Braking in Gen III-better or same as in Gen II?

Or someone saying... What can I blame that isn't me? If you can't stop due to ABS engaging your no doubt driving to fast in the snow/ice/gravel/first rain etc. That said damn this car stops fast.

 

When I had to evade a Uhaul truck changing lanes into my front fender at 65 mph on Wednesday, the brakes were so fast that it startled me. Maybe it was Brake Assist in action?. There was no delay, the rubber was digging at the pavement instantly, faster than my pre-hybrids without Brake Assist. Regenerative brakes cannot possibly do that, it has to be the friction pads.

 

If you believe that I have a nice bridge for sale here....
:rockon:

 

I think the Gen III brakes are smoother than the IIs. It seemed to me that the II had a really touchy pedal while the III feels more like your average car.

 

I've not had to brake hard on my 2010 but did a number of times with my 2006 Prius. The 2006 stopped very well in comparison with most cars. The problem with ABS brakes is most folks don't know how to use them. In an emergency you press hard on the brakes and let the computers and sensors figure out how to give max traction for max stopping. Many folks will hear the noise and feel the vibration from the ABS and let up on the brakes resulting in very poor emergency stopping.

The 2010 brakes are smoother other than when backing up out of my garage first thing in the AM. I like to get out of the garage before the engine kicks in and it's as if the brake power assist isn't up to pressure. What I found helps that is I pump the brakes once when the Ready light comes on and then put in reverse and back out. Now problem then. This is a total non-issue after the first few seconds of driving.

Both Prius stopped as well as my wife's Volvo and some of the other various vehicles and trucks we've had around.

 

My 2010 has much better brakes than my 2008. Used to be I could feel the brakes switch between the regenerative and the mechanical ... sometimes it was very noticeable. The computer control on the new model is much better and the brakes are seamless in operation. Oh, yeah, you can lock them up if you hit the pedal hard enough in an emergency. And with the 17 inch Brigestones, it is like dropping anchor.

 

Correct, and you can maintain steering, which is gone if you lockup on a car without ABS.

 

I would discount the second quote, as it conflicts with ABS. From experience with a non-hybrid with ABS, I would follow the advice of a previous federal advertising campaign -- "Stomp and Steer". Stomp on the brakes, and steer around the problem. Without ABS, you can't do both.

During my emergency avoidance last week, my GenIII did not lock up, but did dig very hard and fast at the pavement. If my most recent non-hybrid (which is still here and healthy) had the same emergency Brake Assist as this Prius, it likely would have avoided a very expensive distraction related boo boo five years ago. Another 6 feet and I would have been completely clear.

 

It's important to realize that disc brakes do not inherently stop faster than drum brakes. With disc brakes it is easier to dissipate heat, so fade is less of an issue. Fade is mostly an issue with repetitive braking or long downhills, not panic stops. In a panic stop situation, I wouldn't expect to see much difference between four-wheel disc brakes and rear drum brakes on a Prius. Tires are probably a bigger factor.

Tom

 

Tom is correct. The rear disks have -nothing- to do with stopping ability. They have -everything- to do with sales. People think disk brakes are modern and drums are so last century. The rear wheels of a Prius, GII or GIII, impart only 10-20% of the stopping force. The previous drums were more than adequate.

Be aware, there are many issues affecting braking -perception-.
Many people thought there was a delay with the GII braking. There was only extra pedal travel.

There are two braking "functions".
In "normal braking" (gentle slowing and stopping) regeneration provides most of the stopping power. The brake pads (front and rear) are just brought to barely touch the rotors to be ready when regeneration must end.
In "emergency or panic braking" (OMG slam them on!!) regeneration is bypassed and brake assist is also used. I've only had to use this once with Pearl, and it worked startlingly well!

Then there is the perception of ABS. NO, the car doesn't "speed up" when the ABS engages. How would it do that? It needs energy to do so. YES, the car will stop faster with ABS than it would if you didn't have it. -Most people- (read most people without proper race training in performance braking) will lock up a/the wheels and it will take much longer to stop. They will also loose steering control. While you may -think- ABS caused you to loose braking, it doesn't except in two circumstances - on loose gravel and in heavy snow. In those two cases without ABS you will stop sooner by "plowing" the road media but you will -still- loose steering control.

If you don't stop soon enough with ABS you were traveling too fast for the conditions (except as noted above - but of course you knew you had ABS and it would be difficult to stop but still didn't slow so you are -still- at fault). Accept responsibility!

 

I just bought my first Prius (2010 Prius II) and there is definitely an issue with braking. The first time, I thought it was my imagination but it just happened again on my way to work this morning so I'll be taking it in a.s.a.p. It rained overnight so the roads were damp but I wasn't emergency braking - just normal braking at a stop sign. The brakes slowed the car initially and then it felt like the brakes were suddenly not catching and the car was accelerating (though it may be that the car maintains the same speed and it feels like acceleration because I expect it to be slowing instead).

This is the only problem I've had with the car and totally love it otherwise. I'll post results from my consultation with the dealership next week.

 

It sounds as though you may have experienced the quick switchover from regenerative braking to friction braking.

This happens when there is a surface change encountered during braking. It is most noticeable when you are in a significant braking event (approaching a stop sign, for example) and hit a bump or pot hole. The uneven road event may cause the car to drop the regenerative braking and switch to friction braking. Even though the car has 4-wheel discs, the regenerative braking is applied (as I understand it) only to the front wheels. The loss of regenerative braking is a significant change, so that the decreased braking results in decreased deceleration. The common reading of this by the driver is a "lurch" or a "jump forward" that feels like acceleration. It can be a bit scary.

The good news is that you haven't lost braking at all. The friction braking jumps right in, and you never have a loss of braking. The regenerative braking will come back, though I don't believe you will have it available until you completely let up from braking.

There are a number of threads discussing this issue. One of the more informative is called Braking problem. Look for qbee42's Post #4 in that thread for a good overview.

 

Prius 2010 - Edmunds reports 60 to 0 in 118 ft (they also report the 2009 as 119ft) . For reference my old 1999 911 60-0 in 105 ft and if I recall correctly my Suburban was something like 60 to 0 in 160ft.

Fade and water on the earlier drums not factored into these numbers

 

Bingo! You have just touched on the main reason ABS has reduced the accident rate. It allows you to do what a poor driver has always done and still maintain control of your vehicle. There are millions of poor drivers out there every day. When faced with an emergency their reaction is to slam on the brakes and try to steer around it. That used to be the recipe for disaster. With ABS it's called technique.

 

All this tech talk in interesting, but for me, it all comes down to this:

We bought a 2010 Prius V about 6 weeks ago.

I was driving down a back road in Michigan at dusk at couple of weeks ago, when a kid riding his bicycle in the left lane suddenly swerved in front of me. It hit the brakes as hard and fast as I could and steered to avoid him. The tires screeched, but I never lost control. My wife and I were shaking afterward, but the kid was untouched and simply rode away. I have no complaints with the brakes.