Grabby brakes

[Curly]

I have had my 2017 SE for three years now and in most ways I love it. The one thing that really bothers me is that the brakes grab sometimes, causing a very abrupt stop. Of course my passengers hate it more than I do.

As best I remember, it has always does this. It had about 10,000 miles on it and now has about 18,000, so only about 2,500 miles per year. I drive in B mode, so I don't make heavy use of the brake pedal. Even when I do, the braking is usually smooth, but there are stops where the brakes just grab unexpectedly. At the time I usually have slowed quite a bit using regen and then use the brake pedal. These are not hard or panic stops and I'm pretty sure that my brake application is smooth. In these instances the resulting stop is anything but smooth.

I doubt it's related, but I'll mention that I also have the minor squeaking others have reported that seems to be from the brakes, often when the car is cold, and when I'm turning the wheel.

My other car currently is a 2011 Audi A4, and before that an Audi A3, neither of which had grabby brakes.

 

[f1geek]

I have had my 2017 SE for three years now and in most ways I love it. The one thing that really bothers me is that the brakes grab sometimes, causing a very abrupt stop. Of course my passengers hate it more than I do.

As best I remember, it has always does this. It had about 10,000 miles on it and now has about 18,000, so only about 2,500 miles per year. I drive in B mode, so I don't make heavy use of the brake pedal. Even when I do, the braking is usually smooth, but there are stops where the brakes just grab unexpectedly. At the time I usually have slowed quite a bit using regen and then use the brake pedal. These are not hard or panic stops and I'm pretty sure that my brake application is smooth. In these instances the resulting stop is anything but smooth.

I doubt it's related, but I'll mention that I also have the minor squeaking others have reported that seems to be from the brakes, often when the car is cold, and when I'm turning the wheel.

My other car currently is a 2011 Audi A4, and before that an Audi A3, neither of which had grabby brakes.

I have the same experience. Granny brakes at times and squeaking.

I believe the grabby brakes are due to VW’s tuning of the transition from regeneration to friction brakes. I have driven other EVs like the BMW i4 and Volvo XC40’Recharge and those cars have a much smoother transition from regen to physical brakes or just have strong enough regen that there is no transition (hard to know).

 

[cctop]

On a concurring note that it might be related to regen, I drive in D mode not B and I’ve never felt grabby brakes.

 

[f1geek]

On a concurring note that it might be related to regen, I drive in D mode not B and I’ve never felt grabby brakes.

Maybe. FYI when you press the brake pedal in D mode, you get regen first and then friction brakes when regen can’t supply required stopping force.

 

[cctop]

Maybe. FYI when you press the brake pedal in D mode, you get regen first and then friction brakes when regen can’t supply required stopping force.

Good point.

I max out the regen and switch to friction a couple of times per week trying to scrape the brake pads to get rid of the squeaky noise. (I have some nice steep hills on my way to work where I can do it).

I’ll try it in B mode for a while to see if I can replicate the grabby feel.

On a related note regarding the squeaking, I believe regeneration doesn’t engage in reverse so I sometimes go down a steep hill slowly backwards. Also sometimes I press both the accelerator and the brake pedal at the same time and move slowly. When I do that it sounds like the friction brakes are engaged, but it’s not as effective as pressing harder.

I wish VW had provided a setting with regen off completely.

 

[Curly]

On a concurring note that it might be related to regen, I drive in D mode not B and I’ve never felt grabby brakes.

I spoke to an owner of a 2019 today about this, and he confirmed that his brakes were grabby also. That didn't bother him too much, but the squeaking from his brakes was so terrible that he was embarrassed to back out of his driveway. Because of that he had his front brakes changed to all-ceramic. He said that cured the squeaks, but they still grab unexpectedly sometimes. He also drives in B mode normally.

Several months ago, I tried driving in D mode to see if it would eliminate the grabbiness problem, and it did not. That makes sense to me, because there will always be a transition from regenerative to mechanical braking, regardless of which mode you're in, and it seems almost certain that the transition is the source of the problem.

I came across the other owner at the 2024 DeutscheMarques car show at the Gilmore Car Museum, billed as the largest all-German car show in the country. I showed my e-Golf there last year and showed my 2011 Audi A4 Avant today.

 

[f1geek]

Good point.

I max out the regen and switch to friction a couple of times per week trying to scrape the brake pads to get rid of the squeaky noise. (I have some nice steep hills on my way to work where I can do it).

I’ll try it in B mode for a while to see if I can replicate the grabby feel.

On a related note regarding the squeaking, I believe regeneration doesn’t engage in reverse so I sometimes go down a steep hill slowly backwards. Also sometimes I press both the accelerator and the brake pedal at the same time and move slowly. When I do that it sounds like the friction brakes are engaged, but it’s not as effective as pressing harder.

I wish VW had provided a setting with regen off completely.

If D mode had no regen when braking, range would suffer greatly for regulatory approval purposes. Even Porsche has regen always on for braking, and Porsche refuses to offer one pedal driving.

 

[Curly]

If D mode had no regen when braking, range would suffer greatly for regulatory approval purposes. Even Porsche has regen always on for braking, and Porsche refuses to offer one pedal driving.

He didn't ask for a change to D mode, but an additional mode that has zero regen braking.

 

[f1geek]

He didn't ask for a change to D mode, but an additional mode that has zero regen braking.

Ok. That won’t happen either due to efficiency/ range loss. I do not believe there is a single BEV with such a feature. Even hybrids don’t offer this feature.

 

[Curly]

Agreed. I understand the reason for wishing the feature existed, but it is such a specialized feature that the manufacturers have no incentive to do it.

 

[solarEV]

Maybe. FYI when you press the brake pedal in D mode, you get regen first and then friction brakes when regen can’t supply required stopping force.

Possibly relevant observation: I had the rear seats folded forward once and noticed a very different sound from the rear brakes when braking lightly in D mode vs. slowing at the same rate in B regen mode. Regen mode was quieter and D mode sounded like the rear brakes were applied slightly.

Anyone else care to do the same test?

 

[f1geek]

Possibly relevant observation: I had the rear seats folded forward once and noticed a very different sound from the rear brakes when braking lightly in D mode vs. slowing at the same rate in B regen mode. Regen mode was quieter and D mode sounded like the rear brakes were applied slightly.

Anyone else care to do the same test?

How fast were you driving before you applied the brakes? What deceleration (in fractions of a g) did you request?

 

[solarEV]

How fast were you driving before you applied the brakes? What deceleration (in fractions of a g) did you request?

I don’t recall how fast. Not sure how many 0.1 g’s, or how to determine that. Low though. Less than full B mode deceleration.

 

[f1geek]

I don’t recall how fast. Not sure how many 0.1 g’s, or how to determine that. Low though. Less than full B mode deceleration.

At speeds low enough for regen to be insufficient, the car activates rear friction brakes. That is the sound you heard. You will see much more break dust on rear wheels, too, a further confirmation of this strategy.

 

[cctop]

Following up on this thread with my anecdotal experience:

I've been driving in B mode the past month instead of my regular D mode, and I haven't encountered grabby brakes. My commute includes a couple of steep hills where I max out the regen.

So the grabby brakes may be something specific to your car.

To be clear I'm talking about the transition from regen to friction brakes when the regen maxes out. I'm not talking about the abrupt slowdown you get from the regen when you take your foot off the accelerator too quickly in B mode.

 

[Curly]

Yes, as I said earlier, changing to D mode did not alleviate the problem on my car. It seems pretty clear to me it's something about the transition from regeneration to friction brakes. It's a behavior that has been mentioned frequently by car reviewers for numerous different models. What's not so clear is why it affects some of our e-Golfs more than others. Here's a discussion from another forum: