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Help understanding 4WD and lockers.


TannerTheWD21
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So I have a 1990 WD21 that has an open diff in it and someone said to get some lockers for it. How do I engage the lockers if I wanna go four wheeling Because slowly but surely I am building up my own off-road rig. Also, how would I go about installing manual locking hubs on the front from my autos?

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There are a few locker types out there:

  1. Mechanical lockers aka lunchbox lockers aka unlockers: these have spring-loaded side gears that keep the diff locked most of the time, but will disengage (unlock) when making turns to allow one tire to rotate faster than the other.  They'll make a click-click-click or tap-tap-tap noise during the turn.  This allows them to be streetable to some degree, but loose terrain (including wet road) may prevent them from disengaging, which could prove hazardous; simple solution: slow down, brake earlier.  Because they are already locked, there's nothing extra the driver needs to do to engage them.  Most lockers of this type fit inside the OE differential carrier; some (like a Detroit Locker) replace the carrier.  If you have rear LSD, you'll need an open carrier to put non-Detroit mechanical lockers in.  These are rather economical options, running around $200-$300 for most brands, and can be installed with basic tools.
  2. Air lockers (ARB) or Pro Locker (TJM): these require an air compressor and some electrical wiring to engage.  The air pressure is what locks the locker, and the locker unit replaces the entire OEM differential carrier.  The wiring portion puts electric solenoid on the air line, which opens to fill the air hose between it and the locker.  This is engaged by a switch that the user toggles.  One air compressor can power both front and rear locker, so it usually makes sense to run dual air lockers, budget permitting.  When not engaged, the locker acts like an open diff.  These lockers run around $1K and require more advance mechanical skills for installation, as gear setup is required.  Factor in another $200-$400 for the air compressor and fittings.  
  3. E-lockers: while not readily available in the US, an Australian brand, Harrop, makes the Eaton equivalent of their E-lockers for Nissans.  Like the air lockers, these replace the entire carrier and are open diffs when off.  They don't require air, of course, but do require some light electrical wiring.  A 12V source and a driver-operated switch engages the locker.  Harrop and other importers sell them for around $1200-$1300 USD depending on the exchange rate.  Although they are more expensive, they also don't need an air compressor.
  4. Cable lockers: Although I don't think there's a Nissan option, cable-actuated lockers (like OX) do exist.  Same concept as the air and e-lockers, except they are engaged by lever and cable.  However, there are kits that can convert them to air-driven.
  5. Spools: these replace the carrier internals, or the entire carrier.  Not sure if aftermarket options exists for Nissan, but these "lock" the diff 100% because they completely eliminate the "differential" function of the diff.  The idea is that all the moving pieces are held stationary to each other, which means that you can weld all the internals together to turn the diff into a spool.  Cost in that scenario is just labor and welding wire.

Since you will be installing manual hubs, these tend to pair well with mechanical lockers as a budget-friendly option.  Since you have a WD21, you also have rear mechanical diff options if budget is an issue.  Either route, lockers are worth every penny.

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The other way not mentioned by  hawairish is to go shopping around for an LSD equipped wd21 and swap the whole axle assembly. Admittedly, that's a lot of wrenching but parts should be very inexpensive, it will depend on what kind of space arrangements you have / can make and what kind of wrenching skillz you got but it's an option.

 

The manual locking hubs swap is quite easy and can be done trailside, in your parking space or on the street. You'll need to get a set of snap-ring pliers if you don't already have them, a 6mm hex key (L shape, because you can't get the socket version onto the nuts.) to unbolt the hub bodies and a pair of magnets to get the "brakes" that engage the autolocking hubs off. Remove the covers (with a 3mm hex(?) I think, remove the snap ring off of the axle end, remove the "brakes", then unbolt the  hub bodies. Replacement is going to depend on which ones you get.... but those should have instructions!!

 

I did mine in my parking space without the snap-ring pliers (which is why it took me over and hour)

 

Bring clean rags and some wheel bearing grease!!

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I put a video together when I did my manual hub swap ages ago. Not the best but here it is --should give you an idea of what you're up against if nothing else. +1 on the snap ring pliers. I've had my hubs off several times since and it's much quicker and easier with the right tools. You can also service/adjust your front wheel bearings while you're in there if they need it.

 

My truck's got the factory rear LSD in it. It's much better than an open diff but it's certainly not a locker. Could be a good option depending on your budget.

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@SpecialWarr Yes, an LSD is a good traction device, but I omitted it from the list because it’s not a locker.  Having run a front mechanical locker with a rear re-packed LSD, though, I can attest to its capabilities.  Costs-wise, changing from open-to-LSD or re-packing an existing LSD might not be cheaper than mechanical locker either. 

Edited by hawairish
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I put a video together when I did my manual hub swap ages ago. Not the best but
--should give you an idea of what you're up against if nothing else.

Is darwinpasta you? Wow, you’ve got a lot of videos!
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4 hours ago, TannerTheWD21 said:

That helps alot guys! Now where do I install the lockers? I'm def gonna do front lockers but idk how to install them. 

 

(Manual hubs are next on my list)

 

The lockers go inside, or replace, the differential, if that’s what you’re asking.  If you’re wondering “where”, on the other hand, any 4x4 or differential shop can do it.

 

Depending on the type of locker, you’ll need other special tools, particularly if you need to “set up” the gears again. Set up is normally required if you replace the carrier, or if you put a locker in an H233B. For R180/R200 (front) and C200, you can get away with putting everything back in the way it come out (i.e., don’t mix up the bearing races and any shims). 

 

If doing a mechanical locker up front, it’s pretty easy. Just disassemble the axle and carrier, pop the ring gear off, replace the carrier internals with the locker pieces, then put it all back together. 

 

Only thing you might need to check, as I’m not familiar with WD21 drivetrain options, is whether you’ve got the R180 or R200 up front...I don’t know what options exist for the R180. 

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A front Lokka is a super easy install and the best bang for your buck when compared to any performance enhancer you can throw at a 4x4. Hands down. $300+/- for a whole new beast is a steal. If I could do it all over again with my truck I would have done the Lokka first. 

 

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Man that lokka's tempting.

I haven’t heard of anyone running it who doesn’t like it. Lots of positive press in the Australian forums & TowndawgR50 loves his. Also, you can occasionally get them for $350. My only reservation is that I use the AWD (open center-as opposed to 4Hi or Lo) on my tx14 quite alot here in the wet NW. The Lokka would always be ticking on turns & occasionally doesn’t unlock in the slick-both of which would be annoying. Nevertheless, with a rear LSD already in place it’s a much cheaper option than an air locker. Frankly, It’s a no brainer with the tx10 transmission as you’d only notice it when you switch into 4WD & have your front hubs locked.
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  • 2 weeks later...

Along with this topic I have a question about changing manual hubs from a 89 pathy into 91.

What would need to be done? Is it an unbolt and  rebolt? 

I have purchased the spartan lunchbox locker for my 91, my concern is as I remove the 3rd member will I have to reset the gears? Backlash? Should I take the axles all the way out and replace the seals or could I get away with pulling them out just far enough to get the 3rd member out?         Thanks for the help!

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