A Thru D on Gear & Axle-related products

Also known as a control arm, there are two types: upper and lower. This triangular suspension component gets its name because it pivots on the A-shaped chassis at two points: the wide end and the pointy end, which attaches to the spindle. Generally used on independent suspensions.

Stands for Anti-Lock Braking System. If forced to brake suddenly, an ABS helps equalize the wheel speed so you don't skid out of control. The system is electronically controlled and provides two options: a two-channel that only controls the rear wheels, and a four-channel that controls all wheels.

Also known as a toe-out on turns, this is the principle that the inner wheel will have greater steering control than the outer wheel because it travels a shorter distance.

The method of adding an extra leaf to the leaf spring to provide additional lift. It is an inexpensive lifting method, but will take away some of the ride quality.

This encompasses all parts and equipment that are not produced by the original, OE manufacturer.

When driving up an incline, it is the largest angle between the road and the vehicle before the front of the vehicle hits the road, whether it's the body, chassis, or mechanicals.

The total amount of amp hours, or ampere hours, it takes to run a particular electrical device.

See definition for Camber

This is also known as Articulation or Cross-Axled. It is the moment when one tire is at its lowest travel, the other tire is at its upper travel, and the axle is at a severe angle to the body.

When the suspension compresses and droops on one axle, leaving the axles at severe angles so the body remains reasonably level.

Articulation - The ability of a suspension to combine compression and droop on one axle.

This is also known as Articulation or Cross-Axled. It is the moment when one tire is at its lowest travel, the other tire is at its upper travel, and the axle is at a severe angle to the body.

The ratio, expressed as a percentage, of a tire's width to its height. In this case, the height equals the distance between the tread and the rim, while the width is the section width. This is the tire's profile.

An axle wrap occurs when the axle is twisted into an "S" shape by the combined power of torque and traction, which cause the nose of the differential to go up while going forward and down while going backward. When this happens, the spring stores all of the energy until the tire slips, causing the spring to forcefully snap back and putting extra strain on the U-joints and driveshafts. It is also known as an axle hop, since it can create a hopping feeling.

The distance between the mounting flange and the inside edge of a wheel. Also known as wheel offset.

One of the key components of a tire's construction, it the area where the tire mates with the wheel. It uses a hoop of high tensile steel wires to anchor the belts and give the rim a firm grip.

On the bead section of a tire, it is the part with a smooth surface that seals against the rim to hold air.

This is a dense wedge made out of rubber in the lower side-wall of the tire. It strengthens the area near the bead of the tire.

A wheel rim designed to keep the tire from abruptly deflating when used at low pressure.

Any 4x4 that's looking beaten down and worse for the wear but still runs pretty well.

When you add beef to a vehicle, you add strength to it or upgrade it.

Any 4x4 that's looking beaten down and worse for the wear but still runs pretty well.

Refers to vehicles constructed by the International Harvester Company. Short for Cornbiner.

This six-ball constant velocity joint was initially designed in the 1920s by Hans Rzeppa, but it's the later British manufacturer, Birfield Ltd., that stamped the name "Birfield" onto these complex and pricey CV joints. In the 1960s, it was presented for the Toyota land cruiser and to this day it is most commonly used by Toyota, and other Japanese 4x4, enthusiasts. It's unkown whether initial production was actually in Britain or Japan.

A sudden, "start/stop" thrust of the throttle.

A vehicle designed for trekking through the mud. Also a type of tire built for off road mud use.

These keep spring leaves in alignment on top of one another. These are generally a better option than cinch type of clamps because they don't limit mobility.

The spot where the suspension completely compresses and meets the bump stops.

Reinforcing the chassis by shutting the open part of a "C" or "U" section. The extra material significantly strengthens it.

Refers to a vehicle that has been greatly modified. Short for "built-up."

This occurs when the suspension is bumped and forced to move, which in turn causes the steering system and steering wheel to go one direction or the other. This can occur to 4x4s at both low and high speeds, but is considerably more dangerous when going faster.

This is a much smaller type of bumper that is installed to control the upward movement of the wheel, or the compress point. Generally made of rubber or polyurethane.

Stands for Center Axle Disconnect. It is designed to minimize the parasitic drag of the front axle by using a splined, sliding collar to separate a differential from a front axle shaft. It also stops the driveshaft from turning in 2WD and is another option for locking front hubs. A CAD system can only be used on a vehicle with open differentials because it permits the spider gears and differential side to rotate. Do not use a CAD system with a limited slip or locker because the left axle will control the driveshaft and ring and pinion, which will then cause your vehicle to vibrate when you drive at higher speeds.

On a leaf spring, it is the curve or arched part. This term can also be used to describe when the top of a front tire is tilting one way or the other. When looking at a tire from the front, a tire that tilts out would be described as having positive camber, while a tire tilting in would have negative camber.

When a vehicle suddenly veers one way or the other, it enhances the camber. This increase is the camber roll.

This is a common type of universal joint that gets its name from Jerome Cardan, an Italian mathematician from the 1500s who developed its key operational procedures. Also known as a Spicer-style universal joint.

When the steering access slants. If the top pivot tilts from the vertical towards the rear, then it is known as positive castor. The opposite would be known as negative castor.

This controls the balance of a vehicle and describes the spot where all planes are balanced equally. The lower the center of gravity is, the more difficult it is to roll the vehicle. Generally, the center of gravity can be found slightly in front of the mathematical center of the vehicle, one to two feet above the ground.

This refers to any little pieces of tread that fly off of the tire. This is generally caused by the friction and heat of day-to-day use, but it can also be caused by regular rock crawling or tire siping.

Chunk - When a tire throws off small pieces of tread.

The distance a suspension travels above the static ride height.

The section of the tire that meets with the ground, providing traction for the vehicle. This section is different for each tire based on size and pressure.

This type of steering system uses a tie rod to connect the two steering knuckles at the wheel ends. The steering input is attached to one of the knuckles by a drag link from the steering box.

Crossover Steering - The steering system in which the two steering knuckles at the wheel ends are tied together directly with one rod called the tie rod.

A vehicle designed for all wheel drive. Generally a car or minivan platform.

Also see articulated. A vehicle is cross-axled if the rear and front axles are oppositely articulated.

This ratio factors in the transfer case low range, first gear, and axle ratio to determine the peak multiplied lowest ratio gear. In the case that another gearing device is in use, it must be factored in as well. Also called the final drive ratio.

Stands for Constant Velocity joint and encompasses several types, including Birfield, Bendix, Rzeppa, and Herrington. These joints are used on steering axles and driveshafts to ensure there is no vibration with the transmission of power.

Any solid object that is heavy enough act as an anchor and withstand the weight applied during winching.

When the steering vibrates rigorously.

See definition of Low Gearing.

The difference between the radius of a tire when it's unloaded and the radius when it's fully loaded. Also a term for the compression of a spring.

When descending an incline, it is the largest angle between the road and the vehicle before the rear of the vehicle hits the road and drags its tail.

A tire's capacity to drive in a straight line despite any irregularities in the road.

A steering rod that attaches the tie rod to the steering box Pitman arm.

Also known as jounce, this is how far a suspension travels below a vehicle's normal height ride.

This is lower than a stock Pitman arm to minimize bump steer and drag link angularity.

The maximum amount of time a device can be used before damage starts to occur.