Brake pad question

"wle" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"Mark South" <[email hidden]> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

Today I exeperienced something new to me.

About 20 km into my Sunday morning ride, I was coming up a gentle hill into

a

Quoted message said:

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tiny village and thinking "Hell, I must be getting weaker every day, why is

this

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incline so hard?"

well, after all that, what was it?

Good question. I still am not certain, but it seems to me that my original
explanantion based on thermal expansion of the brake pads was the correct one.

When the bike is left in my cool garage overnight the brake develops a little
more travel and this reduces again when I'm out on the road.

I run the pads very close to the rim to start with, so it didn't take much to
make them bind, I guess.
--
"Since you must keep improving, a $5 bike offers a lot more opportunities
to improve it, and can be improved cheaper. It's expensive to improve on
a $2000 bike." - Rick Onanian in rec.bicycles.tech

I am betting it's dirty calipers that are sticking. I have noticed that
my dual pivots "gunk up" a lot more often than my old single pivots.

--

Mark South said:

Quoted message said:

Quoted message said:

Today I experienced something new.

Quoted message said:

Quoted message said:

Quoted message said:

About 20 km into my Sunday morning ride, I was coming up a gentle
hill into a tiny village and thinking "Hell, I must be getting
weaker every day, why is this incline so hard?"

Quoted message said:

Quoted message said:

well, after all that, what was it?

Quoted message said:

Good question. I still am not certain, but it seems to me that my
original explanation based on thermal expansion of the brake pads
was the correct one.

Thermal expansion, even in soft material like bicycle brake pads
cannot take up that clearance unless they were dragging after they
were last adjusted.

Quoted message said:

When the bike is left in my cool garage overnight the brake develops
a little more travel and this reduces again when I'm out on the
road.

Quoted message said:

I run the pads very close to the rim to start with, so it didn't
take much to make them bind, I guess.

You must be running with less than 0.5mm total clearance for that to
go away thermally but then you didn't comment on whether the brake was
off center (more clearance on one side than the other). Dual pivot
brakes cannot swivel except permanently, by rotating the anchor bolt.
That is what I think happened. Somewhere along the way the brake
caliper got pushed to one side.

Check how easily the caliper and bolt can be rotated bolt with the
wheel removed. It should not be movable by hand if the bolt is tight.
If this brake is operating with less than 0.5mm clearance it is set
too closely and will drag even if perfectly centered when pedaling
standing on hills. When the bottom of the wheel is side loaded to the
right, the top moves to the right also and will cause drag.

Wheel flex of rear wheels in climbing is why Campagnolo reverted to a
single pivot, lower mechanical advantage brake for the rear with more
clearance. Such a brake does not need to be dual pivot. Clearance is
governed by how high the mechanical advantage. Car disk brakes, for
instance, run with practically no clearance and have a high mechanical
advantage that is still too low without power assist. At least their
brakes have float to accept elastic movement of the wheel and disc.

Jobst Brandt
[email hidden]

Quoted message said:

...Car disk brakes, for
instance, run with practically no clearance and have a high mechanical
advantage that is still too low without power assist....

The only reason for power assist brakes in a car of reasonable mass
would be to assist a driver with physical disabilities. If people find
non-assisted brakes too hard to use, then they are either weak or lazy.
This is similar to finding a bicycle frame pump too hard to use. 😉

--
Tom Sherman – Quad City Area

Tom Sherman said:

Quoted message said:

Car disk brakes, for instance, run with practically no clearance
and have a high mechanical advantage that is still too low without
power assist...

Quoted message said:

The only reason for power assist brakes in a car of reasonable mass
would be to assist a driver with physical disabilities. If people
find non-assisted brakes too hard to use, then they are either weak
or lazy. This is similar to finding a bicycle frame pump too hard
to use. 😉

I suggest you test your hypothesis by shutting off the engine of your
car on a safe stretch of road and see how easily you can stop it by
stepping on the brake pedal. That is what no-assist would be. Of
course if you are driving one of the 650,000 recalled Mercedes-Benz
cars with electronic control, you won't have any rear wheel brakes
anyway.

The spongy response that is variable with dynamic pad clearance from
cornering is undesirable and has too much travel due to the mechanical
advantage in such systems. I drove my last disc brake car with no
assist long ago and it didn't weight as much as the cars we normally
use.

Jobst Brandt
[email hidden]

Quoted message said:

Tom Sherman said:

Quoted message said:

Car disk brakes, for instance, run with practically no clearance
and have a high mechanical advantage that is still too low without
power assist...

Quoted message said:

The only reason for power assist brakes in a car of reasonable mass
would be to assist a driver with physical disabilities. If people
find non-assisted brakes too hard to use, then they are either weak
or lazy. This is similar to finding a bicycle frame pump too hard
to use. 😉

I suggest you test your hypothesis by shutting off the engine of your
car on a safe stretch of road and see how easily you can stop it by
stepping on the brake pedal. That is what no-assist would be. Of
course if you are driving one of the 650,000 recalled Mercedes-Benz
cars with electronic control, you won't have any rear wheel brakes
anyway.

The spongy response that is variable with dynamic pad clearance from
cornering is undesirable and has too much travel due to the mechanical
advantage in such systems. I drove my last disc brake car with no
assist long ago and it didn't weight as much as the cars we normally
use.

I have driven older cars without power brakes and did not find the
effort excessive: certainly nothing out of the normal range for fit
cyclist. Brake boosters (in most cases) change the feel of the brakes in
a manner that makes modulation more difficult. Power brakes (in a
reasonably sized vehicle) are no more necessary that power steering is. [1]

[1] I used to drive a 1972 Oldsmobile with a broken power steering pump.
That car had close to 3000 pounds of weight on the front wheels. At
the time I weighed less than 140 pounds and certainly DID NOT have above
average upper body strength.

--
Tom Sherman – Quad City Area

Quoted message said:

Tom Sherman said:

Quoted message said:

Car disk brakes, for instance, run with practically no clearance
and have a high mechanical advantage that is still too low without
power assist...

Quoted message said:

The only reason for power assist brakes in a car of reasonable mass
would be to assist a driver with physical disabilities. If people
find non-assisted brakes too hard to use, then they are either weak
or lazy. This is similar to finding a bicycle frame pump too hard
to use. 😉

I suggest you test your hypothesis by shutting off the engine of your
car on a safe stretch of road and see how easily you can stop it by
stepping on the brake pedal. That is what no-assist would be. Of
course if you are driving one of the 650,000 recalled Mercedes-Benz
cars with electronic control, you won't have any rear wheel brakes
anyway.

The spongy response that is variable with dynamic pad clearance from
cornering is undesirable and has too much travel due to the mechanical
advantage in such systems. I drove my last disc brake car with no
assist long ago and it didn't weight as much as the cars we normally
use.

Jobst Brandt
[email hidden]

Dear Jobst,

Gotta go with you on this one. I just peeked at an ancient
Subaru site devoted to elderly light-weight vehicles

http://www.cars101.com/oldsubaru.html#1983%20Subaru

Even in 1975, the first 1-ton Subarus all had power-assisted
front disc brakes. Despite their feeble 1.3, 1.4,
and--gasp!--1.6 liter engines, it was thought wise to borrow
engine power to help the brakes stop the thundering
behemoths.

Oddly, the site says only that my state-of-the-art
dog-hauling 1983 Subaru has "vented" front discs and remains
coy about whether they are assisted by the pavement-rippling
1.8 liter 73-horsepower engine.

Carl Fogel

Tom Sherman said:

Quoted message said:

Quoted message said:

> Car disk brakes, for instance, run with practically no clearance
> and have a high mechanical advantage that is still too low
> without power assist...

Quoted message said:

Quoted message said:

Quoted message said:

The only reason for power assist brakes in a car of reasonable
mass would be to assist a driver with physical disabilities. If
people find non-assisted brakes too hard to use, then they are
either weak or lazy. This is similar to finding a bicycle frame
pump too hard to use.

Quoted message said:

Quoted message said:

I suggest you test your hypothesis by shutting off the engine of
your car on a safe stretch of road and see how easily you can stop
it by stepping on the brake pedal. That is what no-assist would
be. Of course if you are driving one of the 650,000 recalled
Mercedes-Benz cars with electronic control, you won't have any rear
wheel brakes anyway.

Quoted message said:

Quoted message said:

The spongy response that is variable with dynamic pad clearance
from cornering is undesirable and has too much travel due to the
mechanical advantage in such systems. I drove my last disc brake
car with no assist long ago and it didn't weight as much as the
cars we normally use.

Quoted message said:

I have driven older cars without power brakes and did not find the
effort excessive: certainly nothing out of the normal range for fit
cyclist.

What "older cars" did you drive that had unassisted disc brakes?

Quoted message said:

Brake boosters (in most cases) change the feel of the brakes in a
manner that makes modulation more difficult. Power brakes (in a
reasonably sized vehicle) are no more necessary that power steering
is.[1]

I think you are mistaking the poor response of drum brakes for power
disc brakes. Todays disc brakes are as linear and controllable as you
can expect, far better than brakes without power assist.

Drum brakes got by without power assist for a long time because drums
use self servo (self activating leading shoes) whose effectiveness
varied with temperature and humidity, so much so that they locked up
on occasion. The non-linearity of drum brakes is what got rid of
them. Discs in contrast are linear (braking proportional to pedal
pressure) but because they have a low coefficient of friction that,
except for the lightest cars, require a brake booster. These boosters
are vacuum driven in most cars.

Quoted message said:

[1] I used to drive a 1972 Oldsmobile with a broken power steering
pump. That car had close to 3000 pounds of weight on the front
wheels. At the time I weighed less than 140 pounds and certainly DID
NOT have above average upper body strength.

So what are you proposing? How does this affect brakes?

Jobst Brandt
[email hidden]

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Tom Sherman writes:

<snip>

Quoted message said:

Quoted message said:

I have driven older cars without power brakes and did not find the
effort excessive: certainly nothing out of the normal range for fit
cyclist.

What "older cars" did you drive that had unassisted disc brakes?

VW beetles from the late 60's early 70's.
Porsche 911/912 from introduction (64) until quite recently (late 80's?)

Quoted message said:

Quoted message said:

Brake boosters (in most cases) change the feel of the brakes in a
manner that makes modulation more difficult. Power brakes (in a
reasonably sized vehicle) are no more necessary that power steering
is.[1]

Porsche factory said this re the 911 for a long time.

Quoted message said:

I think you are mistaking the poor response of drum brakes for power
disc brakes. Todays disc brakes are as linear and controllable as you
can expect, far better than brakes without power assist.

Drum brakes got by without power assist for a long time because drums
use self servo (self activating leading shoes) whose effectiveness
varied with temperature and humidity, so much so that they locked up
on occasion. The non-linearity of drum brakes is what got rid of
them. Discs in contrast are linear (braking proportional to pedal
pressure) but because they have a low coefficient of friction that,
except for the lightest cars, require a brake booster. These boosters
are vacuum driven in most cars.

Porsche customers said this for even longer - they won!

Bruce Graham said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Tom Sherman writes:

<snip>

Quoted message said:

Quoted message said:

I have driven older cars without power brakes and did not find the
effort excessive: certainly nothing out of the normal range for fit
cyclist.

What "older cars" did you drive that had unassisted disc brakes?

VW beetles from the late 60's early 70's.
Porsche 911/912 from introduction (64) until quite recently (late 80's?)

Quoted message said:

Quoted message said:

Brake boosters (in most cases) change the feel of the brakes in a
manner that makes modulation more difficult. Power brakes (in a
reasonably sized vehicle) are no more necessary that power steering
is.[1]

Porsche factory said this re the 911 for a long time.

Quoted message said:

I think you are mistaking the poor response of drum brakes for power
disc brakes. Todays disc brakes are as linear and controllable as you
can expect, far better than brakes without power assist.

Drum brakes got by without power assist for a long time because drums
use self servo (self activating leading shoes) whose effectiveness
varied with temperature and humidity, so much so that they locked up
on occasion. The non-linearity of drum brakes is what got rid of
them. Discs in contrast are linear (braking proportional to pedal
pressure) but because they have a low coefficient of friction that,
except for the lightest cars, require a brake booster. These boosters
are vacuum driven in most cars.

Porsche customers said this for even longer - they won!

Dear Bruce,

The customer is always right.

It may also be worth pointing out in all this talk about
assisted braking that about half the auto industry's
customers are of a sex and size woefully under-represented
here on rec.bicycles.tech.

Forget any smaller-than-average men who ride bicycles and
post here. Think of women around 5'4" and 110 pounds.
Several such sources have just told me that power brakes
(and steering) are damned useful.

Sensitively,

Carl Fogel

Quoted message said:

Tom Sherman said:

Quoted message said:

>>Car disk brakes, for instance, run with practically no clearance
>>and have a high mechanical advantage that is still too low
>>without power assist...

Quoted message said:

Quoted message said:

>The only reason for power assist brakes in a car of reasonable
>mass would be to assist a driver with physical disabilities. If
>people find non-assisted brakes too hard to use, then they are
>either weak or lazy. This is similar to finding a bicycle frame
>pump too hard to use.

Quoted message said:

Quoted message said:

I suggest you test your hypothesis by shutting off the engine of
your car on a safe stretch of road and see how easily you can stop
it by stepping on the brake pedal. That is what no-assist would
be. Of course if you are driving one of the 650,000 recalled
Mercedes-Benz cars with electronic control, you won't have any rear
wheel brakes anyway.

Quoted message said:

Quoted message said:

The spongy response that is variable with dynamic pad clearance
from cornering is undesirable and has too much travel due to the
mechanical advantage in such systems. I drove my last disc brake
car with no assist long ago and it didn't weight as much as the
cars we normally use.

Quoted message said:

I have driven older cars without power brakes and did not find the
effort excessive: certainly nothing out of the normal range for fit
cyclist.

What "older cars" did you drive that had unassisted disc brakes?

I have driven various MG's and Triumph's with unassisted front disc/rear
drum brakes. Admittedly these car are significantly lighter than today’s
porkers (where a midsize sedan can weigh 2 tons), but the braking did
not take an unusually high effort.

Quoted message said:

Quoted message said:

Brake boosters (in most cases) change the feel of the brakes in a
manner that makes modulation more difficult. Power brakes (in a
reasonably sized vehicle) are no more necessary that power steering
is.[1]

I think you are mistaking the poor response of drum brakes for power
disc brakes. Todays disc brakes are as linear and controllable as you
can expect, far better than brakes without power assist.

Drum brakes got by without power assist for a long time because drums
use self servo (self activating leading shoes) whose effectiveness
varied with temperature and humidity, so much so that they locked up
on occasion. The non-linearity of drum brakes is what got rid of
them. Discs in contrast are linear (braking proportional to pedal
pressure) but because they have a low coefficient of friction that,
except for the lightest cars, require a brake booster. These boosters
are vacuum driven in most cars.

Having driven 135,000+ miles in cars with 4-wheel disc brakes and power
assist but no anti-lock, I feel that I am quite familiar with that type
of system. I have also driven plenty of pickups and vans with rear wheel
drum brakes, so I am all too aware of their poor modulation and
"self-energizing" effect.

Quoted message said:

Quoted message said:

[1] I used to drive a 1972 Oldsmobile with a broken power steering
pump. That car had close to 3000 pounds of weight on the front
wheels. At the time I weighed less than 140 pounds and certainly DID
NOT have above average upper body strength.

So what are you proposing? How does this affect brakes?

The point is that power assisted braking and steering (not to mention
automatic transmissions) are used in cars because they are designed for
lazy people who expect to put out no effort, not out of necessity.

--
Tom Sherman – Quad City Area

Bruce Graham said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Tom Sherman writes:

<snip>

Quoted message said:

Quoted message said:

I have driven older cars without power brakes and did not find the
effort excessive: certainly nothing out of the normal range for fit
cyclist.

What "older cars" did you drive that had unassisted disc brakes?

VW beetles from the late 60's early 70's.

Our '75 VW Rabbit (aka Golf) had unassisted front disc brakes. As does
the '87 Chevy Nova that I gave to our daughter last year. My primary
vehicle is now an '89 Cannondale - it also has unassisted disc brakes
(the discs being the rims).

Quoted message said:

Porsche 911/912 from introduction (64) until quite recently (late 80's?)

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Mark South said:

Quoted message said:

> Today I experienced something new.

Quoted message said:

Quoted message said:

> About 20 km into my Sunday morning ride, I was coming up a gentle
> hill into a tiny village and thinking "Hell, I must be getting
> weaker every day, why is this incline so hard?"

Quoted message said:

Quoted message said:

well, after all that, what was it?

Quoted message said:

Good question. I still am not certain, but it seems to me that my
original explanation based on thermal expansion of the brake pads
was the correct one.

Thermal expansion, even in soft material like bicycle brake pads
cannot take up that clearance unless they were dragging after they
were last adjusted.

They were not dragging, but they were very close. The rim is laterally true
within less than .5 mm and the pads have only enough clearance to not drag on
the rim when everything is cool.

Quoted message said:

Quoted message said:

When the bike is left in my cool garage overnight the brake develops
a little more travel and this reduces again when I'm out on the
road.

Quoted message said:

I run the pads very close to the rim to start with, so it didn't
take much to make them bind, I guess.

You must be running with less than 0.5mm total clearance for that to
go away thermally but then you didn't comment on whether the brake was
off center (more clearance on one side than the other). Dual pivot
brakes cannot swivel except permanently, by rotating the anchor bolt.
That is what I think happened. Somewhere along the way the brake
caliper got pushed to one side.

The brake is and was perfectly centred. When I stopped and noticed the pads
binding, they were both squeezed onto the rim.

Quoted message said:

Check how easily the caliper and bolt can be rotated bolt with the
wheel removed. It should not be movable by hand if the bolt is tight.
If this brake is operating with less than 0.5mm clearance it is set
too closely and will drag even if perfectly centered when pedaling
standing on hills. When the bottom of the wheel is side loaded to the
right, the top moves to the right also and will cause drag.

Perhaps you're right. The brake pads remained dragging on the rim when I got
off the bike though.

As I said, I fixed it by adding some clearance, but I can still see (and feel
through the levers) the variation in clearance with temperature.

Perhaps I got a batch of pads with an unusually large (tail of the distribution)
thermal expansion ratio?

Quoted message said:

Wheel flex of rear wheels in climbing is why Campagnolo reverted to a
single pivot, lower mechanical advantage brake for the rear with more
clearance. Such a brake does not need to be dual pivot. Clearance is
governed by how high the mechanical advantage. Car disk brakes, for
instance, run with practically no clearance and have a high mechanical
advantage that is still too low without power assist. At least their
brakes have float to accept elastic movement of the wheel and disc.

So you are saying I should fit disk brakes on my road bike?

(Ducks and runs :-)
--
Mark South: World Citizen, Net Denizen

Tom Sherman said:

Having driven 135,000+ miles in cars with 4-wheel disc brakes and power
assist but no anti-lock, I feel that I am quite familiar with that type
of system. I have also driven plenty of pickups and vans with rear wheel
drum brakes, so I am all too aware of their poor modulation and
"self-energizing" effect.

Just because you drive cars doesn't qualify you as understanding the
works of the brakes. I'm sure you can strike up a conversation with a
truck driver at a truck-stop cafe and get all sorts of testimonials on
the benefits of various equipment, some of which is pure folklore and
other parts that happen to coincide with fact. Mileage does not an
automotive engineer make, so take it easy on the mileage claims.

Quoted message said:

Quoted message said:

Quoted message said:

[1] I used to drive a 1972 Oldsmobile with a broken power steering
pump. That car had close to 3000 pounds of weight on the front
wheels. At the time I weighed less than 140 pounds and certainly DID
NOT have above average upper body strength.

Quoted message said:

Quoted message said:

So what are you proposing? How does this affect brakes?

Quoted message said:

The point is that power assisted braking and steering (not to mention
automatic transmissions) are used in cars because they are designed for
lazy people who expect to put out no effort, not out of necessity.

Tell that to Michael Schumacher and his competitors. The power brake
is an essential part of good braking and cars that don't use it are
either light enough to squeak by or too cheap to use it.

The basic concept of a brake is that it is a force transducer, not a
position transducer as steering is. Good Brake response is
proportional to pedal pressure, not stroke. In fact the stroke
involved is counterproductive because it changes the leverage of the
leg and the feel of how hard the brake is being applied. Stroke on
power assisted brakes is a necessary evil of having to also work (with
diminished capacity) without assist.

Your "lazy people" reference discredits what you say on this at the
outset.

Jobst Brandt
[email hidden]

Quoted message said:

...
Your "lazy people" reference discredits what you say on this at the
outset....

It was in reference to a certain rec.bicycles.tech regular who likes to
comment on the inability of people to use items such as full size frame
pumps, ride long distances without drinking water, and to use lower
mechanical advantage bicycle brakes.

--
Tom Sherman – Quad City Area

Tom Sherman said:

Quoted message said:

Your "lazy people" reference discredits what you say on this at the
outset....

Quoted message said:

It was in reference to a certain rec.bicycles.tech regular who likes
to comment on the inability of people to use items such as full size
frame pumps, ride long distances without drinking water, and to use
lower mechanical advantage bicycle brakes.

Why don't you speak for yourself instead of dodging and making
allusions? There is no doubt that many riders are not able to pump
tires with a 20mm diameter piston frame pump or stop their bicycles
safely with 4:1 ratio hand brakes. They have said so here on this
group and have ceased to complain about it with the advent of dual
pivot brakes and micro-pumps. What does this have to do with power
brakes and their response?

"Lazy people" is not a parameter here nor is it with power brakes.

Your "a certain rec.bicycles.tech regular" doesn't say what your
problem with this is. You display inhibitions in expressing what you
mean. Speak up!

Jobst Brandt
[email hidden]

Bruce Graham said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Tom Sherman writes:

<snip>

Quoted message said:

Quoted message said:

I have driven older cars without power brakes and did not find
the effort excessive: certainly nothing out of the normal range
for fit cyclist.

What "older cars" did you drive that had unassisted disc brakes?

VW beetles from the late 60's early 70's.

Sorry, drum brakes. At least if my wife's '72 Super Beetle was
anything to go by.

Quoted message said:

Tom Sherman said:

Having driven 135,000+ miles in cars with 4-wheel disc brakes and power
assist but no anti-lock, I feel that I am quite familiar with that type
of system. I have also driven plenty of pickups and vans with rear wheel
drum brakes, so I am all too aware of their poor modulation and
"self-energizing" effect.

actually, the two reasons brakes have gone to disk from drum are:

1. disks cool much quicker so therefore are much more fade resistant.
ask any big rig driver about fade in drum brakes.

2. if they get wet, drums are hard to dry out - disks dry almost
immediately so disks are much safer.

and it's too simplistic to claim "poor modulation" on a rear drum brakes
- it takes no account of load compensation or proportioning devices.

Quoted message said:

Just because you drive cars doesn't qualify you as understanding the
works of the brakes. I'm sure you can strike up a conversation with a
truck driver at a truck-stop cafe and get all sorts of testimonials on
the benefits of various equipment, some of which is pure folklore and
other parts that happen to coincide with fact. Mileage does not an
automotive engineer make, so take it easy on the mileage claims.

Quoted message said:

Quoted message said:

>[1] I used to drive a 1972 Oldsmobile with a broken power steering
>pump. That car had close to 3000 pounds of weight on the front
>wheels. At the time I weighed less than 140 pounds and certainly DID
>NOT have above average upper body strength.

Quoted message said:

Quoted message said:

So what are you proposing? How does this affect brakes?

Quoted message said:

The point is that power assisted braking and steering (not to mention
automatic transmissions) are used in cars because they are designed for
lazy people who expect to put out no effort, not out of necessity.

Tell that to Michael Schumacher and his competitors. The power brake
is an essential part of good braking and cars that don't use it are
either light enough to squeak by or too cheap to use it.

The basic concept of a brake is that it is a force transducer,

technically, it's an energy transducer - turns the energy of motion into
heat.

Quoted message said:

not a
position transducer as steering is. Good Brake response is
proportional to pedal pressure, not stroke. In fact the stroke
involved is counterproductive because it changes the leverage of the
leg and the feel of how hard the brake is being applied. Stroke on
power assisted brakes is a necessary evil of having to also work (with
diminished capacity) without assist.

air brakes on buses & trucks are sensitive only to stroke, not force.
you can bottom the pedal on an air braked vehicle no problem. a common
mistake make by people learning to drive an air braked vehicle is to
brake much too fiercely because they're expecting the pedal to stop
going down as they reach some kind of bite point.

Quoted message said:

Your "lazy people" reference discredits what you say on this at the
outset.

Jobst Brandt
[email hidden]

jim beam said:

air brakes on buses & trucks are sensitive only to stroke, not
force.

Not the ones I drove. Would be a counter-intuitive concept, btw.

--
MfG/Best regards
helmut springer

On Sat, 19 Jun 2004 06:06:48 GMT [email hidden]

Quoted message said:

What "older cars" did you drive that had unassisted disc brakes?

VW type 3s came with unassisted front disks from '66 to the end of
production in '73. They certainly require more pedal effort than a car
with power brakes, but that's really only because power brakes require
virtually no effort. I've never had any problem getting one of mine to
stop, but I keep the brakes in good condition. In general, I've always
considered their brakes to be excellent.

People who are used to power brakes are often surprised by the pedal
effort, but I have always assumed that this was simply because they
were used to the zero effort that power brakes required.

Their rear drum brakes have one leading and one trailing shoe on each
side, but even with the leading shoes, braking is poor if the fronts
aren't working.

Yes, these were light cars; only about 2250 lbs. There are modern
cars, however, that weigh the same and still use power brakes, but
they are generally front engine/drive, and have virtually all their
weight on the front wheels, so their rear brakes are almost pointless.

-
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Jim Adney [email hidden]
Madison, WI 53711 USA
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