Research on Transmission Repair in San Francisco

Common Transmission Repair Terms

Automatic Transmission - An automatic transmission shifts itself. A fluid coupling or torque converter instead of a manually operated clutch connects the transmission to the engine. Newer automatic transmission vehicles use electronic controls to regulate shifting and torque converter lockup.

Automatic Transmission Fluid (ATF) - A special kind of oil used in automatic transmissions. There are several types: Dexron II, Dexron III, Type F, Mercon, Mercon V, Chrysler 7176 and several varieties of Chrysler ATF-Plus. All of these automatic transmission fluid types are are friction-modified lubricants except Type F. Dexron II, Dexron III, Mercon and Mercon V have similar additives. You should only use the automatic transmission fluid specified by your vehicle manufacturer. If you use the wrong automatic transmission fluid, you can cause transmission problems. Read your user's manual if you do not know what type of ATF your transmission calls for. Some dipsticks list the type of automatic transmission fluid required. Some universal ATF fluids are available that meet requirements for many friction-modified vehicles. Newer automatic transmission fluid such as Dexron III and Mercon V last longer than past types of automatic transmission fluid, but they can still oxidize if your transmission runs too hot. Towing is especially hard on automatic transmission fluid unless your transmission is equipped with an oil cooler. It is recommended you change your older vehicle's transmission fluid around every 30,000 miles. Newer vehicles have different automatic transmission fluid change recommendations. See your owner's manual for details.

Clutch - A pedal or lever that engages or disengages the rotating shaft and driving mechanism in manual transmission vehicles.

Clutch Pedal - The pedal to the left of the brake pedal on manual transmission vehicles. Pushing down the clutch pedal enables the driver to change gears.

Differential - A special gearbox designed to spilt and deliver the torque into two outputs that turn at different speeds. Axel differentials are designed to split torque evenly; however, when a center differential is used between the front axles and rear axles in four-wheel-drive systems, it can allocate torque unevenly.

Drive Train - The system that connects the transmission to the drive axles.

Manual Transmission - A transmission in which the driver changes gears using a hand-operated gearshift and a foot-operated clutch. Also known as a "standard transmission".

Transmission - Transmission is the gearbox that multiplies engine torque through gear reduction and torque conversion. Most manual transmission vehicles have four or five speeds, with the highest gear being either a 1:1 drive ratio or an overdrive ratio that is less than 1:1.

Automatic transmissions multiply the engine torque as it passes through the fluid coupling, also called the torque converter, then through different gear ratios. Vehicles with manual transmissions usually have better fuel economy than cars with automatic transmissions because of slippage that frequently occurs in automatic transmission torque converters. Manual transmissions are usually easy to maintain, except for the clutch, which can break or malfunction if adjusted incorrectly or treated roughly. With automatics, the leading mechanical problem is fluid breakdown that results from overheating. You can avoid transmission failure with transmission fluid changes and filter changes every 24,000 miles.