It only took one week-long trip to Moab to get me hooked. Ever since that fateful trip April of 2000 I've been talking about getting my Montero ready for Utah in 2001. Now it's February of 2001 and I've finally saved up enough moola to purchase an ARB Air Locker - the ultimate in offroad traction (at least that's what it says on the box, so who am I to argue?). I am fortunate to be an applicant in the Minnesota Trialriders Club and met up with John Nutter, a true off-road enthusiast who graciously offered to help me with the install. Of course I asked how many ARBs he's done, and his answer was one, but that he has done dozens of gear settings and has all the necessary tools. John's a good guy so that was good enough for me. All I had to do was set a date and time to show up at his ultra-clean and organized garage.

An exploded view of the parts to be installed.

This installation was done on my beloved 1989 Mitsubishi Montero 4dr V6 with factory LSD. It has 149,000 miles on it and the rear diff had never been apart. The axles have only been pulled once when the inner rear axle seals were replaced in early 2000. We had the shop manual at our disposal, which helped tremendously. I will have to print it out again because now it's totally covered in grease.
What follows is a summary of the installation process of the rear ARB Air Locker (Part number RD46) from my perspective. What's my perspective? I am not a mechanic, but love to know how things work. I'm still striving to become an adequate bush mechanic so I can get home in the same vehicle I left with.

• Raise the truck

• Set it on jack stands

• Pull the wheels

• Disconnect the hydraulic brake lines

• Disconnect the emergency brake lines

• Drain the diff

• Unbolt and remove the axles

• Unbolt and remove the driveshaft

• Unbolt and remove the 3rd member 

• Take it to a shop or make friends with folks who like to do gears and have all the necessary tools

• Measure and record the preload and backlash

• Remove the LSD

• Pull the bearings from the LSD (requires special bearing puller)

• Remove the primary ring gear and see how it dwarfs a Dana 44 ring gear - modeled beautifully by John Nutter

The "third member" of the installation team.	The LSD prepares to get its bearings pulled.	Can you see the difference?

• Compare the LSD with the ARB - ARB is the stout one in the foreground

• Find a cool place for the air line fittings and drill a hole in the top of the diff - make sure to cover the pinion gear

• Thoroughly clean all shavings out of the diff

• Tap the hole from the outside (don't tap it too far)

• Thoroughly clean out the diff

• Press new bearings onto the ARB using a bearing press

• Bolt the primary ring gear to the ARB

• Install the ARB into the diff using the homemade spanner wrench

• Set the preload and backlash to the original measurement (assuming it's within factory specs)

The factory LSD (behind) makes way for "air power".	The ARB in the fore- ground wins the heavyweight title.	Drill a hole in the top of the diff, but be sure to cover the pinion gear!
After dumping the shavings, tap the hole from the outside.	A homegrown spanner wrench helps the put the ARB in its new home.	Preload and backlash setting... its not rocket science, but darn close!

• Fiddle with it a lot at this point (dial indicator, spanner wrench, and expertise needed for this)

• Double-check the preload and backlash after tightening all bolts to spec

• Install the ARB seal housing without the o-rings

Carefully... Bend the metal seal housing tube so it is exactly centered in the tapped diff hole - make sure it's routed about " away from the locker and does not press the seal housing at an odd angle with the locker - it should line up perfectly!

• Cut the metal tube to length - so it just sticks out the tapped hole

• Lube and insert the o-rings and install the seal housing

• Insert the ferule and inner air-line fitting

• Insert the outer air-line fitting

• Reinstall the 3rd member and fill it with fluid (preferably gear lube)

• Reinstall the drive shaft

• Install new inner oil seals if necessary

• Reinstall the axles (I used the existing shims and just bolted the axles on the way they came off)

• Attach the air line and fittings

• Route and zip-tie the air line away from the muffler and to the compressor

• Make sure you leave enough slack in the air line for full suspension droop

• Lower the truck and have a beer (or two)

• Mount the compressor (I installed mine in the spring of 2000 - it was the ultimate father's day gift!)

• Mount the switches

Switch mounting step one: console removal.	Step two: marking the holes with the template	The mounted switches look OEM
Keep the airline away from that hot muffler!	The compressor sits in front of the battery tray.	The finished install - like it came from the factory!

• Install the wiring

• Connect the air line to the compressor

• Take a break and . . .

• FIRE IT UP!!