Computer Help
 Contact
 Search
 
  
    

Jeep JK Lift Kits
Black Diamond JK Lift Kits
Black Diamond PR
Poly Performance JK Lifts
Teraflex Jeep JK Kits
Skyjacker JK Kits
Rancho Jeep JK Kits

Rubicon Express JK Kits

ATV World
ATV Clubs
ATV Tire FAQs
ATV Tire Mounting
Cool ATV Products
LiteFoot Track Sys
ATV Lift Installs
Quad Tire Reviews
ATV Laws By State
ATV Repair
ATV Manuals

Jeep Project CJ-7

An ongoing Budgeted Rebuild/Build up of a Rock
Crawling Machine.

Offroaders Guide to Gearing up for Offroad
From Basic Equipment to Well Equipped.  An extensive list guide to help you prepare your vehicle for the offroad.


Trailering Safety and Trailer Hitch Information


Off-Road Truck Driving Techniques and Safety

25 Top To Do Tips Before Going Offroad
 

Troubled
Computer?

Got Pop-ups
Spyware & Viruses?
Offroaders.com feels your pain. Let our Geeks help you...
RalphtheGeek.com

 


Rausch Creek
Off-Road Park

 

Jeep Central
From Jeep History to Tech Specs and Projects.  This section is all about Jeeps.
Jeep Technical Info
Engines
Transmissions
Transfercases
Axles
Engine Swaps

Installing 23,000 Volt Offroad Lights


Onboard Air
Converting a York
AC Compressor
to Pump Air

What are HID Lights?

Onboard Air
Converting a York
AC Compressor
to Pump Air

Warn 9500i Winch Installation

Warn X8000i
Winch Installation

 

HEI Ignition
Installation & Review

Lockers, Limited Slips &
other Differentials Explained

 

 

 

Wheeling in the Valley of the Ferns

1.jpg (70086 bytes)
Tellico North Carolina


Paragon Adventure Park
Rock Krawl

Thousands more photos here..

 
 

 

 

 

Differential Differences
Lockers, Limited Slips, Differentials and the sport
of Offroading.

An Overview of Standard Carriers, Positraction & Limited Slips,
Locking Differentials, Spools and Mini-Spools

 

   

 

Got Traction?

In the sport of offroading almost inevitably the conversation turns to improving performance.  When offroad an important keyword is traction.  Better traction generally boils down to four components, your tires.  Quality tires designed for offroad make a world of difference in your ability to find traction and have fun.  But if a tire is not turning due to a lack of power being sent to that tire, the best tires in the world won't help you.  That's where the right differential makes a difference.   This article will attempt to explain what role your differential plays in traction and the different types of differentials available on the market and how they will affect your vehicle's traction and handling characteristics.

The Differential

The differential in a vehicle is located in what is sometimes called the "pumpkin", or that center section of the front or rear axle that intersects with the drive shaft.  Within that center part of the axle is contained the differential.

In a vehicle, the differential usually consisting of a set of gears, that allows each of the driving wheels to rotate.  The gears convert the rotating motion of the driveshaft or drive train and split power to each of the driving axle shafts of that axle.  In 4 wheel drive vehicles there are two differentials, one in the rear axle and one in the front axle.

The differential has three jobs.  It directs engine power to the wheels.  It acts as the final gear reduction in the vehicle, slowing the rotational speed of the transmission (and transfer case of 4 wheel drive vehicles) before it hits the wheels.  The differential also transmits the power to the wheels while allowing them to rotate at different speeds, thus the term "differential". 

The main purpose of the differential is to allow each half of the axle (each tire) to spin at different speeds, while supplying an equal amount of force to each wheel in that axle.  The need for the wheels to rotate at different speeds is especially apparent when turning corners.  When cornering the inner wheel travels a shorter distance than the outer wheel.  With an open differential they both propel the vehicle forward with equal force, so long as both wheels remain in contact with the road and have traction.  However if one wheel slips, for instance on ice, more torque is sent to the wheel that spins. If that slipping wheel completely looses traction, all power will be sent to that wheel and you have no forward momentum.   When offroad, this is where the common open differential fails to remain effective.  When offroad there are many situations where a wheel will spin free.  In most stock 4x4 vehicles the common Open Differential can be found in both the front and rear axles.  When a wheel in the front AND a wheel in the back are allowed to spin free due to the Open Differentials, that 4x4 is essentially a 2 wheel drive vehicle.  One front wheel, and one back wheel.  This is where other types of differentials will make drastic improvements to traction.

Types of Differentials

Differentials can be generally classified into 4 categories.  Open Differentials, Limited Slip Differentials, Locking Differentials and Spools.  Spools are really just the elimination of the differential, so really, there are three categories.

Beyond the open differential, the various types of "non-open" differentials will provide varying degrees of limiting of the spin or slip of an open differential.  What also varies is the feel of these differentials, which translates into varying degrees of handling characteristics on road and offroad.

 

Open / Standard Carrier Differential

The standard differential, or what is referred to as an open carrier, is what comes with most OEM vehicles.  The open carrier holds the ring gear in place and within the open carrier is generally a set of gears called spider gears.  These spider gears are responsible for allowing a vehicle to negotiate a turn and allow the outside wheel to travel farther and turn faster than the inside wheel.  This type of open design works great for most of vehicles on the road today.  However when a vehicle with an open differential meets a lack of traction, it directs power to the wheel with the least amount of resistance. The result is the wheel on the traction-less surface spins free, while the opposite wheel of that axle on the better traction surface provides little or no power.

 

Limited Slip Differentials, Posi-Traction (Posi, Posis)

Limited Slip and positraction (posi) differentials are designed to "limit" the tendency of open differential to send power to a wheel that lacks traction and redirect the power to a degree to the other wheel of the axle.  The Limited Slip and Positraction differential will send power to both wheels equally when traveling straight, however when one wheel spins due to a lack of traction, the differential will automatically provide torque to the other wheel with traction.  Limited Slip and Positraction (posi) differentials limit the loss of torque to a slipping wheel through various mechanisms such as clutches, gears cones, and other methods dependant on the unit.  The limited slip and positraction will not provide 100% lock up of the differential in extreme situations such as when a wheel completely looses traction.  Limited Slip and Positraction (posi) differentials are recommended for daily driven vehicles and are used in many applications where traction is sometimes needed as in emergency vehicles.  They are also ideal for front axles of 4x4 vehicles that are not equipped with front hubs that can be disengaged.  The term "positraction" ("posi" for short) was used by General Motors years ago for their limited slip differential and has been used to refer to limited slips since.

CLUTCH-TYPE LIMITED SLIP
GEAR-DRIVEN LIMITED SLIP

 

Lockers, Locking Differentials

A locking differential or "Locker" uses a mechanism that allows left and right wheels to "lock" relative to each other and turn at the same speed regardless of which axle has traction and regardless of how little traction a slipping wheel has.  In this state, the axle acts more as a "Spool".  This means traction can be sent to a wheel that may be planted firmly on the ground while the other wheel of the axle is completely off the ground.  In this situation an open differential will spin the free (lifted) wheel sending absolutely no torque to the wheel in the ground.  A limited slip in this situation will send some torque to the wheel on the ground but possibly no enough to provide any forward momentum. 

Lockers use various mechanisms to provide lock-up and can be divided into two categories, Automatic Lockers and On-Command, or selectable Lockers.

Automatic Lockers:

Automatic locking differentials are designed to lock both wheels of an axle automatically when torque is applied so that both wheels are providing power.  When torque is not being applied such as when the clutch is press down, the differential is allowed to unlock, permitting a variance in wheel speed while negotiating turns.  Automatic lockers tend to create odd handling characteristics on the street as they lock and unlock and take some getting used to.

Detroit Locker - Automatic Lockers

Lock-Right Locker

Detroit EZ Locker

Aussie Locker

Lunchbox Lockers - What is a Lunchbox Locker?

What are Lincoln Locker & Fozzy Lockers?

 

On-Command Lockers (Selectable, Manually Operated):

On-command lockers are the best of both worlds providing the benefits of a locking differential and an open differential.  An on-command locker uses a switch activated electric motor or vacuum diaphragm or a cable / lever to engage the locker.  When an on-command locker is not engaged, it acts like a standard open differential with none of the quirky handling characteristics of an automatic locker.  When the on-command locker is engaged, the differential locks the axle shafts together where it is now more like a spool with no differential of speed between the wheels of that axle.  Some OEM on-command locker designs are available on the market including 1998 and newer Toyota Tacoma and Land Cruiser and the Jeep TJ and JK Rubicons. 

ELECTRIC SELECTABLE LOCKER:

Toyota TRD Locker
Auburn Gear Electronic Locker ECTED

PNEUMATIC SELECTABLE LOCKER:

ARB Air Locker - About ARB Air Lockers
How the ARB Air Locker works

MECHANICALLY ACTUATED:

Ox Locker - About OX Lockers
 How the OX Locker Works

  

Spools, Mini Spools

Spools are actually the lack of a differential.  Spools are a 100% lock-up between both wheels of an axle all the time.  Spools are generally used for racing and serious offroad use where little or no street driving is seen by the vehicle and a stronger, lighter rear end is needed. 

          

 

 

 

        

 

Other sources of axle differential information:

Axle Related Glossary of Terms - Terms and definitions of Axle related components.

Detriot EZ Locker Install

www.ringpinion.com

en.wikipedia.org/wiki/Differential_(mechanical_device)

Introduction To Gearing by Trails Less Traveled

www.houseofthud.com/differentials.htm

www.drivingfast.net/technology/Differentials.htm

auto.howstuffworks.com/differential.htm

Jeep Project CJ-7

An ongoing Budgeted Rebuild/Build up of a Rock Crawling Machine.

All Terrain 
Mud Terrain
Tire Reviews & Info

All Terrain
AT Tire Reviews


Mud Terrain
MT Tire Reviews

 

 

Ramp Travel Index
RTI / Ramp Travel Index What it is and how to calculate it, with and without the ramp.

Offroad Tire Info
P-Metric Tire Sizes Conversion to Inches
Tire Terminology
Wheel Terminology
How to Pick the Right
Tires for your Truck
Truck Tire Info
Tires - What Hits What Fits
  
All Terrain  Mud Terrain
Tire Reviews & Info
Mud Terrain MT Tire Reviews
All Terrain AT Tire Reviews
Super Swamper Bogger
Super Swamper SSR
Super Swamper SX
Super Swamper Vortrac
Interco IROK TSL
Super Swamper LTB
Super Swamper TSL
Super Swamper TSL Radial
Super Swamper Narrow
Interco SS-M16 Swamper
Thornbird TSl Radial
Thornbird TSl Bias
Thornbird TSL
Parnelli Jone Dirt Grip
BFGoodrich Krawler
BFGoodrich MT T/A KM
BFGoodrich MT T/A KM2
BFGoodrich AT TA KO
BFGoodrich Mud King XT
Bridgestone Dueler MT
Cooper Discoverer ST
Cooper Discoverer STT
Cooper Discoverer ST/C
Federal Couragia MT
Firestone Destination AT
Firestone Destination MT
General Grabber MT
General Grabber AT2
Green Diamond Icelander
Ground Hawg Mud Tire
Hankook Dynapro MT
Hankook Dynamic MT RT01
Hercules Terra Trac MT
Hercules Trail Digger MT
Kelly-Springfield Safari DTR
Kelly-Springfield Safari MSR
Kumho Road Venture MT
Kumho Road Venture KL71
Kumho Road Venture AT
Dick Cepek Mud Country
Dick Cepek F-C II
Dick Cepek Fun Country II
Dick Cepek Fun Country Nylon
Dick Cepek Fun Country Kevlar
Mastercraft Courser MT
Mastercraft Courser HTR
Mastercraft Courser HTR Plus
Maxxis BigHorn Radial
Maxxis Creepy Crawler
Maxxis Trepador
Maxxis Buckshot Mudder
Maxxis MA-SW
Maxxis M-8080 Mudzilla
Maxxis MT-754 Buckshot
Maxxis MT-753 Bravo
Maxxis MA-751 Bravo
Maxxis MA-S2 Marauder II
Maxxis MA-S1 Marauder
Maxxis MT-762 BigHorn
Nitto Mud Grappler
Nitto Terra Grappler
Nitto Dura Grappler
Nitto Dune Grappler
Nokian Vatiiva MT
Pit Bull Rocker Extreme
Pit Bull Maddog
Pit Bull Growler
Goodyear Wrangler MT/R
Pro Comp Xterrain
Pro Comp All Terrain
Pro Comp Mud Terrain
Pro Comp Xtreme AT
Pro Comp Xtreme MT
Toyo Open Country MT
TrXus Mud Terrain
TrXus STS All Terrain
Michelin LTX A/T
Michelin LTX AT2 Press
Michelin LTX AT2
Mickey Thompson MTZ
Mickey Thompson MTX
Mickey Thompson Baja Claw Radial
Mickey Thompson Baja Claw Bias
Mickey Thompson Baja Crusher
Mickey Thompson Baja ATZ Radial SLT
Competition Claw
Dunlop Mud Rover
Federal Couragia M/T
Nitto Dura Grappler
Yokohama Geolandar
  
Dick Cepek's 2008 F-250 Super Duty Project Vehicle Project CRUSHER
 
Mud Tire Reviews
Product Reviews
Tire Reviews
 
  
 
ATV Tire Index
Carlisle 489 Titan
Dunlop Quadmax
Dunlop Quadmax Sport
Quadmax Sport Development
Highlifter Outlaw
ITP Holeshot
ITP Holeshot MX
ITP Holeshot ATR
ITP Holeshot XC
ITP Holeshot XCR
ITP Holeshot MXR
ITP Holeshot XCT
ITP Mud Lite
ITP Mud Lite XTR
ITP Sandstar
Kenda K538 Executioner
Tubeless Bearclaw K299
Kenda Klaw K532
Kenda Klaw K533
Kenda K534 Sand Gecko
Maxxis M961/M962 Mud Bug
Maxxis Rooster Paddle Tire
Maxxis M917/M918 Bighorn
Maxxis M966 Mudzilla
Super Swamper TSL ATV
Super Swamper TSL Vampire
Super Swamper Vampire EDL
Swamp Lite ATV Tires
 
ATV Tire FAQs
ATV Tire Mounting
ATV / Quad Links
 
Quad Tire Reviews Index

 


Off-Road Lights
by LightForce Product Review / Installation.
from Off-Road Lights

 


Jeep Dana 300 TeraLow - 4:1 Gearset for the Dana 300 Transfer Case

Jeep Trans Swap
T-18A Transmission Rebuild & Short Shaft Conversion
  


Black Diamond Suspension Lift install for CJ-7

 

From the
Department of Cheap   Tricks and Useful Tips

  
Ultra-Cool Hand Throttle for Free!

Jeep V8 Swap Tips

The Exploding Clutch

Radiator Protection using 6 bucks worth of material

Cracked Under Pressure - Fixing a smashed fingernail

A Cheap, effective alternative to undercoating

Home-built Saginaw Gearbox Brace for the cost of lunch!

Ammo Box Storage - Mounting Them for Quick Disconnect

Home-built Serious Skid-Plate protection for the Oil Pan for under 20 bucks!