Manual transmissions, on the other hand, are just gears; and properly used they won't wear out before the car collapses from rust. The clutch is the only wear component, and diagnosing a worn clutch is pretty easy: does it slip in gear? No? You're good! As long as the transmission shifts smoothly, you're probably in pretty good shape.
Generally speaking, if you're hard on a car, the transmission is going to bear the brunt of it--the trans and the brakes. Brakes are usually overengineered, because the last thing any automaker wants is to be sued because someone couldn't stop. But overengineering the transmission means useless weight in what is already the second-heaviest assembly in the car; and most people don't need a severe-duty transmission in the first place.
"Most people," I said.
My brother styles himself a great driver.
Generally speaking, I dislike riding in a vehicle driven by him. I especially don't like it when he's in a hurry, because he drives like a total retard.
Last week I said this:
He speeds--I mean, 20+ over the limit--brakes hard, weaves through traffic, tailgates, stands on the gas; he's one of those morons who--seeing that the left two lanes are not clear but the right lane is--will dive across both lanes and get behind the guy in the right lane and tailgate him....and worse.
He bought, in the late 1990s, a Dodge Intrepid. It was a pretty nice car; but when he got rid of it he told me that the transmission had already gone out once in it, and that he could tell the transmission was fixing to go again, so he traded it in on his Acura TL.
...ever since that day in 2006 when he drove my parents and I up to the Arlington Heights area to see his son play baseball, I've thought, "Small wonder the damn car ate two transmissions."
So during the big foo-raw about me having to pick my niece and nephew up from Midway on 2 hours of sleep, my sister told me that four out the last five cars he and his wife have owned have needed transmissions replaced. And back when he had his Camaro, my brother went through a clutch every 30,000 miles.
I detect a pattern.
I have had to replace the transmission in one vehicle I've owned: my 1977 Chevy Impala, bought used (in 1990) from my cousin's husband after he bought it used from my uncle. This was a car with an early version of GM's "Metric 200" transmission, which is a shitty transmission. Its designed service life was about 50,000 miles; it was a "planned obsolescence" car. That philosophy is one of the reasons GM is no longer the #1 manufacturer in the world; the Japanese spanked US carmakers who adopted that philosophy and they never quite regained their reputation for building quality merchandise.
The Impala's transmission was probably on its way out before I bought it.
I don't know about the Jeep's transmission. I have no idea how the thing was treated for its first 80,000 miles of service; but I drive it the way I normally drive any vehicle, and I don't beat on the poor thing, and keep my fingers crossed. That's the problem with used cars, though.
The Thunderbird--which I'd bought new--had 92,000 miles on it when I traded it on the green '95 Escort. Nary a transmission problem. The '95 Escort had 105,000 on it and the clutch and flywheel were like new.
Oh, but the Escort is an economy car, and his Camaro was a sports car, which is why my clutch lasted so much longer. See?
...or else he just drives like a retard. Look: there is not a "one size fits all" clutch. Different vehicles have different clutches; the clutch which works fine for my Escort wouldn't last a minute in a Peterbilt. The 1980 Camaro's clutch is bigger and thicker than the 1995 Escort's clutch, because the 1980 Camaro's clutch was selected for a big V8 with lots of torque. The Escort's clutch was selected for a 4-cylinder engine with moderate torque. (Lots for the size of the engine, though!)
But ignore all that. Chalk it up to inferior manufacturing or something. How does that change the fact that 80% of the vehicles he's owned since 1995 (which were bought new) have needed their transmissions replaced?
Thankfully, it's not my problem. Just, make sure never to buy a used car from my brother.
(Or any machine, really, because he's really hard on machines.)
I notice, by the way, that I have never heard anything from him about how his vehicles fare. He got a Corvette in 2001, with a manual transmission; no word on how many clutches it's gotten yet. (He has, however, gone through a couple sets of tires already. Coincidence?)
See, I know machines; and if he told me about this stuff I'd be saying, "That's because...." and he knows it.