Gearboxes

Gearboxes, commonly referred to as "manual transmissions", are simple and reliable in comparison to mainstream automatic transmissions. Gearboxes usually consist of five forward speeds and reverse, and can be either mechanically or hydraulically actuated. A gearbox's primary function is to harness the engine's torque by efficiently transferring that it to the drive wheels in a controlled manner.

Parts

The parts of a gearbox are minimal: gears, synchros, a flywheel and a clutch. The clutch is the main wear item of a gearbox, with a typical service life of anywhere from 50,000 - 100,000 miles. The flywheel, which is attached the engines crankshaft, only needs to be resurfaced and not replaced. It's important to check the flywheel for cracks, however. If the flywheel is cracked, it should be replaced.

The parts of a clutch are:

1. Pressure Plate
2. Clutch Cover
3. Throwout bearing
4. Pilot Bearing
5. Flywheel

Maintenance

Gearboxes are extremely reliable and can easily handle all types of driving conditions, in addition to high horsepower and torque.

The three maintenance items of a gearbox are:

1. Gearbox oil: Gearbox oil varies amongst manufacturers-some take standard, 90W-130 and some even take regular 10W-40 motor oil. It's important to refer to your vehicle's service manual in selecting the proper oil. Not doing so can destroy the synchros in the gearbox.
2. Hydraulic Clutch Fluid: This fluid is often located under the hood or bonnet of the vehicle and can only be found in vehicles with a hydraulically-actuated clutch. Hydraulic clutch fluid is often times the same thing as DOT3 or DOT4 brake fluid. 95% of vehicles manufactured after 1994 have hydraulic clutches.
3. Clutch cable adjustment: This adjustment is only applicable to mechanically-actuated gearboxes and can be found under the hood or bonnet of the vehicle. A threaded rod attached to two adjustment nuts controls the engagement of the clutch.