Yes, this happens when you are slowing down over any kind of bumps in the road. Everyone has probably felt it in their FFE. It should not happen on smooth roads.Yellowzx5 said:I am going to be bringing in my focus soon because when I slow from around 40mph the car seems to slip or skip. Creepy when you slowing down from that speed too.
Anyone else having this issue??
There are also mechanical brakes on all four wheels. These should kick in any time you "request" more braking than regen can provide (which is actually not very hard to do).damania said:Whenever I stop hard on the freeway from speeds 50-70mph down to 20-40mph my front two wheels lock up. It's ultimately unsafe and unreliable because it increases my stopping distance in an emergency. The problems of having only 1 motor on 1 axle on a vehicle and using regen for braking...
A side note: why is this thread in the Pictures, Videos section of the forum?Brake Modes
Because much of the brake torque required to stop the vehicle can be achieved through regenerative braking, it is not always necessary for the conventional friction brakes to be applied. The brake pedal uses a pedal feel simulator that acts against a curved bracket to give the driver a simulated pedal resistance as the brake pedal is applied. The ABS module uses the driver input on the brake pedal, wheel speed sensor input and the lateral deceleration messages from the RCM to determine the amount of deceleration the driver is requesting and which brake mode is necessary.
Regenerative Braking Mode
The ABS module determines the amount of braking torque necessary and sends that info to the PCM along with the current threshold for ABS intervention. The PCM determines how much braking torque the electric motor can provide based on High Voltage Traction Battery (HVTB) state-of-charge and sends this information back to the ABS module. At the same time, the electric motor is switched to a generator which supplies the determined amount of braking torque. Based on the amount of braking torque the PCM can deliver, the ABS module determines whether it is necessary to apply the friction brakes or if the brake torque from the electric motor is sufficient to safely stop the vehicle.
Friction Braking Mode
Under some circumstances, the brake torque generated by the electric motor is insufficient to bring the vehicle to a safe, controlled stop and requires the assistance of the conventional friction brakes. Additionally, the state-of-charge in the High Voltage Traction Battery (HVTB) may not allow for regenerative braking to take place or the vehicle may be experiencing an ABS , stability control event.
In these instances, the ABS module activates a mechanical relay which supplies power to a solid state relay that activates a vacuum pump. At the same time, the ABS module sends a PWM voltage to a solenoid mounted on the brake booster. The solenoid allows vacuum from the vacuum pump to enter the brake booster which moves the booster push rod and applies the conventional brakes.
During certain braking events, the friction brakes can be applied directly by the driver. The brake booster push rod is equipped with an adjustable stop, once the brake pedal travels far enough to engage the stop, the brake booster push rod is forced into the master cylinder and the conventional friction brakes are applied.
Supplemental Braking Assist
In addition to preventing wheel lock up during braking events, the ABS module also provides supplemental hydraulic brake assist through the use of the hydraulic pump motor and the HCU . The ABS module continually monitors the vacuum in the brake booster through the use of a vacuum sensor. When the vacuum sensor indicates vacuum is below a predetermined level during a braking event or if the driver attempts to stop the vehicle with a low vacuum condition in the brake booster, the ABS module activates the hydraulic pump motor in the HCU to assist with vehicle braking.
Electronic Brake Force Distribution (EBD)
On initial application of the brake pedal, full pressure is applied to the rear brakes. The ABS module then uses wheel speed sensor inputs to evaluate rear wheel slip. Once the rear wheel slip exceeds a predetermined threshold, the ABS module commands the HCU to close the appropriate isolation valves to hold the rear brake pressure constant while allowing the front brake pressure to build. This creates a balanced braking condition between the front and rear wheels. If the rear wheel slip continues and exceeds a second predetermined threshold, the ABS module commands the HCU to open the dump valves to decrease the rear brake pressure and allow the rear wheels to recover. A slight bump sensation may be felt in the brake pedal when EBD is active.
If the ABS is disabled due to a DTC being present in the ABS module, EBD continues to function unless the DTC is for wheel speed sensors or the HCU . When EBD is disabled, the ABS warning indicator, the red brake warning indicator and sliding car icon illuminate.
Your location in Southern California precludes you from any winter FFE driving.campfamily said:Has anybody taken their FFE out on an open piece of road and done a true panic stop to see what how the car behaves? I've done this with my son and my wife with their conventional cars so that they're not surprised by the feel of the ABS kicking in, but I've never done it with the FFE.
campfamily said:I have noticed that the tires on my FFE are quick to squeal when applying the brakes aggressively, much sooner than I've experienced from cars with conventional braking systems. I blamed it on the high efficiency tires; perhaps there is more to it than that.
Has anybody taken their FFE out on an open piece of road and done a true panic stop to see what how the car behaves? I've done this with my son and my wife with their conventional cars so that they're not surprised by the feel of the ABS kicking in, but I've never done it with the FFE.
Keith
jmueller065 said:Your location in Southern California precludes you from any winter FFE driving.campfamily said:Has anybody taken their FFE out on an open piece of road and done a true panic stop to see what how the car behaves? I've done this with my son and my wife with their conventional cars so that they're not surprised by the feel of the ABS kicking in, but I've never done it with the FFE.
I did a panic stop from about 25 MPH when a bicyclist didn't look & ran a stop sign & shot out in front of me a few months ago. Since I was focused on not running over the cyclist I wasn't paying much attention to how the car stopped, just the fact that I didn't hit the stupid cyclist.campfamily said:Has anybody taken their FFE out on an open piece of road and done a true panic stop to see what how the car behaves?
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