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Discussion Starter #1 (Edited)
My 2018 LT has 15,500 km on it, and it's been great. I only had the active shutters fail early on (they were replaced under warranty).

However I notice when I have to suddenly brake at very low speeds I feel a sort of small slip/bump in the brake pedal for a second.

I can re-create it very easily. It happens when you are pulling out of a parking space, for example, then you suddenly have to stop because someone is walking in front of your car. So you just start to pull out then you immediately have to brake and stop. I'm sure it's happened to all of us. When you slowly pull out then suddenly slam the brakes - that is when I feel the slight slip (feels like a thump) on the pedal and then the car recovers after about 1/2 a second.

Many have said it's because it is changing from regen to friction brakes...but it still feels weird to me, almost like something is slightly loose. Anyway, it may be nothing...just curious does your Gen2 Volt do the same thing? Usually I am in L mode when driving in parking lots.

My dealer is going to investigate it (apparently they are in contact with the GM mother ship about it) and take my car for 2 days next week. I don't mind that (they are giving me a loaner)...but I am wondering if others have experienced this...

Thanks
Darren
 

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I've noticed this in my 2017 as well. When it happens I've also noticed the Kw number jumps as well, so this appears to be an artifact of the car switching between friction and regen braking.
 

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Discussion Starter #3
I've noticed this in my 2017 as well. When it happens I've also noticed the Kw number jumps as well, so this appears to be an artifact of the car switching between friction and regen braking.
I haven't noticed the Kw jumping, but I wasn't really looking for it. I will see if mine does that as well. It happens so fast though, I will have to keep my eye on it :)
 

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I have not experienced this.

The car will somewhat behave the way you describe in situations where the antilock brakes are engaged as the system goes from regen to friction, but I've never had this happen in low speed maneuvers.

Let us know what the service department uncovers.
 

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Discussion Starter #5 (Edited)
I have not experienced this.

The car will somewhat behave the way you describe in situations where the antilock brakes are engaged as the system goes from regen to friction, but I've never had this happen in low speed maneuvers.

Let us know what the service department uncovers.
Just an update on this. The Service department had ordered a new rear axle (i believe - which was weird - what would a rear axle have to do with brake slippage?)....anyway now they say "several other" Volt owners have reported the same issue, and they are not sure the axle would actually fix the issue, so the Service Manager is in contact with GM about what to do....that is the latest....hopefully I hear back from them soon!
 

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Sounds like the ABS kicking in to me...
 

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I've noticed this in my car too, but I always chalked it up to the blending between regen and friction brakes being off. It's almost like the car temporarily drops out braking force as it tries to blend in friction brakes.

It does seem to coincide with a thump now that I think about it, but didn't ever really give it too much thought.

It doesn't happen often in my commute, but I've felt it a few times. Interested to hear what your solution is.



If what I experienced is the same as the OP, it's definitely not ABS. It happens at least braking force than is needed for ABS to kick in, but more than a "smooth stop."
 

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Discussion Starter #8
I've noticed this in my car too, but I always chalked it up to the blending between regen and friction brakes being off. It's almost like the car temporarily drops out braking force as it tries to blend in friction brakes.

It does seem to coincide with a thump now that I think about it, but didn't ever really give it too much thought.

It doesn't happen often in my commute, but I've felt it a few times. Interested to hear what your solution is.



If what I experienced is the same as the OP, it's definitely not ABS. It happens at least braking force than is needed for ABS to kick in, but more than a "smooth stop."
Yes, it's possible it may be "normal" for the brake design for this car. Some people may not even think of it, or pay any attention to it. I just do because my other car (a 2018 Leaf) doesn't do it, so I notice the difference.
 

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Never experienced this on Gen1 but if it happens when backing up (as well), I thought when in reverse there is no regen so there can't be any switching from regen to friction. Is this not right?
 

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Discussion Starter #10
Just an update on this. The Service department had ordered a new rear axle (i believe - which was weird - what would a rear axle have to do with brake slippage?)....anyway now they say "several other" Volt owners have reported the same issue, and they are not sure the axle would actually fix the issue, so the Service Manager is in contact with GM about what to do....that is the latest....hopefully I hear back from them soon!
Another update. My dealer replaced the rear-axle assembly on my 2018 LT. It did not fix the issue. They are going back to the GM mother ship to consult...I was told now 4 other 2018 customers who bought Volts from that dealership reported the same issue. I still think it may just be a side affect of the way the car was designed...but we will see what they come back with. I will update this thread when they do.

Darren
 
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