In the early days of motoring, the number of gear ratios available to the pioneer motorists soon increased from one to three. This was a brave step, because very few motorists liked to change gear. There was no synchromesh, the clutch action was crude, and the change tended to be noisy. It was usually accompanied by a shock that travelled throughout the drive train, unless the driver managed to synchronize engine and drive shaft speeds.
When I started to drive three speeds were still very common, not only on Yank tanks, but even on a car as small as my 750 cm3 rear-engined Renault. It made perfect sense; first gear was for pulling away, second was for accelerating up the 80 km/h cruising speed that was common in those days, and top gear was engaged for cruising.
Then, in the late 20s, many manufacturers added another gear, to cope with mountains, and to cater for the growing awareness that cars can be more than just transport. They can be fun!
After WW2, most countries started to build freeways, with the result that cruising speeds increased, in spite of the emergence of speed-trapping devices. Many motorists discovered their cars were revving their guts out to maintain high cruising speeds, and some brands even developed the habit of throwing con-rods; others simply overheated.
A British company then started to offer an aftermarket overdrive that could be mounted behind the gearbox. An overdrive is set of gears with a ratio of less than one, (for example 0,87:1).
Very soon the first five-speed gearboxes started to appear. The fifth gear was an overdrive, and fourth gear was usually 1:1. A change was made in the last 20 years when front-wheel-drive gearbox construction made it easy to adopt any ratio, so that today fourth gear is often also an overdrive.
To me, a five-speed gearbox is the ultimate; it gives me four gears, ie three changes of gear, to use in town, and I need to engage fifth only on the open road.
More recently six-speed gearboxes have become commonplace, but the ratios are often such that 5th and 6th gears are both overdrives, giving two freeway gears, but still only four ratios to use in town. What’s the point?
Design engineers say that more ratios enable the engine to spend more time in the combinations of engine speed and throttle opening where the engine is very efficient. This promotes lower fuel consumption. I can understand that, but only if the gearchange is automatic. The average driver spends so much time in the wrong gear that giving him more ratios to play with is a complete waste of time.
Does anybody know where I can get my BMW M5 converted to three speeds?
