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BMW 5-Series (G30) Forum 2017+ BMW 5 Series (G30) General Discussions What is the purpose of the seat belt tightening right after we start driving?

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      12-26-2018, 11:22 PM   #23
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Quote:
Originally Posted by Warp Ten View Post
Quote:
Originally Posted by djrobx View Post
At least on my car, this pre-tension feature sometimes doesn't let go (maybe 1 out of 5 times, enough that a dealer will probably tell me it's normal). Then I have to struggle against it before I can move around normally. All of my other past vehicles have worked fine without this feature, so I'm willing to roll the dice if there's some way of stopping this truly obnoxious behavior.

I don't mind the "tug" when it lets go, but I can't stand it when it doesn't.
Haven't had that experience. Mine just tugs once then the belt is loose. In fact, that is really what prompted me to raise this question in the first place; since it remains loose afterward, what is the point of the initial tug? Other cars don't do the tug yet pass all the same safety mandates. If yours doesn't release on occasion, I would think a dealer look would be a good idea. Even if they say it is normal, good to get your concern on record. It is an important part of the safety system after all and it sounds like it is not working entirely correctly. You could pose the issue by suggesting that if it not working in this regard, who knows if it will work in an accident? --Bob
The tug is simply there to remove any slack that may be in the seatbelt. If the belt is already on tight enough the tug is redundant, however if there is some slack in the belt the tug will reduce it, so if the explosive tensioner go off ( in the event of a serious accident) then they will provide better protection.
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      12-27-2018, 03:28 PM   #24
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I have a UK car and the belt doesn’t tension. Should it?
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      12-29-2018, 10:38 AM   #25
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Quote:
Originally Posted by Symo View Post
The tug is simply there to remove any slack that may be in the seatbelt. If the belt is already on tight enough the tug is redundant, however if there is some slack in the belt the tug will reduce it, so if the explosive tensioner go off ( in the event of a serious accident) then they will provide better protection.
That makes sense, but I would have thought that the spring loading in the belt system would be enough for that. As I noted earlier, other cars don't seem to have the need to do this. But in the end I will just live with it. It is not really a big deal for me,more a minor annoyance. --Bob
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      12-29-2018, 06:13 PM   #26
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Quote:
Originally Posted by Warp Ten View Post
Quote:
Originally Posted by Symo View Post
The tug is simply there to remove any slack that may be in the seatbelt. If the belt is already on tight enough the tug is redundant, however if there is some slack in the belt the tug will reduce it, so if the explosive tensioner go off ( in the event of a serious accident) then they will provide better protection.
That makes sense, but I would have thought that the spring loading in the belt system would be enough for that. As I noted earlier, other cars don't seem to have the need to do this. But in the end I will just live with it. It is not really a big deal for me,more a minor annoyance. --Bob
Quote:
Originally Posted by Warp Ten View Post
Quote:
Originally Posted by Symo View Post
The tug is simply there to remove any slack that may be in the seatbelt. If the belt is already on tight enough the tug is redundant, however if there is some slack in the belt the tug will reduce it, so if the explosive tensioner go off ( in the event of a serious accident) then they will provide better protection.
That makes sense, but I would have thought that the spring loading in the belt system would be enough for that. As I noted earlier, other cars don't seem to have the need to do this. But in the end I will just live with it. It is not really a big deal for me,more a minor annoyance. --Bob

I agree however a spring would apply constant pressure that would get real old real quick. The tug is applied and relaxed.

I can understand that it would be annoying to some and that's ok. But i like that it does it.
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      12-30-2018, 05:03 AM   #27
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Quote:
Originally Posted by 2424 View Post
I have a UK car and the belt doesn’t tension. Should it?
It probably does but you might not feel it. Generally, I don't feel it either unless I try to move at the same time as putting on the seat belt.
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      12-30-2018, 07:05 PM   #28
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If I paid for it, i like it!
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      12-30-2018, 09:28 PM   #29
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After a few months you get used to it and hardly notice anymore.
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      01-15-2019, 02:35 PM   #30
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I was certainly surprised when I first drove my car with the pre-tensioner, but I have grown to like it very much. It gives me a feeling of safety and I miss not having it in other cars.

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      01-16-2019, 04:44 PM   #31
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Quote:
Originally Posted by ADS-UK View Post
It probably does but you might not feel it. Generally, I don't feel it either unless I try to move at the same time as putting on the seat belt.
It's unmistakable in the 7er you can really feel it pulling you back, I find it annoying sometimes.
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      01-17-2019, 08:57 AM   #32
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I like it in my G30. I feel like it's giving me a hug and saying hello every time we set off.
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      03-25-2020, 12:12 AM   #33
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Disable Pretensioner?

Quote:
Originally Posted by otistarda View Post
This „feature“ is annoying. I‘ve had the feature disabled.


Regards, Otis
How did you have the feature disabled? I'm 6' 5" so it's really annoying for me.

Thanks
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      03-28-2020, 10:43 PM   #34
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Turns out this is an option in the UK and other markets.

Perhaps it's standard on all US cars?

Found a description from the BMW UK site:

£280
Dynamic Safety

Dynamic Safety warns the driver if it detects signs of tiredness and initiates protective measures if an accident is imminent. The system is activated after the engine is started and the front seat belts are automatically slightly tensioned when the car starts moving. In a critical driving situation such as emergency braking, or if the vehicle demonstrates excessive understeer or oversteer, the front seat belts are pre-tensioned, the side windows and sun roof (if fitted) are closed and the passenger seat backrest is returned to the upright position (if fitted with electric seats). Reduced belt tensioning provides increased driving comfort. If a crash is unavoidable, the system brakes the car, without requiring intervention by the driver, until the vehicle reaches a standstill. This helps reduce the likelihood of a second or subsequent collision, and or reduces the effects thereof - or in the best case scenario could prevent a further collision altogether.

The Attentiveness Assistant also recognises if the driver is displaying signs of increasing inattentiveness or tiredness. This system analyses the steering response and reacts to irregular driving behaviour by issuing a message in the Control Display suggesting that the driver should take a break and emitting an acoustic signal.
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      03-30-2020, 07:29 AM   #35
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As an aside to this, I attended an M School and got a lot of driving time in the M5 Competition. One surprising aspect is how it tightened the seat belts upon hard driving actions, especially threshold braking. They would get even more tight the next lap doing the same thing. It was great for holding you in-place during hard maneuvering but became suffocating to me. It was easy to release but would re-tighten the next lap!

I assume the standard G30 5 Series does this but the car doesn't pull nearly the same G's as the M5.
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