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tru trac, locker, differential information


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Old 01-04-2007, 09:55 PM
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tru trac, locker, differential information

done some digging around for my buds to help make their decisions, hopefully this will help, it is some old info, but still may be helpful

Differentials - What Are They?
In powered axles, gears that deliver torque from the drive shaft to the left and right axle half - shafts separately. They allow the left and right wheels to turn at different road speeds when turning (thus the term "differential"), so that neither wheel has to scuff. Conventional "open" differentials tend to equalize the torque delivered through both wheels. Thus if one wheel loses traction - "spins out" on snow, mud, sand, or gravel - it delivers very little power to the ground (power = torque x RPM, so if torque goes to 0, so does power). The other wheel will deliver only the same very torque as the spinning wheel and if this is not enough to overcome the inertia and static friction holding the verhicle in place, you are stuck. Traction aiding differentials allow the wheel with traction to deliver more torque than the wheel without traction. Often this is enough to keep the vehicle moving.

In an open differential, the following rule applies:

The average speed of the two axles is equal to the speed of the ring gear.

This means is one wheel is on glare ice and the other on the dry ground, the wheel on the ice can spin twice as fast as the ring gear, or as indicated by your speedometer. So, if you are stuck like this and floor it to 60 MPH, that one tire will be spinning up to 120 MPH and may be damaged.

Because of this feature of one tire losing traction and causing you to get stuck, several other differential designs have been used to get around this limitation. Since there are two variables involved in getting power from the engine to the ground, namely torque and speed, you'll find the different designs make use of one or the other in operation. They can all be classified as traction aiding differentials and there are three main types:

Spool
Locking
Automatic
Manual
Limited Slip
Friction/clutches
Geared
Each type has advantages for specific types of vehicles and driving conditions.

Differentials - Open Type
Open differentials use spider gears to transmit torque equally to both axles while allowing a speed difference between the axles. This results in smooth operation on high traction surfaces and is probably used in 99.9% of all vehicles. The governing rules of operation are that the same torque is applied to each axle, and the avearage speed of the two axles is equal to the speed as the ring gear. Note the 1 and 1 average to 1 as does 0 and 2. So, with one tire in the air and the other one on the ground, the tire in the air may spin as twice as fast as the indicated on your speedometer. This is why you should not over-rev your engine when stuck.

Differentials - Spool Type
Spool type differentials can either be permanently locked (i.e. not really a differential at all, a.k.a. a Lincoln Locker - named after the popular brand of welder used to weld the differential) or manually locked and unlocked, such as the ARB AirLocker or the Toyota electric locker. When locked, a spool allows no difference in speed between the two wheels on a given axle, i.e. each axle turns at exactly the same speed as the ring gear.

Differentials - Locking (speed - sensitive) Type
Locking differentials such as the Tractech NoSPIN® and Detroit Locker® brands (same product, different market segments), the Detroit E-Z Locker[tm] and Detroit Gearless Locker[tm] brands. They keep the wheels locked together (except when turning) so that together the left and right wheels always deliver maximum traction to the ground; neither wheel can spin out. They allow different wheel speeds in a turn by disconnecting the faster - moving wheel (usually the outside wheel which is ground - driven faster throughout the turn), driving the vehicle with the other (inside) wheel. See Locker, below. The governing rule is that at least one axle must turn at the same speed as the ring gear, the other is either locked or coasting, depending on the direction of the applied torque.

Differentials - Limited Slip (torque - sensitive) Type
Tractech's limited slip differentials are the Detroit TrueTrac® brand, and the SureTrac® and the Detroit LSD[tm] brands (same product, different market segments). They provide a controlled amount of resistance to a one-wheel spin-out, so that the other wheel (with traction) receives sufficient torque to keep the vehicle moving. The Detroit Truetrac® uses gears only - no clutch packs. It is ideal for 4WD front axles. It features torque bias ratios from 2.5 to 3.5:1 range.

There are several other manufacturers of geared-LSDs including Torsen and Quaiffe. Other LSD designs employ clutch plates to affect a similar operation, albeit at much lower torque bias ratios. Also, clutch-type LSDs require special additives in the gear oil to operate and are subject to wear and periodic maintenance.
--------------------------------------------------------------------------------

TrueTrac® Operation:
Truetrac® differentials are unique in that they increase traction but do not affect steering or wear out prematurely; these problems are common with limited-slip differentials that use clutch plates and springs. TrueTrac performs like a conventional (open) differential, until there is a loss of traction. Only then will the torque transfer occur - when it is needed.


TrueTrac Differential : Internal Components
As with an open differential, the TrueTrac side (or spider) gears are interconnected by pinion gears, which allow one wheel to slow down or speed up as required. TrueTrac gears have spiral teeth and the pinions are mounted in pockets in the case.

If one wheel begins to lose traction , the pinions separate slightly from the side gear and wedge in the pockets. As torque increases, the separating force increases, thus slowing or stopping the spin-out. This allows torque to be distributed to the wheel with the best traction.

Notes:
TrueTrac differentials require a certain amount of resistance at the ground (i.e. traction) in order to start the torque transfer. A TrueTrac differential may not transfer torque if the spinning wheel is off the ground or on a very slippery surface. If spinning occurs, often a slight application of the brakes, while carefully applying power, will slow the spinning wheel enough to allow the TrueTrac differential to transfer torque to the other wheel.
In low traction situations, like snow and ice, I find the TrueTrac works very good.
Unlike automatic lockers, which require a speed difference between the axles to lock up, the TrueTrac begins to transfer torque before any wheel slip occurs.
In turns, a limited slip diff biases torque to both wheels, with a bias towards the slower turning inner wheel. An automatic locker puts all the torque on the inside wheel in a turn, as the outer wheel automatically unlocks. An open diff transfers torque equally, but combined with the extra steering load on the outer wheel, it may become overloaded and cause a push or understeer.
A similar product on the market is the Torsen Differential which is the model used in the Hummer.

--------------------------------------------------------------------------------

Automatic Locking Differential Operation:

In case you use different names for the parts, using the Lockright as the model for discussion:
The CARRIER is the assembly that contains the locker (or spider gears in an open differential).
Axles are driven by SIDE GEARS (factory calls them 'couplers').
Side gears mesh with CENTER GEARS (factory term: 'drivers').
Center gears are held apart by BIAS SPRINGS to initiate re-coupling.
Center gears are kept from compressing the bias springs by STOP PINS which can slip into holes when center gears rotate relative to one another, through an ELLIPTIC HOLE formed out of round grooves in both center gears runs the PINION SHAFT which is connected to the differential. carrier and actually drives the locker.

Salient points:
The arrangement of stop pins and holes are engineered so that the center gears can only compress together slightly; just enough for only one axle to uncouple. When the pinion shaft is bearing on the elliptical hole in the center gear pair it forces the center gears apart. This happens any time there is torque transferred to the wheels. There has to be a difference in torque between the two axles for the two driver halves (center gears) to turn relative to one another so the pins can slip into their respective holes and the center gears can compress together to uncouple an axle. This happens when one wheel is turning faster than the other, no matter whether you're accelerating or engine braking?

Here's the scenario:
We are engine braking. The pinion shaft is pushing hard on the trailing edge of the 'elliptic' hole through the center gears. It's pushing on the trailing edge because the wheels are pushing on the drive shaft, not vice versa. We start a turn to the right. The right hand tire starts to turn slower, which means the right half of the center gear pair turns backwards (relative to the left half) so that the pinion shaft is now roughly in the center of the trough on the right-hand center gear, but still hard on the trailing edge of the trough on the left-hand center gear. Now the stop pins *can* fit into their holes (once there's force to overcome the bias springs) and it's possible for the center gears to get closer to one another so an axle can uncouple. At this point, the pinion shaft is still hard on the trailing end of the left hand center gear's half of the elliptical hole, but slack on the right hand center gear. This means that it is pushing OUT on the left hand center gear, but *not* pushing on the right hand center gear. Since the left hand center gear *can't* push in, it stays coupled. As soon as the torque built up in the right hand center gear is enough to push away from the right hand side gear using the ramped sides of the teeth, and overcome the force of the bias springs, the pins will slip into their holes and the right side will uncouple. It *has* to. The left side center gear is still being held out by the pinion shaft, so the right side center gear must uncouple. The right side is the slow tire; the inside tire.

Now what happens when you add some throttle while still in the turn? The torque changes direction. Both the left and right halves of the center gear rotate backwards (relative to the carrier). They must rotate together because they are still held by the pins between them. As they rotate backwards the pinion shaft is no longer pushing on the trailing edge of the elliptical hole on the left side center gear. It can now move inwards (if it wants). The center gears continue to rotate backwards (relative to the carrier) until the pinion shaft hits the *leading edge* of the elliptical hole on the right hand center gear (remember it's rotated slightly backwards of the left hand center gear). Now the right hand gear is forced outward by the pressure on the leading edge of the elliptical hole. As soon as the teeth match the right center gear is forced out and the right hand axle (inside) couples. Now, since there is torque on the outside tire (it is currently driven, right?) yet there is no force on the leading or trailing edge of the left center gear to force it outward, it happily disengages (due to the ramped teeth and the fact that the center gears are already compressed together) so that the transfer of torque is quite smooth, but still perceptible due to understeer/oversteer.
-------------------------------------------------------------------------------

Driving Impressions:
Hydraulic Locker:
As mentioned above, the TrueTrac differential, like all limited slip designs, will only work if there is some load on each axle. If one wheel loses all traction (i.e. a wheel in the air), that wheel will spin and no torque will be transferred to the wheel with traction. This is where brake biasing (or as I like to call it: "hydraulically actuated locker") the spinning wheel in order to transfer that torque to the opposite wheel. It can take a fair amount of brake drag to actually make this work. Let's assume a 3:1 torque bias ratio and one wheel in the air (i.e. no load on it) and the other one on the ground. In order to transfer a given amount of torque to the wheel on the ground (say 100 ft.lb.) you need to apply ~1/2 that amount of brake drag to both wheels on that axle (unless you have custom turning brakes). So now the spinning wheel (and axle) "sees" 50 ft.lb. of drag, allowing up to 150 ft.lb. (3x50) of torque to transfer to the other axle, but it also has 50 ft.lb. of brake drag on it, reducing the net torque to 100 ft.lb. applied to the wheel on the ground.
But the "extra" torque to overcome the brake drag must come from somewhere, namely the engine, so you've got to give it some extra throttle at the same time. So basically, the harder you brake, the more torque you put into the ground. Trust me, it is a totally unique experience. If you have a TrueTrac in your rear axle, the parking brakes are another mechanism for biasing the differential.

On Road Behavior:
You do know it is there, but it is much less noticeable than a locker. There are certain characteristics of an LSD and locker that are similar. Likewise there are certain characteristics of an LSD and an open differential that are similar.
Similarities with lockers:
Both lockers and LSDs will bias torque to the inside wheel in turns, causing the vehicle to follow a straighter line under power and a sharper line under engine braking.
In the locker the bias is 100% to the inner wheel, in the LSD it is somewhere between 50 and 100% depending on the radius of the turn.
It is easy to break the inside tire loose in a turn. The sharper and faster the turn and the slipperier the surface, the easier this is.
However, it takes more effort in an LSD-equipped axle than with a locker.
If you break a tire loose and spin it with either a locker or LSD, it will only go as fast as the other wheel/ring gear. With an open differential, the spinning tire can go up to twice the speed of the ring gear.
So in a sense, even though a tire can spin with a traction-aiding differential, its not an uncontrollable spin like an open differential, rather it is spinning the same speed as the wheel with traction.

Similarities with open differentials:
There is no ratcheting or tire chirping with an LSD. The engagement is smooth with no abrupt changes.
You will get some torque steer from the wheels with either an LSD or an open differential. This is no different than a front wheel drive vehicle. The LSD will, however, have a slightly heavier feel in the steering when accelerating due to the torque bias on the inside wheel.

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Old 01-04-2007, 09:59 PM
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Old 01-04-2007, 10:08 PM
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Quote:
Originally Posted by Wifey
Thank you Stinker!! -

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What registered thingys


Differentials and Traction Control

Conventional "open" differentials tend to equalize the power delivered through both wheels. Thus if one wheel loses traction - "spins out" on snow, mud, sand, or gravel - it delivers very little power to the ground. The other wheel will deliver only the same very little power. Often this is not enough to keep the vehicle moving on - it's stuck.
Traction control differentials allow the wheel with traction to deliver more power than the wheel without traction. Often this is enough to keep the vehicle moving. There are two types of traction control differentials:

Locking
Limited Slip
Each type has advantages for specific types of vehicles and driving conditions.

--------------------------------------------------------------------------------

Differentials- Locking Type (Speed-Sensitive)
Tractech’s locking differentials are the NoSPIN® and Detroit Locker® brands (same product, different market segments), the Detroit E-Z Locker™ and Detroit Gearless Locker™ brands. They keep the wheels locked together (except when turning) so that together the left and right wheels, always deliver maximum traction to the ground; neither wheel can spin out.
They allow different wheel speeds in a turn by disconnecting the faster - moving wheel (usually the outside wheel - driven faster throughout the turn), driving the vehicle with the other (inside) wheel.


--------------------------------------------------------------------------------

NoSPIN® / Detroit Locker®


The most rugged positive locking differential, and most widely available for axles from 3,000 to 70,000 lb. capacity.



For severe operational conditions.
Driver may hear and feel "backlash" going from drive-to-coast and coast-to-drive, as reversing torque flow resets the components.
--------------------------------------------------------------------------

--------------------------------------------------------------------------------

Differentials - Limited Slip Type (Torque - Sensitive)
Tractech’s limited slip differentials are the Detroit Truetrac® brand, and the Suretrac® and the Detroit LSD™ brands (same product, different market segments). They provide a controlled amount of resistance to a one-wheel spinout, so that the other wheel (with traction) receives sufficient power to keep the vehicle moving.


--------------------------------------------------------------------------------

Detroit Truetrac®
Uses pairs of "Helical" gear sets



Gears only - no clutch packs.

Ideal for 4WD front axles or rear axles, as well as 2WD; light trucks, SUV’s, cars.

Rugged yet smooth and quiet.

Torque bias ratios of 2.5 to 3.5:1 range.
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Throttle bodies , shifters, ps lines, oil lines, underdrive pullies, over drive pullies, infamous venom hood,catch cans, billet slave cylinders, the list goes on.
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Old 01-04-2007, 10:50 PM
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Quote:
Originally Posted by Stinker
done some digging around for my buds to help make their decisions, hopefully this will help, it is some old info, but still may be helpful

Differentials - What Are They?
In powered axles, gears that deliver torque from the drive shaft to the left and right axle half - shafts separately. They allow the left and right wheels to turn at different road speeds when turning (thus the term "differential"), so that neither wheel has to scuff. Conventional "open" differentials tend to equalize the torque delivered through both wheels. Thus if one wheel loses traction - "spins out" on snow, mud, sand, or gravel - it delivers very little power to the ground (power = torque x RPM, so if torque goes to 0, so does power). The other wheel will deliver only the same very torque as the spinning wheel and if this is not enough to overcome the inertia and static friction holding the verhicle in place, you are stuck. Traction aiding differentials allow the wheel with traction to deliver more torque than the wheel without traction. Often this is enough to keep the vehicle moving.

In an open differential, the following rule applies:

The average speed of the two axles is equal to the speed of the ring gear.

This means is one wheel is on glare ice and the other on the dry ground, the wheel on the ice can spin twice as fast as the ring gear, or as indicated by your speedometer. So, if you are stuck like this and floor it to 60 MPH, that one tire will be spinning up to 120 MPH and may be damaged.

Because of this feature of one tire losing traction and causing you to get stuck, several other differential designs have been used to get around this limitation. Since there are two variables involved in getting power from the engine to the ground, namely torque and speed, you'll find the different designs make use of one or the other in operation. They can all be classified as traction aiding differentials and there are three main types:

Spool
Locking
Automatic
Manual
Limited Slip
Friction/clutches
Geared
Each type has advantages for specific types of vehicles and driving conditions.

Differentials - Open Type
Open differentials use spider gears to transmit torque equally to both axles while allowing a speed difference between the axles. This results in smooth operation on high traction surfaces and is probably used in 99.9% of all vehicles. The governing rules of operation are that the same torque is applied to each axle, and the avearage speed of the two axles is equal to the speed as the ring gear. Note the 1 and 1 average to 1 as does 0 and 2. So, with one tire in the air and the other one on the ground, the tire in the air may spin as twice as fast as the indicated on your speedometer. This is why you should not over-rev your engine when stuck.

Differentials - Spool Type
Spool type differentials can either be permanently locked (i.e. not really a differential at all, a.k.a. a Lincoln Locker - named after the popular brand of welder used to weld the differential) or manually locked and unlocked, such as the ARB AirLocker or the Toyota electric locker. When locked, a spool allows no difference in speed between the two wheels on a given axle, i.e. each axle turns at exactly the same speed as the ring gear.

Differentials - Locking (speed - sensitive) Type
Locking differentials such as the Tractech NoSPIN® and Detroit Locker® brands (same product, different market segments), the Detroit E-Z Locker[tm] and Detroit Gearless Locker[tm] brands. They keep the wheels locked together (except when turning) so that together the left and right wheels always deliver maximum traction to the ground; neither wheel can spin out. They allow different wheel speeds in a turn by disconnecting the faster - moving wheel (usually the outside wheel which is ground - driven faster throughout the turn), driving the vehicle with the other (inside) wheel. See Locker, below. The governing rule is that at least one axle must turn at the same speed as the ring gear, the other is either locked or coasting, depending on the direction of the applied torque.

Differentials - Limited Slip (torque - sensitive) Type
Tractech's limited slip differentials are the Detroit TrueTrac® brand, and the SureTrac® and the Detroit LSD[tm] brands (same product, different market segments). They provide a controlled amount of resistance to a one-wheel spin-out, so that the other wheel (with traction) receives sufficient torque to keep the vehicle moving. The Detroit Truetrac® uses gears only - no clutch packs. It is ideal for 4WD front axles. It features torque bias ratios from 2.5 to 3.5:1 range.

There are several other manufacturers of geared-LSDs including Torsen and Quaiffe. Other LSD designs employ clutch plates to affect a similar operation, albeit at much lower torque bias ratios. Also, clutch-type LSDs require special additives in the gear oil to operate and are subject to wear and periodic maintenance.
--------------------------------------------------------------------------------

TrueTrac® Operation:
Truetrac® differentials are unique in that they increase traction but do not affect steering or wear out prematurely; these problems are common with limited-slip differentials that use clutch plates and springs. TrueTrac performs like a conventional (open) differential, until there is a loss of traction. Only then will the torque transfer occur - when it is needed.


TrueTrac Differential : Internal Components
As with an open differential, the TrueTrac side (or spider) gears are interconnected by pinion gears, which allow one wheel to slow down or speed up as required. TrueTrac gears have spiral teeth and the pinions are mounted in pockets in the case.

If one wheel begins to lose traction , the pinions separate slightly from the side gear and wedge in the pockets. As torque increases, the separating force increases, thus slowing or stopping the spin-out. This allows torque to be distributed to the wheel with the best traction.

Notes:
TrueTrac differentials require a certain amount of resistance at the ground (i.e. traction) in order to start the torque transfer. A TrueTrac differential may not transfer torque if the spinning wheel is off the ground or on a very slippery surface. If spinning occurs, often a slight application of the brakes, while carefully applying power, will slow the spinning wheel enough to allow the TrueTrac differential to transfer torque to the other wheel.
In low traction situations, like snow and ice, I find the TrueTrac works very good.
Unlike automatic lockers, which require a speed difference between the axles to lock up, the TrueTrac begins to transfer torque before any wheel slip occurs.
In turns, a limited slip diff biases torque to both wheels, with a bias towards the slower turning inner wheel. An automatic locker puts all the torque on the inside wheel in a turn, as the outer wheel automatically unlocks. An open diff transfers torque equally, but combined with the extra steering load on the outer wheel, it may become overloaded and cause a push or understeer.
A similar product on the market is the Torsen Differential which is the model used in the Hummer.

--------------------------------------------------------------------------------

Automatic Locking Differential Operation:

In case you use different names for the parts, using the Lockright as the model for discussion:
The CARRIER is the assembly that contains the locker (or spider gears in an open differential).
Axles are driven by SIDE GEARS (factory calls them 'couplers').
Side gears mesh with CENTER GEARS (factory term: 'drivers').
Center gears are held apart by BIAS SPRINGS to initiate re-coupling.
Center gears are kept from compressing the bias springs by STOP PINS which can slip into holes when center gears rotate relative to one another, through an ELLIPTIC HOLE formed out of round grooves in both center gears runs the PINION SHAFT which is connected to the differential. carrier and actually drives the locker.

Salient points:
The arrangement of stop pins and holes are engineered so that the center gears can only compress together slightly; just enough for only one axle to uncouple. When the pinion shaft is bearing on the elliptical hole in the center gear pair it forces the center gears apart. This happens any time there is torque transferred to the wheels. There has to be a difference in torque between the two axles for the two driver halves (center gears) to turn relative to one another so the pins can slip into their respective holes and the center gears can compress together to uncouple an axle. This happens when one wheel is turning faster than the other, no matter whether you're accelerating or engine braking?

Here's the scenario:
We are engine braking. The pinion shaft is pushing hard on the trailing edge of the 'elliptic' hole through the center gears. It's pushing on the trailing edge because the wheels are pushing on the drive shaft, not vice versa. We start a turn to the right. The right hand tire starts to turn slower, which means the right half of the center gear pair turns backwards (relative to the left half) so that the pinion shaft is now roughly in the center of the trough on the right-hand center gear, but still hard on the trailing edge of the trough on the left-hand center gear. Now the stop pins *can* fit into their holes (once there's force to overcome the bias springs) and it's possible for the center gears to get closer to one another so an axle can uncouple. At this point, the pinion shaft is still hard on the trailing end of the left hand center gear's half of the elliptical hole, but slack on the right hand center gear. This means that it is pushing OUT on the left hand center gear, but *not* pushing on the right hand center gear. Since the left hand center gear *can't* push in, it stays coupled. As soon as the torque built up in the right hand center gear is enough to push away from the right hand side gear using the ramped sides of the teeth, and overcome the force of the bias springs, the pins will slip into their holes and the right side will uncouple. It *has* to. The left side center gear is still being held out by the pinion shaft, so the right side center gear must uncouple. The right side is the slow tire; the inside tire.

Now what happens when you add some throttle while still in the turn? The torque changes direction. Both the left and right halves of the center gear rotate backwards (relative to the carrier). They must rotate together because they are still held by the pins between them. As they rotate backwards the pinion shaft is no longer pushing on the trailing edge of the elliptical hole on the left side center gear. It can now move inwards (if it wants). The center gears continue to rotate backwards (relative to the carrier) until the pinion shaft hits the *leading edge* of the elliptical hole on the right hand center gear (remember it's rotated slightly backwards of the left hand center gear). Now the right hand gear is forced outward by the pressure on the leading edge of the elliptical hole. As soon as the teeth match the right center gear is forced out and the right hand axle (inside) couples. Now, since there is torque on the outside tire (it is currently driven, right?) yet there is no force on the leading or trailing edge of the left center gear to force it outward, it happily disengages (due to the ramped teeth and the fact that the center gears are already compressed together) so that the transfer of torque is quite smooth, but still perceptible due to understeer/oversteer.
-------------------------------------------------------------------------------

Driving Impressions:
Hydraulic Locker:
As mentioned above, the TrueTrac differential, like all limited slip designs, will only work if there is some load on each axle. If one wheel loses all traction (i.e. a wheel in the air), that wheel will spin and no torque will be transferred to the wheel with traction. This is where brake biasing (or as I like to call it: "hydraulically actuated locker") the spinning wheel in order to transfer that torque to the opposite wheel. It can take a fair amount of brake drag to actually make this work. Let's assume a 3:1 torque bias ratio and one wheel in the air (i.e. no load on it) and the other one on the ground. In order to transfer a given amount of torque to the wheel on the ground (say 100 ft.lb.) you need to apply ~1/2 that amount of brake drag to both wheels on that axle (unless you have custom turning brakes). So now the spinning wheel (and axle) "sees" 50 ft.lb. of drag, allowing up to 150 ft.lb. (3x50) of torque to transfer to the other axle, but it also has 50 ft.lb. of brake drag on it, reducing the net torque to 100 ft.lb. applied to the wheel on the ground.
But the "extra" torque to overcome the brake drag must come from somewhere, namely the engine, so you've got to give it some extra throttle at the same time. So basically, the harder you brake, the more torque you put into the ground. Trust me, it is a totally unique experience. If you have a TrueTrac in your rear axle, the parking brakes are another mechanism for biasing the differential.

On Road Behavior:
You do know it is there, but it is much less noticeable than a locker. There are certain characteristics of an LSD and locker that are similar. Likewise there are certain characteristics of an LSD and an open differential that are similar.
Similarities with lockers:
Both lockers and LSDs will bias torque to the inside wheel in turns, causing the vehicle to follow a straighter line under power and a sharper line under engine braking.
In the locker the bias is 100% to the inner wheel, in the LSD it is somewhere between 50 and 100% depending on the radius of the turn.
It is easy to break the inside tire loose in a turn. The sharper and faster the turn and the slipperier the surface, the easier this is.
However, it takes more effort in an LSD-equipped axle than with a locker.
If you break a tire loose and spin it with either a locker or LSD, it will only go as fast as the other wheel/ring gear. With an open differential, the spinning tire can go up to twice the speed of the ring gear.
So in a sense, even though a tire can spin with a traction-aiding differential, its not an uncontrollable spin like an open differential, rather it is spinning the same speed as the wheel with traction.

Similarities with open differentials:
There is no ratcheting or tire chirping with an LSD. The engagement is smooth with no abrupt changes.
You will get some torque steer from the wheels with either an LSD or an open differential. This is no different than a front wheel drive vehicle. The LSD will, however, have a slightly heavier feel in the steering when accelerating due to the torque bias on the inside wheel.
here is one with pics...

http://www.offroaders.com/tech/limit...ferentials.htm
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Old 01-04-2007, 11:36 PM
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Awesome Stinker!

Too bad it doesn't mention our stock ones (DANA 60-HD).
Oh well.
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Old 01-05-2007, 07:51 PM
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The TrueTrac® sounds a lot like the old Gleason Torsen differential.

Wifey - For the ® sign, hold "alt" and press 0174, then release the "alt" key.

BTW, if you want degrees (°), it's "alt" 0176
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