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Discussion Starter #1
I have a new Prius and it is hard to make very smooth stops, because the brakes seem to grab unevenly as I come to a stop. Do I just need to wear them in?

I tried to do a search, but the search engine appears to be different from before and nothing came up on this forum.
 

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Actually, it is you that needs to break in. What I mean is, it does take some getting used to, but you will get the hang of it in time.

Unless you are in fail-safe, you don't actually control the wheel cyclinders hydraulically yourself. Instead, the computers determine your intent from the brake pedal stroke speed and distance, and then determines how fast it should stop the car. It first tries to stop using regen braking (the transportation industry calls this dynamic brakes), then uses the hydraulic brakes for any additional needed stopping force. The computers release brake pressure fluid kept under high pressure in the Accumulator (thats why you hear a Brr sound when you use your brakes; that's the pump to keep the pressure up) to the proper wheel cylinders. If there is an emergency/panic stop, or conditions warrrant ABS or VSC, then it forgoes regen braking and uses hydraulic brakes only to the appropriate wheels.

You do have a master cylinder, but it is normally disconnected from the main hydraulic system, but instead applies pressure to a stroke simulator to give you the feel of hydraulic brakes. If there is a system failure, then valves will let you control the front wheel cylinders directly using the master cylinder pressure.
 

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DanMan32 said:
Actually, it is you that needs to break in. What I mean is, it does take some getting used to, but you will get the hang of it in time.
Does this depend on stopping behavior? I honestly don't notice any difference between the Prius and my Sienna. I do stop as gradually as possible by anticipating the need to stop and beginning early. I have tried to "feel" the point where the regen goes to friction braking but can't.
 

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redwein said:
DanMan32 said:
Actually, it is you that needs to break in. What I mean is, it does take some getting used to, but you will get the hang of it in time.
Does this depend on stopping behavior?
I think the behavior is the main determinant on "grabbiness", as I am normally like you in that I anticipate and slowly ease on the pedal... but at times in traffic in front of me out of the blue everyone jams on brakes and so I then hit the brakes quickly but not hitting them hard -- even though I don't put a lot of pressure on the pedal, I think (like Dan is saying) that in this case it senses the speed in which my foot hits the first inch or so of the pedal travel and it makes the brakes "grab" because the system thinks I'm about to stomp the brakes to the floor quickly, even though my foot reaction was one of speed rather than force.

This quick-stop scenario is the only time I ever experience the grabby brakes, the other 99% of my stops are all anticipated and very smooth.

Jeff
 

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New brakes might be the issue too.. how old is the car? For the first month the brakes really needed a wear in they were as you described as "grabby", and now they are MUCH smoother in comparison.
 

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A lot of people notice the transition from regnerative braking to hydraulic braking at about 7 mph when the vehicle removes regen and reverts to all hydro. Some folks think it feel like a grab. It feels like a shift to 1st gear to me. Very normal in comparison to all the other automatic vehicles I have driven.
 

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Discussion Starter #8
I could be wrong, but I really don't think the transition between regenerative and friction braking is my issue. I believe I am so close to stopped that only the friction brakes are in play. Even if I just ease up on the brake pedal from a complete stop and move forward at 1 mph or so and try to ease smoothly to a stop again, the brakes seem to apply or "moan" unevenly. The front disks don't look rusty and I tried the braking in neutral idea to polish them (as someone suggested earlier in this forum, I believe) but still get the grabbiness (even in neutral). My car only has 600 miles on it, so hopefully it's just a matter of the brakes wearing in.
 

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Grabby Breaks

When I first test drove a Prius, I was startled the first time I put my foot on the break because of how "sensitive" it seemed. When I got back into my 2000 Saturn, I felt like the Saturn was like driving a tank.

When I rented a Prius for the weekend as my other "test drive" I was able to get a lot of quality time in the car. The brakes are not hard to get used to. As soon as you get used to being a lot less forceful with them, they're better than what I had in my opinion.

I usually like to take plenty of time to come to a stop. This might account for the Saturn brakes lasting nearly 59,000 miles, which the dealer thought my be a new record.

In the Prius, it pays to take more time to stop. The more time you let gravity slow you down, and be gentle with the brakes, the more you can regenerate that energy back into your battery. In my opinion, this driving style is safer, and will maximize the life of your brake pads. With the way the Prius brakes work, the brake pads will likely last at least 100,000 miles or more from what I've heard.

I have experienced some funny shimmies just as I'm coming to a stop, but it's never been overly bothersome. I trump that up to the computer possibly having some issues with transition between regen brakes and real brake pad braking.

I have a friend that is a "left foot" braker. Those kind of people drive me nuts because they brake even when going up hill! Talk about wearing out your brakes!
:shock:
 

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No no and nope.. I just bought a 13 model C and within one week, it grabbed JUST as it came to a complete stop. A little google search turned up the exact trick it took to fix it. From 30mph, kick to neutral and apply brakes. After doing that 2 times, problem solved.
 

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