car rolling back
On my S320 cdi (2007) I seem to have a problem which the dealer thinks is normal. When I'm on a hill and if my foot is not on the brake; the car actually rolls back untill I stop it by braking or it stops by itself when the incline gets a little shallower. Thi even when the car is in "drive." On all the other cars I've driven, the car atleast stays still or creeps forward on the same hills (even a e320 cdi.)
I mentioned this to my dealer, but they said that is normal for the new 7 speed gearboxes. I really don't think this should be happening, but do any of you have the same problem? I know most of you guys have s550's here and I'm assuming there is a different gearbox in there.
O a side note; I got some new 21" wheels for the car which look totally stunning. Pics coming soon!
Thanks




the car automatically senses uphill terrain and applies the brakes, never rolls back, I love this feature.
My wife's ML350 (7 speed trans.) same thing.
Let see what other members will say about your problem.
Mark.

https://mbworld.org/forums/3191854-post14.html
https://mbworld.org/forums/3191854-post14.html
Thanks Diesel. It was all I could do to hold back comment until I saw your reference to this. It's funny, we've been talking so much about this same thing all week.
To the original poster: Put your gearbox in "C" mode and see if this doesn't help. When mine is in "S" mode, my car too drifts back as I am waiting on a light to change while sitting on a slight hill.
And yes, it is normal.
"On uphill grades with a gradient angle of more than 5°, the hill start assist system maintains the pressure in the brake system for approximately 1second after you have released the brake pedal. Therefore, you can start off smoothly without the vehicle moving immediately after releasing the brake pedal.
The hill start assist system is inactive:
- when starting off on a level road or
- downhill grades
- with the automatic transmission in
- neutral position N
- with the electric parking brake set
- if the ESP® has switched off due to a
- malfunction
Doesn't say anything about S or C modes.
The only thing I'm not sure about is did the Renntech tranny upgrade have anything to do with this? Also, my car does not have the "M" mode like AMG vehicles so I wonder what happens in M?
However, on the other thread similar to this, someone says their car behaves just like mine in this respect.
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C mode = car starts in 2nd gear
Since 1st gear is a lower ratio = more resistence necessary to roll car.
Does my logic make sense?
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Yes , you're logic makes sense but for some reason mine rolls back in 1st (S) and not in 2nd (C). You would think the 1st gear would hold better than 2nd.
1st gear would be providing more torque even at a standstill than 2nd gear.
Try push starting a motorcycle in 1st gear versus 3rd gear. It is much easier and dampening to get a motorcycle/car to start in 3rd gear as opposed to 1st.

The point being that Hill Assist is not based on the torque converter slipping partly and giving a push forward but instead it is an active feature where the car is using brakes to keep it steady, as long as there is enough torque from the engine when the gas pedal is pressed.I did not read my manual, would be interesting to check if this has been changed at some point regarding if C or S modes make a difference.






