I read in this thread <http://priuschat.com/forums/prius-main-forum/38045-canadian-2008-prius-rear-disc-brakes.html> that the Canadian Prius has front discs/rear drums. I'm quite familiar with the benefits of rear discs on a conventional car, but do rear drums present much of a disadvantage for the Prius? Cheers! Joel
Hi JR, A bunch of us argued the merits of rear drums vs discs a couple of months ago. You might want to check out the thread. It's pretty interesting: http://priuschat.com/forums/prius-technical-discussion/41053-conversion-4-wheels-disc-brakes.html
Not really. It has ABS w/EBD and Brake Assist to help you out (assuming the brake pads are of decent grip). The tyres are ok but I don't know what the 16" alloys adorn. Probably Bridgestones if I had to guess. If you take a look at the rear drums of a Prius, it's probably the smallest rear drum of any car (maybe except an old Kia Spectra back in the cost-cutting days). Despite that, it stops just fine. I drove a Prius in the Toyota Hybrid Tour last May and put it through several repeated full emergency stops with some through a large puddle of water at the SilverCity Rmd parking lot. Aside from a bit of smoke and the burnt smell of rubber, it seemed ok. Keep in mind that the brakes aren't used very often so they're not likely to heat up too much during normal driving so smaller rotors/drums will suffice.
Drums are not really a disadvantage on the Prius. The main advantage of disk brakes are that they resist fade during extended braking. With the Prius, the hydraulic brakes are not used for extended braking, but only at low speed or for a fast panic stop. The only exception to this would be a very long and steep downhill where the battery SOC maxes out and engine braking is insufficient to keep the car slowed. In that case, the friction brakes have to pick up the slack. This is a rather rare and specific special case. Tom
I don't really mind having drum brakes on the rear of my Prius. Besides, I do not really go fast enough like a sports car. My old '96 Nissan Quest had rear drums and it performed just fine. I guess it all depends how aggressive you are in your driving habits. For emegency situation, the Prius has lots of stopping power. Drive safe and maintain a safe distance.
Exactly, although B mode doesn't eliminate the problem, it only forestalls it. If a hill is so steep that engine braking is insufficient to keep the car slowed, the friction brakes will eventually have to pick up the slack after the SOC maxes out. There is no other way to slow the car, short of driving into a tree. Admittedly, this is a rare situation that requires a long, long, and very steep hill. Being and engineer, I have to list all of the options, even if they are unlikely. In this type of situation, B mode immediately starts engine braking and wasting energy to forestall maxing the SOC. In D, the same thing happens, but not before the SOC is fairly high. B mode buys you more distance before the friction brakes become necessary. Side note to Bill: I know this is all old hat to you. I posted it again to help n00bs that might be reading this for the first time. Tom
