Strange behaviour when going from R to D
02-11-2017, 09:51 AM
#1
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Thread Starter
Strange behaviour when going from R to D
A couple of times I experienced the following: slowly going back in a parking lot in Reverse, pressing the brake until FULL stop of the car, switching to D and in the moment I release the brake, the car slightly moves more backwards, half a meter let's say, before going to the front instead of instantly moving to the front
Does something similar has happened to somebody here? Vehicle is GLE SUV 350d 4matic.
Does something similar has happened to somebody here? Vehicle is GLE SUV 350d 4matic.
02-11-2017, 01:38 PM
#2
can't say i've experienced that specifically. but (on my gasser) it will move slightly when the EPB is released and it will drop back some when on a hill (unless "hold" is used). 1/2 meter is pretty big though, unless you were also on a hill. probably good idea to have it checked anyway. good luck, ron
02-11-2017, 03:10 PM
#3
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Thread Starter
Maybe not full half a meter, but 30 cm at least. It's not on a hill, imagine you want to get out of a narrow crowded garage and you have to change between R and D a couple of times before being able to turn the car in the proper direction. Of course you try to do this as fast as possible using the maximum space you have around the car, and in a certain moment just after you have been in R, you turn into D, press the gas pedal but before going forward the car continues backwards/after being stopped/ a little bit as if it is still in R. Not so much, but enough to touch your back bumper behind you.
02-11-2017, 03:28 PM
#5
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Thread Starter
it's not delay in the throttle response, to call it turbo lag or whatever, it is more a gearbox lag, you have put it into D but the first half second it still goes in R. If you wait 2 seconds after putting the car into D after R and than hit the gas pedal, that doesn't happen, only if you are fast. Anyway, nothing similar on the BMW ZF 8 speed gearbox.
02-11-2017, 04:10 PM
#6
no, talking more like if the diesel is idling too low. if the torque converter isn't engaged enough, you're basically in neutral. if you take a standard transmission; put it in 1st gear; and step on the clutch -- it's rolling wherever gravity says it will.
but, if there is a delay in the electronic shift, that is really not a good thing and needs immediate attention. if it were me and i couldn't discern that it was simple rollback, i would not drive it until it could be looked at. good luck, ron
but, if there is a delay in the electronic shift, that is really not a good thing and needs immediate attention. if it were me and i couldn't discern that it was simple rollback, i would not drive it until it could be looked at. good luck, ron
02-12-2017, 09:15 AM
#7
I have also noticed a lag when changing from R to D and vice versa. More so if I have a little bit of movement, i.e not at a complete standstill. My 550e has a secondary wet clutch which mates the electric drive motor to the transmission, so I chalked it up a delay in engagement. It appears to be cause by the transmission based on your post.
Last edited by DarrenK; 02-12-2017 at 09:31 AM.
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02-12-2017, 09:23 AM
#8
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I have also noticed a lag when changing from R to D and vice versa. More so if I have a little but of movement, i.e not at a complete standstill. My 550e has a secondary wet clutch which mates the electric drive motor to the transmission, so I chalked it up a delay in engagement. It appears to be cause by the transmission based on your post.
02-12-2017, 09:36 AM
#9
It seems to be normal for this transmission. Honestly, I should be at a full stop anytime I change gears, but when I am in a hurry I may not be. In my previous cars there was always some thunk sound or jerking motion when I did this. It was probably harmful to those transmissions. This is more of a transition and smoother. Not being a MB engineer or mechanic I am unsure if this is how it should be.
Last edited by DarrenK; 02-13-2017 at 06:45 AM.
02-13-2017, 02:34 AM
#10
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Thread Starter
Update on the topic. If you stop fully the car when reversing in R , switch to D after a second let's say and then go, the first moment the car tends to roll back/sitting on a flat surface/ bur it's more like a feel, maybe it moves a couple of cms back and then goes forward. If you are fast and want to start immediately after being in R, it behaves as described above, again the car being to a full stop before moving your foot from the brake to the throttle.
02-13-2017, 09:15 AM
#11
Update on the topic. If you stop fully the car when reversing in R , switch to D after a second let's say and then go, the first moment the car tends to roll back/sitting on a flat surface/ bur it's more like a feel, maybe it moves a couple of cms back and then goes forward. THIS IS THE TYPE OF "NORMAL" ROLLBACK THAT I MEAN.
If you are fast and want to start immediately after being in R, it behaves as described above, again the car being to a full stop before moving your foot from the brake to the throttle. IF YOU MEAN "AS DESCRIBED" TO BE IT MOVES IN REVERSE BEFORE IT MOVES FORWARD, IT MAY HAVE A SHIFT DELAY AND AS I SAID IF IT WERE MINE IT WOULD BE PARKED UNTIL IT WENT TO SERVICE.
If you are fast and want to start immediately after being in R, it behaves as described above, again the car being to a full stop before moving your foot from the brake to the throttle. IF YOU MEAN "AS DESCRIBED" TO BE IT MOVES IN REVERSE BEFORE IT MOVES FORWARD, IT MAY HAVE A SHIFT DELAY AND AS I SAID IF IT WERE MINE IT WOULD BE PARKED UNTIL IT WENT TO SERVICE.
