u-bolt: U-shaped bolt for attaching leaf springs to the axle or securing exhaust pipes, ring bolts, and shackles
ULC: Acronym for "Underwriter's Laboratories."
Underbody: The underside of a car.
Underbody Coating: A coating of the underbody of a vehicle, usually with organic coating materials (plastic, wax, bitumen-based products), to protect it from mechanical damage and corrosion
Undercoat: [1] All of the products used to prepare the surface to receive color coats (primers, surfaces, putties, sealers, etc.).
[2] A rustproof coating with sound-deadening properties applied to the underbody
Under inflated tire: A tire which has too little air in it, causing increased wear at the tread edge
Underpowered: A description of a vehicle with an engine that provides less power than is necessary for acceptable performance; especially noticeable when accelerating, passing, or going uphill
Underslung: suspended below a supporting member, e.g., of a chassis suspended below the axles
Understeer: The tendency for a vehicle, when negotiating a corner, to turn less sharply than the driver intends. The front end wants to run wide in a turn. To correct this problem, the suspension needs to be stiffer in the front or softer in the rear. A front-engine vehicle has a natural tendency to plow straight ahead on turns (i.e., understeer) unless its suspension is adjusted to counteract it.
Unicycle: A one-wheel cycle having pedals attached to the axle and a saddle attached to the upper end of the fork tubes.
Universal Joint: UJ) A flexible double-pivoted joint that allows driving power to be carried through two shafts that are at an angle to each other. It consists of two Y-shaped yokes and a cross-shaped member called the spider. The four arms of the spider are assembled into bearings in the ends of the two yokes. With the normal cross-and-two-yoke universal joint there is some change in speed when the driveshaft and the driven shaft are at an angle to each other. The change in speed occurs because the driven yoke and driven shaft speed up and then slow down twice with every revolution of the drive line. The greater the angle between the drive and driven shafts, the greater the speed variation. To eliminate this speed variation, which results in increased wear of the affected parts, constant velocity joints are used on many cars. In front drive vehicles, it is called the constant velocity joint. Also called "Hooke joint" or "cardan joint."
Unleaded Gas: Gasoline which has no tetraethyl lead.
Updraft Carburetor: A carburetor in which the air passes upward through the carburetor into the intake manifold.
UPH: Abbreviation for "upholstery."
Upholstery: (Uph) The fabric used to cover the seats and other panels.
Upshift: Shifting to a higher gear.
(Br) "upward change."
Upstroke: The ascending stroke of a piston.
urban driving: Driving in cities and towns where the common speed limit is 50 kph (30 mph) with traffic lights, etc
used car dealer: A proprietor who sells used cars. In some instances it is part of a new car dealership.
Used Vehicle: vehicle that has been previously owned or driven. Also called preowned.
Utility Truck: A pick-up truck