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      03-20-2015, 08:19 PM   #1
80386i
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Unhappy Rolling back problem

Hi everyone,

I just realized today that my 35d rolls back when brake is not applied on uphills (moderately steep) even with D gear.

Today is the first time I actually realize this and I don't think it was like this before.

Is this normal?

Thanks in advance!
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      03-20-2015, 08:36 PM   #2
Kzang
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I think this is normal since it would be very bad for the transmission gear to hold your 4800 lbs SUV while your brakes are not applied. I would utilize auto hold to remedy your concerns.
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      03-20-2015, 09:33 PM   #3
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Quote:
Originally Posted by Kzang View Post
I think this is normal since it would be very bad for the transmission gear to hold your 4800 lbs SUV while your brakes are not applied. I would utilize auto hold to remedy your concerns.
+1 - Auto hold is a nice feature. Very useful in stop and go traffic too
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      03-20-2015, 09:53 PM   #4
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Quote:
Originally Posted by 80386i View Post
Hi everyone,

I just realized today that my 35d rolls back when brake is not applied on uphills (moderately steep) even with D gear.

Today is the first time I actually realize this and I don't think it was like this before.

Is this normal?

Thanks in advance!
Yepp , it bothers me too , my old LincNavigator never roll back , without any "Premium Autohold " it's really sucks .
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      03-20-2015, 10:30 PM   #5
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My guess is, it's part of the fuel saving structure they implemented on F15. I don't remember my E70 rolling back, but then again it's idle rpm was higher compared to F15.

I haven't tested my X5 on a steep hill (how steep are we talking about) but the rollback should actually be limited, I don't think it would continuously roll backwards at a steady speed. I always thought it would compensate the rollback (if it becomes excessive) by adjusting the idle rpm (or un-accelerated D rpm).

I think Auto-Hold is a gift, most of my traffic lights are long, I love being able to just move my feet back and relax like I am sitting my couch and let the vehicle stay where it is without moving about. I didn't use auto-hold for a whole year when I first got a BMW thinking it would spoil me and I would end up rolling and rear-ending vehicles if I got another car without auto-hold.
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      03-20-2015, 11:05 PM   #6
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It shouldn't roll back if you apply the brake then let off, it should hold without auto hold on (that's more for stop and go traffic, I believe, as it works even on level ground..). But are you saying you never even applied the brake at all? I'm pretty sure you have to engage the brake at least for a second before it will hold on the hill for you.
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      03-20-2015, 11:30 PM   #7
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chrisny is right. If you tap at the brakes to bring the car to a complete stop at a slope, upon removing the foot from the brakes, the X5 should NOT roll back immediately. This is a feature found in my X5 - as I'm sure it is in every X5 - called "Hill Start Assist". However, if you let the car roll to a stop against a slope without actually stopping it with the brakes, it will not engage the Hill Start Assist & will begin to roll backwards.
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      03-21-2015, 12:18 AM   #8
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Hill start assist is on my E70 and was on my E60 cars as well. But the hill start assist only holds the car for a few moment allowing you to let off the brakes and drive off without rolling backwards.
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      03-21-2015, 09:39 AM   #9
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Quote:
Originally Posted by chrisny View Post
It shouldn't roll back if you apply the brake then let off, it should hold without auto hold on (that's more for stop and go traffic, I believe, as it works even on level ground..). But are you saying you never even applied the brake at all? I'm pretty sure you have to engage the brake at least for a second before it will hold on the hill for you.
What I was saying is I stop in the middle of the hill with break engaged. But when I let go the break, car stays there for about 1 or 2 seconds and begins rolling back almost at constant speed.

I haven't tested how far the car rolls back (because I was scared to hit something in the back), but I think that it would just continue if I don't hit the break.
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      03-21-2015, 09:42 AM   #10
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Quote:
Originally Posted by Wobbles View Post
chrisny is right. If you tap at the brakes to bring the car to a complete stop at a slope, upon removing the foot from the brakes, the X5 should NOT roll back immediately. This is a feature found in my X5 - as I'm sure it is in every X5 - called "Hill Start Assist". However, if you let the car roll to a stop against a slope without actually stopping it with the brakes, it will not engage the Hill Start Assist & will begin to roll backwards.
OK, my car doesn't roll back "immediately". But it starts doing that after 1 or 2 second after break pedal is lifted.
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      03-21-2015, 09:43 AM   #11
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Quote:
Originally Posted by hyde View Post
My guess is, it's part of the fuel saving structure they implemented on F15. I don't remember my E70 rolling back, but then again it's idle rpm was higher compared to F15.

I haven't tested my X5 on a steep hill (how steep are we talking about) but the rollback should actually be limited, I don't think it would continuously roll backwards at a steady speed. I always thought it would compensate the rollback (if it becomes excessive) by adjusting the idle rpm (or un-accelerated D rpm).

I think Auto-Hold is a gift, most of my traffic lights are long, I love being able to just move my feet back and relax like I am sitting my couch and let the vehicle stay where it is without moving about. I didn't use auto-hold for a whole year when I first got a BMW thinking it would spoil me and I would end up rolling and rear-ending vehicles if I got another car without auto-hold.
It was like 5 degree or max 7,8 degree steep. That is about the slope of public parking garage in basement of buildings. Once you test out with yours, would you mind sharing the result here?
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      03-21-2015, 09:55 AM   #12
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Quote:
Originally Posted by 80386i
Quote:
Originally Posted by chrisny View Post
It shouldn't roll back if you apply the brake then let off, it should hold without auto hold on (that's more for stop and go traffic, I believe, as it works even on level ground..). But are you saying you never even applied the brake at all? I'm pretty sure you have to engage the brake at least for a second before it will hold on the hill for you.
What I was saying is I stop in the middle of the hill with break engaged. But when I let go the break, car stays there for about 1 or 2 seconds and begins rolling back almost at constant speed.

I haven't tested how far the car rolls back (because I was scared to hit something in the back), but I think that it would just continue if I don't hit the break.
Definitely should not do that. It should hold a lot longer than 2 seconds. Not as long as auto hold but longer than 2 seconds. The intention is just to hold so you don't roll back when you let off the brake and accelerate, so technically 2 seconds is enough for that.. But I don't ever remember not being held for long enough to also recheck traffic etc, longer than 2 seconds. I honestly can't say I've ever sat long enough for it to disengage, but that in itself says something. I'll check on the F15 to confirm, maybe I've never tried at length with this particular car.
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      03-21-2015, 10:26 PM   #13
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OK, I woke up really early today (it's Sunday here in my neck of the woods), and I thought I'd help 80386i out with his predicament. So, the "official" test results, as verified by Wobbles :

The Hill Start Assist will hold the car from rolling back for 2 - 3 seconds, and after that, it WILL roll back.

At least that's what it does on my car

Hope that helps!
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      03-23-2015, 04:14 PM   #14
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This was scary and I blame you guys.

Quote:
Originally Posted by 80386i View Post
It was like 5 degree or max 7,8 degree steep. That is about the slope of public parking garage in basement of buildings. Once you test out with yours, would you mind sharing the result here?

I got up on a ramp to my parking lot, xDrive status indicated 8 degree incline with total %14.

So I come up half way to ramp, I stop accelerating, without touching the brake pedal I come to a full stop and it starts rolling back, to a point where it rolls back as if it was in Neutral. Then I hear warning chimes and it says secure my vehicle for rolling, and I hit brake. I noticed that the shifter switched to Neutral, it may have done that to prevent damage to drivetrain, but that's extremely unsafe. At that point, if you hit gas, it will keep rolling back and it was rolling pretty fast too.

Once I made the rolling stop, it did not let me switch into Drive. I tried putting it in Park then switching to Drive, did not work either. I had to put it in Park, stop the engine, start the engine again, then it allowed me to shift it into Drive.

I was going to do more tests, but I had someone coming up behind me, and I didn't want to roll back into and possible over them like a giant boulder in Takeshi's Castle.

I will test this again tomorrow by applying brake and coming to a full stop mid-ramp and see if it behaves differently.
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      03-23-2015, 08:14 PM   #15
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Quote:
Originally Posted by hyde View Post
This was scary and I blame you guys.




I got up on a ramp to my parking lot, xDrive status indicated 8 degree incline with total %14.

So I come up half way to ramp, I stop accelerating, without touching the brake pedal I come to a full stop and it starts rolling back, to a point where it rolls back as if it was in Neutral. Then I hear warning chimes and it says secure my vehicle for rolling, and I hit brake. I noticed that the shifter switched to Neutral, it may have done that to prevent damage to drivetrain, but that's extremely unsafe. At that point, if you hit gas, it will keep rolling back and it was rolling pretty fast too.

Once I made the rolling stop, it did not let me switch into Drive. I tried putting it in Park then switching to Drive, did not work either. I had to put it in Park, stop the engine, start the engine again, then it allowed me to shift it into Drive.

I was going to do more tests, but I had someone coming up behind me, and I didn't want to roll back into and possible over them like a giant boulder in Takeshi's Castle.

I will test this again tomorrow by applying brake and coming to a full stop mid-ramp and see if it behaves differently.
That's what I said - if you let it roll to a stop in neutral, the hill start assist will not engage, and you and the guy behind you will have a field day arguing about a fender bender insurance claim

Try it again (when the coast is clear) with depressing the brake pedal in coming to a full stop - and then you'll see the car holds for about 3 seconds
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      03-24-2015, 10:56 AM   #16
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You are right about holding, but no, it doesn't hold for 3 seconds, it's more like 1.5 second, probably because the ramp was too steep.

I tried, it holds just fine and there should be no reason for X5 to roll back if you came to a stop, then let go of the brake, it gives you enough time to hit the gas before it starts rolling even at a %15 incline.

I'll conclude it works as designed, except I have nothing to compare against, if other vehicles actually hold when you never touch the brakes.
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      03-24-2015, 03:49 PM   #17
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Quote:
Originally Posted by Wobbles View Post
OK, I woke up really early today (it's Sunday here in my neck of the woods), and I thought I'd help 80386i out with his predicament. So, the "official" test results, as verified by Wobbles :

The Hill Start Assist will hold the car from rolling back for 2 - 3 seconds, and after that, it WILL roll back.

At least that's what it does on my car

Hope that helps!
Thanks a lot for the verification. That's sorta consistent with what my x5 does to me..
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      03-24-2015, 03:51 PM   #18
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Quote:
Originally Posted by hyde View Post
You are right about holding, but no, it doesn't hold for 3 seconds, it's more like 1.5 second, probably because the ramp was too steep.

I tried, it holds just fine and there should be no reason for X5 to roll back if you came to a stop, then let go of the brake, it gives you enough time to hit the gas before it starts rolling even at a %15 incline.

I'll conclude it works as designed, except I have nothing to compare against, if other vehicles actually hold when you never touch the brakes.
Thanks for the experiment and posting here. I have driven cars with auto transmission for about 15 years but I never experienced this roll back behavior and I thought there is something wrong with my car.
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      03-24-2015, 11:26 PM   #19
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Quote:
Originally Posted by 80386i View Post
Thanks for the experiment and posting here. I have driven cars with auto transmission for about 15 years but I never experienced this roll back behavior and I thought there is something wrong with my car.
I wonder what's the reason for letting it all go. If anything, it should at least apply brakes if the transmission is in Drive and the vehicle starts rolling back. What if driver had a seizure or heart attack while going up hill slowly? A vehicle in D should never roll back that much and that fast.

Maybe we should do some tests in Reverse. I can stop on same steep hill going down, put it in reverse, go back a little then let go of gas to see if it holds or rolls forward under same conditions (1 with Brake applied then let go, 2 with just letting go of gas)
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      03-24-2015, 11:35 PM   #20
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Just a wild thought here, but could it (the rolling back behavior) have anything to do with our new ZF-8 transmissions and the way those things are designed?
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      03-27-2015, 01:53 PM   #21
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On same steep ramp,
In reverse, it actually holds much longer and it rolls forward much slower, takes a lot of roll before it speeds up, although I did not let it roll all the way down until it switches to N.

I also did not hit the gas as much because I don't think the Reverse gear is all that strong in X5.
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      03-31-2015, 04:59 AM   #22
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My x5m50d doesn't roll back and stays that way as long as I want it to. If I dont brake, it slowly rolls forward or stops in a hill, no rolling back. If the engine does auto stop, the car rolls back a few cm, before engine starts, but thats it, auto h not engaged.
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