49 votes
Accepted

What's the Purpose of Park on an Automatic Transmission?

In an automatic transmission there is a ring with teeth on the output shaft of the transmission. When the transmission is shifted into park a lever called the parking pawl is lowered against the ring. ...
user avatar
  • 15.9k
26 votes
Accepted

Does a Car Keep Moving If Neither Accelerator, Nor Brake Is Pressed?

In short, find a better driving instructor and, if possible, learn to drive a car with manual transmission. The long (still simplified) answer: Does the accelerator control and ensure gas is flowing ...
user avatar
  • 1,912
25 votes
Accepted

How do the latest automatic transmissions match the efficiencies of manual gearboxes?

Traditionally... The major drawbacks of automatic transmissions were: parasitic losses in the torque converter, something which manual transmissions don't have. fewer gears, so a given engine was ...
user avatar
  • 39k
22 votes

Why is towing a manual transmission car, in neutral, with the drive wheels on the ground, considered safe?

Manual transmissions (most, but not all) lubricate not through a pump, but through the action of the gears and secondarily through the level of the transmission fluid itself. In some transmissions, ...
user avatar
21 votes

How do the latest automatic transmissions match the efficiencies of manual gearboxes?

A lot of new automatic transmissions (e.g. Volkswagen DSG) arent actually auto transmissions, at least not in the traditional sense. They have a normal computer-controlled dry clutch (well two ...
user avatar
  • 1,350
20 votes
Accepted

What is a governor and what is it used for?

Old automatic transmissions were shifted entirely using hydraulics, not electronics. For this operation the transmission would generate 3 pressures; line pressure, throttle pressure and governor ...
user avatar
  • 15.9k
17 votes

Use of Neutral Gear in Automatic Transmission

When the car is in D and you start the engine the hydraulic pump in the automatic transmission is not providing fluid pressure until the engine starts. This fluid pressure is used to engage clutches ...
user avatar
  • 181
15 votes

What are the "1" and "2" or "L" gears used for on an automatic?

To go down hill By setting L (or 1 or 2), the gear will stay low and you will be able to use engine brake, instead of using brakes all the way down the hill and suffering from fading. The ...
user avatar
15 votes
Accepted

How exactly does Sport Mode work in an automatic Subaru Outback?

Sport mode will "increase pickup" by providing a more instantaneous response to throttle inputs. As akadian mentioned, the car will stay in lower gears as you accelerate, allowing the engine to stay ...
user avatar
  • 6,017
14 votes

Ford Focus won't rev high when slipping on snow

There's nothing wrong with the vehicle, from what you've described. It sounds like it's doing exactly what it's supposed to. I'm not sure you understand how to get out of a slide (or snow), which ...
user avatar
14 votes

Are manual transmission cars disappearing?

According to NY Daily News, only 6.5% of cars in the United States were Manual Transmission in 2013. That number may even be an overestimate. More helpful is Fix.com, which actually has a useful ...
user avatar
14 votes
Accepted

Does putting an automatic car into neutral at stop lights significantly harm the transmission?

No. Not by any significant or even measurable amount. Constantly using the shifter may, over time, wear the bushes and linkages prematurely but these parts are usually inexpensive and simple to ...
user avatar
  • 1,658
13 votes

Why do you use the "park" gear to park a car and not only the handbrake?

Putting the transmission into "Park" engages the "parking pawl" - essentially a metal pin that locks the output shaft of transmission (and thus the driven wheels) in place. As to why it exists - it ...
user avatar
  • 9,773
12 votes

Can a car with automatic transmission be damaged by being towed in neutral with the engine not running?

Most owner's manuals state that the vehicle should not be towed with the drive wheels on the ground for longer than x miles or faster than y MPH. The reason for this is that Neutral only disengages ...
user avatar
  • 2,045
12 votes
Accepted

How does the transmission not strip itself when applying the brake?

The somewhat longer answer is that the device that makes what you're asking possible is the torque converter. This device is a pair of curved blades setup as an impeller, and a turbine. The following ...
user avatar
  • 9,286
12 votes
Accepted

Do Manual transmission cars perform better than Automatic transmission?

The difference comes down to the driver. While automatic racing gearboxes can beat a driver when it comes to performance, for the type of vehicle you describe, a manual can perform significantly ...
user avatar
  • 18.5k
12 votes
Accepted

Why is the ATF Level checked with the engine running?

There are two main things about tranny fluid: Transmission fluid is checked when it's hot (up to running temperature). As the fluid gets up to temperature it expands. If the fluid is cold, it won't ...
user avatar
12 votes
Accepted

Found a 10 mm nut in the transmission fluid

Okay. Lot's of research, long story, found the answer, don't like it. Overall design of the Nissan B13: one of the things that always impressed me about this vehicle is that it seems to have been ...
user avatar
  • 12.1k
11 votes

Any truth to the "myth" about changing transmission fluid in older vehicles?

NOTE: I have anecdotal vs. empirical data on this, so please understand that caveat. I believe the problem which is actually being discussed is doing a transmission flush when it has never been done ...
user avatar
11 votes
Accepted

What should one do to reduce the HP lost at the wheels on an automatic transmission?

The power losses in a MT are primarily do to friction. Everything in a MT is positively locked together, meaning there is no slip anywhere. Beyond friction at least one of the rotating assemblies is ...
user avatar
  • 15.9k
11 votes
Accepted

Mysterious "5th" Gear on a 4-Speed Automatic?

The transmission has a lock up torque converter. The torque converter sits between the engine and transmission. It is kind of like a clutch on a manual transmission car. When the engine is idle, it ...
user avatar
  • 8,413
11 votes

Does a Car Keep Moving If Neither Accelerator, Nor Brake Is Pressed?

Note, most of these answers are very specific to an automatic transmission and also a gasoline (petrol) engine - The position of the throttle generally controls the volume of air allowed to enter the ...
user avatar
  • 20.9k
10 votes
Accepted

Automatic Transmission - Shifting from Neutral to Drive while in motion

This is a bad idea for several reasons. First, you run the risk of a runaway car. Second, you risk damaging your transmission, which could cause the runaway car in the first place. Thirdly, in newer ...
user avatar
10 votes
Accepted

What disadvantages a car with 4-speed transmission have compared to 5, 6 or 7 speed with similar engine?

For a car that has 4, 5, 6 and 7 gear options, if all else is the same, then your top speed will be the same; all that would change would be your acceleration: In each gear you have a range where ...
user avatar
  • 18.5k
10 votes

1996 Mustang GT won't start with shifter in Park, but will start in Neutral

The range switch doesn't think the car is in park. On Fords theres an adjustable cable if you look on the driver side of the transmission there will be lever with a cable attached. Sometimes the clip ...
user avatar
  • 10.7k
10 votes
Accepted

How Does a Quick Shifter work in a motorcycle

Why the Quick-Shifter? Since these are called quick-shifters we'll dub slow-shifting the traditional way of shifting gear. When you slow-shift you usually close the throttle, disengage the clutch, ...
user avatar
  • 1,755
10 votes
Accepted

Bump on the floor in the back of sedans

The hump provides longitudinal rigidity in the unibody. The fact that it also provides a place to route the exhaust is a bonus. Notice that modern CAD-designed vehicles have much less of an obvious ...
user avatar
  • 1,713
10 votes

Switch from N to D without brake

Should be no problem at all. The manual is being overly cautious, since the usual case for shifting from neutral into drive is when you're stopped hold the brake will prevent the car from starting to ...
user avatar
  • 14.3k
10 votes
Accepted

Switch from N to D without brake

No harm done On contemporary vehicles there is no direct mechanical linkage between the gear selector and the automatic transmission. Instead, the gear selector selects a "state" (e.g. N, D, R, 1, 2....
user avatar
  • 39k
9 votes

Why doesn't anyone ever repair an automatic transmission?

I know that this is an old question, but I want to provide a brief answer. Amount of work that is necessary to fix anything inside the transmission is very close to the amount of work that is ...
user avatar

Only top scored, non community-wiki answers of a minimum length are eligible