Two people have commented that manuals are better than automatics for towing heavy loads.
Is this really the case? I have often heard the opposite (and wondered why this was so). For example, the 2001 Mazda B4000 pickup has a considerably higher rated towing weight when configured with an automatic. (2WD configuration: Max trailer weight of 3320 lbs w/ manual; 3781 lbs w/ automatic) I’ve been led to understand that this is typical.
I do realize that most big rigs have manuals, which clouds the issue in my mind somewhat. Anybody care to shed some light? Which is better for towing, and why?
When towing a heavy load at certain speed ranges, many automatic transmissions tend to “hunt”, i.e. shift back and forth between gears at every slight grade. Most modern light truck transmissions have shift algorithms that reduce this behavior, but it can still pop up at certain speeds, especially 35-45 mph or so. Taking the gear selector out of overdrive usually eliminates hunting at the expense of fuel economy. Most vehicle owner manuals specifically recommend this practice. It can also reduce the likelihood of damage to the transmission since the overdrive gear is not generally as strong as the other 3 gears, depending on the design of the transmission.
My '95 Nissan Sentra has been through over a foot of snow, rocky national park fire roads, 128 degree temperatures in Death Valley, a collision with a Mac truck, and over 200,000 miles of all kinds. She has never faltered, and the manual transmission gives her the same get-up-and-go she had on her initial test drive.
If you drive in the mountains, the ability to use the “engine break” is a real plus of a manual.
Automatics do this, too. That’s what the numbers after “D” indicate. Now, I’m curious, how many people have never moved the selector past “D”? When towing a trailer with my truck, I do it all the time. When in heavy traffic or negotiating a sharp curve in my Celica at a ridiculously fun rate of speed, it’s handy then, too.
Note: It’s a real Celica, with rwd and IRS, not the pretentious econobox Toyota’s sold for the last 15 years.
Yeah, my Mom’s car had those “numbers after D,” but she only had two of them. I’ve got more options to choose from with my 5-speed, which is nice for retaining good control on gravelly exit ramps, mountains or no.
I forgot to mention this in my last post. This is another plus of a manual. An auto will let you use engine braking, but there’s still that “clutch slip” you get in the torque converter which reduces its usefulness a little. That said, it’s still worth doing. When I owned an automatic, I used to drop it into 2nd (it had D, 2, 1) to descend the notorious Mt Victoria Pass west of Sydney. I just never felt quite safe in an automatic having to rely on brakes alone (I’d get to the bottom of the mountain, and could smell the hot pads if I’d kept it in ‘D’).
The thing to remember is that if your speed is too high, the auto box won’t let you change down. This is a plus for prolonging gearbox and engine life in normal use, but it’s a definite problem in an emergency.
Feh, if you ask me, a semi-auto is the worst of both worlds. It’s not just the ability to shift when you want that makes a manual preferable, it’s the direct connection between engine and wheels (and the ability to control that in addition to the shifting itself). Even the most modern automatic transmission still has a slushy feel compared to a manual. So with a semi-auto, you don’t get the “snap” of the direct connection, but you still have to do your own shifting. Why bother?
One aspect of towing that has not been mentioned is clutch wear. If you are pulling a trailer or large boat through traffic, having a torque converter sure makes things a lot easier on you and the vehicle. Yes, the manual may have more torque available at the wheels to move the object, but you have to slip the clutch a bit. And if it’s something you do all the time, you either have to have a work vehicle, where the cost of clutches is included in your operating and maintenance costs, or you need an automatic.