Number 1, the lurch

[Guest]

No, this post isnt monty python related. Its about what I call the lurch. Sometimes when I apply the brakes it seems as though the car is stuck in drive for a split second and the resulting "lurch" is felt. Its almost like a hard downshift in an ice vehicle. I guess it has something to do with the transition from drive mode to regenerative braking mode. It happens most often in a certain place on my way to work when I have to apply the brakes but the car still has a lot of momentum behind it. I can almost reproduce it in that spot. But it does happen in other places infrequently. Its not a huge deal but I wondered if anyone else had experienced anything like this also. And if so, was there a fix for the issue such as a software upgrade. My car is a 2013.

 

[campfamily]

No, this post isnt monty python related. Its about what I call the lurch. Sometimes when I apply the brakes it seems as though the car is stuck in drive for a split second and the resulting "lurch" is felt. Its almost like a hard downshift in an ice vehicle. I guess it has something to do with the transition from drive mode to regenerative braking mode. It happens most often in a certain place on my way to work when I have to apply the brakes but the car still has a lot of momentum behind it. I can almost reproduce it in that spot. But it does happen in other places infrequently. Its not a huge deal but I wondered if anyone else had experienced anything like this also. And if so, was there a fix for the issue such as a software upgrade. My car is a 2013.

Is there a bump in the road right where you are applying the brakes? I've noticed I get a similar feeling if I apply the brakes just as the back wheels are going over a bump; I call it the "bunny hop".

Keit

 

[triangles]

A bump in the road can cause the traction control to stop the regen braking which then causes an awkward transition to friction brakes. It's kind of like you lose brakes for a fraction of a second.

 

[Guest]

Wow, you guys are right on the money. The spot where it happens frequently is where theres a little bump in the road where it seems like the tire goes airborne for a split second. This is usually where Im applying the brakes too. So this is normal and not an issue? Thats good to know. It was really the only small glitch in the way the car drives and handles. Good to know its no big deal.

 

[spirilis]

Wow, you guys are right on the money. The spot where it happens frequently is where theres a little bump in the road where it seems like the tire goes airborne for a split second. This is usually where Im applying the brakes too. So this is normal and not an issue? Thats good to know. It was really the only small glitch in the way the car drives and handles. Good to know its no big deal.

Used to happen to me in a short dip (trenched to run a new conduit and the asphalt laid down wasn't quite flat) coming downhill to a 4-way stop at the entrance to my neighborhood, now they've diverted that intersection elsewhere so I don't see it...

You figure the great majority of the braking is happening via the front wheels through the drivetrain (regen) with the front rotors providing little resistance and the rear pads providing only a little more, and it makes sense that it would "dive" as it goes airborne. Also I wonder if the differential has something to do with this, i.e. if one wheel is airborne while the other is trying to regen, would the differential defeat the regen (and since the front rotors aren't engaged much the tractive tire probably isn't braking much on its own outside of the regen?)

 

[Guest]

Amazing how a simple thing like coming to a stop can be so complicated. I think the guys who designed the systems and software did an amazing job getting the car to drive as "normal" as it does. Ive been using my jeep for the last couple of days and really notice the spongy feeling pedal of an ice vehicle. Cant wait to get my focus back.

 

[Pearl]

I feel the "Bunny Hop" (named well, btw) at very specific points that I frequent, in my FFE and in my C-Max Energi.

 

[scottt]

No, this post isnt monty python related. Its about what I call the lurch. Sometimes when I apply the brakes it seems as though the car is stuck in drive for a split second and the resulting "lurch" is felt. Its almost like a hard downshift in an ice vehicle. I guess it has something to do with the transition from drive mode to regenerative braking mode. It happens most often in a certain place on my way to work when I have to apply the brakes but the car still has a lot of momentum behind it. I can almost reproduce it in that spot. But it does happen in other places infrequently. Its not a huge deal but I wondered if anyone else had experienced anything like this also. And if so, was there a fix for the issue such as a software upgrade. My car is a 2013.

Is there a bump in the road right where you are applying the brakes? I've noticed I get a similar feeling if I apply the brakes just as the back wheels are going over a bump; I call it the "bunny hop".

Keit

Hey.....I think I was the one who first named it the Bunny Hop

Just experienced it in my 2017 the other day. Still scares the #@#$ out of me when it does.

 

[triangles]

Also I wonder if the differential has something to do with this, i.e. if one wheel is airborne while the other is trying to regen, would the differential defeat the regen (and since the front rotors aren't engaged much the tractive tire probably isn't braking much on its own outside of the regen?)

Yes the differential would absolutely defeat regen if one wheel is in there air or has no traction. Ignoring for a moment the fact that there is rotational inertia, if the car is moving forward with one front wheel on the ground and the other front wheel in the air the motor would stop spinning, the wheel on the ground would continue to rotate in the forward direction as expected and the wheel in the air would start rotating the opposite direction.

Now in the real world that wouldn't exactly happen. The ABS/traction control would sense one wheel "slipping" and cut the regen. Then it would transition immediately to friction brakes. In an extreme case it would then pulse the brakes as ABS normally would to prevent the front wheels from locking up.

I am curious to see what it does when the wheels start slipping on snow/ice when driving in L and lifting off the accelerator. Looks like tomorrow I may find out as we're supposed to get 2-4 inches of snow. It's kind of funny that this is my 4th winter with this car and I haven't had and adverse driving conditions where I would find out yet.

 

[jmueller065]

Yes the differential would absolutely defeat regen if one wheel is in there air or has no traction. Ignoring for a moment the fact that there is rotational inertia, if the car is moving forward with one front wheel on the ground and the other front wheel in the air the motor would stop spinning, the wheel on the ground would continue to rotate in the forward direction as expected and the wheel in the air would start rotating the opposite direction.

Now in the real world that wouldn't exactly happen. The ABS/traction control would sense one wheel "slipping" and cut the regen. Then it would transition immediately to friction brakes. In an extreme case it would then pulse the brakes as ABS normally would to prevent the front wheels from locking up.

I am curious to see what it does when the wheels start slipping on snow/ice when driving in L and lifting off the accelerator. Looks like tomorrow I may find out as we're supposed to get 2-4 inches of snow. It's kind of funny that this is my 4th winter with this car and I haven't had and adverse driving conditions where I would find out yet.

I've had different experiences with the car depending on which version of software is running the car. It seemed as if Ford was constantly dialing in or out the amount of regen, when the ABS kicks in or not with the various flashes I had with my FFE over the 3 years I had it.

Early versions had a really bad bunny hop as described--even on snow and ice. Later software versions got a lot better as Ford pulled out some regen and put in more ABS. It always seemed to me that when it was in regen the ABS wouldn't grab the brakes when you're slipping.

I barely notice it in my C-Max now but I think it doesn't regen nearly as much as the FFE did/does.

 

[FiSh]

Same happens to me, usually when I do slight breaking with pedal during turns.