Copied this from an old Talkboard topic.  It's a combination of Wolverine's explanation and mine.

From Wolverine:

"An LSD unit acts like a locker wherein the left and right tire are made to spin regardless of traction available to the tires.  This is how a "full" locker works.  In the case of an LSD, the differential allows some slippage or, more appropriately, a "limited" amount of slip to the tire that has more traction in order it to function more practically in high traction situations. Hence the name LSD.

For example, if the lsd was fully engaged at 100% (i.e. "no slip"), can you imagine what it would feel like when making a turn? In an open differential, the inside tire turns less than the outside tire because it has a smaller turning radius to negotiate.  If you had a full locker, the inside and outside would turn exactly the same distance and this would upset the balance or static traction of the vehicle into the turn.  The usual effect is to either force the vehicle to go straight when you want to turn or to push the rear out (in a rear LSD) when you want it to hook on a turn.  This is also why full lockers are only used for offroad vehicles because the terrain that 4x4's travel in have a certain amount of slippage so as to allow the vehicle to behave more "naturally".

The reason a "street" LSD unit has less percentage (about 40%) of transfer is because for practical reasons, the vehicle is used on the road and must behave more like an open diff in order to be "benign" in its behavior and handling.

A race diff, on the other hand, can have more percentage of transfer (e.g. 70%) because it is more critical for the vehicle to have traction in high horsepower situations and also in the manner that racers wish their vehicles to hook up as they exit a turn (fast out!).  If you pay attention to street cars that have race LSD's on them, you may notice that their tires chirp as they negotiate a u-turn or a slow tight turn because the inside tires are trying to rotate more than necessary.

The way that manufacturers create these differences in the street and race LSD is by varying the tension or reciprocity of the springs and clutches found inside the LSD unit. Pretty much like a race clutch and a street clutch on a car. "  
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From johnqpublic318:

"Another type of LSD that wasn't covered but is common on Audis and many European makes, Hummers, GM F-bodies and now on the Ford Ranger FX4 is the Torsen.  It was formerly known as Gleason Torsen and now called the Zexel Torsen, this gear type limited slip operates without cones, clutches and friction materials that can wear out.

The Torsen is a torque biasing diff that  "sort of" multiplies torque to the wheel with the most traction.  The torque transferred is dependent on its Torque bias ratio-- normally 2.6-3.0 to 1.

Torque bias ratio (TBR) represents the "locking effect" of the differential. More specifically, it indicates how much more torque is sent to the high traction wheel (or axle) then is sent to the spinning wheel. For example, when a differential has a TBR of 3:1, 3 times the torque the spinning wheel can maintain (75% of the total torque) will go to the higher traction wheel. If a wheel is spinning and can support 100 lb-ft, the other wheel will get 300 lb-ft.

The biggest drawback of this type of differential is that the "spinning or slipping wheel" needs at least some traction for torque to be transferred.  If you have a wheel hanging up in the air with 0% traction then no torque can be transferred to the wheel that is still touching the ground unless you "ride" the brakes to slowdown or stop the spinning wheel.

The Detroit Tru-Trac operates in a similar manner.  
 
When cornering, an open diff will send more power to the inner wheel since this is the wheel that is lifting and the loaded outer wheel has more traction.  A LSD will try to equalize this power distribution while a full-locker will split it exactly 50:50.

A LSD or locker is part of the differential.  It is inside the diff case which houses the spider gears.  In most cases, you'll have to replace the differential inside the axle housing to install a LSD or locker.  

DO YOU WANT LOCKERS?

It really depends... but, if you've enjoyed and taken my tech columns in the now defunct Automotion magazine as gospel truth then you probably do.  You're the type of individual who grimaces at the sight of step-boards, fashion bars and bulging over-fenders that cover nothing more that puny sized stock tires.

If we're on the same wavelength, read-on...

Let's begin by discussing what a standard or open differential does.  An open differential allows the left and right wheels to rotate at different speeds during a turn.  For instance, during a left turn, the right rear wheel will be rotating faster than the left since it must cover more ground.  This is done by the set of spider gears inside the differential carrier that allows the two wheels connected by axles to rotate independent of each other.  Without a diff, you'd be screeching your tires at almost every turn and would have a wider turning circle.

The problem with an open differential occurs during drag strip-style acceleration runs and off-roading.  Try dropping the clutch of your Honda City at 6,000 rpm and you'll find only one black tire line on the pavement.

Off-road, when one wheel has very little or no traction and the other is gripping fairly well, the wheel with the least traction will spin while the wheel with the most traction will just remain idle as if it weren't needed.  This situation will get you stuck.

Limited-slip differentials utilize clutch packs that keep the axles slightly locked together.  The friction of the clutch packs limits speed differentiation.  However, being limited-slips, slip is still allowed.  A limited slip won't pull you over a boulder if the tire on one side has nothing but air to grab.  For these situations, you need a locker.

Lockers will fully-lock your axles together.  Automatic lockers like Detroit lockers and Powertrax No-Slips will allow speed differentiation during turns but will fully lock the axles if power is applied and one wheel stops turning.  Manual lockers like those offered as option by Toyota or as aftermarket by ARB are on-demand units.  Manual lockers are engaged by pushing a button or some sort of switch.  When turned-off they function like an open differential and function like a spool, locking both axles together, when turned-on.  

Off-road, the advantage of having a locker is tremendous.  When the axleshafts are locked, you simply won't have a your left and right wheels rotating independently from each other.  So when it's time to crawl up that boulder or pull yourself out of the muck, you have both tires working for you full-time.  Even when both wheels have little traction, at least they'll be working together.

However, lockers do have their drawbacks.  With a locker you can load up an axle and it components and increase its chances of breakage.  Lockers also chatter and bang at times during corners and while engaging and disengaging.
In addition, the sudden jerking caused by lockers can be unwieldy on ice and can cause an understeer condition (especially if placed or activated on the front diff).

For true off-roaders, the pros of having a locker far outweigh its cons.  If you're thinking of adding a limited-slip to your open rear differential: Don't.  Put the limited-slip in front and save up for a locker in the rear.  The only time when an off-road vehicle should have a limited-slip in the rear is when it originally comes with it.

Want the best of both worlds?  Want the street superiority of a limited-slip and the off-road advantage of a locker at the same time?  If so, then you want a Tractech (Detroit) Electrac.  The Electrac acts like a Truetrac limited-slip when "off" and locks like an ARB when "on".  It is electric and doesn't need an air compressor.  At worst, if the electrics fail on the trail, you won't be left with an open diff but still a mechanical gear-type limited-slip.  What's not to like?

Unfortunately, the Electrac is only available for American vehicles at the moment so I doubt if it will pique anyone's interest.  And, at $700 or so uninstalled, it's no free lunch.

Thanks brother for your many services to the offroading community - you are truly appreciated and read.
I'd like to know how reliable an EZ locker is (detroit).  Would its grip persist in difficult situations.  I'm planning on one for my IFS front (hi-lux).  A full detroit according to some friends could make steering more difficult and might even break some things underneath.  Are they right?  And what about a tru-trac?  Which of the three would be best, budget considered but not to rule my decision.  I'd rather spend an additional sum than find myself stuck in some murky situation where cellphone signals don't exist.

Quote from: Benny on March 31, 2003, 01:35:21 PM
Thanks brother for your many services to the offroading community - you are truly appreciated and read.
I'd like to know how reliable an EZ locker is (detroit).  Would its grip persist in difficult situations.  I'm planning on one for my IFS front (hi-lux).  A full detroit according to some friends could make steering more difficult and might even break some things underneath.  Are they right?  And what about a tru-trac?  Which of the three would be best, budget considered but not to rule my decision.  I'd rather spend an additional sum than find myself stuck in some murky situation where cellphone signals don't exist.

The Tractech (Detroit) E-Z locker will have all the advantages and disadvantages of the Detroit locker except for strength.  The E-Z locker just drops in your stock carrier and you will be limited by the strength of the E-Z locker and your stock IFS diff carrier.  A Detroit Locker will be much stronger and you will break your front IFS components before you break a Detroit Locker.  For this reason, I don't think a Detroit locker is available for the HiLux IFS and only the E-Z locker is.  Check with Tractech or Reider Racing if you want to be sure.

As with any auto locker installed in front, steering will be affected if you don't have manual hubs.  If you have a local HiLux then you probably do-- so you don't have to worry about this drawback.  Once you lock the front manual hubs to go off-road, you'll feel the effects of the locker on steering.  Unlocked-- it won't matter.

A Truetrac is just a limited-slip and is fairly expensive.  For this price, I would go for a locker.  However, Truetracs do work well on front axle applications.

Remember, ONLY install a locker in front of your IFS HiLux if you're already LOCKED at the REAR.  This will distribute stress among all axle shafts and help your front-end live longer.  

As durable as Toyotas are, with both axles locked, limit tire size to 33s" with that HiLux IFS front end.

The IFS in V8 FJ100s is stronger.

As far as lunch-box or drop-in lockers are concerned, I have a preference for Powertrax No-Slips.  Four Wheeler has had good experience with them on a Dodge Ram and Powertrax claims that No-Slips are 50% stronger than stock.  Check if they're available for the Hilux IFS.

Detroits lockers and ARBs are the strongest but require a more complex installation process unlike a drop-in.

 hello dudes im the guy from isabela....even though the detroit truetrac is very expensive it offers an unsurpassed traction that a limited slip will offer. I got one in front of my 86 toyota hilux competition vehicle and really satisfied. On my rear the brute of the lockers the detroit no-spin locker, a real locker,never let the tire stop spinning. i think this is the best set-up for those toyota hilux owners. Many do a weld on the spider gear to make a temporary locker but the  push is sideward. if you are using a real locker the push is forward and backward plus unsurpassed traction on both wheels.
im building now a toyota fj40 with chevy 350 4 bolt engine and the same real things also inside my diffs......

Is any body here familiar with the Toyota 4 runner SSR model, my question is can the factory installed front diff lock applicable to the solid axle hilux differential? just wondering if its possible to transfer it to a hilux.
To Jean Tsam off road,
I just arrived from Cagayan Valley this weekend particularly Tabuk, Kalinga, looks like ill be there several times this summer, where in Isabela are you from maybe we can hook up one time on my way there.

Wolf,

Toyota has 4 differential types in pickups and 4Runners -- the 8" standard, the 7.5", the 8" V6/Turbo, and the 8.25/8.4 in the Tacoma/Tundra/T100.

Yes, it seems possible that you can adapt the "on-demand" or electric locker from the 3rd Gen 4Runner (96 to 02) into the 2-pinion 8-inch diff of the Hi-Lux.  You must use the entire 3rd Gen 4Runner drop-out 3rd member and locker activation motor in order to do this.   There's also wiring and electrical work involved.

The 3rd Gen 4Runner also uses the Toyota 8-inch but is of the stronger 4-pinion variety.

Check out this link for installation and wiring instructions.

http://www.4x4wire.com/toyota/tech/electric_locker/

For Toyota diff info:

http://home.off-road.com/~bibelheimer/diffs/diff_info.html#top

The Hi-Lux front diff is also a 2 pinion 8" and adapting the 3rd Gen 4Runner rear locker to the Hi-Lux front should be similar in nature.  However, check if the locker motor will clear all front end components.  You may also try adapting the High-Pinion 8" 3rd member with locker from the front of '90-97 Landcruiser FJ-80 and FZJ-80's  which use a high pinion, reverse-cut front diff based on the 8" V6/Turbo rear diff.

I hope this also provides additional answers to TED's query.

Personally, unless you're getting the Toyota locker for free or for a song, I think this is all way too much work.

Quote from: johnqpublic318 on March 31, 2003, 02:52:33 AM
However, lockers do have their drawbacks.  With a locker you can load up an axle and it components and increase its chances of breakage.  Lockers also chatter and bang at times during corners and while engaging and disengaging.

how would you describe the noise when turning?(can u give an example)

can u give a percentage increase of its(axle and its component) "breakage probability"?

thanks

C'mon Ted, kinda hard to describe noises in writing.  Well, they sound like clunks or similar to driveline slack.  Sorry, that's the best I can do.

Percentage?  Can't give you one.  Too many factors involved such as driving style, engine power, axle strength, etc.

If you're driving a diesel, you wont probably notice it as you need to listen carefully to hear it.  Sometimes there's a loud thug sound as if a part as broken, but this is normal.

Quote from: johnqpublic318 on April 24, 2003, 10:36:27 AM
C'mon Ted, kinda hard to describe noises in writing.  Well, they sound like clunks or similar to driveline slack.  Sorry, that's the best I can do.

Percentage?  Can't give you one.  Too many factors involved such as driving style, engine power, axle strength, etc.

well, that will do!!!! sa isang artikuladong nilalang na katulad mo, buti na lang HINDI KA ...NAGKLAK, KADUG, PLAKPLAK, TING!, KACHAK! hehehe

Quote from: sixpack on April 24, 2003, 11:42:18 AM
If you're driving a diesel, you wont probably notice it as you need to listen carefully to hear it.  Sometimes there's a loud thug sound as if a part as broken, but this is normal.

i hav a diesel, so its quiet enough that passengers wont bother/panic on its "thug"?

thanks

The thug or Clunk is loud but if your passenger is not an automobile enthusiast, the wont notice it. (My wife does'nt)  This is due to play in the drive shaft so that it can operate properly

The other 2 noise that it produces, you should listen to it to hear it.

1. It the clicking sound when the locker releases the outside wheel in turn.

2. Chirp is during cornering and with a lot of throttle.

Quote from: ted on April 24, 2003, 06:55:34 PM
well, that will do!!!! sa isang artikuladong nilalang na katulad mo, buti na lang HINDI KA ...NAGKLAK, KADUG, PLAKPLAK, TING!, KACHAK! hehehe

Funny...  Well, this locker noise thing has been asked numerous times and I've always given the same answers.  I even remember Sixpack answering right after or before me.  It's a minor detail that's been beaten up like a dead horse.

If your passengers panic and hyperventilate, push them out the door.  They're too frail for the real world and you'll just be doing them a favor by ending their misery before the next pothole.

Quote from: johnqpublic318 on April 25, 2003, 10:30:02 AM

Quote from: ted on April 24, 2003, 06:55:34 PM
well, that will do!!!! sa isang artikuladong nilalang na katulad mo, buti na lang HINDI KA ...NAGKLAK, KADUG, PLAKPLAK, TING!, KACHAK! hehehe

Funny...  Well, this locker noise thing has been asked numerous times and I've always given the same answers.  I even remember Sixpack answering right after or before me.  It's a minor detail that's been beaten up like a dead horse.

If your passengers panic and hyperventilate, push them out the door.  They're too frail for the real world and you'll just be doing them a favor by ending their misery before the next pothole.

 WELL   SAID   JOHNQ  !!  When we want something, normally its has  drawback and this is a good example.