Auto vs Selectable Lockers
Some things to consider with lockers and feel free to correct me if I say something inaccurately [no flaming please] as I am sure they are better experts out there than myself):
Lockers should be used only at slower speeds (<10 kph), and small turning radii or damage may result.
Auto lockers: they engage when the wheel spin is different on each side, the operator does NOT control this as it is automatic. One does not have to be in 4WD or in low for them to engage. This is most notable when turning corners especially with front lockers, at higher speeds (>10kph) and hard turns. Additional wear is experienced with these types of lockers both in the axle, drive train and gears as well a tires (you will hear a knocking or clicking sound). This condition has the most wear on the lockers and gears, etc. To maintain these properly, inspect (for metal particles, water), monitor and change your differential fluids routinely. BTW Breathers will help these and all lockers) last longer and decrease wear from water digestion.
Selectable lockers: these are engage by the operator via air compression system, electrical or cable (older Toyota technology but very reliable and very expensive addition if not installed at factory) and generally you need to be (or should be) in 4WD low before engaging. As these are all selectable, it is very apparent that the wear is minimal since the operator usually engages these at lower speeds, minimal turning radius and shorter time/distances and then they should be disengaged IMMEDIATELY. Rear lockers should generally be engaged before the front lockers (electrical) and are generally used more than fronts on their own or with both engaged. It is a rare situation to use fronts on their own (electrical do not allow this to happen without custom modifications). As one can see, since the operator selects when to engage/disengage these types of lockers, they are very infrequently used and over relatively short time/distances as compared to their counterparts the auto lockers, hence less wear.
Selectable lockers, barring any defects or misuse/negligence, will last the life time of the vehicle wheres as the auto lockers, depending on the driving habits/conditions of the owner/operator, generally have to be replaced a number of times during the life of the vehicle.
As such auto lockers are generally less expensive than selectable lockers and are general easier/less time to install. Selectable lockers tend to be a bit more expensive and take more time to install due to the electrical, compression lines, or cables that are required for their operation. This price differential is easily offset by one lasting considerable longer than the other.
Since auto lockers engage when the system feels it is required, it indicates that lockers should be engage before or as the difficulty (getting stuck) begins NOT after! Noobs tend to wait until they are in trouble before engaging their selectable lockers. Lockers should be engaged whenever you, the driver (based on your experience and driving skills) feels they are warranted; not after you are stuck or in trouble (however they may still get you out of the problem - but had they been engaged first, the problem may never have occurred). Like a winch, they are like an insurance policy - very infrequently used or needed - but can save you a ton (money, time, effort, frustration, embarrassment, pride, image, etc.) when you have them AND know how to use them correctly and safely.
Selectable lockers have similar maintenance to auto lockers as well as checking the air lines, electrical connects, and for cable lockers they need to be used routinely. Like your 4WD system (should be used in both hi and lo at least 10-15 kms per month to stay lubricated), selectable lockers also need to be used regularly to stay functioning. Do NOT engage your selectable lockers on hard (black top, concrete, etc.) surfaces. Gravel or dirt roads are preferable and one can easily see/feel them engaging and disengaging. Do this a couple of times a month. REMEMBER, slow speeds and small turns.
Noobs tend to feel additional (and falsely) confident when they have lockers; almost as if they are invincible. NOT true! They tend to get into even more difficulty/trouble because of them (the lockers). Having any kind of lockers does NOT mean you can get yourself through any kind of problem. Some problems/difficulties, just plain need to be avoided, period!
I have been off-roading for over 30 years from jungles of Borneo, to the deserts of W. China, N. Africa and Middle East and have only recently had selectable electrical lockers as they came in my rig. I just drove according to the conditions that presented me at the time - never used them before - never had to! Granted, had I had lockers back (if they were even available back in the Cretaceous) then in many situations, I might have missed the problem. Other that, I know people that have had them from day one with their rigs as they came as a factory installed option and have rarely to never used them. Lockers are only used for short distances, i.e. enough to get you out of the situation (usually a hundred feet or less) and that's it! They are not meant to be engaged longer or you will do unnecessary damage to them or the gears, axles, drive train etc.
Be very careful using any kind of lockers on slick rock like Moab area, as the additional weight on the throttle (read gun it!) with lockers engaged will increase torque and you can do considerable damage. Very easily pop a birfield if you have them, snap drive shafts, crack axles, etc. GO SLOW AND DO MINIMAL TURNING!!!!
If your are going to install after market selectable lockers, ARB air lockers are among the best, definitely least expensive (as I know you are all watching your pocket books) and easiest to install. Electrical and cable take far more $$, effort, time and skills to install. They only issue I see (but have not heard of much), is that if the air lines are not installed properly (as in out of the way) they can be torn off, or damaged and hence your lockers do not engage. An additional benefit to ARB air lockers is that if you upgrade to the larger compressor, you also have on-board air for re-inflating your tires after airing down, inflating your flats, and possible (depending on compressor you choose, Wil can help you here) running air tools out on the trail.
An alternative combination of lockers, is to have ARB rears and auto locker in the front. You may well ask what the...is that about; I could have sworn he just said auto lockers in the front are not that good? But this combination keeps the costs lower and makes your auto lockers in the front, slightly selectable when combined with e-hubs (a switch or lever in the cabin to engage the front axle [4 Hi/4 lo) or manual [Warn/Aisin] hubs. For the noobs, this means you determine when you want to be in 4WD (selectable) not AWD or part time 4WD. In the latter configuration, the front axle is freewheeling all the time you are driving and the operator can only select 4 lo or 4 hi (auto lockers would be engaging whenever the conditions prevail). Whereas, having the electrical or manual hubs, the operator engages the axle which in turn engages the auto locker capability and hence less wear and tear on all parts concerned.
I hope this is informative and accurate. Please enlighten me if your see any errors.
