|09/18/12 02:32PM||automatic transmission, E-Transcontrol, MagnaSHift, transmission controllers|
How Many Gears Are Enough?
Decades past in the early days of the automatic transmission there were primarily 2 and 3 forward speeds. Since the early 1990's most US auto makers started making 4 speed automatics and more recently 5 and 6 speed automatics. Some European companies are even making 7 and 8 speed automatics.
So how many gears do you need? Lets first look at some real data; the early 3 speeds had two lower gears for accelerating and then the top gear 3rd was a 1:1 ratio. Under most circumstances in a average car or light truck that is adequate for acceleration and responsiveness. The 4th gear was added in the 90's as a overdrive to assist in gas mileage, but it also achieves other things like lowering the noise level of the engine and by running a lower RPM usually extends the life of the engine and other rotating devices (alternators, air-conditioning compressors, etc.). With the newer 5 and 6 speed transmissions some now have additional ratio's (gears) in between first and the direct drive gear. This can provide additional acceleration for low torque high revving engines, but it can also be a nuisance for daily driving if you have a larger engine that makes plenty of torque.
In most 6 speed transmissions the 5th and 6th gear are overdrive and from all of my experience driving and owning cars with 6 speeds that extra over drive ratio is only useful when you are doing a long trip and/or cruising at highway speeds in excess of 65MPH.
Over the past few years I have had many people ask about installing a GM 6L80 in their older project cars. Unfortunately these 6 speed transmissions were built with a internal TCM (Transmission Control Module) and are not easy to adapt to a older vehicle without the factory ECM and BCM that is programmed to function with this transmission.
I look at the number of gears in transmissions like the number of cylinders in a engine sure you can build 10 and 12 cylinder engines, but it has been proven time and time again that a V-8 can make more horse power per pound than most 10 or 12 cylinder engines and at a fraction of the cost.
I suggest you stick with the GM 4L60E or 4L80E models which can be bought and built at a much more reasonable price and are easy to incorporate into almost any make or model of car or truck. These transmission provide the 2 lower gears, a direct drive (3rd) and then a overdrive (4th). You also get the advantage of a lockable torque converter that improves gas mileage and provides dramatically different performance when compared to the older 2 or 3 speed automatics.
So the moral of this story is if you are building a car with a performance engine and don't plan to drive it often on higher speed highways then don't waste money and time on a heavier, multi speed overdrive. Instead spend that money on something more useful and more fun. If your looking for something to brag about then show off your intelligence and explain to the guy that went with the 6 speed why you opted for the 4 speed.
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