Manual Vs. Automatic

[SplatterTone]

I do not remember the names of the actual parts

Throwout bearing

I coast in neutral quite a bit. After years of doing it, I don't think about; it has become automatic.

Manual transmission has its advantages on snow and ice.

[Todd S. Malicoate]

Again, it's a simple rule...only press the clutch when you are changing gears, or about to come to a complete stop (when you are usually about to change gears, anyway).

There are three basic parts to any automotive/light truck clutch:

1. Cover assembly (the big round part with several little fingers (or three large fingers on older vehicles) in the middle)
2. Clutch disc (also called "pressure plate"...the smaller round disc with embedded springs and the wearable material)
3. Release bearing (also called "throw-out" bearing...the part that pushes on the fingers of the cover assembly)

Most vehicles now have hydraulic type clutches...these include a clutch master cylinder, clutch slave cylinder (usually with the release bearing attached), and a hose connecting the two.

When you "ride" the clutch, you are wearing out the friction material on the clutch disc. As Wade pointed out, you don't want to pay for this area to be serviced. Just keep your left foot off the clutch pedal unless you're changing gears or about to stop.

Todd S. "who sold far, far more clutch kits 15 years ago than today" Malicoate

[tofu]

[Dean]

For SOME vehicles, it is more fuel efficient to let the vehicle coast in a high gear than to pop it into neutral.


The Honda Fit manual, for example. When coasting, in gear, the injectors send ZERO fuel to the chamber, until the RPMs fall below 1100. If you do the same coasting in neutral, the engine must use fuel to idle.

Many current vehicles behave the same way. Coast in a high gear instead of neutral! (Also, coasting in neutral in many states is illegal, as it is inherently dangerous)

[Jesse Brook]

I personally prefer a manual, and on older cars an automatic is almost dangerous. When automakers brought over diesels in the 80's they were predominantly manual-transmission cars because 50 horsepower and an automatic could get you killed in those things. I haven't driven a car that didn't respond better when it had a manual transmission, but nowadays, car makers are making inefficient gearing for manual transmissions and efficient gearing for automatics. That means that there really is little (2 mpg) difference between manual and automatic. Once you've driven either transmission, both would become comfortable. Engine braking is an advantage, and so is coasting on manual transmission cars. Repairs are also cheaper, though neither requires much repair. Automatics require almost no effort in comparison, however, and are easier to drive in the city with.

As stated above, however, I prefer a transmission that keeps me a little bit more awake to one that puts me to sleep. It will be sad when they finally complete the phase-out of manual transmissions that they began in the 1990s.

[Rick Denney]

If you are coasting in neutral you are still burning gas. If the engine is turning it is burning fuel....

Not so much with newer cars. Most new computer-controlled cars will shut off the fuel injectors altogether during coast down. That's why you see more than 99 mpg (or whatever the largest number is) on the car's computer display during coast down.

Don't ever ride the clutch.

You will wear out the friction plate and return spring and do other nastiness to your lovely automobile. (I do not remember the names of the actual parts but I have paid to have them replaced once. I hope to never have a clutch go out on me again!)

Don't ever ride the clutch.

It's not the clutch. It's the throw-out bearing.

'Splanation: When you press the clutch pedal, you push an arm against the spring plate that holds the clutch tight against the flywheel. The spring plate is spinning, but the arm is not, so they put a thrust bearing on it so that the two can touch without destruction. That bearing is call the throw-out bearing. That's what rides constantly when you sit and idle with the clutch depressed. That bearing is not designed to turn under pressure continuously, and if it gets hot it will melt out its grease and then run dry, leading to failure soon after.

So, use the clutch for changing gears and getting started. Don't use it when idling. That's what Neutral is for.

Rick "who has replaced more than his share of college-kid-destroyed throw-out bearings" Denney

[SplatterTone]

You will have to define "newer"

It's like the wagon we just got where you throw it into "coast", and it raises the horse off the ground.

[windshieldbug]

You will have to define "newer"

It's like the wagon we just got where you throw it into "coast", and it raises the horse off the ground.

If you do that a lot though, you may have to replace the rein-out bearing prematurely.

[Rick Denney]

Not so much with newer cars. Most new computer-controlled cars will shut off the fuel injectors altogether during coast down. That's why you see more than 99 mpg (or whatever the largest number is) on the car's computer display during coast down.

You will have to define "newer" as I have never seen anything like this on a car. No one I know has a new vehicle. I have a 2003 and it has nothing like this at all. Seems like a lot of crap that will just break later on down the line.

Your 2003 has it whether you realize it or not, even if you don't have the display on the dash showing fuel consumption. The manufacturer would have had to provide it to meet fuel economy and emissions standards.

Both my former 2001 Subaru Outback and my current '05 Outback have the dashboard fuel consumption display. So did my '93 Eagle Vision, '96 I-30, '00 Audi A6 wagon, and my wife's current RX-330 ('04). The T100, a '95 model, does not have the display, but it does have the computer-controlled port injection. I'm not sure about the '90 Toyota Pickup which I use to haul mulch. Throttle-body injection systems from prior to that time will not do that, even though they have microprocessor-controlled ECM modules. You may not have the display, but your engine will still shut down the injectors on coast-down if your car is as new as 2003. All cars since 1996 have on-board diagnostics which can only be driven by the modern computer control module. And they all have closed-loop fuel management using oxygen and mass-flow sensors.

Even cabureted engines significantly reduce fuel consumption on coast down. The old Rochester Quadrajet had two operational modes above idle: economy mode and power enrichment. The switch from economy mode to power enrichment was done on the basis of a vacuum-controlled power valve that would no longer be held closed below about 11 inches of mercury vacuum (8 for truck engines). When you put your foot in it, the throttle plates would be opened wide, vacuum would drop, and the mixture would change from as high as 17:1 to about 13:1. At 17:1 economy mode, the objective was to make sure every bit of fuel was burned by providing an abundance of air. In power enrichment, the objective is to make sure every bit of air is allowed to make power by providing an abundance of fuel. On coast down, vacuum is typically over 20" Hg, which means that the carb will be firmly held down into economy mode and will run the minimum mixture. At idle, the mixture might be a bit richer to keep the engine idling smoothly--the idle mixture is controlled separately.

Rick "who finds modern computer-controlled engines far more reliable and efficient over the long term than old carbureted engines" Denney