Okay, I'm curious about something. When a car maker offers a car with a manual transmission, why is the automatic version always one gear less?

Example:
6 speed manual and the automatic option is a 5 speed or a 5 speed manual or a 4 speed automatic, 4 speed stick or 3 speed manual.

Anyone know why this has always been so?

Warren

 

i know 6 speed auto trannies are more expensive to produce, head over to Toyota.com and build a Tacoma, you'll see what I mean. So im assuming that car makers will stick for the most part wti 5 speed autos to reduce costs for them and consumers because most people could give a rip how many gears their auto has anyway. and for those who dont, they can get it as an added option.

 

the new M5 has a 7-speed SMG, but will get a 6-speed manual. Also, the MR2 has a 6-speed sequential while only a 5-speed manual. Not making any points, just some facts.

 

This is no longer true, MB now sells a 7-speed AT.

Also Corvettes come with 6-speed AT


I guess it was expensive to make multi speed ATs, usually the better cars were first with 5-speed ATs before cheap econ cars that made do with 3 or 4 speeds.

 

I don't think it was always intended that autos have fewer gears, it just worked out that way.

 

Most automatics rely on planetary gear sets which require more parts for each gear ratio than a manual gear set. It could be that the auto transmission with the same number of gears would be too big for the area they designed for the transmission.

 

note that these are not automatic transmissions. they are manuals that have automated shifting.

true automatics require a buttload more parts when you add gears. the gear selection system is totally different, with planetary gearsets in autos.

 

Cost and size.

 

The current 3-series auto is a 6-speed.

 

An automatic is geared differently than a manual because of the benefit of the torque converter.

From "How Things Work":

In addition to the very important job of allowing your car come to a complete stop without stalling the engine, the torque converter actually gives your car more torque when you accelerate out of a stop. Modern torque converters can multiply the torque of the engine by two to three times. This effect only happens when the engine is turning much faster than the transmission.