Closer Look at the Standard Transmission

This chapter is about a typical standard transmission for a rear-wheel-drive vehicle and, we hope it gives you a few tips to help prolong its life and save fuel. There are also a few handpicked YouTube video clips at the end of the post explaining the transmission’s operation quickly, fully, and in layman’s terms.

Passenger vehicle standard transmissions have at least one reverse and three forward gears but with some of the newer high-performance machinery, the operator has seven or even more gears to choose from. But standard transmissions  can also have as few as two forward  gears.


D 36457448 © Choosakdi Kabyubon |

Passenger vehicle gearboxes hold five main parts. They are a main shaft, lay shaft, dog clutch, and the selector. The power transfers from the clutch via the gearbox input shaft into the transmission housing where the lay gears transfer the power to each of the gears and, in turn, pass on motion to the gears on the main shaft.

A four-speed transmission has four gears on the main shaft with all of them on roller bearings, making them dependent on the lay gears to spin. All of the transmission’s gears rotate when the vehicle is in motion, but the main shaft gears, on the bearings, are just spinning freely until they’re ready for the stationary dog clutch to activate them. This clutch connects to the operator’s shift stick and will slide forward and backward on the main shaft to lock into the selected gear.

The number of teeth on each main shaft gear determines the gear ratio. The earliest transmissions had brass synchromesh rings or blocker rings to help make a smooth transition to all gears, even when downshifting, but many transmissions manufactured during the muscle car era were not fully synchromesh-equipped.

Modern transmissions have an assembly to contain the rings. Without fully synchronized downshifting, the car (transmission) must fully stop to make the change to first gear. This is the setup if a three-speed shifter attached to the steering column, or a “three on the tree,” controls the tranny.  The partial synchromesh gearing arrived in showrooms by the early 1950s, but by 1980, most passenger vehicles used a fully synchronized version.


ID 39545444 © Dmitry Kalinovsky |

The transmission will help keep your fuel bill down when you shift gears at lower rpm but not low enough to lug the engine or get too near its stalling point. The downside is running at low rpm will also keep down the power available to you. A high-performance, V8-powered automobile putting out 500-plus horsepower can burn fuel at an amazing rate, and a little restraint will save some cash. A standard shift transmission is not only more efficient than an automatic style but also, with the ability to opt for power rather than fuel economy, make it a lot of fun to drive.

Originally posted 2015-06-28 04:16:32. Republished by Blog Post Promoter

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Ross Mills

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