)
B the non-‘C’ clip type axle shaft (Refer to Fig.2.)
To eliminate confusion, you should identify which figure your axle
matches with. The section numbers within the guide that refer ONLY
to the ‘C’ clip type have been suffixed with an ‘ A’, and those that refer
ONLY to the non-‘C’ clip type have been suffixed with a ‘ B ’.
PLEASE IGNORE ALL SECTIONS WHICH
DO NOT APPLY TO YOUR APPLICATION
Figure 1.
Figure 2.
A
B
‘C’ CLIP

2 Removing the Existing Differential
6
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
7
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.
2.3.1 A Removing ‘C’ Clip Retained Shafts

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 by unscrewing it.

Rotate the differential carrier again until you can completely remove
the cross shaft from the differential.

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.
2.3.2 B Removing Non-‘C’ Clip Semi-Floating Shafts

Remove both of the rear wheels and brake drums/rotors according
to your vehicle manufacturer’s service manual.

Remove the axle retaining nuts holding the retaining plate to the
axle tube assembly.
NOTE : The axle retaining nuts and bolts are not
recommended for re-use and should be re-placed at
the time of reassembly.

2 Removing the Existing Differential
8

Pull the axle free of the axle bearing using a slide hammer.

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.
2.4 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.3.)
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 3.

2 Removing the Existing Differential
9
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 4.
Figure 4.

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
10
2.6 Removing the Differential Center
IMPORTANT:
YOU MUST SPREAD THE HOUSING ON DANA 35 MODELS
Spreading the differential housing with a differential case
spreader is a step which is critical to set up bearing pre-load on
cast iron Dana 35 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.5.) 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 5.
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
11
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.6.).
Figure 6.

If no drainage exists then two slots 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. Figure 7. shows an example of an axle
housing with no existing oil drainage.

3 Installing the Air Locker
12
Figure 7.
Figure 8.
NOTE : Cover the differential housing cavity and the axle tube
openings with a rag to protect them from metal filings.

3 Installing the Air Locker
13

If no drainage slot is present at the upper left-hand side (refer to
Fig.6.) of the housing at all, then a slot (not a hole) will have to be
created here as clearance for the seal housing tube
(Refer to Section 3.8 Reinstalling the Bearing Caps).

If drainage exists but is inadequate then slots or holes should be
cut into the housing on the upper and lower side of the tubes where
required.
NOTE : Figure 9. shows upper and lower drainage slots cut
into a bearing seat which had no existing drainage at
all before modification.
Figure 9.

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.

3 Installing the Air Locker
14
3.2 Installing 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 one of the bearing
cones (supplied with the Air Locker kit) onto one bearing journal of
the Air Locker (refer to Figure 10.) until the bearing seats firmly
against the bearing journal shoulder.
Figure 10.

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.
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 Installing the Air Locker
15
3.3 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.
Figure 11.

Assemble the original bearing cup onto the cone of the right-hand
side of the original differential carrier.

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 outer face of the
bearing cup to the ring gear mounting face (shown as ‘A’ in Figure
11.) and record this measurement as ‘A’.
NOTE : Be sure to measure using the bearing cup that
originally came off of the right-hand side.

3 Installing the Air Locker
16

Assemble the new bearing cup and master shim (supplied with your
Air Locker kit) onto the right-hand side of the Air Locker (as shown
in Fig.12.) and measure the total distance ‘B’.
NOTE : The shim pack ‘C’ should not be installed at this time.
Figure 12.

Record this measurement as ‘B’.
The thickness of the shim pack ‘C’ should make the distance ‘B’ on the
Air Locker closely match the distances ‘A’ on the original differential
(within 0.1mm [0.004”] ).

Use the following calculation to find the desired thickness of ‘C’:
A – B = C (Replacement Shim Pack)
HINT : If your calculations are correct then the following
equation will also be true:
A – B – C = ZERO

3 Installing the Air Locker
17

Select shims from the shim kit supplied with your Air Locker to
make the thickness ‘C’ as determined above.

Place this shim pack between the master shim and the bearing cup.

Re-measure the new distance ‘B’ from the Air Locker (now
including the shim pack ‘C’) to make sure that it matches the
distance ‘A’ on the original differential.
NOTE : NEVER machine the Air Locker.
3.4 Mounting the Ring Gear
IMPORTANT:
Newer OEM Dana 35 ring and pinion sets use 7/16” bolts.
The flange holes of the Air Locker must be reamed from
Ø3/8” to Ø7/16” to suit.

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
18
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.
NOTE : Higher ratio gearing uses deeper (thicker) ring gears
with teeth that extend much further. Make sure the
intended hole location is far enough away from the
ring gear teeth that the air line will not be at risk of
contact with the current or future ring gears.

Mark a spot on the top of the outside shell of the differential
housing approximately 30mm [1.25”] in as shown in Figure 13.
Figure 13.

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 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.

Carefully remove the rags and inspect with a service light inside the
housing to insure no metal filings are left behind.