Step By Step
The V-6 centersection on the left has bigger bearings, larger and more reinforcement ribs, and a thicker mounting flange at the bolt holes than the stock four-cylinder centersection on the right. The V-6 centersection uses different bearings and carriers than the four-cylinder centersections, but is a drop-in replacement for the four-cylinder unit. So if you’re getting all new stuff you may as well get the better parts.
The worst part about installing an ARB is drilling, tapping, and routing the air lines. That and getting the gear contact pattern bang-on were our two biggest concerns with setting up our own centersections, so we let the experts at West Coast Diffs handle it. They even routed the air line to the correct side without our asking them to so it didn’t interfere with brake or suspension components.
The rear diff installation is cake. For each side you simply unthread and cap off the brake line, disconnect the parking brake cable, and remove the four retaining nuts. The axle/drum assembly can then be slid out enough to clear the carrier.
After unbolting and pulling the stock centersection, we cleaned the housing of any gasket material, siliconed the new centersection, and torqued down the retaining nuts. Then the axleshafts are slid back in place and the brakes hooked up. Don’t forget to bleed them before driving.
The front is a little more involved because you need to pull the spindles off to get the shafts out far enough to remove the centersection. Like the front, just remove the old centersection, clean the housing, and install the new parts. The oil pan gets in the way a little, but it’s still not that difficult. Slam dunk.
Although using anything other than an ARB air compressor voids ARB’s warranty, we’ve seen many people using Advanced Air System’s Powertanks to operate their ARBs. Advance Air Systems recently came out with its ARB Manifold Kit for $69.99. It comes complete with a gauge and all the fittings necessary to run your ARB solenoids and lines with your Powertank.
Along with the complete centersections, West Coast Diffs sent us an ARB compressor and installation kit. We’ve been to ARB’s Melbourne assembly facility and watched them flog each compressor like one of Kathy Lee’s sweatshop kids after it’s assembled to make sure everything is OK before being shipped out.
The ARB compressor comes with blue air hose, switches, solenoids, a wiring harness, and very detailed instructions. The hardest part about hooking everything up is figuring out where to mount the switches. We plumbed our air lines, wired in the compressor, and mounted the switches in the center console.
Everyone who has wheeled an open diff vehicle at one time or another knows the feeling. You’re halfway up a rutted hill or off-camber ledge. You’ve got the transfer case in low range and you can feel the torque of the engine through your seat. The suspension groans as it follows every crack and dip in the terrain keeping the tires in contact with the ground. Then, just when you start getting that cocky feeling that you’re going to make it and that your rig really is the bomb—despite what your friends with their modified rigs say—the engine rpm comes up. You stop going forward and quickly slide back about a foot or so as the tires kick up clouds of dirt from opposite ends of the vehicle. You just reached your potential and nothing but more momentum, greater articulation, or a traction- aiding device will take you farther.
The Situation
Total thrash trail beaters usually leak oil, get crappy mileage, shake on the highway, and have rear spools or auto lockers that chirp tires going around corners or when parking. We’re all for driving them everywhere every day, but we know that’s just not usually the case for most of you. And it wasn’t the case for our ’85 4Runner. Our goal with this vehicle is to develop it into a well-balanced machine that can carry the crew to Vegas for a weekend, cruise through the Rubicon without difficulty, or even trek across the country in comfort while getting respectable mileage.
We wanted lockers, we wanted to increase the gear ratio from 4.10 to 4.88 for better acceleration, highway cruising capabilities, and off-road performance, and we wanted to upgrade our spindly four-cylinder Toyota centersections to the beefier six-cylinder versions. Also, since Toyota axles have a drop-out third member just like a Ford 9-inch, we wanted to order the gears and lockers set up in the new centersections so we could install them ourselves in the driveway the day they arrived.
The Lockers
Since we feel that limited slips belong in cars and automatic lockers or spools were too harsh for a vehicle that the wife would occasionally drive (yes, we realize this isn’t the case with every wife), a pair of ARB air lockers was the natural choice. For the uninformed, an ARB air locker is a pneumatically actuated locker that operates as an open differential when not engaged, but that locks both axleshafts together just like a spool when engaged. That means you get tractorlike grip in the dirt with none of the drawbacks of an automatic locker or spool on the street.
The Parts
We contacted Gary McFadyen at West Coast Differentials for all of the parts we’d need. West Coast Differentials carries just about every part made for every axle, so filling our order was no big deal. McFadyen had his boys assemble a pair of V-6 centersections with quality Sierra Gear ring-and-pinions on the ARBs. Since Toyotas use a crush collar on the pinion, West Coast Diffs also included driveshaft flanges so we needed to let them know our driveshaft type. West Coast Diffs also shipped us an ARB air compressor. There’s nothing worse than hunting down parts so we really appreciate companies where we can one-stop shop.
Driving It
We had reservations going to 4.88s from the 4.10s with only 32-inch tires, but it turned out to be the right choice. The first thing that was noticeable was how quickly we needed to get into Second gear. The little 22RE four-cylinder spools up quicker than before and feels a lot more brisk when pulling away from stoplights. The desire to reach through the firewall to strangle the wheezing squirrel isn’t there anymore. On the highway, we can now pull grades in Fourth or Fifth that used to require a downshift to Third or Fourth. We’re also finding ourselves driving with our foot off of the floorboard, where before we’d just mat the gas and wait for acceleration that never came.
Off road it’s night and day. No matter how many times we experience it, it always amazes us what a total transformation a locker can make in an off-road-driven vehicle. We find ourselves using the rear locker for most situations and engaging the front one only when necessary. We guess we’re a little gun-shy after seeing so many busted Birfield joints. Where we once had to hit nachos and rutted hillclimbs with speed and lots of throttle, we can now just elegantly creep up and over.
Another added benefit is the ability to drive in sand. We’d really need to let the poor four-cylinder have it with the open diffs, but now with all four tires contributing we’re able to make it to the top of dunes that used to totally spank us with less throttle. All in all, the lockers are probably the single biggest improvement to this vehicle’s off-road prowess that we’ll be able to make.
West Coast Diffs did an awesome job setting up the gears and plumbing the air lines. The gears run quiet and cool and when the lockers are engaged there are no annoying air leaks to set off the compressor every five seconds like we’ve seen with some inferior installations.
The rear diff installation is cake. For each side you simply unthread and cap off the brake line, disconnect the parking brake cable, and remove the four retaining nuts. The axle/drum assembly can then be slid out enough to clear the carrier.
