Why do many older cars (roughly until the 1970s) have transmissions that are equipped with only 2 or 3 gears, while newer cars these days come with as many as 5 or 6 forward gears? Is it because newer cars have smaller, weaker engines than their older relatives, and they need the extra “umph” of a more versatile transmission, or is it simply because technology wasn’t quite up to par at the time? Or is it possibly because the price crunch on fuel in recent years has necessitated a transmission that allows for better gas mileage on today’s cars? What irritates me most is even if fuel economy and the additional multiplication of torque weren’t an issue many years ago, then why wouldn’t older cars have 5 or 6 speed transmissions anyway? Afterall, just about any engine, big or small can always benefit from a more versatile transmission, can’t it? Maybe it was too expensive or something. I don’t know. Anyways, I have consulted numerous “gearheads” and auto buffs about this subject and no one has been able to give me an answer. And the same applies to automatic transmissions versus manual transmissions…why do automatics generally have fewer gears than manuals? I know this is a rather trivial question, but it’s bugging the heck out of me.
It’s pretty strightforward, and you have several of the answers correct already. Yes, smaller cars with less engine torque need more gears. And yes, a desire for increased fuel economy has added to the number of gears over time. But add these ones as well:
For a high-torque gearbox, there is a considerable expense in a 5 versus a 4 speed transmission. And yes, for an automatic transmission, there is a very large increase in complexity and cost for adding more gears.
And, it simply was not “traditional” for most of the big American “muscle cars” to have manual transmissions, let alone a 5-speed. Remember - in the late 60’s/early 70’s there was a cultural push towards getting rid of the manual transmission completely, as it was seen as a throwback to “old” technology. I mean really! The thought that you would have to shift your own gears! No one cared about the inefficiency that much pre-oil crisis - we were in a horsepower war after all…
You got it right the first time.
Smaller weaker engines require more gears.
Nothing new about it.
Older cars with small engines have always had more gears, from the '20s onward.
It’s oversimplfying things to say that more gears are required for a weaker engine than for a strong one. Engines that produce good torque over a wide RPM range can do well with fewer gears. Highly tuned engines, in formula one cars or econoboxes, often have a narrow band of hight torque and require more gears to stay in that band.
My WAG: It’s too hard to stick 5 or 6 forward gears and reverse on the steering column. As floor gearsticks became more popular, they advanced the technology so they could have more gears.
Or maybe not.
Well, IIRC manual shifters started out on the floor (where it was most appropriate), moved to the column, then returned to the floor, where they belong IMO.
It still boggles my mind that it is that much more expensive nowadays to make a 6 speed versus a 5 speed transmission. I don’t know why so many high-performance cars don’t have that extra gear.
For my 98 Mustang GT (5-speed) and the 98 Mustang Cobra the excuse given by Ford was that the 6 speed “weighed 20 pounds more and added $500 or more to the cost of the car”, something that as an engineer I find very difficult to believe on both counts. Oh well.