- J -

JFET

(Junction Feld effect transistor) A field effect transistor formed by combining layers of semiconductor material. The JFET has an input impedance equil to the reverse bias impedance of a p-n junction. This imperance is approximately 20,000 Meg. oms.

Jig

1. A fixture for holding work. 2. A device used as an aid to straighten the frame of a vehicle.

JIS

An acronym for Japanese Industrial Standard.

JMS

Jet mixture solenoid.

Johnson Rod

A mythical automotive component that is blamed for any problem that cannot otherwise be explained.

Joint

A junction of members that are to be joined or have been joined.

Joint Penetration

The depth a filler metal extends from its face into a joint, exclusive of weld reinforcement.

Joule(J)

A unit of energy, measured in newtons per meter. The rate of using joules per second is watts.

Jounce

The inward reaction of the spring and shock absorber when a wheel hits an obstruction.

Journal

The part of a rotating shaft that turns in a bearing.

Journal Size

The finished diameter of a crankshaft journal.

JTEC

Acronym for Jeep/Truck Engine Controller (Chrysler).

Jubilee Clip

English term for Hose Clamp.

Judder

A low-frequency vibration of the clutch or brakes.

Jug

A carburetor.

Juice

1. The current in an electrical system. 2. A special racing-fuel formula. 3. Any fluid, such as brake fluid.

Jump

1. To begin early rapid acceleration in a rolling-start race before the green flag. 2. To make an early, sudden start off the line in drag racing before the green light. 3. To bypass the ignition switch to start a vehicle. 4. To jump start a vehicle. 5. An obstacle that causes an off-road vehicle to become airborne.

Jump Out

A condition when a fully engaged gear and sliding clutch are forced out of engagement.

Jump Start

Using battery jumper cables to connect an able battery to a disabled battery to start the vehicle.

Jumper Cable

Two heavy-duty cables used to connect two batteries, as for starting a vehicle.