Brake Pedal Feel

[dannyrrr]

Hi all,

I have posted before about my issues with the brake pedal and the hydraulic pump. Mine pump seems to activate quite often when my foot is on the brake and i am stopped. My Volt advisor suggested I take the car in so I finally took my Volt into the dealer. The mechanic, very nice guy, did some tests and compared my car to demo car (i had driven that before and noticed it didn't do the pump thing as frequent as my car).

He was in communication with the main volt engineers, but they left early because of the holiday so no resolution on my issue. I hope to hear back Tuesday to find out why mine seems to pump quite often.

He showed me an a document #P10307A which is created to deal with the 12 volt battery and the Brake Pedal feel. Just wondering if anyone else has gotten this. He gave me a copy. I can post if you guys want to see it.

[Noel Park]

FWIW, I have driven my Volt almost 5K miles and the brake pedal has felt totally normal at all times - indistinguishable from a conventional car. And I don't hear anything that sounds remotely like a hydraulic pump cycling. So something must be going on with #1849. Keep in their faces and please keep us up to date.

#1756

[scottf200]

FWIW, I have driven my Volt almost 5K miles and the brake pedal has felt totally normal at all times - indistinguishable from a conventional car. And I don't hear anything that sounds remotely like a hydraulic pump cycling. So something must be going on with #1849. Keep in their faces and please keep us up to date. #1756

Ditto for my Volt and brakes. I'm very happy with them but to be honest I use them much less since I drive in (L)ow all the time. Still when I use them they appear normal.

[Steverino]

Like Scott, I use L all the time to regen brake. Have not noticed anything unusual when at a stop light.

I am getting much better at anticipatory braking, but kick myself when I don't let off the accel soon enough and have to hit the brakes harder. My brother noted that the Volt teaches the driver to drive more efficiently.

[WopOnTour]

Hi all,

I have posted before about my issues with the brake pedal and the hydraulic pump. Mine pump seems to activate quite often when my foot is on the brake and i am stopped. My Volt advisor suggested I take the car in so I finally took my Volt into the dealer. The mechanic, very nice guy, did some tests and compared my car to demo car (i had driven that before and noticed it didn't do the pump thing as frequent as my car).

He was in communication with the main volt engineers, but they left early because of the holiday so no resolution on my issue. I hope to hear back Tuesday to find out why mine seems to pump quite often.

He showed me an a document #P10307A which is created to deal with the 12 volt battery and the Brake Pedal feel. Just wondering if anyone else has gotten this. He gave me a copy. I can post if you guys want to see it.

Your VA would have advised you to visit your dealer if you had ANY sort of performance concern with your brakes, so that a trained technician can inspect and if warranted validate those concerns. If they sent you off on your way I suspect there's nothing wrong with your brakes.

FYI The electric pump is supposed to operate whenever you step on the brakes hard enough to demand friction brakes and typcially at all times during lower speeds and stops.(it's replenishing the fluid pressure taken from the accumulator to apply the brakes) Generally it's quite difficult to hear though unless you have EVERYTHING off in the interior (heater/AC/radio etc) OR if you have your window rolled down and are driving close to structures, where the sound reflects back easily. If the motor/pump was excessively noisy they would have just replaced it.

Pedal feel on the Volt is slightly different than "regular" brakes is essentially it's just a "pedal feel simulation" due to the brake-by-wire nature of the system.If you have no brake warnings and the car stops well, there's likely nothing wrong.
WOT

PS> I suspect you actually meant PI0307A which is a "New Product" document for Volt technicians that describes various unique yet NORMAL Volt behavior and details including the somewhat unique brake feel (the 2-mode hybrids are identical).
There are currrently ZERO service bulletins for any sort of brake issues on the Volt, but here is what that document stated about the Volt's brake system.

Normal Brake Pedal Feel and Brake Pedal Vibration

• The Volt has a unique brake pedal feel. This is because the hydraulic system is not the lone provider of vehicle deceleration. The electric system blends in regenerative and hydraulic braking forces depending upon vehicle conditions. Over several braking events, the customer may perceive that they are applying a consistent brake force and yet the vehicle may decelerate at slightly different rates. This is a normal operating characteristic to maximize fuel economy.

• The Volt utilizes a braking system that employs a high-speed electric motor/pump. Pump operation can sometimes be heard and felt in the brake pedal as the system sometimes builds pressure.

[Noel Park]

Ditto for my Volt and brakes. I'm very happy with them but to be honest I use them much less since I drive in (L)ow all the time. Still when I use them they appear normal.

I don't drive in L all the time but I do try to be as gentle as possible on the brakes. I wonder how hard you have to push the pedal to go through the regen and deploy the wheel brakes? I was looking at the brake rotors on the Volt the other day and I noticed 2 things:

1) They are impressively large.

2) The have a light haze of sort of oxidation on them. If i didn't know better, I would swear that they had never been used.

[Noel Park]

I am getting much better at anticipatory braking, but kick myself when I don't let off the accel soon enough and have to hit the brakes harder. My brother noted that the Volt teaches the driver to drive more efficiently.

Me too, LOL.

[dannyrrr]

hi all, thanks for your input but to clarify, the brakes work fine. the issue is when i am at a full stop, i.e. traffic light, and while i am waiting to go again, i hear the pump go off and on several times before i start back up again. i am not worried about the braking ability, its just the noise is quite annoying and if it is not normal, then i want it fixed.

thanks

[chewy]

Hi all,

I have posted before about my issues with the brake pedal and the hydraulic pump. Mine pump seems to activate quite often when my foot is on the brake and i am stopped. My Volt advisor suggested I take the car in so I finally took my Volt into the dealer. The mechanic, very nice guy, did some tests and compared my car to demo car (i had driven that before and noticed it didn't do the pump thing as frequent as my car).

He was in communication with the main volt engineers, but they left early because of the holiday so no resolution on my issue. I hope to hear back Tuesday to find out why mine seems to pump quite often.

He showed me an a document #P10307A which is created to deal with the 12 volt battery and the Brake Pedal feel. Just wondering if anyone else has gotten this. He gave me a copy. I can post if you guys want to see it.

I had some issues with the brake feel initially, and I thought it was that without the regen (was trying to glide in Neutral to hypermile) that my braking pressure was just a lot different feel. I quit with the N and didn't have trouble, but then I had my master cylinder fail (puddle of fluid on the car mat).

good that they are checking yours out. how do you know when the hydraulic pump is ON? do you hear it? I had not noticed mine.

[PatsVolt]

The only time I hear the pump is when I first back out of the garage, and all is very quiet. If it runs at other times, I have not heard it due to noise, from the radio, or just road noise. The pump in its self is very quiet.

I have been using L almost all the time, but have been experimenting with using L only when in heavy traffic and long or steep hills. On some of my commute the terrain is small rolling hills and the country road I follow is the same. So I find that allowing the car to maintain momentum via being in D is better then L and seems to give me a few extra miles of battery range.

Pat