4/28/2000
A little known fact is that the 96+ 3rd generation 4Runners have the same 4 pinion 8" differential as the 2nd generation 4Runners (and older V6 trucks). This differential is often referred to as the V6/turbo dif. Therefore, any Traction Aiding Differential (TAD) for the old 4Runner, will also fit the new one. The V6/turbo 3rd member will swap with the front axle on a newer Landcruiser as well. The newer Landcruiser uses a high pinion reverse 3rd member. In other words the same RD23 ARB locker fits both the rear of the 4Runner and the front of the LC. I'm being a bit liberal with their artwork and documentation. Hopefully they won't mind seeing as how it benefits them.
The Tacoma, T100 and Tundra uses a new axle known as an 8.4" dif. Very few aftermarket parts are available for this stronger axle however ARB has indicated they will have an air locker by the end of 2000 for this axle. To date Powertrax makes a No-Slip locker for the Tacoma/T100/Tundra. Some TRD Tacomas can be had with the factory electric locker which uses a modified V6/turbo housing and internals. The easy way to tell the difs apart is by the drain plug. The 8.0's plug is on the driver's side and the 8.4's is on the passenger's. Be aware, though, that the very old 7.5" housing which came on 4 cylinder trucks also had the plug on the passenger side. To my knowledge all 4x4 trucks, excluding the LC, use the 7.5" dif in the front (different housing obviously and later versions are reverse geared). The 7.5" was also used in the rear of the Celica. This is of note only because the Celica came with a Limited Slip that is a direct bolt-in to the front on trucks.
I decided to go all the way and get the ARB. My
$20 compressor wasn't doing the job inflating tires anyway. I mounted the compressor under
the hood next to the ABS unit which is the only place big enough and high enough. I had to
fabricate a custom bracket to mount it here but it was worth the work. I ran the wiring
harness across the cowl and sent the appropriate wires through the fire wall where an
existing bundle led. Remove the lower valence panel beneath the steering column to get
better access. Assemble the wiring harness. Left of the steering wheel are two switch
blanks mounted high. Pop those out from the back and run the wires for the
isolating/compressor switch through the right one. Run the wires for switch #1 through the
left hole and hook up both switches.
They fit perfectly
in the dash. You will have two leads left over which have to be wired into the car. Remove
the connector from the back of the dash dimmer switch and tap the blue/white wire into the
green wire on the dimmer harness. This illuminates the switch lights with the dash.
Unfortunately the dimmer system dims using the ground wire so the switches run at full
brightness. I am considering splicing a small rheostat in to the blue/white supply wire so
I can set it how I like. On my vehicle there are two unused connectors floating back there
too. I assume they are for fog lights etc. The white connector has a gray wire that is
switched to ACC. I tapped the ARB red/yellow power lead into this gray wire. The
compressor can run with just ACC now. Follow the directions for the other wiring that I
have not described. It is fairly obvious.
I ran the air line from the compressor across the cowl and down with the brake lines. There are unused clips that can be used to hold the line. Make sure to leave some slack in the right places where it attaches to the dif housing. I zip-tied to the upper control arm and looped to the axle. I'd like to tell you how the Locker install went but for $250, I had 4 Wheel Parts do the install. They did a great job! The Locker from them, model RD23, was $617 and the compressor was $185. See also http://www.larsdennert.com/4runner/breather to prevent debris and constant vacuum from damaging the locker's seals.
I also purchased a standard compressor kit from a
hardware store and a tee fitting. I thought I would save money by not buying ARB's $35
kit. I ended up spending that much anyway. My kit consists of a tee fitting where one side
holds the ARB pressure switch and the other a female 1/4" quick release coupler. A
light weight 25' coiled air hose plugs in here and just reaches the furthest wheel. I
attached a universal female quick release coupler on the end of the hose. There are three
types of 1/4" quick release couplers on the market and they all look similar but are
generally not compatible. Sears carries a universal female unit that fits all three male
types. On the end I can fit an air chuck, nozzle or any moderate air powered tool. The ARB
tank is small but I could rig a large tank inline with some more connectors should the
need arise. [See the updated compressor I now have at AIM
Industries Compressor Installation]
What testing I've done has simply indicated that the system functions properly. It engages quietly at any speed as long as you are going straight. The compressor kicks butt inflating the small built-in tank to 100psi in about 20 seconds. I have been told it will inflate a 31" tire in about 4.5 minutes. I recently inflated a front tractor tire (twice) for someone who managed to dismount the bead and I can attest to the compressor's competence. Being under the hood, I have had it overheat when filling multiple sets of tires. The other gripe, which others have had as well, is that the bolt that holds the tank on works itself loose and then the tank leaks. I would recommend a water separator in your system as well.
Unfortunately, the locker will not let you break the laws of physics. I have attempted to climb extremely steep hills, some so steep that I could barely crawl up them on my hands and knees, in an effort to test the locker. Climbing ability was a limitation of tire traction because all four tires would spin. One interesting observation is that with very little weight on the front, if the locker encountered traction on one wheel, the car will sometimes pitch to the opposite side as it found traction. The 4Runner has good axle articulation due to the coil spring setup and it also appears to have some frame flex engineered in because some of the chassis mounts can slide on their bases. For this reason it is hard to max out and lift a wheel. However, I recently found some fairly steep hills which were rutted out, washed out and had deep holes dug from people trying to climb them. First I tried without the locker and barely got a car's length up the hill. I engaged the locker and coasted up the hill. Sometimes one or the other front wheel would lift high in the air and sometimes it would teeter-totter and a rear would come up. However the car was completely unphased and continued climbing all the way up. This would have been a completely impossible task without the locker. I could have spent the whole day filling holes in the road instead and I don't think I would have made it. Having a locker is like going from 2wd to 4wd. Of course all sorts of other limitations start to show. I hung up the differential while going through some other deeply rutted sections and lost traction. Be that as it may, installing the locker has been the single best modification I have done. It works beautifully, seamlessly and is the best bang for the buck.
3/17/2001
Activating the factory RR Diff Lock light in the dash with your ARB wiring requires a
small 12V relay such as Radio Shack part number
275-248A. Remove the lower dash cover from beneath the steering column (4 screws). Remove
the black instrument bezel from around the cluster (4 screws). At least partially remove
the instrument cluster (4 screws) to gain access to the brown electrical connector on the
right side of the cluster (left side of cluster when looking at it from the back). Wire a
connector into pin 5 (pin 8 on earlier models) of the brown connector. They are numbered
on the cluster. I simply fed some solid core copper through the connector and fed it back
on itself to create a connector tab. Run the other end of the wire to the ARB switch area.
This wire is then connected to the N/O (normally open) connector on the relay. When this
wire sees ground the light will illuminate. Use one of the black wires remaining from the
ARB harness (provided for an optional front locker) and connect it to the common lead on
the relay and to one of the coil leads on the relay. Connect the remaining yellow wire
from the ARB harness to the other coil lead on the relay. The yellow lead is enables the
front locker after the rear locker is turned on. We are using this voltage to activate the
relay and ground the RR Diff Lock light when the rear locker switch is thrown.
6/26/2001
I finally got tired of opening the hood all the
time to air up and relocated the air fitting just under the front bumper.
The only problem I've encountered with the ARB system to date is that the O-ring on the compressor's tank doesn't have an optimal seal. Consequently the tank's bolt ocassionally needs to be tightened to prevent a slow leak. Other ARB users have had similar problems. O-ring grease helps the longevity of the ring but eventually I'll have to replace it.
8/6/2002
I'm a glutton for punishment. ARB has managed
to come out with a series of new locker models. One is the RD89 for rear of the Tacoma,
T100, Tundra, Sequoia open axle (8.25/8.4"). The other is the RD90 for the front
7.5" IFS 1986 to 2002. The 2003 4Runner uses a new IFS differential that is not
compatible [FYI it has an 8" OD ring gear with a FZJ80 rear size carrier]. After
numerous discussions with ARB and Jeepers who have locked Dana 30s I figured the front IFS
might be able to handle the locker as long as it was treated nice. So I ordered one. Again
I had 4 Wheel Parts in Burbank, CA do the axle work. Evidently it was a great deal of work
especially since this is an unknown new design. Being locked (and spooled) front and rear
is a different experience. It really claws.
Parts to have on hand when doing this install which are not mentioned in the ARB instructions: one pinion seal, both output shaft seals, both carrier bearings and three snap rings for the tulip shafts and idler shaft. My vehicle sat for days for lack of a $2 part.
Here is an install article I wrote for Outdoorwire/4x4wire http://www.4x4wire.com/toyota/4Runner/tech/ifs_airlocker/
I originally had 4 Wheel Parts do the install. Basically they totally screwed it up. They damaged so many parts and were so careless that I have paid the install cost several times over trying to fix all their mistakes. Recently, June 2003, the locker would no longer hold air. I disassembled the diff myself and discovered that 4 Wheel Parts simply dropped the carrier back in the housing without doing any shimming whatsoever. Consequently, the ring gear carrier bearing was impacted on the Toyota shim, see picture. The cage rubbed on the shim grinding it to pieces. Metal bits traveled into the seal housing, destroying the seals. It amazes me that it lasted as long as it did. Without being properly shimmed, the carrier floated loose in the housing. Had the seals not began leaking, the carrier would have destroyed itself before I would have noticed it. ARB's customer service through out the entire episode was outstanding. They went above and beyond giving me free parts and tips on fixing the trouble. Fortunately a shim kit can be obtained from ARB in the form of SK002 which is originally for a Ford. The replacement ring gear carrier bearing is an LM503349. The trick to setting up a clamshell diff is to first set the carrier preload properly and then adjust the backlash/mesh. I can't say enough for the ARB product, now that it is properly installed.
This locker works awesome! Having two lockers is almost twice as good as having only one. (One is major step up IMO) The front now grabs and pulls over and up big rocks instead of the rear having to push and do so much work. Do you remember what it was like to go from an open diff to locked? If so then maybe you can imagine.
Here is a description from Chris Wood of ARB on how their new locker design works: The RD90 is based on the new timed-gear design that ARB developed about two years ago. To give you an idea of what this means... when a traditional Air Locker locks up, there is no guarantee that the teeth of the side-gears and spider-gears share an equal portion of the load. In other words, the load is purely random based on how the gears are clocked to one another at the moment the Air Locker becomes locked. Strength in a traditional Air Locker is achieved by having the largest side-gears and spider-gears possible and by having four spider-gears whenever possible. This gives the individual teeth a better chance of handling the loads they will be faced with when the Air Locker is locked. C-Clip differentials suffer in this area because they usually have only two or three spider-gears and consequently fewer teeth. The timed-gear Air Locker has its side-gears and spider gears clocked (timed) from the factory to provide a perfect distribution of the load over all teeth when the Air Locker is locked. The resulting strength increase in some applications has approached 300%.
In basing the RD90 on our timed-gear design, changes were also made to the way the air is delivered. Traditional Air Lockers, as you obviously know, receive their air at the bearing opposite the ring-gear. The timed-gear Air Lockers receive their air at the bearing on the ring-gear side. This means that on the IFS Toyota the air line enters on the small side of the split case. In addition to this change, the timed-gear Air Locker also benefits from a two-piece case instead of the traditional three-piece design and we have eliminated the need for the annular piston used to transmit the air's force to the locking clutch-ring. In a nutshell, the RD90 is stronger, simpler in design and easier to install than a traditional Air Locker... especially in IFS applications. Regarding the installation instructions, they have been revised to coincide with the unique set-up procedures of the RD90. Sorry for the long dissertation here, but you seem like a person who would appreciate some of the details. Hopefully this helps.
There have been several issues of gear oil being blown out of the front breather using ARB lockers. There are several things that contribute to the problem. Here are my conclusions.
I mitigated the problem by filling the gear oil to between 1/2" and 1" below the bottom of the fill hole. I then added a second breather. See Toyota Extended Axle breathers These steps shouldn't be necessary if your ARB and breathers are working optimally. I have since solved those issues.
This is useful if you misrouted a line and it gets busted.
Here is the wiring diagram arbwiring.JPG
Here are basic troubleshooting tips beyond the instructions for the RD90 setup.html
The switches are made by http://www.carlingswitch.com/
Specifically http://www.carlingswitch.com/products/switches/contura_ii.asp
The solenoids are built by http://macvalves.com/
Part number Description 35A-AAA-DDBA-1BA Whole assembly 12Volt solenoid 35A-AAA-DDAA-1BA
Whole assembly 24Volt solenoid 35A-AAA Air Valve only DDBA-1BA 12 Volt Solenoid 5.4Watt
DDAA-1BA 24 Volt Solenoid 5.4Watt
Replacement parts source http://www.4by4connection.com/arbairlocrep.html
Their site is brand new http://www.arb.com.au
For more info on traction aiding differentials see my article http://www.larsdennert.com/traction
