jacked up
Describes a 4x4 automobile that has a "lift kit", raising the body and/or frame higher than stock.
jacked up: lifted higher on aftermarket suspension
A jacked up vehicle is one that has been raised above its factory ride height through the installation of a lift kit, longer springs, or coilover suspension. This modification increases ground clearance, typically by 2 to 8 inches depending on the kit and application. The term comes directly from the use of hydraulic jacks during installation, though it has become standard shop vocabulary for the finished result.
Lift kits come in several types. A body lift sits spacers between the frame and body, raising only the body and keeping the chassis geometry unchanged. A suspension lift replaces or extends springs and shocks, raising both frame and body while altering suspension angles. Coilover systems allow both height and dampening adjustment. Each approach has tradeoffs: body lifts are cheaper but offer no improvement in approach or breakover angles; suspension lifts improve geometry but cost more and affect ride quality.
Jacked up rigs are common in off-road work, agriculture, and regions with rough terrain or deep snow. Higher clearance helps clear rocks, ruts, and water crossings, and provides room for larger tires. A typical aftermarket lift adds 100 to 200 pounds of weight, which increases fuel consumption and stresses brakes and steering components.
Common problems emerge when lifts are poorly matched to the vehicle or when supporting systems are not upgraded. Unequal spring rates cause the chassis to sit at odd angles. Extended driveshaft length can cause vibration or binding. Stock brakes and steering may become inadequate for the added mass and changed weight distribution. Tires much larger than stock can create fitment issues and affect speedometer accuracy.
In the trade, jacked up is neutral descriptive language, neither praise nor criticism. You might hear "that truck is jacked up pretty high" to mean it simply has noticeable lift, while "that lift is jacked up" means something is wrong with the installation. Context determines whether the phrase describes a modification method or a malfunction.