Auto braking

[MBCHESTERUK]

Can anyone help. We are using a friends C class 2009 2.2 diesel with an auto box at the moment, we're used to our old A class manual. When driving the car it suddenly braked like an emergency stop from 50mph when touching the autobox lever and not using teh brakes. Not sure what we did, but has anyone come across this we could have caused an accident and we don't want to do it again.

Thanks Rich

 

[Sp!ke]

Did you put it in to P?

 

[MBCHESTERUK]

Hi, Sound daft but we are not sure, surely from 50mph-ish it would not let you select park.

 

[GrahamC230K]

you didn't dip the clutch as you touched the gear lever did you?

 

[wemorgan]

you didn't dip the clutch as you touched the gear lever did you?

It seems to be quite common to see people driving along with the brake lights permanently on. I suspect this is also people driving autos who are more used to driving manuals.

 

[MBCHESTERUK]

Hi Graham,

Not sure if we used the clutch - what difference would that have made ?
Regards Richard

 

[wemorgan]

Hi Graham,

Not sure if we used the clutch - what difference would that have made ?
Regards Richard

I believe it was a tongue in cheek comment.

If you thought you were using the clutch in an auto it means your foot touched the wide brake pedal instead.

 

[alexander patie]

when touching the autobox lever and not using teh brakes. Not sure what we did

in future just leave it in "D" all the time! perhaps if sitting in traffic for more than a minute you could put it in "P", but only when stationary of course! the gearbox will change up and down very well on its own, and you will have no more emergency stops!!

as for what happened, the car has a "+" and "-" function, if you push it to the left and hold it there it will change down to 1st and stay there, only when speeds allow, but the downchanges will be sharp.

a more likely scenario i fear is that you instinctively put your foot on the clutch, being an auto this would have been the extra large brake pedal!!!!!! i suggest the best way to get used to NOT pressing the non existent clutch is to keep your left foot well to the left and constantly remind yourself that it is NEVER needed in an automatic car.

 

[renault12ts]

Hi Graham,

Not sure if we used the clutch - what difference would that have made ?
Regards Richard

LOL. If you dipped the clutch I expect you nearly went through the windscreen!!!!!!!!!!

 

[stevesey]

Richard - People seem to have forgotten their manners, Welcome.

 

[stevesey]

If this is you first Auto could you have inadvertently hit the brake pedal? If so a clutch type push with your left foot could well have been hard/fast enough to engage the Brake Assist, resulting in the car then multiplying the error.

 

[st13phil]

Richard, welcome to the MBClub forums. Hope you find the people here friendly and helpful. Now to your problem...

As others have already suggested, the most likely cause is that you instinctively used your left foot to operate the clutch when you touched the gear selector and, as it's an auto, there's no clutch pedal so you hit the much wider brake pedal instead. The W204 has Emergency Brake Assist which means that if you hit the brake pedal quickly (e.g. in a panic stop situation, or as you would when you operate a clutch pedal in a manual) it senses that it's an emergency situation and automatically ramps up to maximum braking performance. Unless and until you totally release the brake pedal it will maintain maximum braking until the vehicle comes to a stop. This ties in well with your "like an emergency stop" comment.

Best solution is to either keep your left foot firmly on the footrest in the footwell, or to bend your left leg and keep your left heel tight against the seat under your right leg until you condition yourself not to try to use an imaginary clutch pedal. You wouldn't be the first person who's moved from a manual to an auto and had a similar thing happen and you won't be the last, so don't feel embarrassed about it!

 

[pos.k]

welcome to the forum

Reading the original post - if you are sure you didn't go for the clutch, then you will probably have put sideways pressure on the gearshift and shifted down to the lowest possible gear. This can have a dramatic slowing effect if you are not stepping down just 1 gear just before hitting the gas to really 'get going' without having to 'kick down'

if that makes sense?

 

[Chrishazle]

Rich, welcome to the joys of a tiptronic gearbox, Mercedes style (I have 2, a Porsche 968 tip and a Merc C270 tip, and they are different!). As people have already said, if you are sure you did not touch the brake pedal, chances are you pressured the gear lever to the left - it only takes a light touch and the box reacts. Touch it left and let go, it moves 1 notch down the box - in my car from D to 4 as an example (I have a display in the speedo that shows which of the D-4-3-2 options the box is in, don't know if it's the same in the new C). Hold it to the left and it changes down to the lowest gear the car will allow at the speed you are doing - which, if you are only on light throttle, will mean it rapidly goes right down through the box and the car stands on its nose! Once you are used to it, the box is lovely - allows you to use engine braking approaching a roundabout (for example) or use the box like a manual for overtaking rather than relying on the kickdown (pedal to the metal) route.
Hope this helps.

 

[lynall]

My mum bought a mondeo auto some years ago and had owned it for some time when i was talking to her and she was telling me the auto is harder to drive than a manual, more talk followed in which it transpired she was changing up and down the box just like a manual.
She was much happier when i explained to her about D P R etc.




Lynall

 

[alexander patie]

have had this one at work, usually when someone is borrowing an auto. they say how hard it is changing up/down the gears. makes me wonder what they think 'automatic' means...

 

[davidbilyk]

You wouldn't be the first person who's moved from a manual to an auto and had a similar thing happen and you won't be the last, so don't feel embarrassed about it!

I have many memories of heading for the clutch in an auto, normally when you would do a quick downshift in a manual!! A couple of frantic pumps on the bulkhead with the left foot and the brain realises I'm in the Benz!

When I went from my 124 auto to the Chavalier Gsi I was trying to take the handbrake off from under the light switch

Since then I have learnt how to disengage autopilot!

 

[Benzowner]

I remember having an Audi auto company a few years ago, when it came time for replacement, the collection gut tured up, got into the car and after a while came into the office saying the car wouldn't move. His left foot was firmly on the brake pedal, when I told him, I stood well back as he lifted his foot