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Old 02-03-2010, 12:06 AM   #1
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Toyota

Now bad brakes on the prius's

http://news.yahoo.com/s/ap/20100203/...n_toyota_prius

maybe if they used wider tires, for one, these cars would stop better, better grip...
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Old 02-03-2010, 07:47 AM   #2
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"The Prius driver in the accident told police that a brake did not work," Ota said. "Other Prius drivers also complained brakes were not so sharp." The complaints in Japan involve the new Prius model, and the vehicles were all made in Japan, he said.
Don't Prii have brake-by-wire? Sounds like it might not have operated. Else maybe the brakes are merely weak. I don't think they're skidding, so wider tires wouldn't help (but I suspect they wouldn't hurt anything, including FE, per my tire theories).
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Old 02-03-2010, 09:12 AM   #3
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There are certain quirks to the regenerative system, at least on the 2nd gen. When the system switches from regen to friction brakes, there may be a momentary, fraction of second, gap between them. So you get an instant of no braking while depressing the brake pedal, which may feel like acceleration. I personally only had it happen when hitting a bump at that time, so it may actually involve the ABS.

It shouldn't happen,and if it is the current problem, should have been fixed, but the switch over happens at 8 to 10 mph during gentle braking. So the real danger of this quirk is panicking a driver inexperienced with the system. During a hard brake, the system goes right to the friction brakes. I never had a problem then.
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Old 02-03-2010, 12:14 PM   #4
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The regen brakes also cut out when the battery gets fully charged but this will only be noticed if you are braking gently. Beyond that the only problem could be from lack of vacuum boost if the engine is off and they pump the brakes enough to deplete the vacuum reserve. I don't know if there is an electric vacuum pump to create more boost vacuum or it relies on the engine vacuum which when it shuts off generates NONE since it is not turning at all.
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Old 02-03-2010, 12:29 PM   #5
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My company just cut my pay. So I emailed my local toyota dealer and offered to help them retrofit the gas pedals nights & weekends...

(Most dealers are being forced to stay open extended hours, and I'm sure the regular mechanics aren't thrilled about the extra time. So I am guessing they could use the help, and I know I could use some money!)
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Old 02-03-2010, 01:37 PM   #6
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god why is everything drive by wire nowadays! its such a stupid system! especially brakes! if i need to stop i want to be stepping on a pedal thats mechanically and hydrolycally attached to the damn wheels not some computer to decide for me.
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Old 02-03-2010, 02:58 PM   #7
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The Pruis brakes don't use vacuum from the engine boost. I think the brake fluid is pressurized by a pump. There is also a bank capacitors to power the braking system in event of total loss of power.

Poking around it seems what I experienced is related to the VSC reading the bump during braking as slide. Supposedly Toyota updated the software on cars made since Jan.

Fighter aircraft have been by-wire for 30 years now. Done right it can be better.
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Old 02-03-2010, 03:24 PM   #8
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god why is everything drive by wire nowadays! its such a stupid system! especially brakes! if i need to stop i want to be stepping on a pedal thats mechanically and hydrolycally attached to the damn wheels not some computer to decide for me.
In the Prius's case it makes sense, though there should be some kind of backup (for example, a mechanically operated handbrake that is connected to all 4 wheels).
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Old 02-03-2010, 06:20 PM   #9
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http://www.youtube.com/watch?v=og5QhW7uHyY

this is when saturn could have made a comeback, but no, no one wanted to buy it

after all didnt saturn have the highest fleet mpg average of american made cars...?

isn't toyota in the lead right now
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Old 02-03-2010, 06:43 PM   #10
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Quote:
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god why is everything drive by wire nowadays! its such a stupid system! especially brakes! if i need to stop i want to be stepping on a pedal thats mechanically and hydrolycally attached to the damn wheels not some computer to decide for me.
It took Henry Ford 'till 1939 before he put hydraulic brakes on the Ford cars (Lincolns, IIRC, always had 'em). Claimed a good, solid mechanical connection between the brake pedal and the brakes was the only safe system.

Drive by wire may be OK, but there needs to be some sort of redundancy in the system...either a mechanical backup, or a redundant electronic system.

Aren't airliners "fly-by-wire" these days? And spacecraft?

In the case of the gas pedal problem, some sort of "E-Stop" button on the dashboard would be a good addition...not software controlled, just a nice brute-force switch between 12 volts and the ignition system, since it is my understanding that the cars involved don't have an ignition switch you can turn off with a key.
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