Seat Belts Tighten Under Hard Braking
Thread Starter
Newbie
Joined: Jan 2018
Posts: 10
Likes: 1
2018 C43
Seat Belts Tighten Under Hard Braking
Hi All,
I had something very unusual happen last week when I took my 2018 C43 Sedan to the race track and I was wondering if it has happened to anyone else before, and if anyone might know what was going on.
On the racetrack at Nola Motorsports, twice, down the front straight under hard braking towards the turn in, this dinging sound comes on, the same warning sound that comes on when you don't wear your seat belt, and, my seatbelt tightened up a lot. Not in the same way as when you get in the car, when it tightens and loosens. This was tight for a while, l think the first time it went on for 3 to 5 minutes, and, the 2nd time may have been even longer.
Just wondering what was going on and if this is a feature I can turn on. Or, is this a warning of some kind? It was under very hard braking, I'd say once every 10 times with the same braking pressure. It never came on when I did not brake aggressively.
I had something very unusual happen last week when I took my 2018 C43 Sedan to the race track and I was wondering if it has happened to anyone else before, and if anyone might know what was going on.
On the racetrack at Nola Motorsports, twice, down the front straight under hard braking towards the turn in, this dinging sound comes on, the same warning sound that comes on when you don't wear your seat belt, and, my seatbelt tightened up a lot. Not in the same way as when you get in the car, when it tightens and loosens. This was tight for a while, l think the first time it went on for 3 to 5 minutes, and, the 2nd time may have been even longer.
Just wondering what was going on and if this is a feature I can turn on. Or, is this a warning of some kind? It was under very hard braking, I'd say once every 10 times with the same braking pressure. It never came on when I did not brake aggressively.
Senior Member
Joined: Nov 2005
Posts: 410
Likes: 176
2020 GLC 63
The car thinks you're going to crash, most likely you were too close to the car in front of you! Besides tightening the belt, it's probably applying more brakes for you too. It happened to me at the AMG driving academy with the E63 and GTS.
Last edited by 18bora; Jan 28, 2018 at 08:24 PM.
MBWorld Fanatic!
Joined: Mar 2017
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From: Omaha, NE
'16 AMG GTS, '21 AMG GLE53
Mostly this. While I never had the belts tighten during my time at Laguna Seca, it commonly happens for me during "extended" ABS braking in the snow. I'm usually stopping from <20mph, but have never had anything in front of me when it happens.
Thread Starter
Newbie
Joined: Jan 2018
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2018 C43
I'm sure there was no car in front of me the 2nd time. It was point and pass and this happened at the end of the straight. I guess it's a safety mechanism?
Thread Starter
Newbie
Joined: Jan 2018
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2018 C43
I have ToyoR888R's I want to try out. I wonder if that will trigger any warnings. It sounds as if it's an emergency feature.
Junior Member
Joined: Oct 2017
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C450
I have a 16' C450 and have had this happen a few times under both extreme braking and when the car detected I was very close to the rear of another car. According to the manual this is enacted by PRE-SAFE, which for the belt "triggers the tightening of the seat belt in hazardous situations." I'm not sure exactly how the car discriminates between various scenarios, but have had it happen where I didn't expect it and vice versa.
Sounds like you were enjoying yourself and driving the car like cars are meant to be driven nonetheless, so thumbs up for that!
Sounds like you were enjoying yourself and driving the car like cars are meant to be driven nonetheless, so thumbs up for that!
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Thread Starter
Newbie
Joined: Jan 2018
Posts: 10
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2018 C43
I have a 16' C450 and have had this happen a few times under both extreme braking and when the car detected I was very close to the rear of another car. According to the manual this is enacted by PRE-SAFE, which for the belt "triggers the tightening of the seat belt in hazardous situations." I'm not sure exactly how the car discriminates between various scenarios, but have had it happen where I didn't expect it and vice versa.
Sounds like you were enjoying yourself and driving the car like cars are meant to be driven nonetheless, so thumbs up for that!
Sounds like you were enjoying yourself and driving the car like cars are meant to be driven nonetheless, so thumbs up for that!
I was having a blast, lots of fun, very quick car.
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Member
Joined: Mar 2017
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C43 Cab
Hi All,
I had something very unusual happen last week when I took my 2018 C43 Sedan to the race track and I was wondering if it has happened to anyone else before, and if anyone might know what was going on.
On the racetrack at Nola Motorsports, twice, down the front straight under hard braking towards the turn in, this dinging sound comes on, the same warning sound that comes on when you don't wear your seat belt, and, my seatbelt tightened up a lot. Not in the same way as when you get in the car, when it tightens and loosens. This was tight for a while, l think the first time it went on for 3 to 5 minutes, and, the 2nd time may have been even longer.
Just wondering what was going on and if this is a feature I can turn on. Or, is this a warning of some kind? It was under very hard braking, I'd say once every 10 times with the same braking pressure. It never came on when I did not brake aggressively.
I had something very unusual happen last week when I took my 2018 C43 Sedan to the race track and I was wondering if it has happened to anyone else before, and if anyone might know what was going on.
On the racetrack at Nola Motorsports, twice, down the front straight under hard braking towards the turn in, this dinging sound comes on, the same warning sound that comes on when you don't wear your seat belt, and, my seatbelt tightened up a lot. Not in the same way as when you get in the car, when it tightens and loosens. This was tight for a while, l think the first time it went on for 3 to 5 minutes, and, the 2nd time may have been even longer.
Just wondering what was going on and if this is a feature I can turn on. Or, is this a warning of some kind? It was under very hard braking, I'd say once every 10 times with the same braking pressure. It never came on when I did not brake aggressively.
Thread Starter
Newbie
Joined: Jan 2018
Posts: 10
Likes: 1
2018 C43
How can I turn the safety features off?
The belt-tightening is definitely caused by extended abs. This has not happend against since those first two times. I’m also a bit easier and earler on the brakes now, along with more familiar with the track.
The warning bells (ding ding ding) definitely come on if I get too close to another car in front of me, especially during breaking. What is pink noise?
I’ll try to post some video’s next time I’m out.
The belt-tightening is definitely caused by extended abs. This has not happend against since those first two times. I’m also a bit easier and earler on the brakes now, along with more familiar with the track.
The warning bells (ding ding ding) definitely come on if I get too close to another car in front of me, especially during breaking. What is pink noise?
I’ll try to post some video’s next time I’m out.
MBWorld Fanatic!
Joined: Nov 2016
Posts: 1,527
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From: Toronto, ON
2021 Mercedes C63s AMG Coupe
This happens when the forward collision camera detects a probable collision infront of you. I was crusing on the highway once when it suddenly tightened the sealtbelt and squeezed the breath out of me and slowed the car down to 10kmh. I was like what the hell just happened? Just 2 seconds later I hear the sound of a massive crash, which happened 6 cars infront of me. So it literally predicted the crash a good 2 seconds ahead of it happening 6 cars infront of me. Never been more glad that I am in a Mercedes.
Also I love the seatbelt hug. Feels like someone cares. Or may be I just need to get myself a girlfriend.
Also I love the seatbelt hug. Feels like someone cares. Or may be I just need to get myself a girlfriend.
