Auto Transmission Question
Discussion
Hi, recently read a ROSPA article suggesting that it's better for the transmission on an auto to hold in D whilst at red light(etc) using hand brake. In the past I have moved selector to N before applying the h/b but the article suggested that moving the selector from D to P induces unneccesary wear....
Opinions?
Opinions?
V8 Disco said:
Hi, recently read a ROSPA article suggesting that it's better for the transmission on an auto to hold in D whilst at red light(etc) using hand brake. In the past I have moved selector to N before applying the h/b but the article suggested that moving the selector from D to P induces unneccesary wear....
Opinions?
link?Opinions?
If the parking brake isn't applied correctly (surprisingly common), then the car is capable of moving under it's own steam (especially if give assistance by another vehicle), which seems to be a potential risk and would likely contrary to normal ROSPA. I would be surprised if the extra wear doing it on a modern automatic was significant over its life.
Yer 'tis:
http://www.rospa.com/roadsafety/adviceandinformati...
Quote from..
When stationary in traffic, even for many minutes, it is not necessary to move the gear lever into neutral because the torque converter absorbs the engine’s propulsion force but does not transmit it all to the gearbox. No wear is taking place. In fact, more wear will take place if you engage neutral then engage a drive gear when it is possible to move off. Most gearboxes will automatically select first gear when the vehicle becomes stationary.
While guidance may be given regarding the correct actions in certain circumstances, not all eventualities can be covered. The following is intended as general guidance in some common sets of circumstances.
You should cover the footbrake when moving the gear lever when the vehicle is stationary. You may wish to set the parking brake as many vehicles will ‘creep’ and some vehicles may have a tendency to lurch, particularly if fitted with an automatic choke. Stops in traffic, at junctions and at traffic lights leave the selector in D. There is no need to move into neutral, as no damage will result. You may wish to set the parking brake if the pause becomes a wait but your decision will depend on the circumstances
http://www.rospa.com/roadsafety/adviceandinformati...
Quote from..
When stationary in traffic, even for many minutes, it is not necessary to move the gear lever into neutral because the torque converter absorbs the engine’s propulsion force but does not transmit it all to the gearbox. No wear is taking place. In fact, more wear will take place if you engage neutral then engage a drive gear when it is possible to move off. Most gearboxes will automatically select first gear when the vehicle becomes stationary.
While guidance may be given regarding the correct actions in certain circumstances, not all eventualities can be covered. The following is intended as general guidance in some common sets of circumstances.
You should cover the footbrake when moving the gear lever when the vehicle is stationary. You may wish to set the parking brake as many vehicles will ‘creep’ and some vehicles may have a tendency to lurch, particularly if fitted with an automatic choke. Stops in traffic, at junctions and at traffic lights leave the selector in D. There is no need to move into neutral, as no damage will result. You may wish to set the parking brake if the pause becomes a wait but your decision will depend on the circumstances
Edited by V8 Disco on Monday 31st December 21:03
V8 Disco said:
particularly if fitted with an automatic choke.
Definitely up to date then. 
AIUI the only reason neutral is there is to stop drivers going straight from D to R, and for towing. The reasons for putting a manual gearbox into neutral at traffic lights are mainly to avoid release bearing wear, obviously there's no problem with that on an auto, and for safety, which is why we're supposed to apply the handbrake.
I am sure previous handbooks have suggested you should put it in neutral at traffic lights etc., but the PDF of latest one doesn't make any comment - only use neutral in car washes etc.
From my experience in previous autos - the engine sounds more laboured when in drive and stationary than neutral (not sure true with this one), so I assume I'll use as much extra fuel as I would do wear (i.e. not enough to worry about). My latest car has stop-start so often it will kill engine at which point I put on parking brake and wait if expecting a few mins of wait - or if it doesn't stop I put it in neutral and parking brake and wait.
From my experience in previous autos - the engine sounds more laboured when in drive and stationary than neutral (not sure true with this one), so I assume I'll use as much extra fuel as I would do wear (i.e. not enough to worry about). My latest car has stop-start so often it will kill engine at which point I put on parking brake and wait if expecting a few mins of wait - or if it doesn't stop I put it in neutral and parking brake and wait.
It all depends on what the handbook says to be honest.
The Jeep handbook actually said to move the selector to N or P in those circumstances, on the model one of my associates had.
The BMW handbook says the opposite (ZF gearbox), as your gearbox will have no cooling when in N or P, something I've checked with ZF of Nottingham where I do some work.
So, like the handbrake, all down to the manual, regardless of what Rospa or the IAM say.
The Jeep handbook actually said to move the selector to N or P in those circumstances, on the model one of my associates had.
The BMW handbook says the opposite (ZF gearbox), as your gearbox will have no cooling when in N or P, something I've checked with ZF of Nottingham where I do some work.
So, like the handbrake, all down to the manual, regardless of what Rospa or the IAM say.
ks. More AD how many angels dancing on the head of a pin.waremark said:
I don't believe that either approach will cause significant wear, and what works best is totally vehicle dependent - with the introduction of stop/start systems creating a whole new set of issues.
ZF dissagree with you, and as they make mine, they may have a point.They specifically tell you not to leave it in P or N, with the engine running, and at the factory the reason given to me was, "it'll overheat as it has no cooling when used like that", they actually tell you to leave it in D (or R, but I can't see why you'd chose to do that), and use the brakes to stop it moving, the IAM prefer handbrake ..... I prefer footbrake.
The actual mechanical reasons I can't give you, because despite doing quite a lot of work there, having been on several tours etc ...... I still can't understand how they work ...... I just repair some of their test rigs (electrical/electronic control stuff).
davethebunny said:
my stop start auto will cutout when you stop and if you put it into n and take your foot off the brake it'll restart. So i just sit there with my foot on the brake.
My wifes stop start smart car, restarts when you release the footbrake, but obviously has some control over the brakes, as the car has some kind of centrifugal clutch,rather than a torque converter but it won't roll for a couple of seconds (like most modern electronic handbrakes if you drive against it, it releases, but you haven't engaged the handbrake, if that makes sense, it does the same thing when you select reverse).What is funny about the smart stop start system is, if you stop at some traffic lights for example, the engine cuts out as you'd expect, but if you apply the handbrake and release the footbrake (as pendants want you to , as they find 21 watt brake lights damage their eyes), it restarts and just sits then on tickover, like non stop start cars !
davethebunny said:
my stop start auto will cutout when you stop and if you put it into n and take your foot off the brake it'll restart. So i just sit there with my foot on the brake.
Mine leaves it off if I put parking brake (one of these new fangled electronic ones) on and then take foot off brake - moving level to anything other than drive will restart itWhen I drove an Auris Hybrid Synergy drive (CVT) recently, whilst stationary with the (mechanical not electric) hand brake engaged, if I left it in 'D' I thought I could feel it straining slightly to move forward, so I put it in 'N' as there was no torque converter to absorb the mechanical energy.
I'm assuming its a 'dumb' control system on the Auris, in that it wanted to move forward on the electric motor with the foot-brake disengaged whilst in 'D'
I'm assuming its a 'dumb' control system on the Auris, in that it wanted to move forward on the electric motor with the foot-brake disengaged whilst in 'D'
Edited by real4star on Wednesday 2nd January 01:39
creampuff said:
Are there actually people out there who put an automatic into neutral and apply the handbrake when they stop? Do some people actually do this?!?
Not me. I just enable the 'Hold' function before i set off in the morning. When I come to a complete stop the car holds the brakes on for me and disengages them when I touch the throttle.Yes it probably upsets the "brake lights...arrrgh i'm blind" gang, but my car has the feature so I'm gonna use it
jmorgan said:
I just use the hand brake (mine works) and leave it in D, I understand that the auto box takes care of its self in this respect.
Only times I have selected N are traffic jams when there is no movement for a while but tend to turn off more than select N.
I often wonder what uses more fuel: Car in D with brakes applied = lower revs but more load on engine, or, Car in N = higher revs, but lower engine load.Only times I have selected N are traffic jams when there is no movement for a while but tend to turn off more than select N.
Probaly negligable...but I do still wonder....
jimxms said:
jmorgan said:
I just use the hand brake (mine works) and leave it in D, I understand that the auto box takes care of its self in this respect.
Only times I have selected N are traffic jams when there is no movement for a while but tend to turn off more than select N.
I often wonder what uses more fuel: Car in D with brakes applied = lower revs but more load on engine, or, Car in N = higher revs, but lower engine load.Only times I have selected N are traffic jams when there is no movement for a while but tend to turn off more than select N.
Probaly negligable...but I do still wonder....
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