Parking Brake Behavior

[JTK37]

I’ve been experiencing this from day one, so it’s way past time I had it looked at but I always forget when I drop it off.

A few nights a week I park on a severely inclined driveway- put the truck in Park and engage the parking brake, not releasing the brake pedal until the parking brake is fully engaged. No issues there.

When I’m leaving I start the truck, fully depress the brake pedal, disengage the parking brake and put the truck in reverse. The brake pedal is “to the metal” but there is a lurching backward, at least 12” of movement(I don’t know exactly how much). I’m careful not to call this a runaway or unintended movement(while it may be). When this happens there’s a feeling of a surge and knock in the brake pedal. As if theres no pressure in the brake line initially.

Has anyone else experienced this? Is this a symptom of a brake line needing to be bled? Bubbles etc? Low fluid level?

Thanks

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[Brian_B]

So there are 2 different brake systems, depending on what engine you have.

The 2.3 uses the standard vacuum boost method. The 2.7 has a separate electric driven brake boost pump.

So I can say with my 2.3, in similar situations - I've never had what you describe occur. But the vacuum brake system is different than the electric brake system and I can't say if that would be the same or not.

Some people with the 2.3 have had issues with loosing brakes when they kill the engine on an incline (since they lose the vacuum boost) - I haven't but I recall a thread or two about it here, and that isn't the same thing as what you are describing.

 

[Lowcountry Bronco]

You sure the parking brake is disengaged when you back up? I never manually turn mine off, just gear and go but it'll give me a little lurch as it disengages but I expect it so I know to back off the gas.

 

[Clemmy]

I’ve been experiencing this from day one, so it’s way past time I had it looked at but I always forget when I drop it off.

A few nights a week I park on a severely inclined driveway- put the truck in Park and engage the parking brake, not releasing the brake pedal until the parking brake is fully engaged. No issues there.

When I’m leaving I start the truck, fully depress the brake pedal, disengage the parking brake and put the truck in reverse. The brake pedal is “to the metal” but there is a lurching backward, at least 12” of movement(I don’t know exactly how much). I’m careful not to call this a runaway or unintended movement(while it may be). When this happens there’s a feeling of a surge and knock in the brake pedal. As if theres no pressure in the brake line initially.

Has anyone else experienced this? Is this a symptom of a brake line needing to be bled? Bubbles etc? Low fluid level?

Thanks

The procedure they taught at Off Rodeo was:

Stop
Shift to neutral
Engage parking break
Shut off engine
Shift into park

I have no idea if this makes a difference in your situation but maybe?

 

[JTK37]

You sure the parking brake is disengaged when you back up? I never manually turn mine off, just gear and go but it'll give me a little lurch as it disengages but I expect it so I know to back off the gas.

Yes, I manually turn it off and can hear it disengage. The feeling in the brake pedal is one of the items I can’t figure out. That shouldn’t change when the car is already running

 

[Brian_B]

I can definitely feel it in the brake pedal when the parking brake engages and disengages. I don’t have any movement of the vehicle though

I just assumed it was the electric actuator forcing the rear pads, and that acting kind of like a cylinder in reverse on the brake line since the pads are still moving with the piston in the caliper

 

[pillar406]

Yes, I manually turn it off and can hear it disengage. The feeling in the brake pedal is one of the items I can’t figure out. That shouldn’t change when the car is already running

Like was stated above the electric brake booster does make things a little weird. I have driven vehicles with both the vacuum and electric. The electric is a little weird at times. check to see if you have the electric booster

 

[JTK37]

Like was stated above the electric brake booster does make things a little weird. I have driven vehicles with both the vacuum and electric. The electric is a little weird at times. check to see if you have the electric booster

I’ve got the 2.7 so I’m assuming it’s the electric booster

 

[pillar406]

Yeah you have the electric. So I know in mine it does go to the floor sometimes. I think that's just one of the eccentricities of the EBB

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