Simultaneous Application of Gas and Brake Pedals

We're talking about the market place - not subject to rigid rules as are
the laws of physics. That's why claims made about it are subjective.
Certainly you aren't going to claim that you can predict what the
"market" will do in response to some subtile technical change - yet
there likely will be a repsonse to that change. There's just no formula
to calculate the impact.

So that's a 40% increase in piston area = 40% increase in
pedal-to-caliper piston force multiplication. Nice trick using a
throwing out a linear parameter in an attempt to minimize what is a
square law effect. 40% is a big difference when you're talking braking
effort.

Which does away with unobtainable vacuum requirements and gets the boost
from an "always on" source: the power steering pump. Thanks for
reinforcing my point that vacuum source for brakes is unreliable in
certain critical situations like stuck throttle, which is what I believe
we were talking about.

Once again, my points about the difference between drums and disc brakes
were in the context of the cars that 95+% of consumers and no doubt
those here drive. I stand by what I said.

The more commmercially viable vehicle will have power assisted disc
brakes on the front if not on all four wheels - right or wrong, that's
what today's market has determined. It has obviously not always been
that way, nor will it likely always be that way in the future.

 

People don't always behave logically in panic situations. That's why
police find shooting victims with a bullet hole in their hands in their
last desperate effort to stop the bullet from striking their face. Does
that action on their part make sense? No - for if they survive, it just
means an additional injury and/or permanent disability. Both of us are
conjecturing what "most" people will do when they jam on the brakes and
the brakes are not effective enough. Heck - many people will pump the
brakes in any situation out of habit because that's what they used to be
taught. I can't prove it, you can't prove your point - we're both
speculating.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

You can't always explain what a person does in a panic situation - it's
not always a logical though process that stands up to critical analysis
after the fact. Forensics specialists can probably give you lots of
examples of that. I can very easily picture the non-verbal panic
thought process going something like "Damn! I'm pushing as hard as I
can, and it's still moving - maybe I'm pushing on the wrong thing, or my
foots at an angle - I'll take my foot off and jam it as hard as I can
squarely on what I'm pretty sure is the brake pedal!!!" Followed by "Oh
S***!! It's even worse now."

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

I've done significant driving time in a 1985 Chevy 1-ton pickup equipped
with hydraulic brake boost. If I'm not mistaken, the same pump that
provided power steering also boosted the brakes. It worked -- the pedal
feel was different from that of a typical vacuum-boosted brake system, but
it worked well. If you depressed the pedal down to the floor while at a
stop, you got strange "force feedback" (for the lack of a better term)
through the pedal at the end of the travel.

So yeah, 'hydroboost' is a viable alternative to vacuum-boosted power
brakes.

--Geoff

 

I used to drive an International Travelall (similar in size to a Chevy

I'd have paid extra to get my car without power steering, but that wasn't
even an available option. Power steering is great until your engine
stalls in the middle of an intersection; then even a wrestler will have
trouble avoiding a wreck.

 

Oh - I'm sorry - I thought we were living in the present. How silly of
me to exclude cars from 20 and 30 years ago from the here and now.

No - it was a poorly designed standard package that also included an AMC
automatic transmission with no external cooling - fluid needed changing
every 20,000 miles - you knew it needed it when the tranny started
slipping. They quit making them for a reason.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

Especially in situations where you have inadequate vacuum to power the
brakes.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

Heh heh! You wouldn't say that if you drove the vehicle I'm talking
about. Again - picture the size and weight of a Suburban with no power
steering. Perhaps the steering gear could have been geared a little
lower, but parallel parking that thing was a chore and a half (due to
size and lack of power assist both)

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

I thought that they used TF727s? or was this an earlier model than the
ones I'm familiar with? (early 70's)

nate

 

Feeling slow again, Putney? Your claim that "modern" consumer vehicles
"...will be driven by quite a range of ages, mental quickness and physical
strength" implies that such was not the case before the "modern" age, and
you're wrong.

....which means the original owner didn't order power steering. QED.

 

Putney's remembering things that never existed. AMC bought their
automatics from other makers (GM Hydramatics from the early mid '60s
through '71, Chrysler Torqueflites starting in '72).

 

I agree. If anything it would make it worse (assuming locked brakes vs. ABS
stop). If the wheels aren't locked while stopping, all the energy is going
into frictional heat between pads and the rotors. If the wheels are locked,
there is no energy being released as heat in the brakes, they aren't moving,
so it all goes to the tires and the pavement.

 

This was a '65. I was told at the time that it was an AMC. Don't
recall if it was a dealer who told me that or someone else. They must
have changed later.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

You inferred where I did not imply. I simply made a statement about the
modern reality. Anything you read into it beyond that is up to you.

Obviously (I guess that's what "QED" means?).

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

False - I remember what I was told, and it probably was true.

The same tranny apparently was used in AMC's - possibly with certain
AMC-specific options. In either case where does the "never existed"
part come in?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

I believe AMC *did* use a close relative of the Studebaker Flightomatic
(made by Borg-Warner) at the time, and the standard duty version of that
tranny was *not* watercooled. The HD version of that would probably
have been suitable for use in a truck, but why they would have used the
non-watercooled version I don't know. (note that this is all from furry
memory, so don't take anything I say as gospel. I also don't know a
whole lot about the AMC version of that tranny.)

nate

 

Thanks, Nate. That would go along with what I was told. Also strange
about no water cooling was that the Travelall (or as my dad called it,
the Troubleall) was popular and known for its great trailer towing
abilities (you used to see those huge Air Streams behind them), though
most likely there was an optional "trailer towing package" that mine
didn't have.

I did mitigate the ATF problem by installing a cooling coil behind the
rear axle. The tranny had fittings for a cooling loop, but there was
simply a short metal 'U' pipe from the gozinta and gozouta fittings. I
removed that pipe and ran rubber lines to the cooler.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

Now that is bizarre. the tranny I'm thinking of had no provisions for
external cooling at all in standard form, it was cooled through shaped
fins on the torque converter. The HD version *did* have cooling line
fittings, but then it was always used with the appropriate radiator with
built in cooler. (speaking for Studebakers only, not any other vehicles.)

nate

 

Well apparently the IH factory got the HD version for other beefed up
internals and they simply did not put the cooling loop in, which it
needed as evidenced by the fluid cooking every 20k. Perhaps that would
have been part of the trailer towing package.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

The part where there was any such a thing as an "AMC automatic
transmission".