:mellow: Today (Nov 22), I went to my dealer's Body Shop to have them install Body Side Mouldings on my 2007 Touring Edition Prius. In the waiting room [took them less than 30 minutes], I picked up a copy of "Motor Age," a magazine intended for the auto maintenance trade. Want something else to worry about? Here's the text from "Backfire" section of Motor Age, Issue of October 2006: ["Backfire" is the write or email in section] I wasn't able to access it online or find a link. "Proper Hybrid Braking Dear Mr. Gordon, Having read your article on regenerative braking, I was wondering if you could advise drivers of the 2005-and-later Prius how to maximize the energy recovery by managing the way in which the barkes are applied over time. That is, when you step on the brake at various speeds and create various rates of deceleration, how much of the kinetic energy is being converted into electrical energy that is stored in the battery for reuse? Is the percentage of the recovered energy [versus energy wasted as heat in the friction brakes] constant, or does it vary with with deceleration rate? Ultimately, how can the driver maximize the recovery of the kinetic enerby by altering his driving? Thanking you in advance for your expert advice, Doc Iacosucci, via email" Response by Jacques Gordon, Technical Editor of Motor Age: "Hello Doc, It's all managed by the computer, and from what I've learned, there's very little the driver can do to affect the computer's decisions. If the driver could control braking, I would occasionally turn off the regerative braking and make sure the service brakes get a good workout. In normal driving, the service brakes aren't applied until vehicle speed is below five mph (that should answer most of your questions). There are situations in which they're applied at higher speeds, but I haven't been able to discover the logic yet. Because the service brakes are used so rarely and at extermely low speeds, they rarely get hot. This is not good. Heat cycles help brake pads resist attack from chemicals and normal environmental elements. Also, the rotors will rust quickly without heat to dry them out. If the service brakes are used at higher speeds with rusted rotors, the friction material is literally ripped from the brake pad's backing plate. It doesn't fall out due to the design of the caliper, but it can rattle and flake apart, or even jamb and increase rolling resistance. I've seen more than one Prius with severely rusted rotors and delaminated brake pads. I advise Prius owners to have their brakes examined several times per year, and to not be surprised if the car needs front pads and rotors. Jacques Gordon, Technical Editor of Motor Age" I've never seen comments on Prius disc brake problems on PriusChat forums.
brake pads are meant to resist heat. the scoring that pads get from rusted rotors can damage the brake pads, in which case they do need to be replaced along with the rotors. and pads typically only crack from overheating, or from being very warm and driving extended periods through deep, cold water. (the latter can happen to rotors as well) on cars with rusted rotors, you'll see fragmentation at the edges but entire pads shattering out... highly unlikely. this is mainly an issue for conditions where there is road salt involved. DH can tell a car from a northern state by the brake rotors alone in most cases.
I don't know. I "clean" the rotors from time to time, most of the time unintentionally since there will be a moment when I have to brake harder than necessary because someone braked late or I mis-timed a light
This sounds somewhat bogus to me. They are not getting that hot, but they are not cool to the touch by a long shot after even a feather-foot drive (test it yourself), and I've noticed no signs of rotor rust even in humid NC. When I wash the car, and don't drive it again that day, I see a slight rusting of the rotors, but it's gone with one trip to work or whereever.
Well, most of us know the right answer is "long and gentle" to avoid hitting the service brakes, but Mr. Gordon probably never looked into it as deeply as he should have to really understand. And getting it right generally requires a more predictive driving style than most people are willing to perform, after being marketed to mercilessly about speed and power and stop-on-a-dime braking power. . _H*
http://www.motorage.com/motorage/form/form...sp?formId=52182 or http://www.motorage.com/motorage/article/a...l.jsp?id=334258
Hi Dr. Evan... Thanks for the links. I had searched online before posting the text, but failed to find a link to the October 2007 article I quoted. It appears that MotorAge does not provide links to the more current letters and responses. I believe the most recent I could find was in June or July.
