Brakes "mutate" to become grabby in stop & go traffic?

[FairwoodRed]

Somewhere I read this was related to some intentional "brake assist" feature, which is apparently a safety feature to help people avoid accidents in some sort of panic stop situation. Perhaps the "algorithm" is just a little too eager to engage the feature.

The service manual describes how the electric braking force motors will sense the brake pedal position and generate pressure on the brake fluid to match the intended braking force. In the event of a failure, you have to depress the pedal a lot before any braking force is generated by the pedal. Said another way, usual braking is 100% electronic with manual backup and based on whatever formula/table that Nissan is using.

Electronic Braking is more apt than Brake Assist.

 

[TEG]

Electronic Braking is more apt than Brake Assist.

http://www.nissanusa.com/leaf-electric-car/specs-features/index#/leaf-electric-car/specs-features/index" onclick="window.open(this.href);return false;

brakes

* 4-wheel power-assisted vented disc brakes
* regenerative braking system
* 4-wheel Anti-lock Braking System (ABS)
* Electronic Brake force Distribution (EBD)
* Brake Assist (BA)
* electronic parking brake

http://youtu.be/f-6HHoBm2yw?t=1m18s" onclick="window.open(this.href);return false;

"If the driver applies the brake pedal very fast, but not quite hard enough for full stopping power, brake-assist will release a burst of pressure into the braking system to help the vehicle come to a stop."

I think it has to do with "jabbing" the brake pedal quickly, but not pressing it all the way down.

 

[GeekEV]

Perhaps, but then it STAYS grabby until you fully release the brakes. I'm pretty sure I don't stab the brakes, but that could be the trigger. I am, however, sure that I don't continue to do it every time after that when it continues to be grabby.

 

[OrientExpress]

The grabby brake thing seems to have been fixed in the latest software update.

 

[FairwoodRed]

http://youtu.be/f-6HHoBm2yw?t=1m18s" onclick="window.open(this.href);return false;

"If the driver applies the brake pedal very fast, but not quite hard enough for full stopping power, brake-assist will release a burst of pressure into the braking system to help the vehicle come to a stop."

I love this quote and I hadn't seen it before. I'm gonna try to pay more attention to how fast I engage the brake to see if I can find a corralation. Thanks.

 

[turbo2ltr]

I think it has to do with "jabbing" the brake pedal quickly, but not pressing it all the way down.

hmm..

http://www.mynissanleaf.com/viewtopic.php?p=176176#p176176" onclick="window.open(this.href);return false;

I have no updates to my car.

 

[IBELEAF]

actually, I haven't noticed grabby brakes with latest update either... time will tell

 

[DeaneG]

"Brake Assist" is there to make sure the brakes are locked on in a panic stop. Many people let off the brakes near impact. Brake Assist won't come into play unless you slam on the brakes as if a kid had run out into the street just in front of you.

 

[derekjsmith]

The grabby brake thing seems to have been fixed in the latest software update.

No I had ours updated two weeks ago and have the same issue with the brakes. As I think many have pointed out it has to do with the brake assist and anti-lock.

My background is a professional driver, high performance driving instructor on and off the track for some 25+ years Proformace Racing School. So my braking method is different than the average driver. For on track you go to the brakes quickly, firmly, then release as needed but never fully release until you are done with very little modulation. Using this method on the Leaf will case the brake assist to over boost if you try to modulate before a full release. The only way I have found to get it to reset is to fully release the brakes for a couple of seconds.

I think what is happening is the brake assist sees I went to the brake quickly and firmly but did not activate the ABS so that sets up the first condition, did I intend to activate the ABS or not. Then if I modulate the brakes again not activating the ABS and not fully releasing the brake assist thinks yes I did really mean to get into the ABS and it goes into over boost mode. The braking system thinks it knows better and I really needed or meant to activate the ABS in a panic stop so it will over boost to get the car stopped even without getting into the ABS.

I have to adjust my driving style a bit when driving the Leaf. I find that if I don’t get into the brakes quickly kind of drive the car lazily it does not happen.