Auto lockup - Page 2

crofts · 25th February 2013, 03:10

Get hold of 'seancar'. He may have an answer and will almost certainly have an ECU at a reasonable price. He also has T4 so will know if programming an auto ECU is necessary.

Ford Prefect · 25th February 2013, 07:41

Actually I have had a thought about this.. I wonder if this was done deliberatly to stop the 2.5 V6 auto having better economy than the 2.0 V6?
Anyonw know what speed the 1.8 auto locks up at? this may have a better suited programmme to the CDT (rather perversely) as I'd hope it won't get upset at seeing engine RPM over 4K which I would guess a CDT ECU will

tourer · 25th February 2013, 13:48

My CDT auto does not seem dependent on speed to lock up in 5th, but temperature.
Once warmed through it changes up, on low throttle, at 42 mph (true mph as measured by sat-nav).
When the weather is very cold torque convertor may not lock up in 5th until 3 to 4 miles are travelled.
Once warmed up in locks up as soon as it goes into 5th.
Has been this way 8 years since new.

crofts · 26th February 2013, 03:24

That's not my experience. I have a clear run (most times) just after leaving my drive. I quickly get it up to 50 and it never fails to drop into 5th, hot or cold. I always lift off accelerator briefly at 50........never fails to drop in. It is very obvious on the rev counter.

I have an idea 1,8's were not fitted with auto but may be wrong. If I am and they change at 50 then I cannot see any justification for a 2.5 to only drop in at 60-65

SD1too · 26th February 2013, 11:30

Quote:

Originally Posted by crofts

... it never fails to drop into 5th ...

Hello David,

My apologies if I've misunderstood your posting, but they're discussing the operation of torque converter lock-up. Engagement of 5th gear is, as you know, a separate operation. Rather surprisingly, MG Rover says that lock-up is possible in gears 2, 3 & 4 as well as fifth.

Quote:

Originally Posted by tourer

When the weather is very cold torque convertor may not lock up in 5th until 3 to 4 miles are travelled. Once warmed up in locks up as soon as it goes into 5th.

MG Rover confirms this:
"To promote engine warm-up at low temperatures, the EAT ECU will inhibit lock-up if the gearbox fluid temperature is below 40 degrees C."

Simon

crofts · 27th February 2013, 06:04

Well back to school ! Have just read through all pages re Automatic Transmission (pages 95-98) in my owners manual.
Surprisingly the term 'Lock-Up' is not mentioned in any shape or form.
I checked also under 'cruise control' and 'traction control'
I cannot see a practical purpose of 'lock-up' in 1st,2nd 3rd & 4th.
So I have to ask the question 'What changes to indicate 'lock-up' ?
Nothing to my knowledge changes, or is indicated, after the box drops into 5th, other than, naturally, reduction in revs for a given speed. no clunk, click or change whatsoever. And once in 5th a brief lift off of the accelerator, at any speed, does not produce any effect. So how do you know it is 'locked-up' ? ?
I will be grateful for enlightenment ' I'm flumoxed !

SD1too · 27th February 2013, 06:20

Quote:

Originally Posted by crofts

I cannot see a practical purpose of 'lock-up' in 1st,2nd 3rd & 4th.

Not first gear David; just 2nd to 5th as said above!

Quote:

So how do you know it is 'locked-up' ?

Well, in my experience you don't, since any reduction in revs is small and the engagement is softened by a gradual change in hydraulic pressure to the actuator, so there won't be a "clunk". However, folk above say that they can feel it.

There's a brief reference to it in MGR's workshop manual.

Regards,

Simon

wutang · 27th February 2013, 09:40

On my v6 lockup seems to occur at about 60mph but if gentle will then hold until 54mph or so.

you should notice lock up once in fifth gear the reves will then drop again by about 300rpm. if you put your foot down again the revs will rise without an actual gear change as the converter un - locks again.

Shortly after I got my car my dad borowed it and when I got it back he comented that the box was super smooth but that the ratio on sixth gear was so close to fifth that there was no point having it!

Richard

kaiser · 27th February 2013, 13:04

I will bet a case of beer, that the information regarding the lock-up on all gears except first is incorrect.
Further, in Sport mode, 5th gear is not selected at all (as far as I remember), and lock up is not available, at all!.

The lock up locks the output shaft solid, and there is no torque multiplication at all. That also means that acceleration is direct and poor at low revs.

Anyone with an autobox can go and verify this for themselves.

Ambling along in lock up, the first thing the box does, if you want to accelerate even moderately, is to drop about 400 revs. That is when the box goes out of lock up. Even more acceleration, and it drops a gear, more two and maybe three, depending on input and speed. Each gear change will correspond to more than 1000 revs.

So there is simply no point in the box going into lock up at anything less than about 2000 revs. There simply is hardly any torque available.

James.uk · 27th February 2013, 14:01

Kaiser is right. I know that at a certain speed in top gear an auto box will lock to the drive shaft at the same ratio as the manual box of the same make.. All my Jags did it, so did the other auto's I have driven.

Once you stop accelerating in top gear, the auto box can lock up, it wont do it while being driven hard due to excessive pressures in the gearbox. but once you ease off, the pressure equals out and it will lock up.

I remember some of this from the time we stripped a few auto boxes when I was an apprentice engineer doing hydraulics innit..

...

25th February 2013, 03:10	#11
crofts I really should get out more....... 2003 Rover 75 Conn. SE Auto Tourer 131 ps CDTi Join Date: Nov 2006 Location: Bristol Posts: 2,512 Thanks: 38 Thanked 67 Times in 55 Posts	CDTi Auto ECU Get hold of 'seancar'. He may have an answer and will almost certainly have an ECU at a reasonable price. He also has T4 so will know if programming an auto ECU is necessary. __________________ Rover 75 CDTi SE Connoisseur Tourer (2003) In desirable STARLIGHT SILVER (now restored to it's former glory with all the chrome !)

25th February 2013, 07:41	#12
Ford Prefect Loves to post Rover 75 Saloon Join Date: Dec 2012 Location: Wantage Posts: 306 Thanks: 0 Thanked 0 Times in 0 Posts	Actually I have had a thought about this.. I wonder if this was done deliberatly to stop the 2.5 V6 auto having better economy than the 2.0 V6? Anyonw know what speed the 1.8 auto locks up at? this may have a better suited programmme to the CDT (rather perversely) as I'd hope it won't get upset at seeing engine RPM over 4K which I would guess a CDT ECU will __________________ [SIGPIC][http://www.the75andztclub.co.uk/foru...ne=1355821399][/SIGPIC] 1999 Rover 75 Connesieur 2.5 Dealer Launch Spec LPG (Its very blue) 1999 Landrover Disco2, proper one with a V8 no TD5 rubbish 1997 TB called Ed, runs on grass 1992 Range Rover Vogue SE (LPG) 1975 MG Midget 1959 Austin Healey Sprite I think I may have a problem

26th February 2013, 03:24	#14
crofts I really should get out more....... 2003 Rover 75 Conn. SE Auto Tourer 131 ps CDTi Join Date: Nov 2006 Location: Bristol Posts: 2,512 Thanks: 38 Thanked 67 Times in 55 Posts	Lock Up That's not my experience. I have a clear run (most times) just after leaving my drive. I quickly get it up to 50 and it never fails to drop into 5th, hot or cold. I always lift off accelerator briefly at 50........never fails to drop in. It is very obvious on the rev counter. I have an idea 1,8's were not fitted with auto but may be wrong. If I am and they change at 50 then I cannot see any justification for a 2.5 to only drop in at 60-65 __________________ Rover 75 CDTi SE Connoisseur Tourer (2003) In desirable STARLIGHT SILVER (now restored to it's former glory with all the chrome !) Last edited by crofts; 26th February 2013 at 03:30.. Reason: added last para

27th February 2013, 06:04	#16
crofts I really should get out more....... 2003 Rover 75 Conn. SE Auto Tourer 131 ps CDTi Join Date: Nov 2006 Location: Bristol Posts: 2,512 Thanks: 38 Thanked 67 Times in 55 Posts	Lock-Up Well back to school ! Have just read through all pages re Automatic Transmission (pages 95-98) in my owners manual. Surprisingly the term 'Lock-Up' is not mentioned in any shape or form. I checked also under 'cruise control' and 'traction control' I cannot see a practical purpose of 'lock-up' in 1st,2nd 3rd & 4th. So I have to ask the question 'What changes to indicate 'lock-up' ? Nothing to my knowledge changes, or is indicated, after the box drops into 5th, other than, naturally, reduction in revs for a given speed. no clunk, click or change whatsoever. And once in 5th a brief lift off of the accelerator, at any speed, does not produce any effect. So how do you know it is 'locked-up' ? ? I will be grateful for enlightenment ' I'm flumoxed ! __________________ Rover 75 CDTi SE Connoisseur Tourer (2003) In desirable STARLIGHT SILVER (now restored to it's former glory with all the chrome !)

25th February 2013, 13:48	#13
tourer Posted a thing or two Rover 75 Tourer CDT Auto. Join Date: Oct 2011 Location: Long Eaton Posts: 1,343 Thanks: 30 Thanked 220 Times in 160 Posts	My CDT auto does not seem dependent on speed to lock up in 5th, but temperature. Once warmed through it changes up, on low throttle, at 42 mph (true mph as measured by sat-nav). When the weather is very cold torque convertor may not lock up in 5th until 3 to 4 miles are travelled. Once warmed up in locks up as soon as it goes into 5th. Has been this way 8 years since new.

27th February 2013, 09:40	#18
wutang Posted a thing or two Rover 75 2.5 auto (LPG) & mg tf 160 Join Date: Nov 2006 Location: Dartford Posts: 1,124 Thanks: 5 Thanked 39 Times in 36 Posts	On my v6 lockup seems to occur at about 60mph but if gentle will then hold until 54mph or so. you should notice lock up once in fifth gear the reves will then drop again by about 300rpm. if you put your foot down again the revs will rise without an actual gear change as the converter un - locks again. Shortly after I got my car my dad borowed it and when I got it back he comented that the box was super smooth but that the ratio on sixth gear was so close to fifth that there was no point having it! Richard

27th February 2013, 13:04	#19
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	I will bet a case of beer, that the information regarding the lock-up on all gears except first is incorrect. Further, in Sport mode, 5th gear is not selected at all (as far as I remember), and lock up is not available, at all!. The lock up locks the output shaft solid, and there is no torque multiplication at all. That also means that acceleration is direct and poor at low revs. Anyone with an autobox can go and verify this for themselves. Ambling along in lock up, the first thing the box does, if you want to accelerate even moderately, is to drop about 400 revs. That is when the box goes out of lock up. Even more acceleration, and it drops a gear, more two and maybe three, depending on input and speed. Each gear change will correspond to more than 1000 revs. So there is simply no point in the box going into lock up at anything less than about 2000 revs. There simply is hardly any torque available.

27th February 2013, 14:01	#20
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	Kaiser is right. I know that at a certain speed in top gear an auto box will lock to the drive shaft at the same ratio as the manual box of the same make.. All my Jags did it, so did the other auto's I have driven. Once you stop accelerating in top gear, the auto box can lock up, it wont do it while being driven hard due to excessive pressures in the gearbox. but once you ease off, the pressure equals out and it will lock up. I remember some of this from the time we stripped a few auto boxes when I was an apprentice engineer doing hydraulics innit.. ...