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Gear change/stopping question

4K views 45 replies 32 participants last post by  glb 
#1 ·
Please humor a relatively new sports car owner/driver. I have some driving (well, stopping) questions that I would appreciate anyone's input on.

When driving my Lotus in 4th gear, for example, and am approaching an upcoming stop light, I typically take my foot off of the gas and (with the car still in 4th) let the engine do most of the braking until I hit around 15 mph. Apart from extending the brake life, this also allows the engine to make that low growling noise as it winds down through the low rev range that always makes me grin.

When the car reaches about 15 mph, the growling stops and the car feels like it slips into "neutral" and essentially idles. I assume this is normal for the type of clutch and minimizes the "lurching effect" that I am used to with other manuals. I then normally push the gear shifter into neutral at that point, without depressing the clutch, and then bring the car to a final stop using the brakes.

My admittedly novice questions are: Is there anything wrong with this type of stopping? Should I not let the engine "slip" into what seems like neutral on its own? Is it better to use the clutch when putting it into neutral in the few seconds before final stop?

Any meaningful input would be appreciated.
 
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#2 ·
I typically shift into neutral as soon as I start slowing down, and brake the rest of the way.

Imaginie it like this: A clutch is $$ to replace, an engine is $$$$ to replace, and brake pads are $ to replace. Just my $.02...
 
#5 ·
A clutch is $$ to replace, an engine is $$$$ to replace, and brake pads are $ to replace. Just my $.02...
You must feel like your saving a lot of $$$ when your stopping in an Auto tranny car with just the brakes.... :thwack:
 
#3 ·
You may wish to avoid lugging the engine too.
 
#4 ·
You should always have positive control of your car.

You should downshift with a rev-match and you won't have lurching.

Downshifting from 4th to 3rd to 2nd will ensure you can accelerate out or manuver in case of an emergency.

Sounds to me you are just letting the car die and putting it into neutral.

There are many who will make the arguement that using the brakes is better than downshifting because it's cheaper to replace brakes than a tranny, but don't be fooled. Engine braking in combination with brakes is the proper way to drive a manual tranny.

It amazes me that anyone would drive a car such as an Elise/Exige and go neutral w/brakes.
 
#6 ·
Sounds to me you are just letting the car die and putting it into neutral.
Thanks for the response. The car doesn't actually die (i.e. I don't have to re-start it). It acts and sounds as though I have the clutch in. It happens (regardless of gear) right before I would normally start to feel lurching in other manual cars. Are these trannys specifically designed to relieve the strain on the engine at low revs so as to eliminate lurching?
 
#9 ·
No. There is no witchcraft going on in our transmissions. What you experience is probably just simply idling along at 15mph in fourth gear. As long as you're on level ground the car probably isn't going to lurch. If you start up any slight incline whatsoever it's going to lug down the engine below idle speed, unless of course you finally push the clutch pedal in, which you do.

Personally I've owned a large handfull of manual transmission cars, and when coasting down to idle speed in gear I've never had one "lurch." They just slowly and smoothly reach the idle rpm range and stop providing any engine braking at that point. Now they might lurch if you keep slowing the car and don't push in the clutch AFTER you've reached that point, but there is no reason they would lurch prior to that point.

And since you're not working the clutch any more than you would have with another method, your clutch wear is not accelerated.

So the only real (possibly) arguement against your method is extra engine wear. I don't believe this argument myself. Sure, over the lifetime of the car you'll have used a tiny percentage of extra revs, but they're at a pretty low loading condition anyway.

xtn
 
#12 ·
What you experience is probably just simply idling along at 15mph in fourth gear.
What you are saying makes sense. However, when the engine reaches that approx. 15 mph range, there is a definite sound as though something has disengaged (at least partially) the tranny. In other words, the growling does not simply get lower and lower until I finally depress the clutch. Instead the lugging noise reaches a low point and then makes a clear transition to an idle sound. Like you said, I assume that if I left it in gear until the car actually stopped, it would start to lurch and then die.
 
#18 ·
gears

Advanced driving taught here in the Uk, ( police/military) will always say this...... when you are down shifting, always match your gears and revs to the speed you are traveling i still, and always will double de-clutch in my lotus and in every other car, always be in the gear that will get you out of a problem.....no expert, just my £1 ($2) worth.
 
#23 ·
I personally do not use the clutch for my high to neutral shift before my lower gear selection. In every manual car Ive ever driven it seems to be a smooth harmless operation. Is there somewhere I can read anything that proves this puts wear on the syncros? because It doesnt make sense to me, but I wouldnt want to be damaging my trannys.
 
#29 ·
semi trucks have engines designed to vacuum break the vehicle, most cars dont. a friend of mine used to own a honda prelude that he would routinely downshift to slow the car down... he also routinely spun his lower end bearings... till he stopped doing it.

it may not be the "proper" way to do it but I am always in neutral if I am slowing down... and I usually try to anticipate when I need to slow down so I can throw it in neutral and minimize the amount of gas I waste along with wear and tear.

it was already said brake pads are cheap :p
 
#31 ·
semi trucks have engines designed to vacuum break the vehicle, most cars dont.
I undertand the point you are making, but they're exhaust brakes, not vacuum brakes.
 
#30 ·
My opinion is that you should never be rolling along in neutral. To my mind, that's coasting and not driving. Some of this is crossover paranoia from my motorcycling, but I always want to be in the proper gear to GTFO if need be. It's interesting that the UK driving exam seems to agree. In 23 years on driving (manuals only) I've never had premature clutch wear problems nor have I ever had a car I owned long enough fail to make it well over 100k miles.

I'm supremely confident that I put a hell of a lot more wear on the car a few days a year at the track than I do downshifting as I slow on the streets.
 
#38 ·
I never coast...ever for the exact same reason. Just as the brake can be a tool to save yourself, so can the gas. Last thing I want to do is be in a situation where I'm not able to get the car to go where I want to quickly.

Sometimes I heel and toe down to stop lights, but for the most part I just heel and toe for the situations where I'll need a lower gear to exit the corner. With the Elise I'll do it for fun, but I don't in my BMW. While any movement of anything mechanical will cause wear, I don't tend to dwell on it too much. As long as you aren't being overly abusive to your car, you'll get the life out of it that you want.
 
#32 ·
well, i rev match and brake at all lights in both my cars and both my drive trains are perfectly fine. In fact, my Audi clutch feels the same as almost new with about 100,000 miles of "hard driving on it". Can't say much for the Elise b/c I don't have that many miles. But how many here with high millage have had drive train issues? Any?
 
#33 ·
Shifting with out a clutch, if you don’t hear or feel a grind you probably did it right. If it seems to float easily out of gear while costing along I’m vary sure you are doing it right with no damage. I’ve been avoiding using a clutch since I started driving. In this car its not a fast way to up shift, takes to long for the rpm’s to drop so as to get the next gear, But when driving around relaxed no problem if you know how. I’ve taken many a car and truck past 100,000 miles on the stock clutch and had no trany problems. Last manual truck I had a mechanic friend checked the clutch for me because he was sure I was going to need one soon. He was quite surprised to find about 1/3 left, this was at around 110,000 miles if I remember right.
However if you do this wrong you can cause quite a bit of damage in the gearbox.

When sitting at a red light, DO NOT keep the car in gear with the clutch pedal in, not good for the throughout baring or any thing else. A good way to need early repairs.

For trucks (diesel) there’s a valve or a waste gate type set up to help slow them down. Sort of plugs the exhaust. I don’t know if there’s such a thing used on gas trucks.

Kevin
 
#36 ·
Shifting with out a clutch, if you don’t hear or feel a grind you probably did it right. <...>
I’'ve taken many a car and truck past 100,000 miles on the stock clutch and had no trany problems.
I've taken many cars much farther than 100,000 miles while using the clutch every time (and downshifting as I slow down). Our current Honda Accord has 220,000 miles on it's original clutch (although it's starting to need a new one).

When sitting at a red light, DO NOT keep the car in gear with the clutch pedal in, not good for the throughout baring or any thing else. A good way to need early repairs.
Premature wear of the throwout bearing isn't really a problem any more. If you want to worry about something, be concerned that when pushing in the clutch, the force exerted on the clutch mechanism is being resisted by the thrust bearing on the crank. You are more likely to experience premature wear of thrust bearings compared to throwout bearings (especially since most engines are designed nowadays to work with automatics which don't have the problem).

Now, that being said, neither is really a significant problem. A better reason for slipping it in neutral and letting out the clutch is that you can't accidentally slip your foot on the clutch and cause the car to lurch forward unexpectedly. The extra moment it takes to put the car in gear when the light changes has saved my butt a couple of times when some idiot has blown through the red light.

For trucks (diesel) there’s a valve or a waste gate type set up to help slow them down. Sort of plugs the exhaust. I don’t know if there’s such a thing used on gas trucks.
What you are referencing is called and "Exhaust Brake". They don't work as well as an "Engine Brake" (commonly called a Jake Brake after the company that invented/perfected it). A Jake Brake works by opening the exhaust valve at the top of the compression stroke, causing the engine to do more work pumping air in and out of the engine, which acts as a brake.

Here's a couple of links:

http://en.wikipedia.org/wiki/Jake_brake

http://www.jakebrake.com/products/md-engine.php

There also exhaust brakes and bleeder brakes:

http://www.jakebrake.com/products/md-exhaust.php

http://www.jakebrake.com/products/hd-bleeder.php
 
#35 ·
I always downshift, very new to stick shift. Used to just shift to neutral and then engage gear, but downshifting and matching gear is definitely the way to go for me.
 
#39 ·
If I'm going from a highway level of speed, exiting, and approaching a stop light, I will usually let the engine slow down the car (along with appropriate braking) until it hits about 2K rpm), at that point I'll switch gears to a lower one (2nd or 3rd if I'm still rolling, or clutch in to to stop).

I will use normal down shifting if I have to drop speed but not stop.
 
#40 ·
15mph in 4th gear with no throttle input sounds about right... this is called fuel injection. It's what enables you to creep along in slow traffic with no throttle at all.

Not particularly a good idea to do it in 4th gear though as that will be stressing the engine somewhat. 1st gear is fine, and sometimes even 2nd.
 
#41 ·
+ 1 on "X" speed in 4th similar to idle, feels like car is just coasting.

usually down shift match revs to an rpm where the engine is acting as a braking function, down to third if I'm driving like a normal person A to B.

when spirited, down to 2nd

on uneccesarry wear and tear, unless the ecu is programmed to compensate fuel when TP is closed, engine is @ high rpm and low AF ratios (lean) versus at high rpm and high AF, full open TP.
However, engine braking technique is essential to braking (duh) and to balancing dynamics of a car into corners. Can go as far as half clutching (dunno official term) in advanced engine braking...

I think driving is a highly subjective experience, just do what you get kicks out of, that don't brake your wallet, and within safe limits.
 
#42 ·
I'm going to chime in on the having your car engaged IN GEAR at all times whilst it is in motion school of thought. Accelerating and Decelerating. I've driven several cars over my years well over 100k miles without excessive wear or problems of any sort due to this, as in my mind anyway, clearly THIS IS HOW IT SHOULD BE. Concerns over wearing your car (tranny or clutch) over this IMHO are way overblown, and not worthy of the equally (again in just MHO) excessive concern.

My opinion is that you are not fully and PROPERLY in full control of your car as you should be AT ALL TIMES, if you are "coasting" in Nuetral.

But maybe I'm all wet in that thinking? :shrug:
Wouldn't be the 1st time. ;)
 
#43 ·
I never use engine braking except for a specific purpose, inadequate brakes, dangerous grades, ice, etc.
I hope you are considering whether your car can compensate for engine braking with the front/rear brake balance in a panic stop.
If not, you are screwing up the carefully tuned balance of the car.

Some of the fwd automatic gm cars are notorious for heavy engine braking which suddenly cuts loose at a certain point.
This caused a crash for me in slippery conditions.
Unsettling, at best.

I don't worry about keeping the car in gear when I don't need to either.
The shifter is always right there when needed.
I might worry about this in hard driving.
 
#45 ·
Engine braking?
rotfl

8.8:1 and 21 lb.s from the factory - slam the throttle plate closed and the car just keeps going.
:shift:
 
#46 ·
To those who said that the car should always be in a gear (safety, control issues, apparently):

Not buying it.

I can stay in 6th gear to about 1-1-/4 car length in back of stopped car in front of me. (True of both my cars...)

I don't think I'll worry about that last car length.
 
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