NakedJeep.com

The digital garage of my 1998 Jeep Wrangler.

Off Road Glossary

Jeep and Off Road Words and Acronyms

ABS
Antilock Braking System. Designed to keep your vehicle straight when braking. Often associated with a pulsating feeling in the brake pedal when braking hard. Modern computers can keeps track of vehicle speed and the speed of each individual wheel. The computer attempts to keep all 4 wheels moving at the same speed, releasing and reapplying pressure to keep the braking even and the vehicle straight.
Approach Angle
Illustration
The greatest angle your vehicle can approach without hitting anything except your tires. From a profile view of your vehicle, draw an imaginary line from the bottom of the front tires where they meet the road, up and forwards to the leading edge of your front bumper (the furthest point forward).
Articulation
The difference in movement between two tires on the same axle. Greater articulation allows traction over terrain with larger obstacles like boulders and ruts.
Back-lash
The free play between gears. A certain amount of backlash is essential or the gears would bind. Jasafweq s vnksd lkwe fefte.
Back Spacing
The distance from the inner part of the rim where it meets the hub/axle to the inside tire bead. How far back in to the body of the Jeep that your wheels extend.
Bead Lock
A part of the rim that bolts in place to clamp onto the outer edge (bead) of the tire holding it in place even at extremely low tire pressure. Some bead lock rims clamp onto both inner and outer tire beads.
BreakOver Angle
Illustration
The greatest angle your vehicle can rise up over and down without hitting anything except your tires.
Bumpsteer or Bump Steer
When the suspension moving either up or down causes a change in the steering direction. Usually caused by the drag link and the trackbar not being aligned with each other.
Camber
Illustration
The tilt of the front tires as viewed from the front against a vertical axis. The amount of tilt is measured and adjusted when you get an alignment. A tire that leans outward at the top is said to have positive camber; inward tilt is negative. Poor camber adjustment will cause tire treads to wear at one edge and the vehicle to pull to the side that has the most positive camber.
Caster
Illustration
Caster is the forward or backward tilt of the steering axis. The offset angle created by the relative positions of the upper and lower ball joints in relation to a center line drawn perpedicular to the highway.
(Ground) Clearance
On level ground, the distance from the ground to the lowest point of your vehicle, typically the differentials.
Curb Weight
Your vehicle's unladen weight. An empty vehicle plus full fuel and a typical driver
Departure Angle
Illustration
The greatest angle your vehicle can clear as you come down a hill to level ground, without hitting anything except your tires. From a profile view of your vehicle, draw an imaginary line from the bottom of the rear tires where they meet the road, up and backwards to the leading edge of your rear bumper (the furthest point backward).
Differential
The gearing mechanism that divides and delivers power to the wheels at either end of the axles. This part of the axle housing assembly is often called the "Pumpkin" and is typically the lowest point of your vehicle.
EFI
Electronic Fuel Injection. Unlike carbuerators that rely on gravity and suction to draw fuel into the cylinders, EFI sprays the fuel mixture directly into each cylinder. This makes a big difference when operating on a steep incline or at varying altitudes.
Fairlead
The point where the cable exits the winch drum and passes through rollers or a simple steel sleeve called a hawse.
GVW
Gross Vehicle Weight. This is the combination of curb weight plus the driver, passengers and fuel.
Hi-Lift Jack
The Hi-Lift Jack is a rugged, versatile jack carried be serious off-roaders. It is lightweight, easy to maneuver, and has a rated lifting capacity of over 2 tons.
Hub (Automatic / Manual)
The center part of a wheel, fan, or propeller. Typically located on the front wheels of your 4x4, these "lock" the hub and wheel assembly to the front axle. When hubs are "unlocked," the axle shaft is disengaged and the wheel can move independently of the axle.

Manual-locking hubs are usually locked or unlocked by twisting a handle in the center of the hub.

Limited Slip Differential (LSD)
Unlike an open differential that provides no resistance to the differential action when the difference in rotational speed between the output shafts is small, ie. when cornering, a LSD provides increasing resistance as the difference in speed increases.
Locker
A differential locker will lock the two sides of the differential to the center ensuring equal power to both wheels.
MIL (M.I.L.)
Malfunction Indicator Lamp "Check Engine" light.
Multilink
A suspension set up with 3 or 4 arms (links) and no struts. The longer the arms, the greater the travel for the axle and the straighter the drive-line angle.
OEM
Original Equipment Manufacturer.
Open Differential
The most common type of differential that allows the inside wheel to turn at a slower speed than the outside wheel. Most helpful when your vehicle is making a turn. Most vehicles come from the factory with open differentials. It is the preferred setup for paved streets; it provides excellent traction under most conditions.

In poor traction situations such as mud or uneven surfaces where one wheel loses traction an open differential will direct power to the wheel with the least amount of traction. If one of your tires is on solid ground and the other one is hopelessly slipping on air, the tire that is slipping on will receive all of the power and continue to spin. The tire with solid ground under it will not turn you will be going nowhere.

Oversteer
The tendency of a vehicle to turn sharper than the driver intended. This can lead to the rear wheels losing traction. Most common in rear wheel drive vehicles when too much acceleration is applied.
Pitman Arm
Attached to the steering box on a spline shaft, this arm connects to a drag link to turn the wheels. On a lifted vehicle, a "Drop Pitman Arm" may be installed to reduce the angle of the link.
Shackle
Typically used on leaf spring suspensions, it is the coupling device used to attach the leafs to the frame. Installing longer shackles is a quick way to get some lift, but it will not increase your clearance.
Slip Yoke Eliminator (SYE)
A kit made to replace the "Slip Yoke" on the transfer case. On a typical TJ, the connection at the rear output side of the transfer case is a slip joint of sorts. The shaft, or yoke, has grooves, or splines, that transfer the rotational power but allows the yoke to slip in and out of the transfer case. It is the shortening and lengthening of that shaft that allows your suspension to move up and down. This sliding motion should be eliminated from the yoke at the transfer case and moved to the driveshaft.
Snatch Block
A pulley in a case with a shackle or clevis point on one side. Used properly it can double the line pull of your winch.
Splines
The grooves on a shaft that line up with and engage another shaft or gear so that one rotates the other.
Spool
A type of differential with both axle shafts permanently locked together forcing the wheels to always rotate at the same speed.
SOA - Spring Over Axle
On most stock Jeeps equiped with leaf springs, the leaf springs run under the axle. A Spring Over, or SOA is moving the leaf springs from under to over the axle housings.
Three Link Suspension
Suspension setup that uses three control arms to support and control the axle consisting of two lower control arms and one upper. The lower control arms are fixed to the lower portion of the axle on each side and a single upper control arm is placed in the center. The use of a single upper control arm allows for more articulation than does a four link suspension. The upper is also usually formed in a triangular shape to handle the stress associated with the axle articulation.
Transfer Case
The secondary gear box that transfers (and splits) the power to the front and rear axles. On some vehicles there is also another spline available known as PTO or Power Take Off that can be used to power a winch or other device.
Tree Strap
Stuck, and near a tree? Never put a bare metal cable around a tree! Use a wide strap around the base of a strong tree. Tree straps aren't typically long, but should have a strong shackle to connect the two ends together. Hook your winch up to the shackle point and pull slowly.
U-Joint
Universal Joint. A flexible coupling found at the ends of your drive shafts and at the ends of the front axles where they meet the spindle. There is a yoke on each shaft that is connected a four-point center cross.
Unibody
When the body and chasis of the vehicle are one unit instead of body parts bolted to a frame
Winch
Usually fixed to the front of a vehicle, a motor-driven spool around which is wound a steel cable or synthetic rope. Typically powered by an electric motor, by hydraulics, by PTO, or in some cases manually.
Approach Angle
Approach Angle
Close X
Breakover Angle
Breakover Angle
Close X
Camber Angle
Camber Angle
Close X
Caster Angle
Caster Angle
Close X
Departure Angle
Departure Angle
Close X
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