zuby84

hey there all,

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

Red Marko

I don't think this is normal. In my CL (5 speed trans)
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.

Diesel Benz

This thread is about a different topic but this post should explain how it should work:
https://mbworld.org/forums/3191854-post14.html

trumpet1

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.

benz_addict

I dunno if it's the same for the newer S-Class but mine applies the brakes in both C and S modes.

kevine310

Page 374 of manual:

"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.

trumpet1

Well all I know is, if I'm sitting still at a red light while facing an uphill situation, my car will sit motionless while in the C mode without using the brakes at all. If I press the tranny mode button while sitting there and it goes to S mode, within a second , the car will roll back and then if I press the button again, it stops.

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.

nkole

S mode = car starts in 1st gear
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?

trumpet1

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.

Diesel Benz

It sort of makes sense but then again it doesn't. 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.

nkole

Mine holds the hill in either S or C for a few seconds. Long enough to get on the gas and slip rearwards anyway.

Television

This is nothing to do with any effect on the gearing,,in W or C there is a sprag clutch that comes into operation, and the car cannot roll back

trumpet1

In the US , we don't have the W mode. We haven't seen that since the W140 models if I'm not mistaken. Gosh, I can't believe I actually remembered that. I remember my 1996 S420 had the W and C positons.

cjf_moraga

Uh... what is W mode?

Chris

nkole

W=Winter. Car started out in 2nd gear to reduce the likelihood of peeling out from a stop. I guess C mode is a rebranded W mode although W mode didn't have stiffer spring settings.