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Coasting?


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32 replies to this topic

#1 Urban Coyote

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Posted 09 January 2006 - 10:00 AM

If you own a standard and want to coast down a hill, what is the best method to do this? I know, seems like a silly question but recently the clutch went on my dad’s truck. While chatting with him about it he said that when coasting down a hill you should depress the clutch, take the vehicle out of gear and then let the clutch back out and coast. His thoughts were that just putting the clutch in alone and coasting will wear on some of the springs that help operate the clutch. Ok, I’m no mechanic, so does this sound right? What is the best method to coasting without wearing your clutch unnecessarily?? With gas prices the way they are anything to save a little is a help and with all the hills in my area coating is a great way to conserve some gas.

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#2 Andyjo

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Posted 09 January 2006 - 10:49 AM

it might be so you don't slip and dump the car back into gear.... ?

#3 Tiny Clark

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Posted 09 January 2006 - 11:04 AM

Yes, take the car out of gear and let the clutch out. Leaving it in does two things; it causes the throw-out bearing to spin continuously and also assists in wearing out the fingers on the pressure plate just a bit.

You could even tap the gas pedal and slide the shifter into neutral without the clutch. This takes just a bit of practice to learn how, but I do it all the time on my beemer.

#4 SuBrat84

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Posted 09 January 2006 - 11:22 AM

You could even tap the gas pedal and slide the shifter into neutral without the clutch. This takes just a bit of practice to learn how, but I do it all the time on my beemer.


If you're really good at "Rev Matching" you can shift without using your clutch at all... but probalby is pretty bad on your tranny. Handy in a pinch when your clutch shatters though. I have actually had people tell me that with the style of clutch the older Subarus have that it is better to shift out of gear WITHOUT depressing the clutch pedal. I don't believe them though, so I still depress the clutch when shifting out of gear.

Getting back to the original topic. It is best to leave it in gear while going down hills. The difference in gas used is minimal at best and the lack of control while in nuetral or with the clutch fully depressed is hazardous to yourself and other drivers. However, if you insist on coastin down them hills it would be best to shift in nuetral.

#5 mtsmiths

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Posted 09 January 2006 - 12:17 PM

Getting back to the original topic. It is best to leave it in gear while going down hills. The difference in gas used is minimal at best and the lack of control while in nuetral or with the clutch fully depressed is hazardous to yourself and other drivers.


Ditto, especially on a steep hill, all you need to do is heat up your brakes and suddenly they just f-a-d-e away. Not to say I haven't done it.

And yes, if you match revs you can shift without a clutch in a pinch, just don't make a habit of it. I once lost a clutch cable in a VW Bug in Europe. I drove about twenty miles to a VW dealer to get it fixed, and the (very Teutonic) service writer informed in the severest terms that of course I must be wrong, insisting that I could NOT have driven the car without a clutch.

When the technician (read mechaniuc, this was thirty years ago) diagnosed a broken clutch cable, he was actually angry with me for being right.

#6 RallyKeith

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Posted 09 January 2006 - 12:47 PM

Well I hate to burst your bubble, but I'm pretty sure that if you are driving a newer fuel injected car you are using more gas when idling in neutral while the car is moving than just leaving it in gear and letting off the gas. In a newer fuel injected car it is smart enough to see that the car is moving and that the throttle is closed, and it will actually cut fuel to alternating cylinders in order to increase fuel economy.

If you still want to coast in neutral, than yes keep your foot off the clutch.

Keith

#7 Setright

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Posted 09 January 2006 - 01:58 PM

Thanks Keith ;)

#8 Mr Fishums

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Posted 09 January 2006 - 02:55 PM

If you are going to coast, throw it in neutral.

Think of it this way, brakes are easier to change than clutch's. But the ammount of wear and tear you are actually preventing is almost non exsistent. I am sure if we took two cars with 50k miles (one using clutch and the other sing neutral). It would only show minor benifits :rolleyes:

If you a really worried about loosing, your brakes, Emergency brake, and clutching abilty to get it back in gear at the same exact moment, causing you to roll off a cliff into jagged rocks only after running over 12 nons and 3 infants at a bus stop! Keep it in gear! Though if your worried about these things in the first place, why are you on the road? ;)

Personally If it's a long down grade I use neutral, short ones I use the clutch. Use it at your own disgression, my bug has no power brakes or steering. So when I get to those 1-2 mile plus down grades I just shut it off. It makes no difference in this case. :cool:

If you clutch it, make sure you have it fully engauged though. Riding down hills with it half way pressed in will surely destory it. AS well as rengauging it from neutral without have a good idea on how to match your speed with RPMs. Remember some older Subaru's have the hill clutch brake feature too!

Peace, Fishums

#9 Urban Coyote

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Posted 09 January 2006 - 03:12 PM

If you are going to coast, throw it in neutral.

Think of it this way, brakes are easier to change than clutch's. But the ammount of wear and tear you are actually preventing is almost non exsistent. I am sure if we took two cars with 50k miles (one using clutch and the other sing neutral). It would only show minor benifits :rolleyes:

If you a really worried about loosing, your brakes, Emergency brake, and clutching abilty to get it back in gear at the same exact moment, causing you to roll off a cliff into jagged rocks only after running over 12 nons and 3 infants at a bus stop! Keep it in gear! Though if your worried about these things in the first place, why are you on the road? ;)

Personally If it's a long down grade I use neutral, short ones I use the clutch. Use it at your own disgression, my bug has no power brakes or steering. So when I get to those 1-2 mile plus down grades I just shut it off. It makes no difference in this case. :cool:

If you clutch it, make sure you have it fully engauged though. Riding down hills with it half way pressed in will surely destory it. AS well as rengauging it from neutral without have a good idea on how to match your speed with RPMs. Remember some older Subaru's have the hill clutch brake feature too!

Peace, Fishums


Thanks guys!
Just to clear up a point, I do not ride the breaks down the hills when I coast, nor do I try to shift gears without using the clutch. I've heard it can be done, and I have poped my old Loyale out of gear a few times accidentally, but I don't make a habit of it with my Legacy. The coasting referring to mostly is long hills on the highway where you can coast 1-2.5 km without too much trouble.

I keep the clutch pedal completely to the floor when I have coasted in the past....nothing half way :)

How is idling in neutral using more fuel that driving at 3000rpm's?

Ok, last question....it's Monday, what can I say! Being in neutral removes your ability to accelerate, which of course is handy, but how is it a hazard? Most evasive maneuvers I'm used to require breaks and steering, which you do not loose when in neutral.

UC

#10 Mr Fishums

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Posted 09 January 2006 - 09:53 PM

(Ok, last question....it's Monday, what can I say! Being in neutral removes your ability to accelerate, which of course is handy, but how is it a hazard? Most evasive maneuvers I'm used to require breaks and steering, which you do not loose when in neutral.)


senario, out of the blue behind you a speeding semi loading with rocket feul is on fire and jack knifed! You must out accelerate the burning mass before it's to late and you become subaru kabob! ;)


Peace, Fishums

#11 dmanaenk

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Posted 09 January 2006 - 11:58 PM

How is idling in neutral using more fuel that driving at 3000rpm's?


Like it was said here before, cars with fuel injectors and newer ones with carburator (like less than 20 year old), cut the fuel off when the gas pedal is released completely, and engine RPMs are higher than some threshold. So when you coast down a steep slope in gear and with your foot off the gas, the engine is rotated by your wheels, not by burning fuel. If you put it in neutral, it needs fuel to run.

As another argument for coasting in gear, imagine that during way down your engine stalls for some reason (which is more likely in neutral than in gear), and you will end up without power brakes and steering. Scary, huh?

#12 Gnuman

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Posted 10 January 2006 - 12:51 AM

Ok, last question....it's Monday, what can I say! Being in neutral removes your ability to accelerate, which of course is handy, but how is it a hazard? Most evasive maneuvers I'm used to require breaks and steering, which you do not loose when in neutral.

UC


If you are in neutral, you loose the transmission brake that helps you to slow down without using the brakes. Loosing this reduces yoru control over the vehicle, and is also illegal in many states. . .

#13 scrap487

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Posted 10 January 2006 - 02:03 AM

if you really want to save on gas, rip out every unused seat, bit of carpet, all the interior trim, insulation, power steering, powerbrakes, heater core, most of the dash, airbags, spare tire and accessories, start working out, cut off a leg and an arm and maybe an eyeball and a few organs, if you have a roof rack take that off, take off the rear bumper, all antisway bars and related stuff, take off everything behind the front bumper molding if you got a newer car with all that plastic in front, oh yeah take off the rear hatch, cut off the exhaust(after o2 sensor), remove every other none essential bolt from your drivetrain and body, if subarus have them take off your map sensor and put a variable resitor in the circuit. oh yeah might as well cut off your gas tank while youre at it, but ifyou dont want to do that, just never drive with more than a gallon in the tank.

sooo.. thats what, at least 700 lbs lost and some parisitic loss reduced? :headbang: oh yeah not to mention it will be more peppy and there will be considerably less wear on tires brake clutch tranny engine etc...

#14 frag

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Posted 10 January 2006 - 11:47 AM

if you really want to save on gas, rip out every unused seat, bit of carpet, all the interior trim, insulation, power steering, powerbrakes, heater core, most of the dash, airbags, spare tire and accessories, start working out, cut off a leg and an arm and maybe an eyeball and a few organs, if you have a roof rack take that off, take off the rear bumper, all antisway bars and related stuff, take off everything behind the front bumper molding if you got a newer car with all that plastic in front, oh yeah take off the rear hatch, cut off the exhaust(after o2 sensor), remove every other none essential bolt from your drivetrain and body, if subarus have them take off your map sensor and put a variable resitor in the circuit. oh yeah might as well cut off your gas tank while youre at it, but ifyou dont want to do that, just never drive with more than a gallon in the tank.

sooo.. thats what, at least 700 lbs lost and some parisitic loss reduced? :headbang: oh yeah not to mention it will be more peppy and there will be considerably less wear on tires brake clutch tranny engine etc...


That's way too timorous scrap487 ! Why did you stop halfway to the mark? Keep on cutting off parts until there's none left and buy a bicycle. What was your point?

#15 Tiny Clark

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Posted 10 January 2006 - 12:14 PM

Actually, you can do whatever you want, it's your car. Will you get better gas mileage? Coast it for a month, then leave it in gear and report back to us. I doubt either way will make much difference.

As far as any emergency situation out in the middle of bum$#%@, it's take less than half a sec to get it into gear, so don't worry about it.

#16 Mr Fishums

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Posted 10 January 2006 - 01:19 PM

What state is it illegal to coast in neutral in a passenger VEHICLE! please I am very interested to know this. Seeing as I work for a driving simulation company that focuses on teaching students to drive safely. I have never heard that this is illegal. ;)

I coast with my bug turned completely off, as it has no power steering/brakes :cool:

Fishums

#17 blitz

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Posted 10 January 2006 - 02:17 PM

it will actually cut fuel to alternating cylinders in order to increase fuel economy.

Keith, I'm pretty sure it cuts fuel completely off when coasting down (engine braking) off-throttle.

I'm not sure exacly what RPM the fuel turns back on at ...seems to be around 1200 RPM.

#18 Mr Fishums

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Posted 11 January 2006 - 10:21 PM

There are a few engines that do cut feul to certain cyclendars under different loads

http://ohe.cat.com/c...42&languageId=7

Yeah it's a big boy, prolly weighs as much as my hatch lol

I beleive there is a northstar V-8 that depending on what you are doing it runs on 4, 6, 8, I read something about it once. Though I have to get some sleep maybe tomorrow I will try and find a link.

Peace, Fishums

#19 mikie

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Posted 11 January 2006 - 10:40 PM

Fuel injected cars only inject as required, if the throttle is closed and it has a TPS switch, which is most since 1984, it will not inject fuel until the idle falls to the preset level. Anytime you are slowing down in gear you use no fuel, and putting the clutch in will require fuel to keep the engine running. And the least efficent revrange of an engine is idle. This does apparently save a noticable amount of fuel.
You can test this, open the bonnet/hood and rev a multipoint injected engine while listening. You should be able to hear the ticking of the injectors speed up, and then stop completely when you close the throttle and the revs drop back to idle again.

#20 TheSubaruJunkie

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Posted 11 January 2006 - 10:41 PM

When I took my drivers license test, growing up in Alaska, I would have passed with no marks except for I coasted to a stop at a light. I was told by my instructor that I should have downshifted from 3rd to 2nd, that coasting to a stop in 1st was okay but its illegal to remove the car from gear and coast.

So Alaska is one state, and im sure there are plenty of others. I doubt you'll get a ticket for coasting, but if you loose control of your vehicle on a downhill slope, and veer off the freeway and cause an accident... im sure you'll be cited for coasting :)

I wont try to explain why its safer to remain in gear. Anybody who has any bit of common sence should be able to understand why.

-Brian

#21 Ranger83

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Posted 12 January 2006 - 05:02 AM

/// What is the best method to coasting without wearing your clutch unnecessarily?? With gas prices the way they are anything to save a little is a help and with all the hills in my area coating is a great way to conserve some gas.

Urban Coyote

Leave it in gear and apply a little gas. Unless you're coasting down a huge hill to a stop, you're not saving anything.

I'm sure you don't believe that statement (see Click & Clack about "Things your father told you...")
So, borrow an 05 or 06 Subaru that has the instantaneous mpg reading, and see for yourself.

#22 Ranger83

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Posted 12 January 2006 - 05:04 AM

What state is it illegal to coast in neutral in a passenger VEHICLE! please I am very interested to know this. Seeing as I work for a driving simulation company that focuses on teaching students to drive safely. I have never heard that this is illegal. ;)

I coast with my bug turned completely off, as it has no power steering/brakes :cool:

Fishums


What company is that?

#23 Mr Fishums

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Posted 12 January 2006 - 08:47 AM

Doron Precision

http://www.doronprecision.com/

#24 Polaridoo

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Posted 12 January 2006 - 03:13 PM

Are you sure the injectors totally cut off all fuel to the cylinders when coasting down a hill in gear?? I could see them reducing the fuel (perhaps even adjust the timing too), but not cutting it all off.


Not that I want to risk it with my car and my life, but while coasting in gear, if you turned the engine off (one click back of the key) that would shut the spark off. If there was no extra engine braking felt after that, then I guess there is no fuel in the cylinder and thus no injector spraying.

(of coures this would only apply to a manual trans).


Now when I was back in high school ( a long time ago), I was coasting down a hill and turned the engine off while it was in gear. Since my truck had a carb (and other low tech features), I immediately felt the extra engine braking, but I also experienced the biggest back fire of my life when I flipped the key back on. All that fuel that was getting sucked into the motor and then the exhaust did not get a chance to burn until I hit the key!!! Wow! Of course it was a stupid thing to do, but that's what being young is all about.

#25 tunered

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Posted 12 January 2006 - 03:49 PM

i personally think this whole idea is a little silly,if cars or trucks were meant to coast totally free they would have designed a pressure relief valve of some kind on the trans to kick it out,and i cant even imangine somebody teaching to do this.




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