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madd0ct0r wrote:Going the other way,going down steep hills I miss being able to drop down a gear and dump the extra kinetic energy into the engine block instead of my brakepads.

Every automatic I've driven has had the option to do tell the car the highest gear it's allowed to use. So I do use engine breaking if the hill is steep enough.

Exactly. My current car has a four-speed automatic transmission, and of course I normally drive it in "Drive" which allows it to choose from all four gear ratios as it deems appropriate. However, I ALSO have the option of putting it into "Third", "Second", or "First" which respectively limit it to the lowest three, two, or one of the available ratios. Engine braking is absolutely available in an automatic.

Sure it's available, it's just that a lot of people don't know about it.

Broomstick wrote:Sure it's available, it's just that a lot of people don't know about it.

A lot of people seem oblivious to their turn signal, too... Seems to afflict BMW drivers the most.

If "Subaru means love", why are all most of the asshole drivers I encounter driving Subarus?

Broomstick wrote:Sure it's available, it's just that a lot of people don't know about it.

I wouldn't know about engine braking if I hadn't learned from one of the most crazy-competent drivers I know (who, amusingly, I met on this forum).

Khaat wrote:If "Subaru means love", why are all most of the asshole drivers I encounter driving Subarus?

It's a different kind of love...

Zeropoint wrote:Exactly. My current car has a four-speed automatic transmission, and of course I normally drive it in "Drive" which allows it to choose from all four gear ratios as it deems appropriate. However, I ALSO have the option of putting it into "Third", "Second", or "First" which respectively limit it to the lowest three, two, or one of the available ratios. Engine braking is absolutely available in an automatic.

I wasn't aware that doing that with an automatic allowed the car to still select the other gears below the specified number. I thought if you put it in second it was in second etc...but then I haven't driven or even ridden in that many vehicles with an automatic transmission where anyone manually shifted it out of drive for more than a few moments.

I have driven a Ford Ranger that allows you to turn off overdrive with a button on the end of the gear selector.

I used to have an automatic when I drove a '91 trans am GTA. I remember I had to drive in D when below 60kph or so or in city traffic, but when I got on the roads and doing above that it was time to switch to the [D] which put it up another gear when going faster. There was some reason you weren't supposed to drive it in [D] all the time, not good for it, for whatever reason... Think there might also have been 1 and 2 gears in addition to park and reverse.

Now I have a manual 5 speed Yaris.

Tsyroc wrote:

Zeropoint wrote:Exactly. My current car has a four-speed automatic transmission, and of course I normally drive it in "Drive" which allows it to choose from all four gear ratios as it deems appropriate. However, I ALSO have the option of putting it into "Third", "Second", or "First" which respectively limit it to the lowest three, two, or one of the available ratios. Engine braking is absolutely available in an automatic.

I wasn't aware that doing that with an automatic allowed the car to still select the other gears below the specified number. I thought if you put it in second it was in second etc...but then I haven't driven or even ridden in that many vehicles with an automatic transmission where anyone manually shifted it out of drive for more than a few moments.

I have driven a Ford Ranger that allows you to turn off overdrive with a button on the end of the gear selector.

I've been in two 4 speed automatic cars. In one, the button on the side of the gearstick locked off 4th gear (called overdrive for some reason). In the other car:
- If the button was in, 1 on the gearstick meant first gear as max. 2 meant second. D meant 3
- With the button out, 1 meant second gear as the highest allowed gear. 2 meant third. D meant allow all 4 gears to be used.
So I wouldn't be surprised if there are automatics where selecting a gear locked the car into only using that gear.


Secondly, the only times I've used that is during a long downhill without many turns. Engine breaking means I have to hit the break pedal a lot less to keep the car below the speed limit. In those cases, the car stays in the highest allowed gear the whole way down. So it doesn't matter if I'm locking off the lower gears or not.

Tsyroc wrote:I wasn't aware that doing that with an automatic allowed the car to still select the other gears below the specified number. I thought if you put it in second it was in second etc...but then I haven't driven or even ridden in that many vehicles with an automatic transmission where anyone manually shifted it out of drive for more than a few moments.

As I said - most people don't know about it.

As a bonus - these days there's some sort of safety feature that prevents you from screwing up the car by doing that, back when I first learned to drive you have to remember NOT to downshift your automatic at too high a speed or you could cause some problems/do damage.

I have driven a Ford Ranger that allows you to turn off overdrive with a button on the end of the gear selector.

Every car I've owned has also had that option.

bilateralrope wrote:I've been in two 4 speed automatic cars. In one, the button on the side of the gearstick locked off 4th gear (called overdrive for some reason).

Overdrive just basically means: Drive-shaft is spinning faster than the motor. I don't know all the math, but there's a specific ratio on an engine you can achieve the best speed when you work out what ratio your motor and driveshaft need to spin at, combined with other things like air-drag and wheel friction, to maintain a cruising speed (or max speed) with the least amount of engine power.

My Ranger had a 5-speed, 4-gears and a 5th Overdrive gear. I've heard of vehicles with 2 OD gears but I can't name any off-hand. Automatics generally have an OD-off switch because you don't have access to a lot of raw-power when in overdrive since (as said) your drive-shaft is spinning faster than you motor. Compare this to something like 4 Low on a 4x4 when your engine in spinning something like 40 times per turn of the drive-shaft. You get a Maximum amount of torque at this ratio but nearly ZERO speed. Getting above 15MPH in this gear would likely explode your engine.

Pulling a trailer or dealing with hills can damage a transmission that won't shift out of overdrive. Not to mention, your engine won't be able to keep up speed in either case. Also depends on the motor/size of your vehicle. A 3500 Dually could tow a JetSki in overdrive with no issue. But my Taco couldn't tow a flat-bed trailer in it.

I should probably clarify something and also mention I'm a layman at best when it comes to this stuff. For a 4x4, things get weird because you've got 3 (technically 4) different sets of gears: The Transfer Case gears (controls the 4x4 system), the Transmissions gears, and the rear (and matching front, so 4 gears.. well, they BETTER fucking match) axle gears. From what I know, the Transfer Case is 1:1 unless you're in Low.

Many "newer" 4x4s, and by that I mean "I bought this truck off the lot and it happens to have 4x4," are more than capable of doing even 30MPH in 4W Low, though I can't think of any situation where this would be a good idea. Your much more "Off-Road heavy" vehicles will have higher Ratio axle gears. What this means is that the drive-shaft will need to spin many more times to spin the axle/wheels 1 revolution. So, there's some crazy gear ratios on your heavy-duty off-road vehicle where being in 4L and pushing to far past 15MPH would red-line (or maybe rev limit if you've got one) your engine. The guy who sold me my Taco said it would do 30MPH in Low. I.... am never going to test that or even get near testing it.

My old Dodge had a 3.55:1 axle ratio. It would tow, but those were considered Highway gears. There was a 4.94 ratio available. This would mean for every ~5 revoloutions of my drive-shaft, my wheels would spin once. Gas GUZZLER!

To sum up: Cars is complicated. Making me do math and shit.

Also, for the record, I think any manual with more than 5 gears is considered a double-overdrive. So, if you have a 6-speed manual, you have double-overdrive. Passenger vehicle mind you. I had to think about it for a minute before I remembered that. But, and I think this holds true everywhere, to be considered an overdrive gear, you have to be under a 1:1 ratio on your engine to drive-shaft spin. So, .84:1 would count. Double overdrive would likely just push that to around .70:1.

The reason you typically have one overdrive gear is because faster the driveshaft spins, the greater* the risk of catastrophic failure. Even though modern cars typically have more gears (both automatics and manuals) than 20 years ago, they still generally abide by the rule of the highest gear being overdrive, with the second highest being 1:1.

*at normal highway speed, this risk is almost zero for well-maintained cars.

Alferd Packer wrote:The reason you typically have one overdrive gear is because faster the driveshaft spins, the greater* the risk of catastrophic failure. Even though modern cars typically have more gears (both automatics and manuals) than 20 years ago, they still generally abide by the rule of the highest gear being overdrive, with the second highest being 1:1.

*at normal highway speed, this risk is almost zero for well-maintained cars.

This is drive shaft speeds, not drive axle speeds. There's the final drive gear ratio in the differential as well