Bill Putney wrote:

> Steve wrote:
>
>> Bill Putney wrote:
>>
>>> Daniel J. Stern wrote:
>>>
>>>> On Fri, 28 Jan 2005, Steve wrote:
>>>>
>>>>
>>>>> Bill Putney wrote:
>>>>>
>>>>>
>>>>>> The downside of power brakes, which is a necessity with disk brakes
>>>>>> because they do not have the designed-in mechanical amplification,
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Why do people keep saying this?
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> The parrot effect, I'm guessing.
>>>
>>>
>>>
>>>
>>> No. The reality of modern consumer vehicles that will be driven by
>>> quite a range of ages, mental quickness, and physical strength.
>>
>>
>>
>> And the pedal effort in a 4400-lb 1969 vehicle with manual disk brakes
>> is NOT significantly higher than the pedal effort in a Honda Accord of
>> today. And disk vs. drum makes no difference at all. I just don't see
>> whay the staement that power boost "is a necessity with disk brakes"
>> keeps popping into discussions.
>
>
> That's an honest question. So you are telling me that, in the otherwise
> same vehicle, a non-vacuum assisted disc brake will take no more pedal
> pressure and at the same time no more pedal travel than a non-vacuum
> assisted self-energizing drum brake?

Not at all- I'm saying that it will take MORE pedal travel, but that
more pedal travel is a GOOD thing because it allows finer modulation of
braking pressure. The pedal effort will depend on the amount of increase
in the pedal stroke, and will typically be a little higher than a
non-boosted system. But I think its quite safe to say that there are
non-boosted cars out there that have less pedal effort than some boosted
cars. There's a lot of overlap. I'll say again that people equate "power
brakes with a failed booster" to "non-power brakes" and that's just flat
WRONG. A failed booster makes pedal effort FAR higher than non-power brakes.