Auto Box Gear Changes - Page 3

Miff · 13th February 2012, 15:01

I dont think mine hits top until 65mph?

James.uk · 13th February 2012, 15:13

Deeks, maybe your auto box needs an oil change..

The gear changes are all delayed if you accelerate hard.. In fact the harder you put your foot down, the later the gearbox will be in changing gear... You can only get 5th gear around 50 mph if you are very gentle with your foot...

I have often wondered if using snow mode would be more economic when the car is lightly laden in large towns..

...

Canonite · 13th February 2012, 15:19

I'm trying to get my head around how these Autos work as I may soon have one.
Reading through the manual and on Rave is interesting how complex it is to work as it does.
If the Autobox is doing 2150rpm at 70mph why isn't it better on fuel than my manual which at 70mph is around 3100rpm?

Does sports mode allow it to change up quicker or does it detect it by how hard you're pressing the pedal?

David3807 · 13th February 2012, 15:43

Quote:

Originally Posted by James.uk

I have often wondered if using snow mode would be more economic when the car is lightly laden in large towns..

...

Snow mode prevents use of 1st gear - therefore all starts are made in second with a bit extra torque converter slip thus wasting more fuel ???

And the handbook I think refers to D as enonomy mode - perhaps a hint

James.uk · 13th February 2012, 16:05

>>>If the Auto box is doing 2150rpm at 70mph why isn't it better on fuel than my manual which at 70mph is around 3100rpm?<<<

Because 90% of the time you change up at much lower revs in your manual than an auto box would.

>>>Does sports mode allow it to change up quicker or does it detect it by how hard you're pressing the pedal?<<<

Sports mode delays the gear changes allowing the car to reach much higher revs before it changes up, it does respond and vary it's behavior Dependant on pedal input though...

>>>Snow mode prevents use of 1st gear - therefore all starts are made in second with a bit extra torque converter slip thus wasting more fuel ??? <<<

Does it slip more though? (more than what?) No way of telling is there?? I think it just cuts out first gear.. And that would save fuel.. As for calling it "economy" mode, that is just a sales ploy, it is actually normal mode innit..

The hand book does say that in town one should select 4th though, not "D".. Prob because the car wont be going fast enuff to get into 5th gear anyway..

...

MisterTomez · 13th February 2012, 16:27

Arguably the auto is slightly more economical when the torque converter is locked because there's no slip (input shaft locked to output), and the RPM is lower than that of the manual.

Problem is these boxes utterly refuse to lockup at anything other than A-road or dual carriageway speed, which really does hurt the economy IMO, as you're just stirring oil pointlessly - this is in contrast to my BMW which will lock up just below 30mph in 4th - ~1,100rpm and into 5th at 40mph - ~1,200rpm - I really wish the box on the Rover did this, because it would save some serious fuel.

Parker · 13th February 2012, 16:28

This info is really interesting coming in, so to throw into the mix at 70 MPH in 5th driving a 2.5 V6 what would you expect the rev counter to be reading?

MisterTomez · 13th February 2012, 16:35

Locked up at 70, cruising, a fraction over 2,200rpm.

13th February 2012, 16:27	#26
MisterTomez Gets stuck in '00 BMW 535i Auto M-Sport, '99 Rover 75 2.5 V6 Connoisseur SE Auto Join Date: Jan 2010 Location: Midlands Posts: 733 Thanks: 0 Thanked 7 Times in 2 Posts	Arguably the auto is slightly more economical when the torque converter is locked because there's no slip (input shaft locked to output), and the RPM is lower than that of the manual. Problem is these boxes utterly refuse to lockup at anything other than A-road or dual carriageway speed, which really does hurt the economy IMO, as you're just stirring oil pointlessly - this is in contrast to my BMW which will lock up just below 30mph in 4th - ~1,100rpm and into 5th at 40mph - ~1,200rpm - I really wish the box on the Rover did this, because it would save some serious fuel. __________________ ` [SIGPIC][/SIGPIC] "Trimmed like a first class cabin on the Titanic...before it sank." ---------- "The LPG'd, civilized psychopath."

13th February 2012, 16:28	#27
Parker This is my second home Jaguar XJ 3.0 V6 Auto (X350) & Hyundai Tuscon 2020 Join Date: Oct 2008 Location: Bridgend Posts: 10,342 Thanks: 69 Thanked 559 Times in 356 Posts	This info is really interesting coming in, so to throw into the mix at 70 MPH in 5th driving a 2.5 V6 what would you expect the rev counter to be reading? __________________ http://www.the75andztclub.co.uk/foru...a585a72d1c.jpg "The only thing to do with good advice is pass it on. It is never any use to oneself" SOME VERY USEFUL LINKS SIMPLE DOOR MIRROR REPAIR FITTING CROFT DOOR FINISHERS FORUM RULES CLUB SHOP

13th February 2012, 16:35	#28
MisterTomez Gets stuck in '00 BMW 535i Auto M-Sport, '99 Rover 75 2.5 V6 Connoisseur SE Auto Join Date: Jan 2010 Location: Midlands Posts: 733 Thanks: 0 Thanked 7 Times in 2 Posts	Locked up at 70, cruising, a fraction over 2,200rpm. __________________ ` [SIGPIC][/SIGPIC] "Trimmed like a first class cabin on the Titanic...before it sank." ---------- "The LPG'd, civilized psychopath."

13th February 2012, 15:01	#21
Miff Avid contributor 2002 2.5 Connoisseur SE. Join Date: Feb 2011 Location: Sheffield Posts: 223 Thanks: 2 Thanked 4 Times in 4 Posts	I dont think mine hits top until 65mph?

13th February 2012, 15:13	#22
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	Deeks, maybe your auto box needs an oil change.. The gear changes are all delayed if you accelerate hard.. In fact the harder you put your foot down, the later the gearbox will be in changing gear... You can only get 5th gear around 50 mph if you are very gentle with your foot... I have often wondered if using snow mode would be more economic when the car is lightly laden in large towns.. ...

13th February 2012, 15:19	#23
Canonite This is my second home BMW 330d Tourer, MG ZT 180 SE XPG, VW Polo 6R 1.2 TDI Bluemotion Join Date: Jul 2011 Location: York Posts: 6,022 Thanks: 363 Thanked 574 Times in 319 Posts	I'm trying to get my head around how these Autos work as I may soon have one. Reading through the manual and on Rave is interesting how complex it is to work as it does. If the Autobox is doing 2150rpm at 70mph why isn't it better on fuel than my manual which at 70mph is around 3100rpm? Does sports mode allow it to change up quicker or does it detect it by how hard you're pressing the pedal?

13th February 2012, 16:05	#25
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	>>>If the Auto box is doing 2150rpm at 70mph why isn't it better on fuel than my manual which at 70mph is around 3100rpm?<<< Because 90% of the time you change up at much lower revs in your manual than an auto box would. >>>Does sports mode allow it to change up quicker or does it detect it by how hard you're pressing the pedal?<<< Sports mode delays the gear changes allowing the car to reach much higher revs before it changes up, it does respond and vary it's behavior Dependant on pedal input though... >>>Snow mode prevents use of 1st gear - therefore all starts are made in second with a bit extra torque converter slip thus wasting more fuel ??? <<< Does it slip more though? (more than what?) No way of telling is there?? I think it just cuts out first gear.. And that would save fuel.. As for calling it "economy" mode, that is just a sales ploy, it is actually normal mode innit.. The hand book does say that in town one should select 4th though, not "D".. Prob because the car wont be going fast enuff to get into 5th gear anyway.. ...