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Discussion Starter #1
Hi all,

How smooth is your braking? I'm not sure what I'm experiencing in normal, and so I wanted to get your experiences. Basically, braking for me is smooth as I come to a stop --- EXCEPT, sometimes, when it gets to about 5MPH or less, I notice 3 light jerks before it smooths out again. (My wife described the braking as jerky... thump, thump, thump.) It doesn't always happen, but just sometimes... enough for me to wonder if I should get this checked out.

Is this normal?

Thanks in advance.
 

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That is not my experience. My braking is smooth, with a light (normal) vibration at the end until I fully/firmly depress the pedal.

Have it checked.
 

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Assuming you're not braking hard, about 5 miles or less would be when the friction brakes engage. I'd try finding a bit of open road and trying a few emergency stops: maybe there's just dirt or rust or something on the brake pads that needs clearing. If that doesn't help then definitely get them looked at.
 

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I believe there are a number of threads regarding brake topics. I notice a slight "vibration" at about 5 mph as the regen is replaced with friction on the rotors. Check out the other threads as there have been some software upgrades to the braking system to alleviate some of the transitionary vibration owners were experiencing. Steverino has good advice, it's probably normal - but brakes are not something to ignore - so have them checked to be safe..
 

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I'm pretty sensitive to brake feel, being an amateur race driver, and the braking on my Volt is totally smooth down to zero MPH. If clearing the disks and pads with a few hard stops doesn't work, call your Volt Advisor then probably take it into the dealer to be checked out.
 
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Hi all,

How smooth is your braking? I'm not sure what I'm experiencing in normal, and so I wanted to get your experiences. Basically, braking for me is smooth as I come to a stop --- EXCEPT, sometimes, when it gets to about 5MPH or less, I notice 3 light jerks before it smooths out again. (My wife described the braking as jerky... thump, thump, thump.) It doesn't always happen, but just sometimes... enough for me to wonder if I should get this checked out.

Is this normal?

Thanks in advance.
Good Morning Ehenyo,

Sorry to hear about your brakes. If you would like to PM me your contact info and last 8 of your VIN we can look into this for you.

Take Care,

-Ian Chevrolet Volt Customer Service
 

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As others have said, it's the transition point from regenerative braking to traditional friction (disc) brakes. If you're feeling it through the pedal, I'd call it normal. If the whole car is jerking, then it's not.

Hybrids don't have conventional brakes systems due to a) the regen ability previously mentioned and b) the gas engine (ICE) being off much of the time. Conventional brake systems use vacuum pressure from the ICE to power the master cylinder hence the old marking term "power brakes". Hybrids use electric pumps to power and prime the brake system and this is what is occasionally felt through the pedal.
 

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If it is wet out, when switching from regen to regular brakes and if the road is slippery or you hit a painted line on the road or a manhole cover etc, you can activate the anti-lock brakes. That will give you a pulsing and noisy brake feeling for certain. Also, in this case too, the regen will "kick out" giving you a moment of no brakes until you push harder to activate friction braking.

This can happen in dry weather too but certainly not as often.

When braking a little harder than usual, as in a sudden or quick stop, the brakes can feel a bit clunky as it tries to regen but then brake force assist kicks and/or friction brakes apply and that will cause a different than usual brake feeling.

In all other cases, you should "barely notice" the transition to friction from regen and it is usually when you are almost stopped when friction kicks in under normal braking conditions.

If none of these situations fit your experience, you could have a problem.
 

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Discussion Starter #11
Thanks, everyone. "Pulsing" sounds like a better description (maybe that's why I didn't find a proper thread?), but sometimes the whole car pulses forward gently --- like a Jr. version of stalling a stick-shift car. And, always 3 times. Other times, I do feel it in just the pedal. In both cases, I brake lightly all the way to the stop, and I haven't fully pressed the pedal all the way down.

The car is about "3 weeks" old, new from the dealership, and it has been happening since that first week of ownership; is it possible that dirt or software could play a role so soon? Also, clearing the brakes with hard stops sounds like fun, but I'm watching my 2-year until Tuesday while my wife works --- so, I likely won't be able to do this until then. :)

Ian, I've sent you a PM. Thank you.
 

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Thanks, everyone. "Pulsing" sounds like a better description (maybe that's why I didn't find a proper thread?), but sometimes the whole car pulses forward gently --- like a Jr. version of stalling a stick-shift car. And, always 3 times. Other times, I do feel it in just the pedal. In both cases, I brake lightly all the way to the stop, and I haven't fully pressed the pedal all the way down.

Ian, I've sent you a PM. Thank you.
This sounds like a malfunction to me as well. In my Volt, I can feel a single transition during the last few MPH prior to the stop, where it seems the regen is being turned off (due to insufficient speed). But that single transition is subtle and relatively smooth, nothing like stalling a stick shift. So I join the other responders in suggesting that you take the car in.

BTW, in my 2011 Volt, which had been nearly totaled by a red-light runner and then post-repair had an intermittent regen problem, the local Chevy dealer mechanics confirmed the problem by test-drive. Based on past dealer experiences (with non-GM cars, BTW), I had half-expected them to "fail to confirm" the problem (because it was relatively subtle) and deny me warranty service on it. But instead, to my amazed delight, they not only confirmed it, but GM stepped up and did a very generous vehicle buy-back that got that 2011 Volt off the road and got me into a new 2012 Volt at a discount! I can't say enough good about GM and their backing of the Volt.
 

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My brakes have a light jerk (once) during the transition from regen to friction, almost always.

This was much worse and was accompanied by a pedal pulsation when at a stoplight before the most recent brake firmware update. The update improved nearly all aspects of braking so perhaps it'd be prudent to verify whether or not your Volt has a VIN that is eligible for the update.

-Drew
 

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After reading this thread I paid special attention to the brakes on our new Volt this evening when I drove home. I did not notice anything I would says was strange. You can feel a bit od pulse at very low speeds, but only because i was looking for something did i notice it.

As stated above, if in doubt have it checked out. Better safe than sorry and winding up in the trunk of someone else's car.
 

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Smooth with no pulsing/jerking. I can get a jerk if I shift from D to N cutting out the regen, Pulsing regen?
 

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Find a nice unused road. Get up to speed and put in Neutral and then brake to a stop. See what effect that has on the jerkiness.
 

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Discussion Starter #19
well, everyone, thanks for your encouragement and support. Took it to the shop and they found that the master cylinder was failing. I'll be without my Volt for a few days as they wait for the new one to come in. I'm just really disapointed that I just got the car, and I'm already having problems.
 

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Car suddenly jerks forward during braking

The braking of my Volt has always been super smooth and easy to control optimally.

Yesterday I experienced a scary exception: while smoothly braking for a red traffic light, at about 10MPH the car suddenly seemed to jolt forward. I immediately hit the brake harder and it stopped. Luckily there was nobody in front of me. The message 'low traction' briefly appeared in the DIC. Operation was normal immediately after, there is no check-engine light. I checked for OBD code, but I only see a P0007, which I presume is normal. The road conditions were normal, and I was driving in EV mode.

It seems that the regenerative braking suddenly aborted, while the friction brakes were not (or barely) engaged. It is likely that the traction control/ABS decided to pull the plug on regen braking. But road conditions were dry and brake force was very mild. Also, this just does not seem to be the proper thing to do. This happened only once until now, but its is quite a scary experience to abruptly lose brake action. Anybody experience something similar?
 
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