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Old 11-07-2016, 10:55 PM
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Slowing Down -- neutral or not w/ manual transmission

Interesting discussion between my son and I: when I see a red light ahead and need to slow down, I take my foot off the accelerator, leave the vehicle in gear, let the tranny friction and wind on the windshield slow it down, and then push in on the clutch once it has slowed and just before it might chatter. My son on the other hand, just shifts into neutral and uses his brakes as needed (and the wind on the windshield of course) to slow down as needed.

I am not sure which is the best general technique, ignoring of course any concerns about gas mileage, etc. I am not a big fan of propeller shafts spinning rapidly while the tranny is in neutral. I would rather see the system spin down as a whole before disengaging the clutch and going into neutral. He is not a big fan of trading potential clutch wear vs disk brake pads and sees no harm in going right away into neutral.

Other than preference, is there a good reason to for one technique over the other?

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Old 11-08-2016, 05:38 AM   #2
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I have always down shifted and let the motor slow the jeep down then shift into first at a complete stop, never have had any clutch issues doing it this way, dunno if their are any differences other then brake pads like you said.

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Old 11-08-2016, 07:11 AM   #3
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It depends. If coming to a complete stop, I usually coast. (motor idling = saving gas?)
If the light will probably turn green, downshift.
Off road, always in gear.
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Old 11-08-2016, 08:04 AM   #4
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I leave it in whatever gear I'm in, use engine braking and the brakes together, then cluch in / neutral just as the RPM drop below engine idle. I'll downshift in bad weather (snow) and only use the brakes under 20 mph or so. As I come to a stop I can actually hear/feel the drivetrain kind of clunk over as it unloads near idle rpm, my signal to cluch in. Actually, maybe I should look into where that slop is coming from...
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Old 11-08-2016, 08:47 AM   #5
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I'm a down shifter by nature, but after rebuilding too many Ax15's because of worn out synchros, I quit down shifting in my jeeps. My reason is I would rather replace brakes than rebuild a trans, down shifting add a little more wear n tear.
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Old 11-08-2016, 09:25 AM   #6
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Originally Posted by Dr Obbins View Post
It depends. If coming to a complete stop, I usually coast. (motor idling = saving gas?)
If the light will probably turn green, downshift.
Off road, always in gear.
You actually use more gas in neutral. When the wheels are spinning and your clutch is engaged, the engine keeps running from the force transferred from the wheels all the way to your engine (that is part of the reason why you can jump start a manual by getting it rolling and dropping the clutch). But, when you disengage the clutch and the engine has to run on its own, it then has to use gas to keep running.

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Originally Posted by donjpearson View Post
Interesting discussion between my son and I: when I see a red light ahead and need to slow down, I take my foot off the accelerator, leave the vehicle in gear, let the tranny friction and wind on the windshield slow it down, and then push in on the clutch once it has slowed and just before it might chatter. My son on the other hand, just shifts into neutral and uses his brakes as needed (and the wind on the windshield of course) to slow down as needed.

I am not sure which is the best general technique, ignoring of course any concerns about gas mileage, etc. I am not a big fan of propeller shafts spinning rapidly while the tranny is in neutral. I would rather see the system spin down as a whole before disengaging the clutch and going into neutral. He is not a big fan of trading potential clutch wear vs disk brake pads and sees no harm in going right away into neutral.

Other than preference, is there a good reason to for one technique over the other?
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I'm a down shifter by nature, but after rebuilding too many Ax15's because of worn out synchros, I quit down shifting in my jeeps. My reason is I would rather replace brakes than rebuild a trans, down shifting add a little more wear n tear.
I've always been a downshifter as well, but you bring up a good point. Do you think downshifting adds enough wear n tear to worry about?
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Old 11-08-2016, 12:00 PM   #7
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He is not a big fan of trading potential clutch wear vs disk brake pads and sees no harm in going right away into neutral.
I honestly think that clutch wear from engine braking is minimal. The majority of clutch wear comes when the clutch is not fully engaged, i.e., when your flywheel and your clutch plate are moving at different speeds.

Now, if I'm exiting a freeway, I'll stay in 6th gear until the RPMs are down to around idle, then shift to neutral. I rarely downshift through the gears, unless, as others have mentioned, I'm trying to time a stop light.
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Old 11-08-2016, 06:38 PM   #8
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You actually use more gas in neutral. When the wheels are spinning and your clutch is engaged, the engine keeps running from the force transferred from the wheels all the way to your engine (that is part of the reason why you can jump start a manual by getting it rolling and dropping the clutch). But, when you disengage the clutch and the engine has to run on its own, it then has to use gas to keep running.

I've always been a downshifter as well, but you bring up a good point. Do you think downshifting adds enough wear n tear to worry about?
Not alot of wear, but my yj's n tj's are getting up there in age, and I had to re-do my yj's ax15 last fall due to wear and shot syncros.
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Old 11-08-2016, 07:12 PM   #9
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Personally, I use a variety of techniques. Disclaimer: on the trail or off road, I always stay in gear. On the road:

Braking on a down hill run, I leave it in gear until I'm near a stop or it starts lugging. On a STEEP down hill, I'll sift down thru the gears, down shifting, to best use compression to assist the brakes. (As an aside, I'm a big fan of Georgia Overdrive: roll down hill in neutral, and tap the brakes if needed. This may not be legal in some locales).

Flat/level or up hill, I'll fall into neutral (Georgia overdrive? ) and coast. If there is little or no traffic, I'll coast a long way.

YMMV, and invariably will...
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Old 11-08-2016, 07:21 PM   #10
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Great topic! My husband downshifts and I throw her in neutral. It drives him nuts. Off-road of course she's always in gear but on the road I coast. I know in some states the law is a vehicle must always remain in gear and "coasting" is illegal. I know Oregon had that law when I was stationed there. I guess I was breaking the law but old habits die hard!


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Old 11-10-2016, 07:50 PM   #11
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learned to drive on a stick many years ago(well over 30) and was taught to downshift when coming to a stop. Was also told that coasting in neutral was more dangerous as it was easier to lose control of car especially on hills. On my road test to come to smooth stops I used the push clutch in and brake to a stop and had 5 points deducted for it. he also told my mother that he could have failed me for it if he wanted to as that was dangerous. Not sure if what he said was true but I have always downshifted since then..



Just did a quick google to see if what i was told many years ago was true and found this ...........http://www.studydriving.com/safety-o...asting-is-bad/
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Old 11-14-2016, 03:01 PM   #12
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I Always downshift.
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Old 11-16-2016, 07:22 AM   #13
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Modern fuel injected engines (my 01 TJ included.) when you take your foot off of the gas (in gear) if there is enough speed to keep the revs up, the ECM computer will shut off the fuel flow and you can actually get infinite mpg! ( x miles / 0 gal.)
I have a scangauge that shows instantaneous mpg and when I do it, it shows 9999 mpg.
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Old 11-20-2016, 11:20 AM
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All good inputs. Personally, I was thinking of city/highway driving when I originated the note. I think we all agree that offroad, you pretty much always want to be in gear in some manner.
Regarding DrThos input above, that is particularly interesting input. I wonder why the ECM would not also shut off fuel as long as the speed were up, even if the tach were showing 500-800 rpm idle while out of gear? Then again, I admit not knowing the details to the ECM logic.
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Old 11-20-2016, 03:59 PM   #15
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Regarding DrThos input above, that is particularly interesting input. I wonder why the ECM would not also shut off fuel as long as the speed were up, even if the tach were showing 500-800 rpm idle while out of gear? Then again, I admit not knowing the details to the ECM logic.[/QUOTE]

Well, if the ECM were to shut off the fuel while you were out of gear and just coasting, the motor would quit!
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Old 11-20-2016, 10:08 PM   #16
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And if your coasting to the light or the stop sign and all of a sudden you need to take evasive action that extra second and a half to get back in gear may make a huge difference.... way to many stupid people out there
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Old 11-20-2016, 11:39 PM   #17
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If your worried about saving brake pads, then you need to hit the brakes as hard as you can in the shortest amount of time to get max pad life. the longer the braking distance/longer pushing the brake pedal the greater the wear.

Downshifting doesn't do much of anything to save the pads, proper heel/toe should be done to save syncros.

It's really just personal preference on downshifting or not.
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Old 11-23-2016, 10:11 AM   #18
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Originally Posted by DrThos View Post
Modern fuel injected engines (my 01 TJ included.) when you take your foot off of the gas (in gear) if there is enough speed to keep the revs up, the ECM computer will shut off the fuel flow and you can actually get infinite mpg! ( x miles / 0 gal.)
I have a scangauge that shows instantaneous mpg and when I do it, it shows 9999 mpg.
x2. I often coast and try to time my approach so that the light turns green again. And I like to make use of going downhill. All of this is dependent on the surrounding traffic or lack thereof.


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Regarding DrThos input above, that is particularly interesting input. I wonder why the ECM would not also shut off fuel as long as the speed were up, even if the tach were showing 500-800 rpm idle while out of gear? Then again, I admit not knowing the details to the ECM logic.

The engine just idles as if you were parked. It doesn't care how fast the rest of the Jeep is traveling.
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Old 11-24-2016, 05:34 AM   #19
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Remain in gear and/or down shift.

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