Hard or soft braking

I recently read (don't ask me where, it was a couple of months ago) that
brakes last longer with harder+shorter pressure than with softer+longer
pressure. Opinions?

--
Cheers, Bev
"I don't trust carry-out food. When you find hair in my cooking
you don't hafta worry about where it came from!" -- Dinette Set

The Real Bev wrote:
> I recently read (don't ask me where, it was a couple of months ago) that
> brakes last longer with harder+shorter pressure than with softer+longer
> pressure. Opinions?
>

True, stab braking allows the heat to dissipate better and the lower
amount of constant contact lowers wear as well.

--
Steve W.

The Real Bev wrote:

>I recently read (don't ask me where, it was a couple of months ago) that
>brakes last longer with harder+shorter pressure than with softer+longer
>pressure. Opinions?

The amount of energy that needs to be dissipated as heat via the brake
components will be exactly the same however harder braking will result
in higher temperatures as the heat is applied over a shorter period of
time.

The question then becomes whether brakes wear quicker at higher or
lower temperatures?

There are also other factors to consider, particularly the pad
material and its suitability for the conditions that apply (consistent
hard braking from high speeds requires a different material to the
conditions encountered in normal city driving).

--
John H

On Sat, 07 Mar 2020 10:19:30 +1000, John_H wrote:

> The question then becomes whether brakes wear quicker at higher or
> lower temperatures?

I agree that is a fundamental question related to the OP's concern.
o Do hot brakes/rotors wear down rotors/pads faster than cooler ones?

Me?
o I use Silicon Valley finesse when braking - not brute redneck force.

What I do is coast to a stop whenever possible for a variety of reasons.
1. I put the gears in neutral when I can see the red light ahead.
2. Then, I apply the brakes harder at first, so as to scrub momentum.
3. Then I coast, gently, still in neutral, to the stop light.

While this works whether or not it's a manual transmission, I do agree that
some people feel shifting an automatic is (somehow?) bad for the automatic,
but I've been doing this for decades, and haven't destroyed one yet.

The _advantages_ of this "coast to a stop" method are, IMHO, mainly:
A. It saves on gas mileage (as 20% of the time you never need to stop)
B. It saves on pad-deposition (since the rotors have a chance to cool down)

As a bit of finesse, I make sure that if, in the 80% of the time I _still_
have to stop, I simply "almost stop" a car length or two behind the stopped
car in front of me, where I then expend the last bit of braking heat, and
then coast to the final stop and lift the pedal off (if it's flat).

That way I don't get a pad "footprint", which, IMHO, is a major cause of
brake-related vibration at highway speeds (which is a topic we've discussed
in infinite detail in the past on this newsgroup so I won't belabor it).

--
Yes, I know the laws on driving on public roads with gears in neutral.

On 03/06/2020 05:30 PM, Arlen Holder wrote:
> On Sat, 07 Mar 2020 10:19:30 +1000, John_H wrote:
>
>> The question then becomes whether brakes wear quicker at higher or
>> lower temperatures?
>
> I agree that is a fundamental question related to the OP's concern.
> o Do hot brakes/rotors wear down rotors/pads faster than cooler ones?

I would guess that heat is always the enemy. Do they get cumulatively
hotter with hard sporadic braking or soft longer-lasting braking?

> Me?
> o I use Silicon Valley finesse when braking - not brute redneck force.
>
> What I do is coast to a stop whenever possible for a variety of reasons.
> 1. I put the gears in neutral when I can see the red light ahead.
> 2. Then, I apply the brakes harder at first, so as to scrub momentum.
> 3. Then I coast, gently, still in neutral, to the stop light.

In traffic I just take my foot off the gas as soon as possible. Hubby
says I don't do it soon enough, but I hate having someone dive in ahead
of me because I left enough room for them to do so. In my defense, some
assholes haven't a clue about making left turns in heavy traffic -- they
stay behind the limit line until the light turns red and then dive
through -- requiring everyone behind them to wait through an additional
cycle. If done properly TWO cars can go through on each cycle -- maybe
three if all three are quick.

> While this works whether or not it's a manual transmission, I do agree that
> some people feel shifting an automatic is (somehow?) bad for the automatic,
> but I've been doing this for decades, and haven't destroyed one yet.

Brake pads are cheaper and easier to replace than
clutches/transmissions. I'll put the car in 2nd if coming down the
mountains trapped behind some jerk who hasn't a clue about mountain
driving -- long ago I used my brakes far too much in a similar situation
and had serious fade down at the bottom. Some experiences cast long
shadows.

> The _advantages_ of this "coast to a stop" method are, IMHO, mainly:
> A. It saves on gas mileage (as 20% of the time you never need to stop)
> B. It saves on pad-deposition (since the rotors have a chance to cool down)

Fine in traffic.

I'm mostly concerned with mountain and highway driving, which is what I
use my car for most.

--
Cheers, Bev
"The way England treats her prisoners, she doesn't
deserve to have any." --Oscar Wilde

On Sat, 7 Mar 2020 08:55:43 -0800, The Real Bev wrote:

> I would guess that heat is always the enemy. Do they get cumulatively
> hotter with hard sporadic braking or soft longer-lasting braking?

As someone stated, we have to expend the same amount of energy in slowing
down the car no matter how we brake - almost all of which is heat energy.

Seems to me that the "temperature" is a function of how hard we brake and
how fast we stop, where, IMHO, stopping slower "spreads" out that heat,
such that the "temperature" has a chance to not rise as much.

Does it work?
o Dunno.

I do it mostly for two reasons:
a. Save fuel, and,
b. Prevent pad footprint deposition.

> In traffic I just take my foot off the gas as soon as possible. Hubby
> says I don't do it soon enough, but I hate having someone dive in ahead
> of me because I left enough room for them to do so.

Hehhehheh... that happens to me all the time.

I can see their point, as they likely feel I'm "slowing them down"; but
they also likely don't realize that I'm coasting because I _know_ there's a
red light up ahead (or stopped traffic) - where my goal isn't to stop - but
to coast right through the light when it finally turns green and the
traffic in front of me clears out.

> In my defense, some
> assholes haven't a clue about making left turns in heavy traffic -- they
> stay behind the limit line until the light turns red and then dive
> through -- requiring everyone behind them to wait through an additional
> cycle. If done properly TWO cars can go through on each cycle -- maybe
> three if all three are quick.

hehhehheh... I often "need" to go through a yellowish-red light, where
suddenly, my visor comes down to cover my face from the stoplight cameras,
if any.

(Hint: They need to correlate the driver with the license plate, I think.)

> Brake pads are cheaper and easier to replace than
> clutches/transmissions.

Yes. Much.
o I've heard this all the time.

But that assumes putting the transmission in neutral somehow "damages" the
transmission, or, getting it back in gear while coasting damages the
transmission.

The question for this ng is whether that's the case, or not.
o I don't know the answer - but I've been running the test for a long time!

> I'll put the car in 2nd if coming down the
> mountains trapped behind some jerk who hasn't a clue about mountain
> driving -- long ago I used my brakes far too much in a similar situation
> and had serious fade down at the bottom. Some experiences cast long
> shadows.

Are you in a manual or automatic?
o I don't feel much engine braking when using an automatic downhills.

And I travel a _lot_ of downhills!
<https://i.postimg.cc/g004XCLW/mount37.jpg>

Many miles every day in fact.
<https://i.postimg.cc/pT71cQZG/mount41.jpg>

Where my tires take a beating like you can't believe.
<https://i.postimg.cc/8zVxVHVx/mount40.jpg>

Almost always, I'm in neutral because the road is twisty curvy so you're
limited to between 20 and 35 mph almost the entire way downhill (or up).

> I'm mostly concerned with mountain and highway driving, which is what I
> use my car for most.

Me too, as I live in and around the mountains of Silicon Valley.

See details he
o Does the macadem road surface have a great effect on tire wear?
<https://groups.google.com/d/msg/rec.autos.tech/SPr6zNEDYDs/j5v5g3r0DAAJ>

And he
o How would you run a lateral acceleration test in a vehicle on
twisty roads at no more than 40mph?
<https://groups.google.com/d/msg/rec.autos.tech/x7pwhNCqlCo/o-zmIvu-CwAJ>
--
Usenet is so much more valuable, and pleasant, when people act like adults.

On 8/3/20 7:53 am, Arlen Holder wrote:
> On Sat, 7 Mar 2020 08:55:43 -0800, The Real Bev wrote:
>
>> I would guess that heat is always the enemy. Do they get cumulatively
>> hotter with hard sporadic braking or soft longer-lasting braking?
>
> As someone stated, we have to expend the same amount of energy in slowing
> down the car no matter how we brake - almost all of which is heat energy.
>
> Seems to me that the "temperature" is a function of how hard we brake and
> how fast we stop, where, IMHO, stopping slower "spreads" out that heat,
> such that the "temperature" has a chance to not rise as much.
>
> Does it work?
> o Dunno.
>
> I do it mostly for two reasons:
> a. Save fuel, and,
> b. Prevent pad footprint deposition.
>
>> In traffic I just take my foot off the gas as soon as possible. Hubby
>> says I don't do it soon enough, but I hate having someone dive in ahead
>> of me because I left enough room for them to do so.
>
> Hehhehheh... that happens to me all the time.
>
> I can see their point, as they likely feel I'm "slowing them down"; but
> they also likely don't realize that I'm coasting because I _know_ there's a
> red light up ahead (or stopped traffic) - where my goal isn't to stop - but
> to coast right through the light when it finally turns green and the
> traffic in front of me clears out.
>
>> In my defense, some
>> assholes haven't a clue about making left turns in heavy traffic -- they
>> stay behind the limit line until the light turns red and then dive
>> through -- requiring everyone behind them to wait through an additional
>> cycle. If done properly TWO cars can go through on each cycle -- maybe
>> three if all three are quick.
>
> hehhehheh... I often "need" to go through a yellowish-red light, where
> suddenly, my visor comes down to cover my face from the stoplight cameras,
> if any.
>
> (Hint: They need to correlate the driver with the license plate, I think.)
>
>> Brake pads are cheaper and easier to replace than
>> clutches/transmissions.
>
> Yes. Much.
> o I've heard this all the time.
>
> But that assumes putting the transmission in neutral somehow "damages" the
> transmission, or, getting it back in gear while coasting damages the
> transmission.

Depends on the transmission. The FWD driving clutch in a typical 3 or 4
speed auto transmission is engaged in all fwd gears. As a consequence,
the return spring mechanism in the FWD clutch can be a diaphragm plate
spring. Like this;

https://images-na.ssl-images-amazon...._AC_SX355_.jpg

BW35 and similar transmissions use these. Excessive flexing, such as
when you needlessly shift to neutral while stationary in traffic will
cause these to fatigue fail. Pulled many of these down to find broken
diaphragm springs. Bottom line, there is no need to shift to neutral
whilst stationary in traffic. The stall point on the torque converter
means that there will be minimal drag on the engine *at idle*.

Then there is the wait whilst people wake up to the fact that the
traffic situation has changed and the delay whilst they reselect drive.
Annoying for drivers behind, especially so if they miss their turn
through a set of lights.


>
> The question for this ng is whether that's the case, or not.
> o I don't know the answer - but I've been running the test for a long time!
>
>> I'll put the car in 2nd if coming down the
>> mountains trapped behind some jerk who hasn't a clue about mountain
>> driving -- long ago I used my brakes far too much in a similar situation
>> and had serious fade down at the bottom. Some experiences cast long
>> shadows.
>
> Are you in a manual or automatic?
> o I don't feel much engine braking when using an automatic downhills.
>
> And I travel a _lot_ of downhills!
> <https://i.postimg.cc/g004XCLW/mount37.jpg>
>
> Many miles every day in fact.
> <https://i.postimg.cc/pT71cQZG/mount41.jpg>
>
> Where my tires take a beating like you can't believe.
> <https://i.postimg.cc/8zVxVHVx/mount40.jpg>
>
> Almost always, I'm in neutral because the road is twisty curvy so you're
> limited to between 20 and 35 mph almost the entire way downhill (or up).
>
>> I'm mostly concerned with mountain and highway driving, which is what I
>> use my car for most.
>
> Me too, as I live in and around the mountains of Silicon Valley.
>
> See details he
> o Does the macadem road surface have a great effect on tire wear?
> <https://groups.google.com/d/msg/rec.autos.tech/SPr6zNEDYDs/j5v5g3r0DAAJ>
>
> And he
> o How would you run a lateral acceleration test in a vehicle on
> twisty roads at no more than 40mph?
> <https://groups.google.com/d/msg/rec.autos.tech/x7pwhNCqlCo/o-zmIvu-CwAJ>
>


--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 03/07/2020 12:53 PM, Arlen Holder wrote:
> On Sat, 7 Mar 2020 08:55:43 -0800, The Real Bev wrote:
>
>> I would guess that heat is always the enemy. Do they get cumulatively
>> hotter with hard sporadic braking or soft longer-lasting braking?
>
> As someone stated, we have to expend the same amount of energy in slowing
> down the car no matter how we brake - almost all of which is heat energy.
>
> Seems to me that the "temperature" is a function of how hard we brake and
> how fast we stop, where, IMHO, stopping slower "spreads" out that heat,
> such that the "temperature" has a chance to not rise as much.
>
> Does it work?
> o Dunno.
>
> I do it mostly for two reasons:
> a. Save fuel, and,
> b. Prevent pad footprint deposition.
>
>> In traffic I just take my foot off the gas as soon as possible. Hubby
>> says I don't do it soon enough, but I hate having someone dive in ahead
>> of me because I left enough room for them to do so.
>
> Hehhehheh... that happens to me all the time.
>
> I can see their point, as they likely feel I'm "slowing them down"; but
> they also likely don't realize that I'm coasting because I _know_ there's a
> red light up ahead (or stopped traffic) - where my goal isn't to stop - but
> to coast right through the light when it finally turns green and the
> traffic in front of me clears out.
>
>> In my defense, some
>> assholes haven't a clue about making left turns in heavy traffic -- they
>> stay behind the limit line until the light turns red and then dive
>> through -- requiring everyone behind them to wait through an additional
>> cycle. If done properly TWO cars can go through on each cycle -- maybe
>> three if all three are quick.
>
> hehhehheh... I often "need" to go through a yellowish-red light, where
> suddenly, my visor comes down to cover my face from the stoplight cameras,
> if any.
>
> (Hint: They need to correlate the driver with the license plate, I think.)

Our City took those out after only a few years. They didn't get a big
enough cut of the resulting fines, although they claimed it was because
of the increase in rear-enders.

>> Brake pads are cheaper and easier to replace than
>> clutches/transmissions.
>
> Yes. Much.
> o I've heard this all the time.
>
> But that assumes putting the transmission in neutral somehow "damages" the
> transmission, or, getting it back in gear while coasting damages the
> transmission.

Doing something different puts wear on the thing that's doing something
different.

> The question for this ng is whether that's the case, or not.
> o I don't know the answer - but I've been running the test for a long time!
>
>> I'll put the car in 2nd if coming down the
>> mountains trapped behind some jerk who hasn't a clue about mountain
>> driving -- long ago I used my brakes far too much in a similar situation
>> and had serious fade down at the bottom. Some experiences cast long
>> shadows.
>
> Are you in a manual or automatic?
> o I don't feel much engine braking when using an automatic downhills.

Auto. The Corolla engine-brakes fine, and so did the POS 88 Caddy.

> Almost always, I'm in neutral because the road is twisty curvy so you're
> limited to between 20 and 35 mph almost the entire way downhill (or up).

The Corolla rolls really nicely. I think I could easily go over an edge
if I left it in neutral.

>> I'm mostly concerned with mountain and highway driving, which is what I
>> use my car for most.
>
> Me too, as I live in and around the mountains of Silicon Valley.

Highway 330 and 18 to Big Bear. 40-80 depending on where you are and
the direction you're going :-)

--
Cheers, Bev
"In all recorded history there has not been one economist who has
had to worry about where the next meal would come from."
-- Peter S. Drucker, who invented management

On Sat, 7 Mar 2020 20:53:58 -0800, The Real Bev wrote:

>> But that assumes putting the transmission in neutral somehow "damages" the
>> transmission, or, getting it back in gear while coasting damages the
>> transmission.
>
> Doing something different puts wear on the thing that's doing something
> different.

Maybe. Maybe not. I really do not know, and don't claim to know.

My assumption is that transmissions were meant to be shifted from D to N
and back; but that they weren't designed to do that while moving.

Does doing it while moving "hurt" the transmission?
o I don't know.

Maybe someone here, like Xeno, knows "how" that can hurt a 2wd front or rwd
transmission?
--
I'm not saying it does or does not hurt the tranny; I'm only asking how.

On Sun, 8 Mar 2020 12:10:24 +1100, Xeno wrote:

> there is no need to shift to neutral
> whilst stationary in traffic. The stall point on the torque converter
> means that there will be minimal drag on the engine *at idle*.

Hi Xeno,

You've helped me a lot in debugging tire wear on the mountain, where I've
informed all the neighbors of the problem set.

Speaking on warranties...

One of those neighbors went to Costco and kept taking advantage of the free
rotation, but at 7,500 miles, Costco initially _refused_ to rotate the
tires because they were _already_ worn with what we've tentatively
concluded is "camber scrub" due, not to alignment per se, but to the
physics of many daily low-speed tight steep turns.

They talked Costco into rotating that one time by showing recent alignment
results, but the _next_ time we expect it to happen again.

I need to ask them what happened since that was a month or two ago I last
spoke to them about it (they took all my advice on the rotation &
alignment).

As for shifting to neutral, I wonder if you know if there is any damage to
my method (described below) for a non-four-wheel-drive, but for both a
front-wheel drive and a rear-wheel drive?

Is there?

Here's what I do on both the front-wheel drive & rear-wheel drive:
a. Daily, on the downhill, I am in neutral for miles on end, where at the
conclusion of the hill, I wait until the car is about 20mph to 30mph and
then I match the RPM by feel and slip it into gear without lurch.

b. At every opportunity for a "planned stop" (such as a red light up ahead,
or traffic up ahead), I slip it into neutral, slow down harder than I would
otherwise to scrub off speed, and then coast to the blockage - where the
hope is that I can coast right through it as it clears.

c. When it's time to get back in gear, I slip it from N to D while matching
RPM to the road speed, with the goal of eliminating all lurches.

I've been doing that for years.

Dunno if it hurts the transmission or not though, as there's not much value
in a study of just one.
--
Usenet is so much more valuable, and pleasant, when people act like adults.