ARB RD246 Product information sheet

RD246
DANA M210/M220, JEEP JL
RUBICON, 35 SPL
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
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 Carrier
10
3 Installing the Air Locker
12
3.1
Drilling and Tapping the Bulkhead Port
12
3.2
Approximate Backlash Shimming
13
3.3
Calculation & Selection of Backlash Shims
16
3.4
Assembling the Seal Housing
17
3.5
Installing the Carrier Bearings
18
3.6
Mounting the Ring Gear
18
3.7
Preload Shim Measurement
20
3.8
Setting up the Bulkhead Fitting
22
3.9
Profiling the Seal Housing Tube
24
3.10
Bench Testing the Air Locker
25
3.11
Reinstalling Differential and Axles
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
36
6.1
Leak Testing
36
6.2
Testing the Air Locker Actuation
36
6.3
Filling the Differential
37
6.4
Post-Installation Check List
38
7 Parts List
39
7.1
Exploded Assembly Diagram
39
7.2
Specifications
39
7.3
Itemized Parts List
40

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, Allan keys, and drills.
A dial indicator or other suitable measuring tool for checking ring &
pinion backlash.
A differential housing spreader, to facilitate removal of the carrier.
(e.g., ARB Differential Spreader #0770003)
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.
A 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 suitable shim driver (e.g., ARB Shim Driver #0770004)
A slide hammer.
A bearing press or arbor press.
1.2.2 Supplies
Thread lubricant/sealant compound for pressure fittings
(e.g., LOCTITE #567 Teflon past)
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.

1 Introduction
5
1.3 Assembly Type Identification
IMPORTANT :
The RD246 Air Locker is designed for installation in Jeep JL and JT
models equipped with the M220 LSD (limited slip differential) rear axle
assembly or the M210 open front axle assembly (JT only). It does not
suit OEM factory axle shafts and will require custom, aftermarket 35
spline axle shafts.
JL Rubicon Models
The RD246 can be used in JL Rubicon models but requires
aftermarket electronics not supplied by ARB. It CANNOT be used in
rear only applications. It CAN be used in front only applications or
front AND rear applications but requires a programmer to modify the
ECU. These Air Lockers also require custom, aftermarket 35 spline
axle shafts.
Contact ARB or your local ARB distributor if you require more details
or information on locating aftermarket axle shafts.

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 around the differential cover plate seal to prevent dirt from
entering the differential.
Position a fluid drain reservoir under the differential and loosen all
differential cover plate retaining bolts.
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 Removal of the Axles
Remove the wheels, and brakes according to your vehicle
manufacturer’s service manual.
Remove both axle shafts according to your vehicle manufacturer’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
8
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.)
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
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 dial indicator on one of the ring gear teeth. (Fig.2.)
Figure
2.

2 Removing the Existing Differential
10
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.
2.6 Removing the differential carrier
IMPORTANT:
YOU MUST SPREAD THE HOUSING
Spreading the differential housing with a differential case
spreader is a step which is critical to set up bearing pre-load
on cast iron differential housings (See Figure 3.). 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”].
HINT : Be sure not to mix up the left and right hand bearing
cups. Later it will be necessary to know which cup
came from which side.
Once the housing has been adequately spread, the differential may
be removed by pulling forward on the differential carrier.

2 Removing the Existing Differential
11
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
12
3.1Drilling and Tapping the Bulkhead Port
An air line port must be drilled and tapped through the differential
housing to mount the bulkhead fitting into.
Cover the drive pinion and axle tube areas with a rag to protect
them from metal filings.
Mark a spot on the right hand side of the differential, in a position
that will be clear of the ring gear and Air Locker once the seal
housing is installed (Fig.4. & 6.).
Figure
4.

3 Installing the Air Locker
13
Figure
5.
Drill an 11.2mm [7/16”] diameter hole through the differential
housing square to the outside surface.
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.
3.2Approximate 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.
Secure the differential to a workbench.
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 shims, then remove the bearings from both
sides of 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.

3 Installing the Air Locker
14
Examine the bearing cups and cones from Figure 7. for damage or
wear. If necessary, discard and replace with the same size and
type of bearing.
Figure 7.
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 Figure 7.) 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 Figure 7.) and record this
measurement as ‘B’.
FACTORY DIFFERENTIAL

3 Installing the Air Locker
15
Figure 8.
Measure the distance from the Air Locker bearing shoulder to the
ring gear mounting face (shown as ‘C’ in Figure 8.) and record this
measurement as ‘C’.
RING GEAR
FLANGE
AIR LOCKER DIFFERENTIAL

3 Installing the Air Locker
16
3.3Calculation & 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 8.
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
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.
Add small amounts of shim between the bearing cone and the
bearing seat.
NOTE : NEVER machine the Air Locker.

3 Installing the Air Locker
17
3.4 Assembling the Seal Housing
Figure
6.
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
seal housing journal with a gentle twisting motion. This will allow
the O-rings to engage gently (Fig.6.).

3 Installing the Air Locker
18
3.5 Installing the Carrier Bearings
Apply a thin film of high pressure grease to the bearing journals of
the Air Locker, then press the bearing cones onto the bearing
journals as shown in Figure 9.
Figure 9.
3.6Mounting 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, 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.