Pitman Arm - The pitman arm connects the steering box to the drag link. On lifted Jeeps a drop pitman arm is usually needed to restore proper steering linkage geometry.

Ring & Pinion - The ring and pinion transfer power from the driveshaft to the axle shafts. Ring and pinions come in various ratios to allow the wheels to turn at a different rate than the transfer case. Ring and pinions consist of a smaller gear (pinion) which turns a larger circular gear (ring).

Revolver Shackle - The Revolver Shackle is a unique shackle that is hinged to allow additional articulation and down travel. It also will help to reduce leaf spring stress when under articulation.

Rock Crawler - A purpose built 4x4 vehicle to crawl over rocks and boulders.

RTI - RTI or ramp travel index is a measurement of a vehicle’s suspension flex or articulation. This can help to show areas that need attention before the vehicle is taken off-road, or to measure for new components such as shocks or brake lines.

Semi-Float - An axle shaft that transmits the vehicle’s power or torque to the wheel, and carries a portion of the vehicle’s weight. A semi-float axle shaft is held into the axle housing with a wheel bearing retainer plate or C-clip.

Short ShaftA slip yoke eliminator or short shaft kit replaces the transfer case output shaft with a much shorter shaft that accepts a fixed yoke and seal assembly. This allows the use of a CV driveshaft that is longer and can handle a more severe driveshaft angle caused by increased vehicle lift.

Solid Axle - A solid axle refers to the complete differential housing that is rigid from axle flange to axle flange (or knuckle to knuckle). The solid axle has many features that are desirable for off-roading such as increased articulation potential.

Spring Rate - Spring rate is measured by the force required to compress the spring one inch. For instance a spring with a spring rate of 220 requires 220 lbs. to compress the spring one full inch. 

Steering Box - The steering box transfers the movement of the steering wheel to the wheels through the pitman arm, drag link and tie rod.

SWB - A short wheel base vehicle has less than 100” of wheelbase. This includes TJ and YJ Wranglers and CJs.

Tie Rod - The tie rod is part of the steering linkage, connecting both knuckles on a steering axle allowing the vehicle to turn. A bent tie rod is a common failure on the trail and results in your tires being excessively ‘toed-in’.

Triangulated Suspension - A suspension design that uses control arms that when viewed from the top appear in the shape of a triangle. The opposing direction of the arms controls the side to side movement of the axle and allows the track bar to be eliminated.

TJThe TJ Wrangler has been produced since 1997. It features coil springs, and arguably a better on road and off-road ride. It replaced the YJ Wrangler.

Torque - A force that turns or twists resulting in rotation. Torque is measured in ft. lbs. (US)

Track Width - The measurement from right tire to left tire centerline. Track width can be modified in several ways, some of which are new axles, new wheels, and wheel spacers. A wider track width can help to make your vehicle more stable on side hills and uneven terrain.

Track Bar - The track bar locates your axle side to side underneath the vehicle. The track bar must be modified or relocated when the vehicle is lifted to compensate for the additional lift. If it is not re-located the axle will be offset from the center of the vehicle and can result in adverse handling characteristics.

Transfer Case - A gearbox that allows the power from the transmission to be transferred to both the front and rear axle equally. It also allows the driver to shift from 2WD high to 4WD high, and 4WD low

Turning radius - This is a measurement of how sharp a vehicle can turn. The smaller the number the tighter the vehicle can turn. This can be very important on some trails that have very little room to move.

UCA - The upper control arm connects the frame to the axle and can be lengthened or shortened to fine tune the alignment and pinion angle.

U-Joint - Short for universal joint, the u-joint is a coupling device that connects the drive shaft to the yoke and allows the drive shaft to operate at an angle. U-joints are also used in front steering axles to connect the inner axle shaft to the outer axle shaft or stub shaft, and allow the vehicle to turn and still transfer power to the wheels.

Wheel Base - Wheelbase is the measurement from the center of the front wheel to the center of the rear wheel in inches.

Wheel Travel - The measured amount that each wheel can travel between full extension and full compression.

WJ - The WJ Grand Cherokee is a redesigned version of the ZJ Grand Cherokee and has been produced since 1998. It features a coil spring suspension front and rear.

XJ - The Cherokee was one of the original sport utility vehicles (SUV) and arguably created the SUV market that exists today. The Cherokee was produced in the XJ form from 1984 until 2001. It featured a front coil spring suspension and a rear leaf spring suspension. It remains one of the most popular off-road vehicles for modifications today.

YJ - The YJ was manufactured from 1987 through 1995. It replaced the CJ line of open top off road vehicles, and was replaced by the TJ wrangler. It has a leaf spring suspension.

Yoke - Yokes connect the drive shafts to the transfer case and axles via u-joints. 2 yoke styles are used. One style uses straps and small head bolts and the other uses u-bolts with washers and nuts to secure the u-joint.

Z-Box - The Z-Box replaces the factory leaf spring mount on the vehicle frame. The Z-Box opens up during axle droop and works in conjunction with the Revolver Shackle to reduce spring stress and maintain proper driveshaft angles. The opposing construction allows only one side to open at a time.

ZJ - The ZJ Grand Cherokee was produced from 1993 until 1997 when it was updated and introduced as the WJ. The ZJ features a coil spring suspension front and rear making it very capable on and off-road.