Anti lock brake problem

[Liberrian]

I've been spooked by the ABS system several times. I looked up this forum just because of it. Here is what I'm experiencing:

ABS 'kicks in' because of a bump in the road. Usually happens when I'm braking before going into a turn, sometimes when braking before a light. I'm a fairly 'light' braker, ie I anticapate the stop and don't hit the brake too hard.

So the symptom is, I'm in the process of braking, say for 15' before turn or stop. In the last 5' I hit a bump, ABS kicks in, and suddenly I'm going 2-3 feet without brakes. Feels like I've lurched ahead, which may be what others have described as VSC loss of control.

I've been driving since before ABS was invented, and spent ten years prior to Prius driving a Corolla wagon, and have NEVER felt anything like this. I've never had bumps kick in ABS on another car (Yes, the ABS light comes on!), whether Voyager, S70, Mercury or rentals.

If this is at all common, it is going to cause an accident.

I know this thread is a bit stale, but I was searching specifically for this problem.

[Frayadjacent]

REMEMBER: ABS doesn't help you stop shorter compared to non-ABS brakes. They help you MAINTAIN CONTROL while braking instead of locking up the wheels.

If you were braking and ended up a carlength ahead of where you intended to stop, you did not brake soon enough.

[Frayadjacent]

Liberrian, I've experienced what you're describing - coming to a stop and hitting a pothole or a large groove in the road.

I think what we're feeling then is the system STOPPING regeneration. Primary 'braking' force under normal conditions is regeneration - drag from the motor acting like a generator. When we hit a bump that causes the rotation of the front wheels to do something odd, regeneration is disabled, and we feel that lurch before we increase brake pedal force, or the system kicks back in.

That's what it feels like to me.

[qbee42]

Originally Posted by Liberrian

I've been spooked by the ABS system several times. I looked up this forum just because of it. Here is what I'm experiencing:
<snip>

It's the transition from regenerative braking to friction braking. The "loss of braking" sensation is discussed in many other threads.

Tom

[David Beale]

As above, it's normal.
Yup, it induces panic, even in me, expecting it. I don't think it really lengthens stopping distance much. Perhaps 1/2 car length. If that's a problem, you're leaving your braking too late!
They just repaved the road where I felt it most often.
One problem solved. Twenty million to go.

[Liberrian]

Originally Posted by qbee42

It's the transition from regenerative braking to friction braking. The "loss of braking" sensation is discussed in many other threads.

Tom

If it were just a sensation, it would be fine. I think there is a definite effect though - as I said, only a foot or two, and I've only noticed it when I'm going fairly slow anyways - so maybe I tend to be in regeneritve mode more than typical, but it is disconcerting!

[qbee42]

Originally Posted by Liberrian

If it were just a sensation, it would be fine. I think there is a definite effect though - as I said, only a foot or two, and I've only noticed it when I'm going fairly slow anyways - so maybe I tend to be in regeneritve mode more than typical, but it is disconcerting!

You can't have the sensation without some physical cause. As you state, it's a very small hit in braking distance. Many other factors cause an even bigger variation is stopping distance. Any good driver understands that braking distance varies and plans accordingly.

Tom