Scary braking problem

ABS on my Camry saved my butt a couple of times when someone pulled out in front of me suddenly. I barely avoided an accident both times. I am pretty sure I couldn't have stopped in time without the ABS.

BrendanDolan said:

<snip>Just remember, ABS does in no way reduce your stopping distance, and a correctly driven, you can threshold brake a non ABS car to shorter stopping distances (and I threshold brake ABS cars when I need to get with the stopping program in a hurry).<snip>

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I have to agree.My 1982 Toyota Starlet does not have ABS, but the company vehicles I drove while
I was working did. I only invoked the ABS once, in a parking lot. The one time I was in a panic stop
situation on the freeway I was able to threshold the brakes and stop about 1/2 car length before
hitting the car in front of me. (Unfortunately the one behind me did not. ) I think I was able stop the
van about as fast as it could be stopped and maintained control the whole time.

I learned how to threshold, steer a skid, and all sorts of other things playing on wet grass or snow
out in the grasslands of South Dakota. Everyone should "play" in a safe situation, where there is
nothing/no one to hit, even if you can't do the professional driver school.

With those experiences, the very first time, in my teen years, that I hit the brakes on snow and started
to slide off the road, it took just a second or two for me to understand that I had to take my foot off
the brake to allow the wheels to turn and steer back onto the roadway. I now drive around here when
it snows and see lots of 4WD SUVs with ABS in the ditch while my little Starlet is still on the road and
getting around.

Long story short - The most important piece of safety equipment sits in the drivers seat.

highcountryrider said:

Long story short - The most important piece of safety equipment sits in the drivers seat.

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Absolutely true. In performance driving there is a corollary saying: "The first thing to upgrade on your car is the big nut behind the steering wheel."

TT

Just to reiterate...

mogur said:

Also, threshold braking can not compensate for tires with differing coefficients of friction due to different road surfaces, etc.; Four channel ABS can. For 99.4% of drivers and situations, ABS will be better and stop quicker.

BrendanDolan said:

Threshold braking takes a ton of practice, which is why most people were taught to pump the brakes (lock, unlock, lock, unlock).

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highcountryrider said:

Long story short - The most important piece of safety equipment sits in the drivers seat.

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ttweed said:

Absolutely true. In performance driving there is a corollary saying: "The first thing to upgrade on your car is the big nut behind the steering wheel."
TT

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I've been trying for years to tighten that loose nut behind my steering wheel!

I think mine is stripped! :lol:

aqn said:

I've been trying for years to tighten that loose nut behind my steering wheel!

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Problem is, the stud is metric and my nut is SAE! :lol:

mogur said:

I think mine is stripped! :lol:

aqn said:

I've been trying for years to tighten that loose nut behind my steering wheel!

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Careful - you can get arrested for driving like that

I just experienced the behavior describe. In a panic stop situation the car continued to brake hard after the brake pedal was released for a 1/2 second or so. This was not normal behavior and potentially very dangerous. Has anyone that experienced this had any results/explanation from the dealers? I came upon this forum via Google looking to see if this was a known issue and it appears it is. We just got the Leaf (last month), 2011 SL model and are in one of the foresaken states - so we will have to trailer and haul the car a few hundred miles to have this issue looked at by a "authorized" dealer.

I talked to my dealer about this back in August. They gave me a loaner to drive while they worked on it for a couple of days. They were able to duplicate the issue with my car, but not with their demo. They suspected the ABS controller, etc. and were ready to start replacing parts until Nissan corporate told them that the action was a normal function of the brake assist and not to replace any parts. Reluctantly, my dealer called to have me return the loaner and pick up my car. They were very appologetic about not being able to fix the issue and suggested that I contact Nissan customer service to elevate the issue and try to get some action. I eventually called customer service in December to elevate this issue and ask how to keep the heater from coming on while still having forced ventilation. The representative I talked to worked on these issues for several days and kept calling me with updates. Eventually, she had to tell me the corporate answer that this is a normal function of the brake assist system. Although I have not yet done so, I intend to report it to NHTSA to get it into their database.

Before taking my car to the dealer, I did enough testing in a safe area to make some observations about the brake assist system action. I found that the brake assist system seems to function differently if it becomes engaged at higher speeds (say over 50 or 55 miles/hour) than it does when it becomes engaged at lower speeds. If engaged at lower speeds, the brake assist will release the brakes 1/2 second or so after the driver releases the brake pedal. If engaged at higher speeds, the brake assist will keep the brakes applied until the car comes to a complete stop. I also found that the brakes will release immediately when the accelerator pedal is depressed (even slightly) regardless of the speed at which the brake assist becomes engaged.

Gerry

GerryAZ said:

If engaged at lower speeds, the brake assist will release the brakes 1/2 second or so after the driver releases the brake pedal. If engaged at higher speeds, the brake assist will keep the brakes applied until the car comes to a complete stop. I also found that the brakes will release immediately when the accelerator pedal is depressed (even slightly) regardless of the speed at which the brake assist becomes engaged.

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Great information, Gerry. Thanks for sharing. Strange that the demo didn't exhibit the same behavior if this is actually a feature. You should suggest that the dealer inquire with Nissan about getting the demo fixed, and see what they say.

Although I would prefer that the car simply do exactly what I tell it, I can imagine situations where this could be useful. I was once coming towards someone travelling in the opposite direction & waiting to make a left turn. The person behind (older woman) wasn't paying attention, slammed on the brakes too late & rear-ended that car. But after doing so, she went into shock, had her hands over her face, and her car continued to drift into the other lane, towards me. It would have been nice in that situation if her car had just continued to brake.

Gerry thanks for the info. That is a bit disturbing about how the brakes behave and Nissan's response. We have been very happy with the car, but that one incident was scary. In our case it was at low speed, under 30 and we nearly came to a stop before the brakes released. I'll file a report with both Nissan and NHTSA as well. For those who say this could be a good thing, you are very much mistaken. This was NOT good - we were very lucky the car behind us wasn't following too close. It is a defect and not a feature - a 1/2 second delay in any response is an eternity during a emergency situation.

I don't believe this to be true, and if true by design, would be very dangerous behavior. The brakes on my Leaf definitely do not exhibit this behavior (beyond the aforementioned grabby attitude at very slow speeds). When you take your foot off the brakes after a dramatic application that triggers brake assist, they release, albeit perhaps not immediately. I've also not driven any other vehicle with brake assist that exhibited such a behavior of keeping the brakes applied to a full stop, nor do I believe they should.

GerryAZ said:

If engaged at higher speeds, the brake assist will keep the brakes applied until the car comes to a complete stop.

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This "Brake Assist" braking behavior needs to be triggered by "very abrupt", "sudden and strong", or "essentially panic" application of the brakes (enough to normally make your LEAF skid, or lock the wheels, on dry pavement), right?

Does it work any differently on wet pavement, on snow, or on ice?

GerryAZ said:

If engaged at higher speeds, the brake assist will keep the brakes applied until the car comes to a complete stop.

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I'm not liking this behavior at all. I've avoided more than a few nasty crashes by slamming on the brakes coasting a fraction of a second to get the wheels rolling, turning, then hitting the accelerator. If the wheels lock/virtually lock until the car stops or I hit the accelerator this means (1) the ABS isn't working consistently and (2) there will be some situations where I won't get my wheels turning for an extra 1/2 sec.

The car should react to my commands, if I'm a bad driver so be it. If the car is going to do things on it's own 'because it knows better' that is going to cause some accidents, especially since I have a lot more sensors than the car does and probably have a much better idea of what is really happening. Jeez I hope this doesn't happen if someone pumps the brakes, they could easily loose control of the car or get rear-ended when the car behind them freaks out that the car in front of them stopped for no reason.

When I release the brakes the brakes should cease functioning, end of story. If this is reproducible it should be reported to the NHSTA immediately! Fortunately the fix should just be a firmware upgrade.

I too have experienced this same situation. In my case I was traveling about 35 mph down a 4 lane road next to a jacked up ford F250 who decided to come into my lane. I stomped on the brake, activating the ABS. As soon as my front end was behind his bumper, I lifted my foot off the brake so as to avoid being hit from behind. But as others have experienced, the car continued to brake on it's own until the Leaf came to a complete stop.

Luckily the car behind me was far enough back to stop before hitting me, but it was a very disconcerting situation. I didn't press the accelerator but I'll try to remember to do that if the situation come up again.

Still I wish Nissan would correct this to make the car work like every other car on the road. The brakes should disengage once the break peddle has been released, no matter what has happened prior to the brake release.

Dave

I have not experienced this since I first posted about it a while back. It happens under very specific circumstances, as said above, you have to hit the breaks suddenly, something that the dealer could not duplicate after screeching around their parking lot, it really takes a real panic reflex for it to trigger. it does not lock up the wheels and skid per say, but it does bring the car to a stop rapidly. It's disconcerting to experience to have but not worth worrying about.

You can maybe get another 1000 miles or so, but you really should plan on getting a brake job soon!

LTLFTcomposite said:

You can maybe get another 1000 miles or so, but you really should plan on getting a brake job soon!

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:lol: :lol:

I always wondered what those cooling ribs inside the disk looked like! Now I know! :shock:

The Leaf brakes do seem to have an issue or two. There is a another well-reported problem in situations where you ride the brake at minimal speed (like creeping forward in traffic). The brakes can get very, very sensitive, locking hard with minimal pedal movement. Releasing the brake completely seems to reset whatever is going on. Despite claims of successful workarounds no one ever figured out why this happens or how to permanently fix it.

I don't know if these two issues are related but they do have the common thread of the Leaf braking excessively hard. Personally I think there is some programming or calibration errors that happen in unusual situations. I would encourage you to pursue this so hopefully Nissan will finally take a hard look at the Leaf braking system and fix these issues.

By the way this has nothing to do with regen as its braking power is not significant compared to the force of the physical pads.