Brakes unable to stop runaway Lexus in California?

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Old 16 Nov 2009, 10:07 pm   #21 (permalink)
someone@some.domain
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Default Re: Brakes unable to stop runaway Lexus in California?

In article <sJWdnfF9FOHXI5zWnZ2dnUVZ_oKdnZ2d@giganews.com>, "hls" <hls@nospam.nix> wrote:
>
>"Ray O" <rokigawa@NOSPAMtristarassociates.com> wrote in message Before
>power assisted brakes were introduced, people
>> routinely stopped vehicles by stepping hard on the brake pedal.

>
>That is true, Ray, but also in those days we had front and rear drums, for
>the most part.
>Discs required a lot more pressure than drums, hence the power assist brakes
>became
>a necessity rather than just a luxury convenience.
>
>

i wonder about that. i don't think bikes are much different. it tales a lot
more pressure to stop my 650 triumph with a doubling leading shoe front than
a xt 750 jamaha, which had one disc front and weighs more.
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Old 16 Nov 2009, 11:09 pm   #22 (permalink)
dsi1
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Default Re: Brakes unable to stop runaway Lexus in California?

someone@some.domain wrote:
> In article <sJWdnfF9FOHXI5zWnZ2dnUVZ_oKdnZ2d@giganews.com>, "hls" <hls@nospam.nix> wrote:
>> "Ray O" <rokigawa@NOSPAMtristarassociates.com> wrote in message Before
>> power assisted brakes were introduced, people
>>> routinely stopped vehicles by stepping hard on the brake pedal.

>> That is true, Ray, but also in those days we had front and rear drums, for
>> the most part.
>> Discs required a lot more pressure than drums, hence the power assist brakes
>> became
>> a necessity rather than just a luxury convenience.
>>
>>

> i wonder about that. i don't think bikes are much different. it tales a lot
> more pressure to stop my 650 triumph with a doubling leading shoe front than
> a xt 750 jamaha, which had one disc front and weighs more.


I doubt there's much validity that vacuum assisted brakes were required
because of the advent of disk brakes. My first car, a 67 Barracuda had
drums and vac boost, as did most cars of the time. That one had a tiny
V8 - a 273! Of course, today that would be a large engine - 4.5L. :-)
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Old 17 Nov 2009, 08:37 am   #23 (permalink)
hls
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Default Re: Brakes unable to stop runaway Lexus in California?


"dsi1" <dsi1@spamnet.com> wrote in message news:5eqMm.20048
> I doubt there's much validity that vacuum assisted brakes were required
> because of the advent of disk brakes. My first car, a 67 Barracuda had
> drums and vac boost, as did most cars of the time. That one had a tiny
> V8 - a 273! Of course, today that would be a large engine - 4.5L. :-)


Power assist brakes, as I said, became luxury items. They were not
absolutely necessary on drum brake cars, but certainly made braking
effortless. Finally they found their way onto almost every car.

Disc brakes on large American cars, without power assist, can be monsters.

It is just the way things evolved.
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Old 17 Nov 2009, 02:50 pm   #24 (permalink)
Kevin
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Default Re: Brakes unable to stop runaway Lexus in California?

"hls" <hls@nospam.nix> wrote in
newsMGdnVZK6rC8KJ_WnZ2dnUVZ_vGdnZ2d@giganews.com :

>
> "dsi1" <dsi1@spamnet.com> wrote in message news:5eqMm.20048
>> I doubt there's much validity that vacuum assisted brakes were
>> required because of the advent of disk brakes. My first car, a 67
>> Barracuda had drums and vac boost, as did most cars of the time. That
>> one had a tiny V8 - a 273! Of course, today that would be a large
>> engine - 4.5L. :-)

>
> Power assist brakes, as I said, became luxury items. They were not
> absolutely necessary on drum brake cars, but certainly made braking
> effortless. Finally they found their way onto almost every car.
>
> Disc brakes on large American cars, without power assist, can be
> monsters.
>
> It is just the way things evolved.
>


unfortunatly your a moron. the brake peddle effort is easily controled
by the brake peddle ratio. it can have high or low effort with or
without power assist. power assist was simply a sales gimmic just as it
is today. the only reason for power assist is to shorten up the peddle
travel. get your facts right and go away. KB

--
THUNDERSNAKE #9

Protect your rights or "Lose" them
The 2nd Admendment guarantees the others
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Old 17 Nov 2009, 03:25 pm   #25 (permalink)
Heron McKeister
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Default Re: Brakes unable to stop runaway Lexus in California?

"hls" <hls@nospam.nix> wrote in message
newsMGdnVZK6rC8KJ_WnZ2dnUVZ_vGdnZ2d@giganews.com ...
>
> "dsi1" <dsi1@spamnet.com> wrote in message news:5eqMm.20048
> > I doubt there's much validity that vacuum assisted brakes were required
> > because of the advent of disk brakes. My first car, a 67 Barracuda had
> > drums and vac boost, as did most cars of the time. That one had a tiny
> > V8 - a 273! Of course, today that would be a large engine - 4.5L. :-)

>
> Power assist brakes, as I said, became luxury items. They were not
> absolutely necessary on drum brake cars, but certainly made braking
> effortless. Finally they found their way onto almost every car.
>
> Disc brakes on large American cars, without power assist, can be monsters.
>
> It is just the way things evolved.


Ah for the days of non integrated proportioning and
metering valves ;^)


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Old 17 Nov 2009, 05:13 pm   #26 (permalink)
Anyolmouse
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Default Re: Brakes unable to stop runaway Lexus in California?


"Heron McKeister" <not@home.com> wrote in message
news:QwEMm.17416$ET3.8075@newsfe17.iad...
> "hls" <hls@nospam.nix> wrote in message
> newsMGdnVZK6rC8KJ_WnZ2dnUVZ_vGdnZ2d@giganews.com ...
> >
> > "dsi1" <dsi1@spamnet.com> wrote in message news:5eqMm.20048
> > > I doubt there's much validity that vacuum assisted brakes were

required
> > > because of the advent of disk brakes. My first car, a 67 Barracuda

had
> > > drums and vac boost, as did most cars of the time. That one had a

tiny
> > > V8 - a 273! Of course, today that would be a large engine - 4.5L.

:-)
> >
> > Power assist brakes, as I said, became luxury items. They were not
> > absolutely necessary on drum brake cars, but certainly made braking
> > effortless. Finally they found their way onto almost every car.
> >
> > Disc brakes on large American cars, without power assist, can be

monsters.
> >
> > It is just the way things evolved.

>
> Ah for the days of non integrated proportioning and
> metering valves ;^)
>
>


I kind of miss my 1937 Tudor Ford Fastback with mechanical brakes. It
took about as long to go from 60 to 0 as it did from 0 to 60 with the
V-60 engine. <Grin>

--
A man is known by the company he keeps- Unknown

Anyolmouse

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Old 17 Nov 2009, 05:51 pm   #27 (permalink)
clare@snyder.on.ca
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Default Re: Brakes unable to stop runaway Lexus in California?

On Mon, 16 Nov 2009 19:09:19 -1000, dsi1 <dsi1@spamnet.com> wrote:

>someone@some.domain wrote:
>> In article <sJWdnfF9FOHXI5zWnZ2dnUVZ_oKdnZ2d@giganews.com>, "hls" <hls@nospam.nix> wrote:
>>> "Ray O" <rokigawa@NOSPAMtristarassociates.com> wrote in message Before
>>> power assisted brakes were introduced, people
>>>> routinely stopped vehicles by stepping hard on the brake pedal.
>>> That is true, Ray, but also in those days we had front and rear drums, for
>>> the most part.
>>> Discs required a lot more pressure than drums, hence the power assist brakes
>>> became
>>> a necessity rather than just a luxury convenience.
>>>
>>>

>> i wonder about that. i don't think bikes are much different. it tales a lot
>> more pressure to stop my 650 triumph with a doubling leading shoe front than
>> a xt 750 jamaha, which had one disc front and weighs more.

>
>I doubt there's much validity that vacuum assisted brakes were required
>because of the advent of disk brakes. My first car, a 67 Barracuda had
>drums and vac boost, as did most cars of the time. That one had a tiny
>V8 - a 273! Of course, today that would be a large engine - 4.5L. :-)


Disk brake calipers contain more fluid than drum brake cyls, and
require more fluid movement at higher pressure to provide the same
braking force, generally speaking. Therefore, disk brakes derive a
much grater advantage from power assist than servo type (like Bendix)
drum brakes. It allows you to get good braking pressure without
extreme pedal travel.

Non Servo drum brakes like the old Chrysler Center Plane, girling
twinleading shoe, and GM Huck brake systems would have benefited
highly from power assist as well -and GENERALLY required either more
pedal pressure or longer pedal travel than the more common, recently,
Bendix style "self energizing" or "servo" brakes.
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Old 17 Nov 2009, 05:53 pm   #28 (permalink)
clare@snyder.on.ca
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Default Re: Brakes unable to stop runaway Lexus in California?

On Tue, 17 Nov 2009 15:25:40 -0600, "Heron McKeister" <not@home.com>
wrote:

>"hls" <hls@nospam.nix> wrote in message
>newsMGdnVZK6rC8KJ_WnZ2dnUVZ_vGdnZ2d@giganews.co m...
>>
>> "dsi1" <dsi1@spamnet.com> wrote in message news:5eqMm.20048
>> > I doubt there's much validity that vacuum assisted brakes were required
>> > because of the advent of disk brakes. My first car, a 67 Barracuda had
>> > drums and vac boost, as did most cars of the time. That one had a tiny
>> > V8 - a 273! Of course, today that would be a large engine - 4.5L. :-)

>>
>> Power assist brakes, as I said, became luxury items. They were not
>> absolutely necessary on drum brake cars, but certainly made braking
>> effortless. Finally they found their way onto almost every car.
>>
>> Disc brakes on large American cars, without power assist, can be monsters.
>>
>> It is just the way things evolved.

>
>Ah for the days of non integrated proportioning and
>metering valves ;^)
>

Oh for the days of cable and rod actuated brakes, with mechanical
brake force distribution -via different length bellcranks.
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Old 17 Nov 2009, 07:14 pm   #29 (permalink)
dsi1
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Default Re: Brakes unable to stop runaway Lexus in California?

clare@snyder.on.ca wrote:
>>

> Disk brake calipers contain more fluid than drum brake cyls, and
> require more fluid movement at higher pressure to provide the same
> braking force, generally speaking. Therefore, disk brakes derive a
> much grater advantage from power assist than servo type (like Bendix)
> drum brakes. It allows you to get good braking pressure without
> extreme pedal travel.


I'm familiar with basic hydraulics but the fact remains that brakes used
the same system of vacuum assist before disks became popular. It doesn't
matter which system gets more benefit from power assist because the
truth is that both drums and disks pretty much suck without it.

>
> Non Servo drum brakes like the old Chrysler Center Plane, girling
> twinleading shoe, and GM Huck brake systems would have benefited
> highly from power assist as well -and GENERALLY required either more
> pedal pressure or longer pedal travel than the more common, recently,
> Bendix style "self energizing" or "servo" brakes.

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Old 18 Nov 2009, 08:12 pm   #30 (permalink)
clare@snyder.on.ca
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Default Re: Brakes unable to stop runaway Lexus in California?

On Tue, 17 Nov 2009 15:14:11 -1000, dsi1
<dsi1@humuhumunukunukuapuapa.org> wrote:

>clare@snyder.on.ca wrote:
>>>

>> Disk brake calipers contain more fluid than drum brake cyls, and
>> require more fluid movement at higher pressure to provide the same
>> braking force, generally speaking. Therefore, disk brakes derive a
>> much grater advantage from power assist than servo type (like Bendix)
>> drum brakes. It allows you to get good braking pressure without
>> extreme pedal travel.

>
>I'm familiar with basic hydraulics but the fact remains that brakes used
>the same system of vacuum assist before disks became popular. It doesn't
>matter which system gets more benefit from power assist because the
>truth is that both drums and disks pretty much suck without it.
>
>>
>> Non Servo drum brakes like the old Chrysler Center Plane, girling
>> twinleading shoe, and GM Huck brake systems would have benefited
>> highly from power assist as well -and GENERALLY required either more
>> pedal pressure or longer pedal travel than the more common, recently,
>> Bendix style "self energizing" or "servo" brakes.



Big enough self energizing drum brakes do NOT NEED power assist.
Disk brakes DO - they are by nature NOT self energizing, and require a
lot of brake force. Not many disk brake cars, historically, without
power assist. And most Mopars built that way in the seventies have
had major front end damage at some time in their life. Used to be
impossible to find front end sheetmetal at the wreckers for them.
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