5G 'box C/S mode mythology?

[corned]

I have seen many references on this very forum to a 'fact' that when in 'C' mode, the 5G 'box will start off in second gear, not first.

I find this to be incorrect. Mine clearly starts off in first, no matter what mode it's in, nor how gently I set off.

So my question is - is this 'start in second' feature a myth or complete fabrication, or is it a verifiable and documented fact?

 

[MOCAŠ]

My SLK's owner's manual has this to say:

S - Standard mode: for all normal driving conditions


C - Comfort mode:

• The transmission shifts up sooner even if you depress the accelerator pedal further. This means that you drive at lower engine speeds.
• The transmission changes gear less frequently.
• The transmission usually only shifts up or down by one gear.

Mine's a 2004 model with the 7G gearbox. No idea whether the above info is relevant for yours.

 

[Dryce]

So my question is - is this 'start in second' feature a myth or complete fabrication, or is it a verifiable and documented fact?

I'm fairly sure mine does start in 2nd in C.

It certainly behaves differently in very slow moving traffic when in C.

But ISTR my manual only says that it changes the shift programme rather than states explicitly that it starts in 2nd or that it stops the transmission from allowing the car to roll backwards.

 

[corned]

My manual states something similar, I'm sure (without actually checking).

I note that it says it does several things when in comfort mode, but 'missing out a gear' is not one of them.

I have seen this thing quoted on here many times, but it has only ever been anecdotal.

However, I have set off several times in the last couple of days and deliberately checked to see how manygear changes it goes through. The answer is four. Every time. The changes themselves are imperceptible in feel, but I can see the rev counter dip and sweep upwards again. I have been very careful to set off gently to avoid masking the changes with too much tc slip and keeping the throttle input steady and constant, so it is not influenced by any input changes. I have tried it several times in both modes, for that matter. The answer is always four.

 

[Dryce]

I note that it says it does several things when in comfort mode, but 'missing out a gear' is not one of them.

A poster in another thread once kindly pointed out that the 722.6 shift valve setup only allows it to change sequentially. It can't skip. The 7G OTOH can skip intermediate ratios.

I am sure I have seen separare online documentation on the 722.6 that states in W mode it starts in 2nd and that it has a higher reverse ratio as well.

 

[whitenemesis]

From MB's training presentation for the 7G, shows it has the same operation (in this respect) as the 5G

So, it is not myth, the car moves off in 2nd gear when C is selected (with exceptions as listed) and uses a higher reverse ratio

 

[LTD]

No idea about the exact 'gear' selected but my 5g box behaves totally differently in S/C modes.

It is, of course, much more fun in 'S' and using the full benefit of manual.

 

[markjay]

This may sound odd, but for the comfort of my passengers, I drive mine regularly in S because the shifts are more smooth and subtle. But I think this has to do with the fact that my 180K is a bit short of torque so does not work very well with the high gearing of the C mode.

 

[whitenemesis]

I only use C mode in slippery conditions or when manoeuvring on steep roads (to prevent the car rolling back). I find the 2nd gear start too 'revvy'. Changes are just as smooth in either mode.

 

[Igurisu]

Can anybody explain to me how the reverse gear ratio is different depending on C or S setting? Mechanically its the same equipment, are there two reverse gears or some CVT for reverse?

Just curious.

 

[GP801]

Ours are left in S mode unless there is ice or snow. Its just so slow to pull away in C that it cant possibly be starting in first.

 

[Troon]

My 5G starts in first from rest in either C or S mode. I don't have a W mode.

 

[markjay]

Reading more about this... it seems that when in C it will only start in 2nd if you start-off gently, but if you do so with a heavy foot then it will start in 1st anyway.

 

[renault12ts]

My manual states that in W (or C for later cars) the car will start off in 2nd (except if 1st is selected). I can confirm that no matter how heavy footed I am in W, the car starts off in 2nd.

No myth here.

Corned, maybe yours is not working as it should. Try this test. Stop your car on a hill, release your foot from the brake. Now note what happens when in C or S. If I do this, the car creeps forward in S, but stops and stays put in W. In fact I can control the car by flicking the switch between the two.

 

[corned]

The thing is, it is a long time since I have had any trouble counting to five.

The only thing I can presume is that my 'tests' have been conducted when the 'box still considers itself to be cold. Or. as Renault suggests, mine is not working properly.

I'll see if I can get a second-gear start later today when fully warmed up! I'll try that hill start test too.

Igurisu - there are two separate reverse gears, switched according to mode selected.

 

[artyman]

I'm pretty sure my W204 starts in first no matter what program mode is selected. I live in C pretty much all the time.

 

[st13phil]

I can say with certainty that the 5g box on my W204 always started off in 1st gear, regardless of the C/S setting. The shift program was significantly different in the two modes though, with the up shift points being much lower in C mode, and the throttle response was softer too. I suspect that MB chose to use a changed throttle map and shift program rather than have the box start off in 2nd on that model.

My wife's SLK350 with the 7g box definitely starts off in 2nd when C mode is selected, but just like my W204, the shift program is modified as is the throttle response.

My W212 with the 7g Plus box is like my W204 was in that it always starts off in 1st gear, regardless of the C/S setting. However, the shift program is even more markedly different in the two modes than it was on the W204.

In summary, my point is that MB have employed different strategies on different models over the years to achieve essentially the same thing. I doubt very much that there's anything wrong with a 5g car that starts off in 1st when in C mode. Much more likely that it's behaving as it should.

 

[whitenemesis]

Can anybody explain to me how the reverse gear ratio is different depending on C or S setting? Mechanically its the same equipment, are there two reverse gears or some CVT for reverse?

Just curious.

As far as I can make out the two reverse ratios are provided by a Ravigneaux Gear Set.

 

[Peter DLM]

My 2004 211 starts in 2nd gear in C mode no matter how brutally I mash the throttel into the bulkhead.

 

[renault12ts]

Not doubting what anybody says, but C (and W) mode is designed so that our cars can start off in very slippery conditions and not lose traction.

Thus they start in 2nd. If your car starts in 1st then this feature is completely negated and you must ask why MB would do this? I suspect those who think their cars start in 1st have either malfunctions, or are not aware of what is really happening.














































Ducks.