OK: fuggedaboutit---I hear you, thanks;....I was hoping that the pedal-swap
might have been a simple procedure/experiment (NOT-)....
But, FWIW, the "manual-braking" effort, when the power assist has been lost,
is not any major effort or ordeal to endure, and absolutely nothing to
be feared
(like a complete loss of brake fluid is).
Kinda-really looking Forward to the full power braking effect of that
reconditioned
booster assembly, as compared to what's happening now, with the reportedly
full-manual-braking effort that is required.
The major stopping difference will probably be felt during a concerted
braking effort.
And, that's a scary thought, because the 11x3" Bendix's on Horrie, now,
are plenty
powerful enuf---it would be neat to see how well they could perform,
when controlled
by an ABS system, because 'you' can lock them up, with an OEM power
brake system.
Thinking back, now, I don't recall that I have been able to lock up the
Bendix's, in the
full-manual mode--altho I never had to try an expedited stop maneuver...
I was kind of hoping that the manual-pedal might have allowed for more
brake pedal feel
or modulation.
Neil Vedder
jrawa@xxxxxxx wrote:
57-59, just as earlier hung pedal assemblies- requires an entire
hanging pedal assembly- so.. plan on steering column removal and
unbolting the lower half of the dash from the side jambs to wing it
out- i usually swap in the power assembly when the body is still a
shell.. on the way back together- if i opt to do so.... the pedal has
a lever above the lower swinging arm- the carrier/support has an
elongation where it pivitos up and through, im pretty sure the fulcrum
point is also a little different- aiding in the advantage ratio change
-----Original Message-----
From: Eastern Sierra Adjustment Svc <esierraadj@xxxxxxxxxxx>
To: L-FORWARDLOOK@xxxxxxxxxxxxx
Sent: Thu, Feb 11, 2010 11:20 am
Subject: Re: [FWDLK] Hissy-fitting brake booster
So, what do you think about the mechanical advantage of installing a
manual pedal to my P/B system,
assuming that the pedal may be a bolt on replacement deal?
Should I try to find one, anyway???
Neil Vedder
Dave Homstad wrote:
> On my car, I converted the non-power brakes to PB. I bought my car
with non-power brakes. Then I rebuilt the original wheel cylinders and
linings, turned the drums slightly, and replaced the linings and
hoses. Everything worked OK, but the car required more pedal pressure
to stop than before. A hard stop took both feet. I concluded that
modern off-the-shelf lining materials are designed for power brakes,
which seem to be standard on most everything, and these require more
pressure. >
> Then I installed a factory power brake set up from a parts car. I
thought I could just install the PB pedal, but it didn't fit the old
support structure. So the entire structure got replaced. The master
cylinder didn't even need to be disconnected from the hose, so no
bleeding was necessary. Wth the power brakes, the car now needs half
the pedal pressure to get twice the stopping power of the old system.
I am sure that with the same pedal pressure, such as one foot as hard
as possible, the line hydraulic pressure is much higher. Probably as
earlier stated going from 750 psi non-PB to 1100 psi with PB. >
>
> Dave Homstad > 56 Dodge D500
>
> ---- jrawa@xxxxxxx <mailto:jrawa@xxxxxxx> wrote: > >> interesting
note they published... the line pressures should inevitably be the
same to create the same stopping effect- whether manual or power-
figuring all master cylinders are 1-1/8 bore as are all 6 wheel
cylinders- and, the same amount of fluid [under the same systemic
pressure] would have to be displaced from the master to all cylinders
to achieve stopping pressure, shoes to drum.... i dont buy into higher
line pressure of power brake systems. the position of the pushrod in
relation to the point of pivot of the brake pedal arm is different-
giving a less advantageous aspect ratio of pedal:master piston travel
in a situaution of "manualized" power brakes, the manual ratio has a
higher multiplication ration of applied pedal pressure>piston
displacement.
>>
>> i can attest that the instantaneous line pressure may be higher
upon brake aplication, but a higher systemic pressure would mean
nothing more than the fact that in comparison to pedal pressure- the
booster adds that much more applied pressure- raising line pressure-
causing the car to stop quicker, giving a more touchy pedal [which i
feel in my bellows and cannister booster 57-61s] but by laws of
physics, a panic stop would lock all 4 wheels, which i havent had the
wonder of experiencing....
>>
>> my fastest fwdlk cars run manual discs, one with a fully
retrofitted gm pedal/booster/master assy. other commonly driven
fwdlk's have dual masters in manual and boosted apps... the resto cars
all retain single masters, man and power...
>>
>> so from the fluid dynamic engineering standpoint- the systemic
fluid pressure is in proportional relativity to applied stopping
power.... so.... back to basics, power brake cars stop "sooner" or
easier- using the same components from master to drum, and differ only
in pedal apply ratio and have that good old booster making your
footwork a little less arduous >>
>> >>
>>
>> >>
>> >>
>> -----Original Message-----
>> From: Eastern Sierra Adjustment Svc <esierraadj@xxxxxxxxxxx
<mailto:esierraadj@xxxxxxxxxxx>>
>> To: L-FORWARDLOOK@xxxxxxxxxxxxx <mailto:L-FORWARDLOOK@xxxxxxxxxxxxx>
>> Sent: Wed, Feb 10, 2010 12:36 pm
>> Subject: [FWDLK] Hissy-fitting brake booster
>>
>>
>> Well, for anyone interested, you might recall that my car's
canister-type power >> brake booster has been hissing badly, whenever
the pedal is depressed, and >> that I'd been quoted O/H prices of
several hundreds, and up, for that work. >> >> When this condition
occurs, with our cars, a mere reversion to manual- >> braking-effort
results, and if so, that is NO big-deal, believe me. Biggest >> PITA
is the hissing noise, at red lights (so, don't STOP there, I hear you
say). >> >> As I never like risking sending out an essential part with
the car remaining >> undriveable, I bought a flea-pay booster, very
economically, which was claimed >> to be in working condition, and
sent it out to "Booster Dewey", in Portland OR >> for O/H, at the VERY
reasonable cost of $175.00. >> >> They just called and will be
returning that guy to me; they say that they use a very >> viscous
lubricant to seal up the booster's internal compression. >> >> I've
asked them to send me some pics of their representative internal work,
as I may be >> praising their product to others. They say that my
'new' booster has been tested by >> them to work like a champ! >> >>
So, I may be interested in selling my car's canister to someone who
might be interested >> in having IT be O/H'ed, and installed in (one
of-) your car(s), too. >> >> Anyway: and here's a question for you
Engineering-types: the manual brakes apparently >> have a different
configuration of the brake pedals/system, from the power brake models
(called >> the "aspect ratio"--IIRC) which allow for different p.s.i.
line pressure ratings, between the two >> systems. >> >> E.G.:
according to the 1957 D501 A.M.A. specs, the manual brakes have a 750
p.s.i. >> rating, while the power brakes have a 1,100 p.s.i. rating ;
a considerable difference. >> >> (Here it comes: ) so, to what extent
would a manual brake car realize an increase in >> braking
effort/effect if a power brake's pedal-lever-connections were to be
installed >> onto it, and, vice-versa---given, that the master
cylinders are identical, which I >> believe that they are???? >> >>
Neil Vedder >> >> >>
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