More on that runaway Prius...

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"Gomez said the best evidence that his client was frantically slamming the brakes is that a California Highway Patrol officer who was giving Sikes instructions over a loudspeaker smelled burning brakes and saw the lights on." http://www.foxnews . com/leisure/2010/03/15/govt-explain-runaway-calif-prius-incident/
Brake lights on, brakes getting hot enough to stink, yet the car isn't slowing down -- brakes clearly are *not* fully applied.
I wonder if there's some sort of problem that prevents the brakes from being fully applied, no matter how much pressure is applied to the pedal. That would be consistent with the multiple reports of drivers "standing on the pedal" while the car continues to accelerate.
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On Mon, 15 Mar 2010 15:55:05 +0000, Doug Miller wrote:

If they cook then they'll fade and might not be enough to stop the vehicle - maybe the 'problem' is that the owners partially apply the brakes to try and combat the acceleration, then the brakes overheat and it's not going to stop until they've been released and allowed to cool off.
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Nope. That won't happen if the brakes are fully applied. Try it in your own car: floor the accelerator, then step on the brake with your left foot. The brakes will *easily* overcome the engine. The only way applying the brakes doesn't bring the car to a stop, even under full throttle, is if the brakes are not applied all the way.
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On Mon, 15 Mar 2010 16:49:37 +0000, Doug Miller wrote:

Yeah, I can believe that *if done from cold* - my speculation is that drivers might be partially applying the brakes and overheating them - after which they might not be sufficient to overcome the engine even with the pedal pushed down as hard as they can manage (I've only ever experienced severe brake fade in one vehicle when driving down mountain roads, but it was surprising how quickly it came on and how utterly useless the brakes were once they'd got too hot - on a downhill grade, barely enough to stop the vehicle, but they were fine again once they'd cooled off for a while)
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Right, that's exactly what I mean -- in which case the drivers are idiots.

That's why you should use the transmission to slow down, rather than the brakes...
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On Mon, 15 Mar 2010 18:27:11 +0000, Doug Miller wrote:

No argument there...

Yes - I admit I was doing a certain amount of playing :-) Lots of the grades were around 1:3, so it gave the car a pretty good work-out.
cheers
J.
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On Mar 15, 4:22pm, Jules Richardson

There is one somewhat longer hill (about half a mile?) on the way into this community. The speed limit is supposedly 50 kilometres = 30 mph. With most traffic doing 60 = about 35 mph. With a school zone at the bottom. In a line up of cars it is very easy to see which ones have transmissions that effectively slow down the vehicle without using the brakes! Most automatic drivers will use their brakes; the brake lights popping on the moment we are over the crest of the hill. Others including a relative's older model Lexus have paddle shifters on the steering wheel that work well. Otherwise we prefer the series of manual transmission vehicles we have owned since the late 1970s. Owning a brake franchise must be a money maker in this area? Generally we get well over over 60,000 to 75,000 miles on a clutch and at least 35,000 to 40,000 miles on disc brakes. Doing the brake work ourselves a full set, including new rotors can be done for around $200 or less. The whole thing is we think; know your vehicle, know how to stop it no matter what, know how vehicle handles (steering and brake wise) if the engine stalls or conks out. Know how to use the emergency brake and drive on it if necessary. Above all have not encountered yet, although modern vehicles may be different, a vehicle that one couldn't get 'out of gear'. Vehicle driven since the early 1950s (that's about 60 years) have included everything form a 1926 crash (non synchro) box, a Wilson pre- selector (semi automatic), a British column shift manual; 1973 Plymouth, 1960s and 1970s Chev Impalas, manual VWs, manual Toyota pickups, manual Nissans etc. etc.
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On Mon, 15 Mar 2010 13:11:41 -0700, terry wrote:

I'm not sure what the total descent I did in this case was - it took a while to get to the bottom (with a stop partway down to give the brakes a rest!)...

Yes, I've always owned vehicles with manual transmissions in the past - the wife's Toyota (not one affected with problems ;) has a slushbox and I much prefer something with a manual, even if it's a clunky one.

I was going to say that I like to keep everything mechanical if I can - but then the elderly truck has a 3-speed manual with column-mounted shifter, so there's probably quite a bit of scope for something failing, given all the linkages involved!

I've normally had about 100,000 out of a clutch - I don't think I've ever figured out brake life, though; I just check periodically and do whatever needs doing.

Sure... I just did rear rotors on the Toyota (currently 170,000 miles on it) and I think they were $30 each side, and a similar amount for pads. The front ones are still the originals, with very little wear on them.

Absolutely. I wish there were more places folk could go to deliberately try out some of the "unexpected" stuff...

I've had cars before with hydraulic clutch mechanisms, so I suppose there's some opportunity there for something breaking such that the clutch doesn't operate - but it's not usually difficult to pull out of gear even without a clutch (and harder but not impossible to get one smoothly into gear without a clutch, too)
cheers
Jules
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On Mar 15, 2:21pm, Jules Richardson

Yep on the hydro clutch. Blew the slave cylinder at the clutch out in the boonies on my f150. Started it in gear and used 2, 3 and 4 through back roads back to the house. Did have a problem with a few stop signs but California stops work ;)
Harry K
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Ok, I'm probably going to end up through the ringer by people on here, but thats beside the point. I am currently the owner of a 2000 Toyota Camry LE 4cyl. with 213,000 kms. I know its not a Prius, but I tried something with the car that surprised me. Recently I had all of my brake pads replaced due to wear. They were squealing and old and needed changing, but before I changed them, I did an experiment. I took my Camry on the highway (rated at 100 km/h) and slammed on the brakes while also applying the accelerator. The car stopped. I could smell the brakes burning, and she didn't slow down as quickly as normal, but the damn thing stopped. I know, there have been cases of unintended acceleration that were deemed to be at fault to Toyota, and I completely agree, but now, some of these claims are getting ridiculous. Sikes' claims that he was too scared to shift into Neutral for fear of control loss of the vehicle, but was able to try and grab the 'stuck' accelerator without incident? C'mon, something stinks with his story. Its more then just problematic pedals and faulty floor mats, its politics. Chrysler and GM are both children of the US government. As most investors would want, the government now wants to see that investment thrive. Toyota, being the new #1 seller of vehicles in North America is now the enemy and must be removed from their throne at all costs. I'm trying not to be biased here, but its kinda hard. It seems like every day, GM has a new recall, whether it be with the Camaro's wiring suddenly igniting the car on fire, or a malibus transmission that will without notice slip into Neutral while parked on its own. I have had my share of GM's. Nothing beats the trucks they put out, but the cars imo stink. I had a brand new Cavalier that was nothing but problem after problem. So, I ask, why can a 10 year old car manage to stop itself with old brakes while the accelerator is also depressed, but a 2 year old prius can't?
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camryguy wrote:

Hi, Your car was not running away. Wrong analogy. At this point no one knows for sure of what is going on.
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wrote:

[...]
Oh, bullshit. He proved that the brakes are perfectly capable of stopping the vehicle even at wide open throttle -- which points directly to driver error (or driver stupidity) as the reason for the "runaways".

Only partially true. At this point, no one knows for sure why some Toyotas _seem to_ suddenly and spontaneously go to WOT. But we *do* know that *when* this happens, if the vehicle keeps going at high speed for an extended period, *that* is due to panic, error, or stupidity on the part of the driver -- or, as appears to be the case in the Sikes incident, deliberate action.
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[...]

It's not necessary to invoke elaborate conspiracy theories to explain the rash of "runaway acceleration" reports involving Toyotas. Mass hysteria is a more than sufficient explanation, and the news media are certainly fueling it.
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On Mon, 15 Mar 2010 21:21:01 +0000 (UTC), Jules Richardson

Hmmm, very little front brake wear at 170,000 miles [on the original pads] might indicate a serious malfunction. I'd give those front brakes a very close inspection to make sure they even work.
(Yes, I'm replying to an old post.)
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He's was talking about the rotors, not the pads.....
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The post is more than 2 yrs. old. The OP is certainly long gone.
Dave M.
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On 08/29/2012 08:41 AM, Levee wrote:

It's a Prius, they use regenerative braking:
http://en.wikipedia.org/wiki/Regenerative_brake
Jon
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Not at all. The regen does better than 80% of the braking on a Prius, so extremely long brake life is not out of the ordinary at all, outside the rust belt.
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On Wed, 29 Aug 2012 22:07:43 -0400, snipped-for-privacy@snyder.on.ca wrote:

Thanks, but that doesn't explain why the rear rotors needed to be replaced, does it? Does regen only apply to the front wheels?
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It only works on the front brakes. Any rear braking still needs to be performed by the friction brakes. Rear braking is something about 30% of the stopping power, more or less. With regen, the front friction brakes can be responsible for less than 10%, depending on driving style.
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