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 Post subject: Re: Grabby Brakes?
PostPosted: Wed Dec 26, 2012 10:41 pm 
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Joined: Thu Jan 20, 2011 9:40 am
Posts: 1353
Location: Chattanooga, TN
Delivery Date: 17 May 2011
Leaf Number: 2026
I had NTB 12-086 installed at Mountain View Nissan in Chattanooga on 12-17-2012, first install of it they had done.
No problems, done in less than two hours, done under warranty at no charge.
After driving the vehicle for five days (~100 miles), my opinion is that the change is modest. A bit smoother brake activation more similar to an ICE with no regenerative braking. Bit less grabby / abrupt.
I have never experienced the other condition that some have reported of a significant excessive braking until the brake pedal is fully released on my fairly early production 2011 LEAF. I think that is a separate issue from what many consider to be "grabby brakes".
Since the software change, I have yet to end up stuck in slow bumper to bumper traffic jam that would probably be the more complete test of the software change.
It is my opinion that a big part of the "grabby brake" issue on the LEAF is due to the excessive "creep" built into the motor control. I have never driven an ICE vehicle with an automatic transmission that moves forward this much when you take your foot off the brake. On level ground most ICE vehicles will hardly even move forward when you take your foot off the brake.
An ICE might gradually move forward at 1 to 2 feet per second. In comparison the LEAF will move forward at more like 5 feet per second. It has way too much creep.
The only ICE vehicle I ever drove that had issues with forward movement when you took your foot off the brake was a 1988 Merkur Scorpio built in Germany. When engine idle was working properly, it would not move forward at all with your foot off the brake. But it had a defective Throttle Position Sensor, and I did experience one dangerous event in which engine speed swung low, and engine control in responding to this had a bad inadequately damped response and raised engine speed to near 1200 rpm, and it abruptly lunged forward at about 10+ feet per second. I'm still of the opinion that most of the Audi unintended acceleration issue was caused by a similar issue. But the few horrific accidents which occurred resulted mostly from the driver hitting the accelerator pedal instead of the brake when this occurred.
The LEAF would be a much better vehicle if Nissan significantly reduced the amount of built in "creep" in the LEAF, or eliminated it entirely.
It would make for much smoother, easier, and safer driving in very low speed / stopped situations such as fast food drive throughs, drive through car washes, or in backed up bumper to bumper traffic jams.
I do not consider NTB 12-086 an adequate complete fix for the "grabby brakes" issue on the LEAF.

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Tim Lee
Chattanooga, TN

Man. Date: 03/10/11, VIN # 2026
Delivered 05-17-2011
Blue Ocean, 2011 SL-eTec


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 Post subject: Re: Grabby Brakes?
PostPosted: Thu Dec 27, 2012 9:44 pm 
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Joined: Wed Sep 26, 2012 10:25 am
Posts: 60
Delivery Date: 15 Oct 2012
I think it's OK. If I'm in traffic and let it roll with my foot on the brake it's very touchy the second or third time you step on it. If you totally release it and roll at least 3-4 seconds it feels fine.


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 Post subject: Re: Grabby Brakes?
PostPosted: Wed Jan 02, 2013 5:38 pm 
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Joined: Mon Jul 05, 2010 9:34 pm
Posts: 410
Location: Seattle, WA
Delivery Date: 19 Jan 2011
Leaf Number: 0228
I didn't even know about the update for the brake issue but I just brought my LEAF for it's 2 year check in and noticed improvements with the brakes.

For those that care - 20k miles on my Seattle based LEAF with ~20 QC's under the belt and no noticeable drops in battery capacity. (No 3rd party meter installed though to see GUID).

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Ocean Blue LEAF Delivered: 1/19/11
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 Post subject: Re: Grabby Brakes?
PostPosted: Wed Jan 02, 2013 6:11 pm 
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Joined: Sat Apr 24, 2010 7:51 am
Posts: 5349
After almost two years with my car I had the first slow speed braking issues similar to what is described. My pedal even felt different at times.


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 Post subject: Re: Grabby Brakes?
PostPosted: Wed Jan 02, 2013 6:29 pm 
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Joined: Sun Aug 08, 2010 12:09 pm
Posts: 9285
Location: Foothills of Granada Hills, CA
Delivery Date: 01 Mar 2011
Leaf Number: 000360
+1

TimLee wrote:
The LEAF would be a much better vehicle if Nissan significantly reduced the amount of built in "creep" in the LEAF, or eliminated it entirely.
It would make for much smoother, easier, and safer driving in very low speed / stopped situations such as fast food drive throughs, drive through car washes, or in backed up bumper to bumper traffic jams.

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SL-e with 55K miles/9 bars/195 Gids/45.72 AHr/69% SOH/48.88% Hx on 22Nov14. Ordered 9/1/10 (Fontana Nissan).


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 Post subject: Re: Grabby Brakes?
PostPosted: Wed Jan 02, 2013 8:38 pm 
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Joined: Tue Jan 18, 2011 4:11 pm
Posts: 1794
Location: NorCal, USA
Delivery Date: 15 Feb 2011
Leaf Number: 0308
I've noticed the issue seems to be coming back in the colder weather. Not quite as bad as before, but definitely happening again. Has anyone else noticed this?

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 Post subject: Re: Grabby Brakes?
PostPosted: Mon Jan 07, 2013 6:50 pm 
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Joined: Fri Aug 06, 2010 10:54 am
Posts: 1363
GeekEV wrote:
I've noticed the issue seems to be coming back in the colder weather. Not quite as bad as before, but definitely happening again. Has anyone else noticed this?
I haven't had the software upgrade applied but I've noticed that the problem seems worse when it's wet. Where I am when it's wetter it's usually also colder.


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 Post subject: Re: Grabby Brakes?
PostPosted: Mon Jan 07, 2013 7:08 pm 
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Joined: Sat Apr 24, 2010 7:51 am
Posts: 5349
My first instance happened when it was the coldest and I noticed the braking is different for the first time in almost 2 years. Seems odd it just started.


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 Post subject: Re: Grabby Brakes?
PostPosted: Fri Feb 22, 2013 6:54 am 
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Joined: Wed Jul 11, 2012 1:25 pm
Posts: 3
Delivery Date: 07 Aug 2012
It appears that everyone started having these issues around the same time. It appears to not matter how long you've owned the Leaf or how many miles you've put on it. What does this tell me? They beamed down a software update for the smart brake controller via CarWings to increase the regen efficiency in an attempt to extend the range of the Leaf.

Cold weather has no effect in my Leaf. The grabby brake issue occurs at all temperatures and at all speeds for me, but especially at low, creeping speeds. You look like an idiot at stop lights and drive thru windows because it looks like you're slamming on the brakes. At highway speeds, I notice the issue when lightly pressing the brake pedal to maximize the amount of regen. The brakes feel like they are pumping at a frequency of about 2 per second. Then once the speed drops below 15mph it's almost like the brakes let go suddenly (maybe the disc brakes are taking over at this point).

I also notice an audible clicking noise (sounds like an electrical relay switch) when I begin to lift my foot off the brake pedal.

Does anyone know if Nissan field quality engineers read these forums?

2012 Nissan Leaf SL (black)
15,000k miles
Nashville, TN


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 Post subject: Re: Grabby Brakes?
PostPosted: Fri Feb 22, 2013 6:57 am 
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Joined: Wed Jul 11, 2012 1:25 pm
Posts: 3
Delivery Date: 07 Aug 2012
I should also mention that I had the Nissan Technical Bulletin performed on my Leaf with zero success. I am still experiencing the same braking condition...maybe even worse now.

robinsone1706 wrote:
It appears that everyone started having these issues around the same time. It appears to not matter how long you've owned the Leaf or how many miles you've put on it. What does this tell me? They beamed down a software update for the smart brake controller via CarWings to increase the regen efficiency in an attempt to extend the range of the Leaf.

Cold weather has no effect in my Leaf. The grabby brake issue occurs at all temperatures and at all speeds for me, but especially at low, creeping speeds. You look like an idiot at stop lights and drive thru windows because it looks like you're slamming on the brakes. At highway speeds, I notice the issue when lightly pressing the brake pedal to maximize the amount of regen. The brakes feel like they are pumping at a frequency of about 2 per second. Then once the speed drops below 15mph it's almost like the brakes let go suddenly (maybe the disc brakes are taking over at this point).

I also notice an audible clicking noise (sounds like an electrical relay switch) when I begin to lift my foot off the brake pedal.

Does anyone know if Nissan field quality engineers read these forums?

2012 Nissan Leaf SL (black)
15,000k miles
Nashville, TN


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