TimLee
Gold Member
Posts: 2130
Joined: Thu Jan 20, 2011 9:40 am
Delivery Date: 17 May 2011
Leaf Number: 2026
Location: Chattanooga, TN

Re: Grabby Brakes?

Wed Dec 26, 2012 10:41 pm

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.

Tim Lee
Chattanooga, TN

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

mrdcmills
Posts: 61
Joined: Wed Sep 26, 2012 10:25 am
Delivery Date: 15 Oct 2012

Re: Grabby Brakes?

Thu Dec 27, 2012 9:44 pm

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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SeattleBlueLeaf
Posts: 411
Joined: Mon Jul 05, 2010 9:34 pm
Delivery Date: 19 Jan 2011
Leaf Number: 0228
Location: Seattle, WA
Contact: WLM Yahoo Messenger AOL

Re: Grabby Brakes?

Wed Jan 02, 2013 5:38 pm

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).

SeattleBlueLeaf
Ocean Blue LEAF Delivered: 1/19/11
EV Project participant

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EVDRIVER
Posts: 5508
Joined: Sat Apr 24, 2010 7:51 am

Re: Grabby Brakes?

Wed Jan 02, 2013 6:11 pm

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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TomT
Posts: 9938
Joined: Sun Aug 08, 2010 12:09 pm
Delivery Date: 01 Mar 2011
Leaf Number: 000360
Location: Foothills of Granada Hills, CA
Contact: Website

Re: Grabby Brakes?

Wed Jan 02, 2013 6:29 pm

+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.
SL-e with 59,983 miles/8 bars/187 Gids/43.47 AHr/66% SOH/45.19% Hx 13Mar15.

59,991 miles/12 bars/289 Gids/68.54 AHr/101% SOH/101.64% Hx 7May15 with new Lizard battery.
62,141 miles/12 bars/276 Gids/66.14 AHr/100% SOH/102.58% Hx 11Jul15.

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GeekEV
Posts: 1824
Joined: Tue Jan 18, 2011 4:11 pm
Delivery Date: 15 Feb 2011
Leaf Number: 0308
Location: NorCal, USA

Re: Grabby Brakes?

Wed Jan 02, 2013 8:38 pm

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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SanDust
Posts: 1363
Joined: Fri Aug 06, 2010 10:54 am

Re: Grabby Brakes?

Mon Jan 07, 2013 6:50 pm

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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EVDRIVER
Posts: 5508
Joined: Sat Apr 24, 2010 7:51 am

Re: Grabby Brakes?

Mon Jan 07, 2013 7:08 pm

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.

robinsone1706
Posts: 3
Joined: Wed Jul 11, 2012 1:25 pm
Delivery Date: 07 Aug 2012

Re: Grabby Brakes?

Fri Feb 22, 2013 6:54 am

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

robinsone1706
Posts: 3
Joined: Wed Jul 11, 2012 1:25 pm
Delivery Date: 07 Aug 2012

Re: Grabby Brakes?

Fri Feb 22, 2013 6:57 am

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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