CMBS and Track Use

Dave B

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CMBS stands for Collision Mitigation Braking System which is a Honda safety euphemism for applying brakes automatically when the car determines there is a high risk of rear ending another car or hitting a pedestrian. Obviously on a race track this needs to be eliminated to avoid unexpected braking which can be a disaster for following cars. There seem to be a number of conditions required for the system to work and fortunately (according to the manual, page 488) CMBS is turned off when using VSA fully off by using the long push double beep method.

My Time-Attack series is, quite rightly, very concerned about this issue and I know of some clubs that will not allow cars on track that cannot fully disable this "safety" feature. What is your experience with this while tracking your CTR?
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dwag0588

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I guess I’m not understanding what the issue is. Do the marshalls not believe the system is deactivated? I think it’s actually a very track friendly system. You will always want to be in +R with VSA off for the best times, and the CMBS defaults to disabled in this state. Shouldn’t be a problem. I’m not aware of any circumstances that would allow the system to turn itself back on. You would just need to ensure that you have it fully disabled before beginning a session.
 
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Dave B

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Fortunately, going in to VSA fully off mode stops CMBS from working but it is not rare for newbies to be advised to run with at least some of the "nannies" on. Sudden unexpected braking especially if you are in a train of cars can obviously lead to a real disaster. Not sure if the "pedal dance" stops CMBS.

The issue is more with a few other makes and making sure their similar systems can be fully disabled. I wanted to make sure there was no issue with the CTR
 

MadMage

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There is a switch, on the left side of the steering wheel. In the same cluster as the VSA switch. Press it, and it turns off CBMS regardless of VSA status.
 
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Dave B

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Thank you MadMage. I was aware of the switch but have concerns re some drivers not turning it off before going on track. BTW, do cheaper Honda products have the same option and what year did it start? Apparently for some BMWs it is quite difficult to turn off.
 


Shred

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It's becoming standard on most Hondas, varying by country. It became standard in 2020 for the Type R after becoming standard in 2019 for all other Civics in the US for example but I believe the Euro spec Rs have always had it as an option.

BMWs are probably an all or nothing deal- you can't disable rev matching without turning off traction so I'd imagine the safety stuff is the same. Haven't driven any, and not a beemer guy. Just going off reviews so disclaimer in case I'm wrong.
 

haltamer

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As a practical suggestion, The CMBS Relies on both the camera and radar working - As a visible proof that the system is not active, you could cover the camera sensor with some (Brightly coloured) tape which would allow everyone to see that the system would not be able to function.

That would trip the DTC for "Camera obscured by dirt" and give you a clean sensor error on the dash, whilst disabling the LKAS / ACC / CMBS etc.

Peel off at the end of the day, and wipe off any adhesive residue, and you're ready to go.

That also allows you to run with the car in modes other than VSA Full off, should you desire.
 

MadMage

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but have concerns re some drivers not turning it off before going on track
I don't know how a track organization deals with this. It's certainly not a CTR only issue. Next to me at the paddock last moth was a brand new Audi sedan. I had no doubt that it had all sorts of nannies. Who knows if the driver knew to turn them off? Or all the other cars out there that have similar systems?

At what point does good faith / reasonable effort end and the organization have to rely upon each driver knowing what and how to do to prep their car for the track?

I don't have enough experience to answer that.
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