Possibly doing damage to engine/transmission
02-12-2010, 11:13 AM
#11
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
OP - It might be worth checking your state motor vehicle code - coasting in neutral may be specifically prohibited.
In any of the newer electronically-controlled AT's, I'd have some concern that the PCM might try to learn something it shouldn't, and perhaps end up shifting harshly when it should be shifting gently.
In a car with a MT, particularly if the clutch action is relatively heavy, the throwout bearing won't put up with frequently having to hold the clutch disengaged for long periods of time. That cheap little part involves several hundred $ to replace if you can't do the job yourself (or several hours time if you can). Wisdom here is knowing when you need to hold the clutch disengaged vs when you don't.
Norm
In any of the newer electronically-controlled AT's, I'd have some concern that the PCM might try to learn something it shouldn't, and perhaps end up shifting harshly when it should be shifting gently.
In a car with a MT, particularly if the clutch action is relatively heavy, the throwout bearing won't put up with frequently having to hold the clutch disengaged for long periods of time. That cheap little part involves several hundred $ to replace if you can't do the job yourself (or several hours time if you can). Wisdom here is knowing when you need to hold the clutch disengaged vs when you don't.
Norm
Last edited by Norm Peterson; 02-12-2010 at 11:23 AM.
02-12-2010, 01:44 PM
#12
3rd Gear Member
Thread Starter
Join Date: Aug 2009
Location: Jasper, IN
Posts: 772
I can see the point of quicker slowing when engine breaking. However, when you downshift if throws the car into a lower gear, while traveling at a fast speed and so the engine revs up. I know it is not a lot, but I can't see how that is "good" or "better" for the car than just pushing the clutch in ( or putting the auto into nuetral) and letting it coast and slow via the breaks. True, you may wear your breaks faster, but breaks are must cheaper to replace over time than a transmission is even once. That was why I was concerned, but my car is not a manual. So I didn't know if dropping into N while driving for coasting and dropping into D without stopping first would do transmission damage over time.
Also, whats the difference from holding in the clutch or putting the gears in neutral? Either way the car's gears are not engaged. It seems that it also give less resistance when going down a hill or coasting on a flat road. Why is it so important to give the car gas, auto or manual, right up to the point when you are going to stop. If your car will coast for about 2 to 3 miles and loose little speed, save the extra gas and wear on your car and let the tires free spin.
Also, whats the difference from holding in the clutch or putting the gears in neutral? Either way the car's gears are not engaged. It seems that it also give less resistance when going down a hill or coasting on a flat road. Why is it so important to give the car gas, auto or manual, right up to the point when you are going to stop. If your car will coast for about 2 to 3 miles and loose little speed, save the extra gas and wear on your car and let the tires free spin.
02-12-2010, 01:56 PM
#13
4th Gear Member
Join Date: Nov 2008
Location: California
Posts: 1,495
I agree with those who say it is generally safer to keep an automatic transmission in D rather than N when braking.
Once I was coming to a stop, and heard screeching tires behind me. I looked in the mirror and there was a truck that was probably not going to stop without hitting me if I stopped behind the limit line. My car was in D, so I gave it some gas to get out of the way.
Once I was coming to a stop, and heard screeching tires behind me. I looked in the mirror and there was a truck that was probably not going to stop without hitting me if I stopped behind the limit line. My car was in D, so I gave it some gas to get out of the way.
02-12-2010, 02:11 PM
#14
Gentleman's Relish
Join Date: Feb 2005
Location: AZ
Posts: 13,090
There is absolutely no point in this. For one it's going to just cause faster wear on the brakes by not using engine braking. Also you're not going to cause damage/wear to the trans due to the slippage of the torque converter. It's made to do this.
The same thing applies to people who have a manual and put it in neutral when coming to a stop. Makes no sense at all and is actually dangerous to do that.
Shifting behaviors some people come up with is really strange.
For an auto, really the only time neutral should be used is if you need to push the car. But it's never a good or smart idea to put it in neutral while you're driving. For a manual, the only times it makes sense to go in neutral is when starting (safety) and if you need to jump start it. Any other time, stay the fak out of N!
The same thing applies to people who have a manual and put it in neutral when coming to a stop. Makes no sense at all and is actually dangerous to do that.
Shifting behaviors some people come up with is really strange.
For an auto, really the only time neutral should be used is if you need to push the car. But it's never a good or smart idea to put it in neutral while you're driving. For a manual, the only times it makes sense to go in neutral is when starting (safety) and if you need to jump start it. Any other time, stay the fak out of N!
They down shift yes, but that's only to drop into the next logical gear given the speed and RPM. the only time it will engine brake is if you're coming off the freeway and drop it out of O/D then, it will be forced to downshift into 4th. Autos by design will pick the tallest gear (not shortest gear) at any given speed.It will not hurt the tranny if he puts in 'N' while stopped (no different than a manual tranny). What will hurt it is a 'Nuetral Drop' that's when the car is in Nuetral, you rev up, and you drop it into drive.
Would i recommend putting into N as you drive? No, that could damage it if you decide you need to drop it back into gear while still moving (similar to a Nuetral drop).
02-12-2010, 02:31 PM
#15
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
True, you may wear your breaks faster, but breaks are must cheaper to replace over time than a transmission is even once. That was why I was concerned, but my car is not a manual. So I didn't know if dropping into N while driving for coasting and dropping into D without stopping first would do transmission damage over time.
Also, whats the difference from holding in the clutch or putting the gears in neutral?
Either way the car's gears are not engaged. It seems that it also give less resistance when going down a hill or coasting on a flat road.
Why is it so important to give the car gas, auto or manual, right up to the point when you are going to stop. If your car will coast for about 2 to 3 miles and loose little speed, save the extra gas and wear on your car and let the tires free spin.
Under some circumstances accelerating/coasting can be a hypermiling trick that (sort of) works, at least under some circumstances. Then again, there are lots of things those guys do in the search of another fractional mpg improvement that at best can't be recommended and at worst are either illegal already or should be.
Norm
02-12-2010, 03:40 PM
#18
6th Gear Member
Join Date: Jan 2007
Location: Southeast Virginia
Posts: 6,409
If something suddenly happens in front of you and you need to be under power to avoid the obstacle you are going to waste precious time putting it in gear and most likely in that situation it will not go in the appropriate gear due to panic. Plus there's the issue of not using engine braking relying completely on the brakes to stop. Using both will allow you to stop quicker.
There's no reason at all to coast in N. It does not save anything and keeping it in gear engine braking or just holding the clutch in while slowing is not hurting anything either.
There's no reason at all to coast in N. It does not save anything and keeping it in gear engine braking or just holding the clutch in while slowing is not hurting anything either.
I've always put it in Neutral when I have to slow down or come to a stop. I find it's less wear and tear on the engine and tranny when you don't have to down shift. Again, I've been driving manual for 30+ years.
02-12-2010, 03:56 PM
#19
If you downshift properly in a manual (waiting until you slow to a proper speed appropriate to the gear you want to shift down into), your revs won't be so high. I always downshift and usually don't have to actually press my brakes until I'm probably less than two car lengths from the stopped vehicle in front of me. And in some instances when traffic is flowing well, I only have to press the brakes to stop me moving the last couple feet and to also flick on the brake lights for the vehicle behind me.
Generally, in the Mustang, when downshifting, I slow the car down to about 2k, then shift down, which puts me back to just under 3k, and repeat for each remaining gear. This way, I'm not at high revs and lower gears. Of course, some instances I have to brake harder or sooner than I can downshift, but then again, you can't always judge how everyone else is driving around you. I firmly believe in having the car in a gear appropriate to the speed I'm travelling to aid in defensive driving. It has helped a few times in the past.
But, to each his own. I know a friend of mine drives stick, and is always sticking it in neutral or mashing down the clutch when coming to a stop, even if we're still travelling at 50mph or something. Though, he does drive a base Honda Fit with a five speed...........................pointless.
Though I'm more accustomed to downshifting because I drive large Mack Trucks (Concrete Pumps to be exact) and it is critical to using downshifting and engine braking to slow those large suckers down. So I've just used that experience to regular vehicles.
Generally, in the Mustang, when downshifting, I slow the car down to about 2k, then shift down, which puts me back to just under 3k, and repeat for each remaining gear. This way, I'm not at high revs and lower gears. Of course, some instances I have to brake harder or sooner than I can downshift, but then again, you can't always judge how everyone else is driving around you. I firmly believe in having the car in a gear appropriate to the speed I'm travelling to aid in defensive driving. It has helped a few times in the past.
But, to each his own. I know a friend of mine drives stick, and is always sticking it in neutral or mashing down the clutch when coming to a stop, even if we're still travelling at 50mph or something. Though, he does drive a base Honda Fit with a five speed...........................pointless.
Though I'm more accustomed to downshifting because I drive large Mack Trucks (Concrete Pumps to be exact) and it is critical to using downshifting and engine braking to slow those large suckers down. So I've just used that experience to regular vehicles.
