Another gearbox question...

[Anders]

As I am new to the wonderful world of MB and automatic gearboxes, I was hoping someone could enlighten me on what the correct manual override in the 5 speed auto-box is.

As mine is a '98 it does not have the later TouchShift.

First, I assume it is is OK to move the gearlever from D to e.g. 4 or 3 at speed?

Second, for maximum overtaking, I select "3" and will then move the gearlever to "4" or back to "D" after overtaking. OK?

Thanks, and sorry for what might be rather naive questions!

 

[sym]

For maximum overtaking, use the kickdown switch located under your right foot, as far as the pedal will travel, and then a little further - you will feel it engage !

Yes to your assumption that it is safe to move the gear shift manually betweeen gears at speed. The ECU will not allow it to select a gear that does not match the road / engine speed, so no fears about destroying your gearbox in this way - although I only ever found this feature useful on the Nurburgring, to make use of some engine braking.

S.

 

[jimmy]

As Sym has siad you can use the gear lever like a manual if you wish, there is no chance of damaging the gearbox. I don't find it neccessary unless I want to drive 'enthusiastically' along country or twisty roads where leaving it in 4th helps with engine braking and preventing the box changing to 5th for powering out of corners.

I would say 97% of the time leave it in D, occasionally I have tried shifting to 4 just before overtaking but found if you floor it then the ECU takes care of it all for you.

 

[Anders]

Thanks!

Despite my limited experience with automatics, I was aware of the kickdown-switch

A typical situation where I use e.g. "3", is on a B road waiting behind a slow vehicle, and to eliminate the slight hesitation of the kickdown, I simply put it in "3" before overtaking. The rest of the time I leave it in "D" to do its own thing, which it does very well.

 

[Shude]

The ECU will not allow it to select a gear that does not match the road / engine speed

The ECU has no knowledge of this, believe it or not it is a completely different computer inside the automatic tranmission

 

[sym]

The ECU has no knowledge of this, believe it or not it is a completely different computer inside the automatic tranmission

Doh ! OK - the 'TCU' then ! lol.

 

[simonl]

another use of 3 and 4 are on decents in built up areas. if you're going downhill in a 30, lock it down to 3 or 4 (depending on the gradient) - you won't have to keep applying the brakes to prevent speeding.

 

[Dieselman]

The ECU has no knowledge of this, believe it or not it is a completely different computer inside the automatic tranmission

As ECU stands for Electronic Control Unit, and that they are used for Engine, gearbox, ABS etc, then the term ECU is correct.

 

[Dieselman]

another use of 3 and 4 are on decents in built up areas. if you're going downhill in a 30, lock it down to 3 or 4 (depending on the gradient) - you won't have to keep applying the brakes to prevent speeding.

Good idea, I used this over the weekend to prevent run-away. The speed limiter and cruise control will perform this for you if selected. It goes "ding, ding..change down".