Automatic Transmission

woody320 · 09-30-2015, 03:34 AM

This may be a silly question but...

Is the BMW 8AT Transmission designed to sit in Drive at all times?

Assuming you have DESELECTED the Auto Start Stop system, I never know if I should shift to N at the Traffic lights or not.

As the footbrake is released whilst in D you do feel a slight "bump" as the transmission feels as though the gear is selected.

I would be really keen to hear anyone's views.

jusdorange · 09-30-2015, 03:37 AM

Why would you switch to neutral ??

teaston · 09-30-2015, 03:38 AM

Yes that's how it's designed to work

creepy coupe · 09-30-2015, 03:43 AM

If I leave mine in D I don't feel any bumps,when taking off.

k44ENT · 09-30-2015, 04:43 AM

Leave mine in D with the handbrake on when waiting at traffic lights, junctions, roundabouts etc.. If I know I'm going to be stood for a long time I put it in P and apply the handbrake. Never use stop start, turning it off is part of my startup routine.

dopper99 · 09-30-2015, 07:19 AM

Quote:

Originally Posted by k44ENT

Never use stop start, turning it off is part of my startup routine.

+1

Yes also leave it in D all the time. Only time it comes out of D is for reversing - or when I park it on the drive.

Russbmw · 09-30-2015, 07:47 AM

Quote:

Originally Posted by k44ENT

Never use stop start, turning it off is part of my startup routine.

Same here, I find it dangerous to be honest. The car always seems to want to turn the engine off just as you're about to pull out at a roundabout or something. Complete PITA.

ep22jg · 09-30-2015, 08:09 AM

I just push the 'P' button to put it in Park when I stop. If I'm on the flat, that's it. If I'm on a slope, I'll also put the hand brake on.

Are you saying that if you put the hand brake on while in 'D', it disengages the gearbox?

97suited · 09-30-2015, 10:09 AM

Quote:

Originally Posted by k44ENT

Never use stop start, turning it off is part of my startup routine.

Err, does that mean have to disable it on every startup? You can't just disable it once and have it stay like that?

Mrs97 is going to be a very unhappy bunny if that's the case.

k44ENT · 09-30-2015, 10:13 AM

Quote:

Originally Posted by 97suited

Err, does that mean have to disable it on every startup? You can't just disable it once and have it stay like that?

Mrs97 is going to be a very unhappy bunny if that's the case.

I think it can be coded to stay off all the time but from factory it's a turn it off every time situation i'm afraid.

HighlandPete · 09-30-2015, 10:17 AM

Quote:

Originally Posted by woody320

..As the footbrake is released whilst in D you do feel a slight "bump" as the transmission feels as though the gear is selected.

I would be really keen to hear anyone's views.

The slight bump may be Neutral Idle Control (NIC) deactivating as you release the footbrake.

Shouldn't really be any bump as such, as you are still in gear. What is happening, holding on the footbrake NIC engages, the Torque Converter is off loaded (almost like a neutral position). Drag is reduced to something like 10% of conventional TC drag. You could be feeling that transition.

The first generation of ZF 6HP gearboxes did suffer from a snatch, one reason was the NIC strategy, sorted with software. Not read of any issues with the ZF 8HP series boxes.

HighlandPete

woody320 · 09-30-2015, 11:22 AM

Highland Pete

Many thanks for this. That's the detail that I really wanted. Thanks again.

Russbmw · 09-30-2015, 01:40 PM

Quote:

Originally Posted by k44ENT

I think it can be coded to stay off all the time but from factory it's a turn it off every time situation i'm afraid.

Yeah, it can be coded to be off all the time.

97suited · 10-01-2015, 03:28 AM

OK, thanks for that. Looks like I better gen up on coding before it arrives.

dangerous_al · 10-01-2015, 03:34 AM

Quote:

Originally Posted by 97suited

OK, thanks for that. Looks like I better gen up on coding before it arrives.

There are two options available, either code it so it remembers last setting or code it so it is always off at startup. Very easy to do and works.

Beancounter_74 · 10-01-2015, 08:19 AM

Quote:

Originally Posted by 97suited

OK, thanks for that. Looks like I better gen up on coding before it arrives.

You can also knock the shift lever into sport, that disables the start/stop too.

I was going to code t out but don't find it too intrusive if I'm honest.

jusdorange · 10-01-2015, 08:26 AM

I personally leave it in sport so disables S/S

Unless I'm in a traffic stop/jam

Occean · 10-01-2015, 08:52 AM

Am I the only one who doesn't really experience any problems with stop/start? I cannot think of a good reason to turn it off.

jusdorange · 10-01-2015, 08:56 AM

Quote:

Originally Posted by Occean

Am I the only one who doesn't really experience any problems with stop/start? I cannot think of a good reason to turn it off.

At junctions and even roundabouts it can be anything from a mild annoyance to dangerous

Other than that , at lights I leave it on & place car in park

Occean · 10-01-2015, 08:57 AM

Quote:

Originally Posted by jusdorange

Quote:

Originally Posted by Occean

Am I the only one who doesn't really experience any problems with stop/start? I cannot think of a good reason to turn it off.

At junctions and even roundabouts it can be anything from a mild annoyance to dangerous

Other than that , at lights I leave it on & place car in park

I live in London, so it kicks in a lot and never experienced anything that could be considered dangerous. Tbh it works a treat.

dangerous_al · 10-01-2015, 09:00 AM

With a manual I would say it is no problem at all, put it in neutral and take foot off the clutch to use it, or leave it in gear with foot on the clutch if you don't want to use it so you can choose dependent on the situation. With an auto it is different and you don't have the choice. At traffic lights it is not an issue, stops at the lights and restarts as soon as you take your foot off the brake, the problem I found was at roundabouts and give way junctions. If you come to a complete stop the engine shuts off, which means if you want to pull out quickly there is a delay. Until I coded it off, I found myself creeping up to the junction trying to make sure I didn't come to a complete stop which wasn't always possible. Much easier with it turned off.

Trialskings · 10-01-2015, 10:25 AM

S/S is a real PITA when queuing on a hot day as it also affects the A/C.

Tend to switch it off then to stop HEAT RAGE creeping up on me!

09-30-2015, 03:34 AM	#1
woody320 Second Lieutenant 117 Rep 286 Posts Drives: G20 330e M Sport Join Date: Jun 2013 Location: UK iTrader: (0)	Automatic Transmission This may be a silly question but... Is the BMW 8AT Transmission designed to sit in Drive at all times? Assuming you have DESELECTED the Auto Start Stop system, I never know if I should shift to N at the Traffic lights or not. As the footbrake is released whilst in D you do feel a slight "bump" as the transmission feels as though the gear is selected. I would be really keen to hear anyone's views.
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09-30-2015, 03:37 AM	#2
jusdorange YOLO 440 Rep 2,854 Posts Drives: #mw Join Date: Dec 2013 Location: Monaco iTrader: (0)	Why would you switch to neutral ??
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09-30-2015, 03:38 AM	#3
teaston Banned 10995 Rep 32,881 Posts Drives: X3 M40d Join Date: May 2012 Location: The High Seas iTrader: (1)	Yes that's how it's designed to work
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09-30-2015, 03:43 AM	#4
creepy coupe Lieutenant General 1867 Rep 13,043 Posts Drives: BMW M340I G20 Join Date: Aug 2007 Location: UK iTrader: (2) Garage List 2015 BMW 435d [0.00] 2009 335i [0.00]	If I leave mine in D I don't feel any bumps,when taking off. __________________ -------------------------------------------------------------- Current car.M240i. Previous.MINI JCW. E92 325i. 435d M235i.M135i. 635d Coupe, E92 M3 manual, E92 M3 DCT Competition Pack. E92 335i, Porsche Cayman S Gen2, 135i Coupe. E92 320d, MK5 R32. MK5 Golf GTi,MK5 Golf GT-TDI,E46 318Ci.
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09-30-2015, 04:43 AM	#5
k44ENT Lieutenant Colonel 492 Rep 1,503 Posts Drives: M2 LCI DCT Join Date: Jun 2009 Location: UK iTrader: (2)	Leave mine in D with the handbrake on when waiting at traffic lights, junctions, roundabouts etc.. If I know I'm going to be stood for a long time I put it in P and apply the handbrake. Never use stop start, turning it off is part of my startup routine.
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09-30-2015, 08:09 AM	#8
ep22jg Captain 234 Rep 738 Posts Drives: G01 M40i Join Date: May 2015 Location: Hampshire iTrader: (0)	I just push the 'P' button to put it in Park when I stop. If I'm on the flat, that's it. If I'm on a slope, I'll also put the hand brake on. Are you saying that if you put the hand brake on while in 'D', it disengages the gearbox? __________________ X3 M40i Carbon Black
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09-30-2015, 11:22 AM	#12
woody320 Second Lieutenant 117 Rep 286 Posts Drives: G20 330e M Sport Join Date: Jun 2013 Location: UK iTrader: (0)	Highland Pete Many thanks for this. That's the detail that I really wanted. Thanks again.
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10-01-2015, 03:28 AM	#14
97suited Private 9 Rep 74 Posts Drives: 535d 118d 325i 320XD Join Date: Jul 2015 Location: UK iTrader: (0)	OK, thanks for that. Looks like I better gen up on coding before it arrives.
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10-01-2015, 08:26 AM	#17
jusdorange YOLO 440 Rep 2,854 Posts Drives: #mw Join Date: Dec 2013 Location: Monaco iTrader: (0)	I personally leave it in sport so disables S/S Unless I'm in a traffic stop/jam
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10-01-2015, 08:52 AM	#18
Occean Private First Class 24 Rep 199 Posts Drives: 1 series Join Date: Nov 2011 Location: London iTrader: (0)	Am I the only one who doesn't really experience any problems with stop/start? I cannot think of a good reason to turn it off.
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10-01-2015, 09:00 AM	#21
dangerous_al Major 405 Rep 1,034 Posts Drives: X3 M40i G01 2020 Join Date: Apr 2009 Location: Bristol England iTrader: (0)	With a manual I would say it is no problem at all, put it in neutral and take foot off the clutch to use it, or leave it in gear with foot on the clutch if you don't want to use it so you can choose dependent on the situation. With an auto it is different and you don't have the choice. At traffic lights it is not an issue, stops at the lights and restarts as soon as you take your foot off the brake, the problem I found was at roundabouts and give way junctions. If you come to a complete stop the engine shuts off, which means if you want to pull out quickly there is a delay. Until I coded it off, I found myself creeping up to the junction trying to make sure I didn't come to a complete stop which wasn't always possible. Much easier with it turned off.
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10-01-2015, 10:25 AM	#22
Trialskings Lieutenant 130 Rep 413 Posts Drives: Daddy Wagon Join Date: Oct 2014 Location: Bristol iTrader: (0)	S/S is a real PITA when queuing on a hot day as it also affects the A/C. Tend to switch it off then to stop HEAT RAGE creeping up on me!
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