Do automatic gearboxes improve with age?

[philharve]

Hi All

I have been reading a lot lately about automatic gearboxes and how they should be used and the advice dispensed has proven to be invaluable. Generally I put mine in 'D' and forget about it. However, in the last few months I have come to realise that the manual ratio selector is not there for show and there are times when flicking from 'auto' to 'manual' and back to 'auto' again is definitely an advantage, for example, like accelerating uphill to pass slower moving traffic. If I left it in 'auto' the electronics may/may not allow me to kickdown. There's an uncertainty factor which at times I find a little annoying.

However, notwithstanding, I'm finding my gearbox seems to be improving with age. The changes in 'auto' are almost imperceptable and I rely upon the rev' counter to confirm the change. I realise I have an adaptive gearbox system that 'tunes' itself to the driver but I gather this is not an ongoing process and after a few days the tuning ceases.

I'm currently looking at ways of achieving smooth changes whilst in 'manual'. For example, when overtaking I go from 'D' to '4' to '3', which gives enough torque for overtaking, then I move back to '4' and back into 'D'. The '4' to '3' step gives a little jolt, nothing severe, but it is noticeable. The '3' to '4' step is fine. Can I adapt my driving style to minimise the down-shifting jolt?

REGARDS

Phil

 

[JEZ.S320L]

Hi All

I realise I have an adaptive gearbox system that 'tunes' itself to the driver

REGARDS

Phil

Ooooooooooh - THAT sounds good. Does mine have it? If so, can the experts out there please explain how it works? Interesting.!

 

[philharve]

Ooooooooooh - THAT sounds good. Does mine have it? If so, can the experts out there please explain how it works? Interesting.!

Hi JEZ.ML270

And I thought most modern Mercedes had adaptive gearboxes!!!

I realised I had one when I disconnected the battery one day and reconnected it. I think it may have been a battery swap. When I went to drive the car after the swap, the gearbox felt very different. I thought I was going crackers. Then I discovered I had a clever gearbox that matches itself to the driving style of the driver: adapting change points, etc. Within 2 - 3 days the gearbox felt fine again: it had adapted itself to my style (again).

I guess removing the battery reset the adaptive electronics and the gearbox 'forgot' about me.

REGARDS

Phil

 

[philharve]

Adaptive accelerator

Just had a thought ... what about an adaptive accelerator subsystem? It starts off slow and gets faster until the subsystem learns at what speeds the driver feels safe driving. It effectively adjust the sensitivity of the accelerator pedal so the pedal travel matches a range from 'slow' to 'as fast as I dare travel'.

REGARDS

Phil

 

[kth286]

I believe it is all controlled by "fuzzy logic" electronics, but please do not ask me to explain.

 

[Blobcat]

I think a lot of it is the driver getting used to the car and adapting their style. I have found the 7G box very very different to the 5G in my previous E. I drive in C most of the time as it changes up sooner and sits in 7th longer. When driving it in S I notice it tends to stay in 5th & 6th a lot longer. When I get to a decent road I do change to S and enjoy the ride I also hold the lever to the left to select the best gear to fly.
The 7G box has little or no engine breaking IMO and can coast for ages without losing speed. Even though you lock it to a gear it will change up when it reaches max revs this is great for acceleration. It won't always allow you to drop to a low a gear which occasionally I would like to give some engine braking.

 

[JEZ.S320L]

Hi JEZ.ML270

And I thought most modern Mercedes had adaptive gearboxes!!!

I realised I had one when I disconnected the battery one day and reconnected it. I think it may have been a battery swap. When I went to drive the car after the swap, the gearbox felt very different. I thought I was going crackers. Then I discovered I had a clever gearbox that matches itself to the driving style of the driver: adapting change points, etc. Within 2 - 3 days the gearbox felt fine again: it had adapted itself to my style (again).

I guess removing the battery reset the adaptive electronics and the gearbox 'forgot' about me.

REGARDS

Phil

Call me Stupid if you want to ............... BUT. Take a motorway situation whereby, if I accelerate GENTLY to 80mph and then engage CC all is OK. I then brake down to say 50mph and then select RESUME - the car GENTLY accelerates back up to 80mph. Still with me? Different motorway and I accelerate HARD to 80mph and then select CC. Brake down to 50mph and then select RESUME - work with me on this - I am SURE that the car then accelerates HARD back up to 80mph. If I DO have 'adaptive' electronics, then I am NOT going mad, as this is what I feel the car does do.

Go on - someone tell me that mine isn't adaptive, and that I really AM going daft. :roll:

 

[television]

I think a lot of it is the driver getting used to the car and adapting their style. I have found the 7G box very very different to the 5G in my previous E. I drive in C most of the time as it changes up sooner and sits in 7th longer. When driving it in S I notice it tends to stay in 5th & 6th a lot longer. When I get to a decent road I do change to S and enjoy the ride I also hold the lever to the left to select the best gear to fly.
The 7G box has little or no engine breaking IMO and can coast for ages without losing speed. Even though you lock it to a gear it will change up when it reaches max revs this is great for acceleration. It won't always allow you to drop to a low a gear which occasionally I would like to give some engine braking.

The 7G box never locks the torque converter completely ever so in top it will always feel flexible, TCC is used for forcing the car into a lower gear but not as much as with other boxes and fits in exactly with what you have found

 

[philharve]

Call me Stupid if you want to ............... BUT. Take a motorway situation whereby, if I accelerate GENTLY to 80mph and then engage CC all is OK. I then brake down to say 50mph and then select RESUME - the car GENTLY accelerates back up to 80mph. Still with me? Different motorway and I accelerate HARD to 80mph and then select CC. Brake down to 50mph and then select RESUME - work with me on this - I am SURE that the car then accelerates HARD back up to 80mph. If I DO have 'adaptive' electronics, then I am NOT going mad, as this is what I feel the car does do.

Go on - someone tell me that mine isn't adaptive, and that I really AM going daft. :roll:

Hi JEZ.ML270

No, you're not stupid or Kevin Kline (re: Fish called Wanda) but aren't you describing the operation of CC rather than adaptive gearbox control? I have CC but seldom use it because I do a lot of cross country driving with lots of bendy bits and junctions. I've also got a variable speed limiter which I've never used. I gather from friends that they use it to prevent themselves driving beyond the local speed limit. Something to do with not losing their licenses. But this feature has nothing to do with the adaptive control either. This is an independent subsystem.

It is my understanding that the adaptive controller monitors the driver's style and alters the gearbox change points accordingly. Some drivers like to change up early, others late. The controller works out where these points are and applies them. Yes, I think the controller probably does use Fuzzy Logic.

I have a friend who likes to change up late (very late!) and the engine is usually red-lining when he makes the changes. Being a passenger is most uncomfortable. I have a more relaxed driving style and tend to change up early. That way I don't assault passengers' ears to a cocophony of screaming engine. When I first drove my Merc' the gearbox change points were somewhere between these two driving styles. Now it changes when I expect it to change. However, I've never gotten used to kickdown. I find it's not always predictable. That's why I now switch to manual and to Hell with the fuel consumption.

REGARDS

Phil

 

[JEZ.S320L]

Hi JEZ.ML270

No, you're not stupid or Kevin Kline (re: Fish called Wanda) but aren't you describing the operation of CC rather than adaptive gearbox control? I have CC but seldom use it because I do a lot of cross country driving with lots of bendy bits and junctions. I've also got a variable speed limiter which I've never used. I gather from friends that they use it to prevent themselves driving beyond the local speed limit. Something to do with not losing their licenses. But this feature has nothing to do with the adaptive control either. This is an independent subsystem.

It is my understanding that the adaptive controller monitors the driver's style and alters the gearbox change points accordingly. Some drivers like to change up early, others late. The controller works out where these points are and applies them. Yes, I think the controller probably does use Fuzzy Logic.

I have a friend who likes to change up late (very late!) and the engine is usually red-lining when he makes the changes. Being a passenger is most uncomfortable. I have a more relaxed driving style and tend to change up early. That way I don't assault passengers' ears to a cocophony of screaming engine. When I first drove my Merc' the gearbox change points were somewhere between these two driving styles. Now it changes when I expect it to change. However, I've never gotten used to kickdown. I find it's not always predictable. That's why I now switch to manual and to Hell with the fuel consumption.

REGARDS

Phil

Phil,

I probably didn't explain myself very clearly. What I was getting at, was HOW you arrive at 'cruising speed' - gently or quickly. If it is 'adaptive', would the 'fuzzy logic' remember when 'resume' is selected?

Has my car got 'adaptive control'?

 

[television]

This is a debatable subject, sure the Gearbox ECU talks to the engine ECU and has a short term memory for trying to be in the right gear at the right time.

This has to be the case as if you were belting down a road, overtaking everything in sight and then hit a 30 limit, the car reverts to its normal self immediately.

There is nothing in the WIS manuals about this at all, some folk say that they have never noticed anything, others say that they do

 

[JEZ.S320L]

This is a debatable subject, sure the Gearbox ECU talks to the engine ECU and has a short term memory for trying to be in the right gear at the right time.

This has to be the case as if you were belting down a road, overtaking everything in sight and then hit a 30 limit, the car reverts to its normal self immediately.

There is nothing in the WIS manuals about this at all, some folk say that they have never noticed anything, others say that they do

In which case, I will align myself with those who DO.

 

[philharve]

Phil,

I probably didn't explain myself very clearly. What I was getting at, was HOW you arrive at 'cruising speed' - gently or quickly. If it is 'adaptive', would the 'fuzzy logic' remember when 'resume' is selected?

Has my car got 'adaptive control'?

Hi JEZ.ML270

In that case I would have to say quickly. I once engaded CC by accident and the car took off like a scalded cat.

REGARDS

Phil

 

[jberks]

Call me Stupid if you want to ............... BUT. Take a motorway situation whereby, if I accelerate GENTLY to 80mph and then engage CC all is OK. I then brake down to say 50mph and then select RESUME - the car GENTLY accelerates back up to 80mph. Still with me? Different motorway and I accelerate HARD to 80mph and then select CC. Brake down to 50mph and then select RESUME - work with me on this - I am SURE that the car then accelerates HARD back up to 80mph. If I DO have 'adaptive' electronics, then I am NOT going mad, as this is what I feel the car does do.

Go on - someone tell me that mine isn't adaptive, and that I really AM going daft. :roll:

It isn't adaptive. I don't know you well enough to call you daft!

The gearbox is, as has been discussed, hence, drive like a nutter and it will change up later, so boot it a few times to clear a lump of traffic and then back off suddenly to slow back down and drive more sensibly now you have some clear road, and hey presto, find yourself stuck in 3rd for a ages as the gearbox expects you to want to tear off like a scalded cat again.

The cruise is different. It tries to gently accelerate back to the preset speed, but the longer it takes to achieve this, the harder it will try. So, 50-80 on the flat/downhill and it only takes a few sconds so it will be gentle. Do the same uphill in 5th and it will start off gently, not achieve much so gradually get more and more aggressive until either the speed is finally reached or if the throttle is applied hard enough, the gearbox kicks down.
It's all down to time taken, not how hard you accelerated last time.

 

[JEZ.S320L]

Hi JEZ.ML270

In that case I would have to say quickly. I once engaded CC by accident and the car took off like a scalded cat.

REGARDS

Phil

I which case, I have to disagree in part. When arriving at the cruise speed, the car SEEMS to 'remember' how I had arrived at the cruise speed previously - i.e. quickly or slowly.

I am not going mad. In fact, I shall conduct a test on the M4 this afternoon. So if any readers are travelling Westbound Bracknell - Bath and see me @rsing about - please forgive me, as I am conducting an experiment!

Watch this space!!

 

[philharve]

... The cruise is different. It tries to gently accelerate back to the preset speed, but the longer it takes to achieve this, the harder it will try. So, 50-80 on the flat/downhill and it only takes a few sconds so it will be gentle. Do the same uphill in 5th and it will start off gently, not achieve much so gradually get more and more aggressive until either the speed is finally reached or if the throttle is applied hard enough, the gearbox kicks down.
It's all down to time taken, not how hard you accelerated last time.

Well that answers a question I have had on my mind for some time. I've noticed that engaging the CC on the flat results in gentle acceleration and the only time I engaged CC uphill (a mistake) it accelerated fiercely giving me a bit of a scare. Now I know why it behaves differently.

REGARDS

Phil

 

[philharve]

It isn't adaptive. ...

The gearbox is, as has been discussed, hence, drive like a nutter and it will change up later, so boot it a few times to clear a lump of traffic and then back off suddenly to slow back down and drive more sensibly now you have some clear road, and hey presto, find yourself stuck in 3rd for a ages as the gearbox expects you to want to tear off like a scalded cat again. ...

Hi jberks

But isn't your description that of an 'adaptive' system? From your description it would seem the gearbox/ECU is continually monitoring the driver and if I were to drive like a nutter for a few days/hrs it would learn my driving style. If, subsequently, I reverted to my normal style of driving, the gearbox/ECU will revert back too?

REGARDS

Phil

 

[television]

Hi jberks

But isn't your description that of an 'adaptive' system? From your description it would seem the gearbox/ECU is continually monitoring the driver and if I were to drive like a nutter for a few days/hrs it would learn my driving style. If, subsequently, I reverted to my normal style of driving, the gearbox/ECU will revert back too?

REGARDS

Phil

These boxes revert to normal immediately on hitting traffic, it cant work any other way, by V70R does the same thing with the ZF box

 

[stevesey]

I am not going mad. In fact, I shall conduct a test on the M4 this afternoon. So if any readers are travelling Westbound Bracknell - Bath and see me @rsing about - please forgive me, as I am conducting an experiment!

Missed you on the Swindon -> Bath stretch. Traffic slowed suddenly several times though, perhaps you where up ahead!

 

[stevesey]

Hi JEZ.ML270

In that case I would have to say quickly. I once engaded CC by accident and the car took off like a scalded cat.

REGARDS

Phil

Was pondering that the other day, how long does the CC memory last. What happens if flick the wrong stick to flash the lights and let someone out? Does resume work below 40? Even if doing over 40 it would be a bit of a shock, especially if the gap was large enough that the other car didn't need my encouragement to pull into it.