On Thu, 12 Mar 2020 12:17:16 +1100, Xeno wrote:

Whilst on that topic, the thinner the disc (through wear or machining)
the less it is able to hold heat and the sooner it will reach the point
of brake fade.

Hi Xeno,
Much appreciated all your kind help & advice!
o I'll pass it on to one of my granddaughters who will be driving soon!

On that topic of the amount of metal, I'm one of the (apparently rare)
shade-tree mechanics who owns calipers and dial gauges such that I check
rotor thickness, runout, and brake drum diameter.
http://www.bild.me/bild.php?file=9428041drum_brakes_3.jpg

I do realize a lot of people on Usenet "talk" that they check rotors and
drums, but IMHO, without pictures, it didn't happen (most don't seem to
even own the proper tools with which to check them, particularly those who
spout that their brake rotors 'warped').

I replace a rotor or drum when it's due, but not before it's due.
http://www.bild.me/bild.php?file=9335528drum_brakes_2.jpg

It's impossible to be in any gear higher than 2nd on the way up.

So, given that level of steepness, the *rule* informs the gear you
should engage on the way down.

As I said, I _love_ your "golden rule" of being in the same gear in both
directions, which I will steal (with your permission) to use with my
upcoming driving lessons for one of my grandkids.

I thank you for your advice, where today I ran a tracking program:
https://i.postimg.cc/qMj0ZFMh/pskill00.jpg

On the way downhill, the average speed was 21.81 mph which is a bit lower
than the 25mph I would have guessed, and the maximum speed, surprisingly,
was a bit higher than I would have guessed, where it was 35.48 mph.

Thanks for all your helpful advice over the years, where I'm a sponge for
facts, and hence, I love when others deal with logic, sense, and facts!
--
Usenet is so much more valuable, and pleasant, when people share ideas.

Arlen Holder wrote:
On Thu, 12 Mar 2020 12:17:16 +1100, Xeno wrote:

Whilst on that topic, the thinner the disc (through wear or machining)
the less it is able to hold heat and the sooner it will reach the point
of brake fade.

Hi Xeno,
Much appreciated all your kind help & advice!
o I'll pass it on to one of my granddaughters who will be driving soon!

On that topic of the amount of metal, I'm one of the (apparently rare)
shade-tree mechanics who owns calipers and dial gauges such that I check
rotor thickness, runout, and brake drum diameter.
http://www.bild.me/bild.php?file=9428041drum_brakes_3.jpg

I do realize a lot of people on Usenet "talk" that they check rotors and
drums, but IMHO, without pictures, it didn't happen (most don't seem to
even own the proper tools with which to check them, particularly those who
spout that their brake rotors 'warped').

I replace a rotor or drum when it's due, but not before it's due.
http://www.bild.me/bild.php?file=9335528drum_brakes_2.jpg

I hope that isn't the caliper you use to measure drums. The jaws are not
long enough to reach the friction areas inside the drum for a good
measurement of wear. Same thing with a set of rotors, you need to check
thickness in at least three areas on the friction surface and to do that
you need longer jaws on the calipers to reach to the depth of the hat.



It's impossible to be in any gear higher than 2nd on the way up.
So, given that level of steepness, the *rule* informs the gear you
should engage on the way down.

As I said, I _love_ your "golden rule" of being in the same gear in both
directions, which I will steal (with your permission) to use with my
upcoming driving lessons for one of my grandkids.

I thank you for your advice, where today I ran a tracking program:
https://i.postimg.cc/qMj0ZFMh/pskill00.jpg

On the way downhill, the average speed was 21.81 mph which is a bit lower
than the 25mph I would have guessed, and the maximum speed, surprisingly,
was a bit higher than I would have guessed, where it was 35.48 mph.

Thanks for all your helpful advice over the years, where I'm a sponge for
facts, and hence, I love when others deal with logic, sense, and facts!



--
Steve W.

On Thu, 12 Mar 2020 23:43:40 -0400, Steve W. wrote:

I hope that isn't the caliper you use to measure drums. The jaws are not
long enough to reach the friction areas inside the drum for a good
measurement of wear. Same thing with a set of rotors, you need to check
thickness in at least three areas on the friction surface and to do that
you need longer jaws on the calipers to reach to the depth of the hat.

Hi Steve,

Thanks for that purposefully helpful advice, which, I hadn't thought of
until you mentioned it, which I appreciate, where, yes, while I have a few
calipers, that was my largest set of calipers, and, I do _agree_ (fully)
with you that the jaws don't go deeply enough to check the deeper brake
drum wear areas.
http://www.bild.me/bild.php?file=9335528drum_brakes_2.jpg

BTW, did anyone notice the two long metric bolts sticking out of the drum?
o They are one of the most useful tools to have in your brake tool arsenal!

As for the rotors, I have all sizes of micrometers (as I'm sure most of you
do too), where my normal one-inch mic usually works best but your point is
well taken that most micrometers don't necessarily have a "deep" enough "C"
shape to get any deeper than about an inch or two over the rotor.

As for my dial gauge, I have a block mount on a bar, a magnetic mount and
the weird looking "S" shaped clamped mount, where I generally clamp that
S-shaped rod to the springs and measure runout on the rotor that way.

As you noted, the tools are NOT what a professional mechanic would use, but
they are, I posit, better than what I think most shade tree mechanics use,
as I've heard too many times on forums the oft-asked question...
o *How do I know when to replace my drums and rotors*?
Which seems, in retrospect, to come from those with no mics or calipers.

Also, I've heard the similar question often of...
o *Do we replace the rotors after every brake pad or every second pad*?

That question seems to be most often asked by the same people who claim
that their rotors "warped" (which is almost impossible to actually happen
in a passenger vehicle, even under extreme circumstances, due simply to the
temperature required to melt steel being almost impossible to attain,
AFAICR).

In summary, I appreciate and agree with your statement that even my
calipers and mics are not the right tools that a professional will use for
a typical brake job; but I maintain that these tools are more than most
will use (in my experience on the automative forums).
--
Together we can learn far more than any one of us can by learning alone.

On 13/3/20 2:43 pm, Steve W. wrote:
Arlen Holder wrote:
On Thu, 12 Mar 2020 12:17:16 +1100, Xeno wrote:

Whilst on that topic, the thinner the disc (through wear or
machining) the less it is able to hold heat and the sooner it will
reach the point of brake fade.

Hi Xeno,
Much appreciated all your kind help & advice!
o I'll pass it on to one of my granddaughters who will be driving soon!

On that topic of the amount of metal, I'm one of the (apparently rare)
shade-tree mechanics who owns calipers and dial gauges such that I check
rotor thickness, runout, and brake drum diameter.
Â*http://www.bild.me/bild.php?file=9428041drum_brakes_3.jpg

I do realize a lot of people on Usenet "talk" that they check rotors and
drums, but IMHO, without pictures, it didn't happen (most don't seem to
even own the proper tools with which to check them, particularly those
who
spout that their brake rotors 'warped').

I replace a rotor or drum when it's due, but not before it's due.
Â*http://www.bild.me/bild.php?file=9335528drum_brakes_2.jpg

I hope that isn't the caliper you use to measure drums. The jaws are not
long enough to reach the friction areas inside the drum for a good
measurement of wear. Same thing with a set of rotors, you need to check
thickness in at least three areas on the friction surface and to do that
you need longer jaws on the calipers to reach to the depth of the hat.

What you also won't be able to check with those is bell mouthing of the
drum. In fact, the only part you *may* be able to measure is the
*unworn* lip, if any. Used to use dedicated drum calipers, designed for
the task.


It's impossible to be in any gear higher than 2nd on the way up.
So, given that level of steepness, the *rule* informs the gear you
should engage on the way down.

As I said, I _love_ your "golden rule" of being in the same gear in both
directions, which I will steal (with your permission) to use with my
upcoming driving lessons for one of my grandkids.

I thank you for your advice, where today I ran a tracking program:
Â*https://i.postimg.cc/qMj0ZFMh/pskill00.jpg

On the way downhill, the average speed was 21.81 mph which is a bit lower
than the 25mph I would have guessed, and the maximum speed, surprisingly,
was a bit higher than I would have guessed, where it was 35.48 mph.

Thanks for all your helpful advice over the years, where I'm a sponge for
facts, and hence, I love when others deal with logic, sense, and facts!





--

Xeno


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

On Fri, 13 Mar 2020 16:45:55 +1100, Xeno wrote:

What you also won't be able to check with those is bell mouthing of the
drum. In fact, the only part you *may* be able to measure is the
*unworn* lip, if any. Used to use dedicated drum calipers, designed for
the task.

Hi Xeno,

I appreciate greatly and agree with the "proper tools" advice from you and
Steve, where I must also note though, that I hadn't "noticed" a problem
with the general purpose tools in so much as you can get pretty deep with
general purpose mics, particularly if you use a larger mic than one inch
mic on rotors where the wear is pretty even in almost all cases I've seen.
http://www.bild.me/bild.php?file=9428041drum_brakes_3.jpg

Also, if you zoom into this photo I took long ago and look to the right,
you'll see that the "lip" is pretty much almost perfectly taken into
account by the stairstep shape of the inside jaws:
http://s1.bild.me/bilder/110417/9335528drum_brakes_2.jpg

Still, I don't disagree with your main point of view which is that special
purpose calipers and mics and dial gauges would be best for those of us who
do all our own automotive work at home.

The tools are usually free, except for their storage, where I get high
friction pads and shoes for a great price (around $25 to $50 or so an axle)
and rotors/drums for about the same price per wheel, where I've seen people
spend upwards of thousands of dollars for a four wheel brake job.

Given that I save hundreds, if not thousands of dollars by doing my own
brakes, it wouldn't be a bad idea to purchase brake-intended tools for
measuring runout, rotor thickness, and drum diameter.

Where do you purchase your brake-related measuring tools from?

Amazon "suggests" these for brake rotor inside diameter measurement:
o Fowler 72-010-777 Drum and Rotor Measuring Kit
https://www.amazon.com/Fowler-72-010-777-Drum-Rotor-Measuring/dp/B003Z344Y2/

o Brake Drum and Rotor Measuring Kit w/Caliper
https://www.amazon.com/Brake-Drum-Rotor-Measuring-Caliper/dp/B000XQ0YF2/

o iGaging 20" Brake Drum Caliper Gage Digital Electronic
https://www.amazon.com/iGaging-Brake-Caliper-Digital-Electronic/dp/B00HMJLOUW/

o K-D Tools 3774 Digital Brake Rotor Gauge
https://www.amazon.com/Tools-Digital-Brake-Rotor-Gauge/dp/B000RLLESE

o Central Tools 3M130 .300"-1.300" Brake Rotor Micrometer
https://www.amazon.com/Central-Tools-3M130-1-300-Micrometer/dp/B000P6UOJQ

And Amazon added this weird looking gauge for "resetting" brake drums:
o AMPRO T71558 Brake Drum Resetting Gauge
https://www.amazon.com/AMPRO-T71558-Brake-Resetting-Gauge/dp/B00A8FOEFE/

Note I don't even know how to use that last tool, as I've never seen one.
--
BTW, I love how well two simple long metric bolts work to loosen drums!
http://www.bild.me/bild.php?file=5687240drum_brakes_0.jpg

On 14/3/20 1:05 am, Arlen Holder wrote:
On Fri, 13 Mar 2020 16:45:55 +1100, Xeno wrote:

What you also won't be able to check with those is bell mouthing of the
drum. In fact, the only part you *may* be able to measure is the
*unworn* lip, if any. Used to use dedicated drum calipers, designed for
the task.

Hi Xeno,

I appreciate greatly and agree with the "proper tools" advice from you and
Steve, where I must also note though, that I hadn't "noticed" a problem
with the general purpose tools in so much as you can get pretty deep with
general purpose mics, particularly if you use a larger mic than one inch
mic on rotors where the wear is pretty even in almost all cases I've seen.
http://www.bild.me/bild.php?file=9428041drum_brakes_3.jpg

Also, if you zoom into this photo I took long ago and look to the right,
you'll see that the "lip" is pretty much almost perfectly taken into
account by the stairstep shape of the inside jaws:
http://s1.bild.me/bilder/110417/9335528drum_brakes_2.jpg

Still, I don't disagree with your main point of view which is that special
purpose calipers and mics and dial gauges would be best for those of us who
do all our own automotive work at home.

The tools are usually free, except for their storage, where I get high
friction pads and shoes for a great price (around $25 to $50 or so an axle)
and rotors/drums for about the same price per wheel, where I've seen people
spend upwards of thousands of dollars for a four wheel brake job.

Given that I save hundreds, if not thousands of dollars by doing my own
brakes, it wouldn't be a bad idea to purchase brake-intended tools for
measuring runout, rotor thickness, and drum diameter.

Where do you purchase your brake-related measuring tools from?

When I was in the trade, I used the ones in my workplace. The college
had all the gear I needed. These days I have sources where I can borrow
such things as required.

Amazon "suggests" these for brake rotor inside diameter measurement:
o Fowler 72-010-777 Drum and Rotor Measuring Kit
https://www.amazon.com/Fowler-72-010-777-Drum-Rotor-Measuring/dp/B003Z344Y2/

o Brake Drum and Rotor Measuring Kit w/Caliper
https://www.amazon.com/Brake-Drum-Rotor-Measuring-Caliper/dp/B000XQ0YF2/

o iGaging 20" Brake Drum Caliper Gage Digital Electronic
https://www.amazon.com/iGaging-Brake-Caliper-Digital-Electronic/dp/B00HMJLOUW/

o K-D Tools 3774 Digital Brake Rotor Gauge
https://www.amazon.com/Tools-Digital-Brake-Rotor-Gauge/dp/B000RLLESE

o Central Tools 3M130 .300"-1.300" Brake Rotor Micrometer
https://www.amazon.com/Central-Tools-3M130-1-300-Micrometer/dp/B000P6UOJQ

And Amazon added this weird looking gauge for "resetting" brake drums:
o AMPRO T71558 Brake Drum Resetting Gauge
https://www.amazon.com/AMPRO-T71558-Brake-Resetting-Gauge/dp/B00A8FOEFE/

Note I don't even know how to use that last tool, as I've never seen one.

It tells you what it does in the description. It measures clearance
between the brake lining and the drum.

--

Xeno


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

On Sat, 14 Mar 2020 17:04:31 +1100, Xeno wrote:

It tells you what it does in the description. It measures clearance
between the brake lining and the drum.

That doesn't explain how to use it, but that's OK as the way I do the
shoe-to-drum clearance is I adjust that by a friction fit and then back it
off a few notches, and then I engage the self adjusting mechanism once it's
all put back together.

Luckily, nowadays, very few vehicles I've worked on have drum brakes, where
that specific drum was on an SUV that went something like 180K miles on one
set of rear shoes (and there was _still_ meat on those rear shoes but I
replaced them anyway because I didn't want to have to take it apart again).

It's shocking, actually, how long the rear brake shoes lasted on that SUV,
where I replaced the clutch twice in the time that I did the shoes just
once, and that rear drum had plenty of meat left for another 180K miles.
--
Usenet allows purposefully helpful adults to share solutions with others.

On 14/3/20 6:18 pm, Arlen Holder wrote:
On Sat, 14 Mar 2020 17:04:31 +1100, Xeno wrote:

It tells you what it does in the description. It measures clearance
between the brake lining and the drum.

That doesn't explain how to use it, but that's OK as the way I do the
shoe-to-drum clearance is I adjust that by a friction fit and then back it
off a few notches, and then I engage the self adjusting mechanism once it's
all put back together.

BTW, do you radius grind brake shoes when fitting them to an oversized
(worn or machined) drum.

Here is something for you to cogitate on. You have a drum that requires
machining. You do that and it is now *oversize*. You now go out and buy
a set of new shoes. What you will find now is that the diameter of the
shoes no longer matches the diameter of the shoes. When you adjust the
shoes up, as you describe above, the linings only contact the drum in a
small section at the centre of the length of the lining. Both ends of
the lining will not contact the drum. That means that, as you are
bedding in your nice new brakes, only, say, 25% of the linings contact
the drum. Guess what that does to brake efficiency?

There are 3 solutions to this issue.

The first is to radius grind the new shoes so that their arc matches the
arc of the drum. Used one of these radius grinders in the 70s.
https://www.youtube.com/watch?v=afuwxWqBBa8
Just need to be sure the dust extraction and capture system works and it
looks pretty absent on the video.

The second is to replace the drum rather than machining it. In fact, a
lot of manufacturers don't recommend drum machining these days.

The third is to get new shoes with thicker (oversize) linings to match
the larger diameter of the drum.

Some say all linings should be matched to the drum diameter - oversize
or otherwise to ensure an efficient and rapid bed in. Like this one;
https://www.youtube.com/watch?v=WQhnTidoJEM

Anyway, just something more for you to think on.



Luckily, nowadays, very few vehicles I've worked on have drum brakes, where
that specific drum was on an SUV that went something like 180K miles on one
set of rear shoes (and there was _still_ meat on those rear shoes but I
replaced them anyway because I didn't want to have to take it apart again).

It's shocking, actually, how long the rear brake shoes lasted on that SUV,
where I replaced the clutch twice in the time that I did the shoes just
once, and that rear drum had plenty of meat left for another 180K miles.



--

Xeno


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

On 14/3/20 7:57 pm, Xeno wrote:
On 14/3/20 6:18 pm, Arlen Holder wrote:
On Sat, 14 Mar 2020 17:04:31 +1100, Xeno wrote:

It tells you what it does in the description. It measures clearance
between the brake lining and the drum.

That doesn't explain how to use it, but that's OK as the way I do the
shoe-to-drum clearance is I adjust that by a friction fit and then
back it
off a few notches, and then I engage the self adjusting mechanism once
it's
all put back together.

BTW, do you radius grind brake shoes when fitting them to an oversized
(worn or machined) drum.

Here is something for you to cogitate on. You have a drum that requires
machining. You do that and it is now *oversize*. You now go out and buy
a set of new shoes. What you will find now is that the diameter of the
shoes no longer matches the diameter of the shoes. When you adjust the

Correction, ..... shoes no longer match the diameter of the drum.

shoes up, as you describe above, the linings only contact the drum in a
small section at the centre of the length of the lining. Both ends of
the lining will not contact the drum. That means that, as you are
bedding in your nice new brakes, only, say, 25% of the linings contact
the drum. Guess what that does to brake efficiency?

There are 3 solutions to this issue.

The first is to radius grind the new shoes so that their arc matches the
arc of the drum. Used one of these radius grinders in the 70s.
https://www.youtube.com/watch?v=afuwxWqBBa8
Just need to be sure the dust extraction and capture system works and it
looks pretty absent on the video.

The second is to replace the drum rather than machining it. In fact, a
lot of manufacturers don't recommend drum machining these days.

The third is to get new shoes with thicker (oversize) linings to match
the larger diameter of the drum.

Some say all linings should be matched to the drum diameter - oversize
or otherwise to ensure an efficient and rapid bed in. Like this one;
https://www.youtube.com/watch?v=WQhnTidoJEM

Anyway, just something more for you to think on.



Luckily, nowadays, very few vehicles I've worked on have drum brakes,
where
that specific drum was on an SUV that went something like 180K miles
on one
set of rear shoes (and there was _still_ meat on those rear shoes but I
replaced them anyway because I didn't want to have to take it apart
again).

It's shocking, actually, how long the rear brake shoes lasted on that
SUV,
where I replaced the clutch twice in the time that I did the shoes just
once, and that rear drum had plenty of meat left for another 180K miles.





--

Xeno


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

Xeno wrote:
On 14/3/20 6:18 pm, Arlen Holder wrote:
On Sat, 14 Mar 2020 17:04:31 +1100, Xeno wrote:

It tells you what it does in the description. It measures clearance
between the brake lining and the drum.
That doesn't explain how to use it, but that's OK as the way I do the
shoe-to-drum clearance is I adjust that by a friction fit and then back it
off a few notches, and then I engage the self adjusting mechanism once it's
all put back together.

BTW, do you radius grind brake shoes when fitting them to an oversized
(worn or machined) drum.

Here is something for you to cogitate on. You have a drum that requires
machining. You do that and it is now *oversize*. You now go out and buy
a set of new shoes. What you will find now is that the diameter of the
shoes no longer matches the diameter of the shoes. When you adjust the
shoes up, as you describe above, the linings only contact the drum in a
small section at the centre of the length of the lining. Both ends of
the lining will not contact the drum. That means that, as you are
bedding in your nice new brakes, only, say, 25% of the linings contact
the drum. Guess what that does to brake efficiency?

There are 3 solutions to this issue.

The first is to radius grind the new shoes so that their arc matches the
arc of the drum. Used one of these radius grinders in the 70s.
https://www.youtube.com/watch?v=afuwxWqBBa8
Just need to be sure the dust extraction and capture system works and it
looks pretty absent on the video.

The second is to replace the drum rather than machining it. In fact, a
lot of manufacturers don't recommend drum machining these days.

The third is to get new shoes with thicker (oversize) linings to match
the larger diameter of the drum.

Some say all linings should be matched to the drum diameter - oversize
or otherwise to ensure an efficient and rapid bed in. Like this one;
https://www.youtube.com/watch?v=WQhnTidoJEM

Anyway, just something more for you to think on.

I haven't cut a drum or rotor in a lot of years, in my area the rust
kills them faster than the shoes or pads can eat them. I only know of
one shop that still turns them and their machine gets powered on about 2
times a year.
Same issue with calipers, if the vehicle is over a year old, forget
trying the bleeder and 99% of the time the slides are stuck from rust.
SOP in my place is pads and rotors unless they have really good coated
rotors that haven't rotted away.

As for shoes, I've ground them a few times but generally they get
replaced due to rot. Especially if they are drum in hat rotors used as
parking brakes. Since maybe 1 in 5000 use them the shoes are generally
rotted apart and the drum looks like it sat on the ocean floor for years.



Luckily, nowadays, very few vehicles I've worked on have drum brakes, where
that specific drum was on an SUV that went something like 180K miles on one
set of rear shoes (and there was _still_ meat on those rear shoes but I
replaced them anyway because I didn't want to have to take it apart again).

It's shocking, actually, how long the rear brake shoes lasted on that SUV,
where I replaced the clutch twice in the time that I did the shoes just
once, and that rear drum had plenty of meat left for another 180K miles.



Not shocking on many trucks and SUVs, unless they have weight in the
rear the load sensing valve barely lets the rear brakes apply. I've seen
many that the rear brakes were barely worn at 100K. Now on work trucks
that had a load the results are much different.


--
Steve W.

Arlen Holder wrote:
On Thu, 12 Mar 2020 23:43:40 -0400, Steve W. wrote:

I hope that isn't the caliper you use to measure drums. The jaws are not
long enough to reach the friction areas inside the drum for a good
measurement of wear. Same thing with a set of rotors, you need to check
thickness in at least three areas on the friction surface and to do that
you need longer jaws on the calipers to reach to the depth of the hat.

Hi Steve,

Thanks for that purposefully helpful advice, which, I hadn't thought of
until you mentioned it, which I appreciate, where, yes, while I have a few
calipers, that was my largest set of calipers, and, I do _agree_ (fully)
with you that the jaws don't go deeply enough to check the deeper brake
drum wear areas.
http://www.bild.me/bild.php?file=9335528drum_brakes_2.jpg

BTW, did anyone notice the two long metric bolts sticking out of the drum?
o They are one of the most useful tools to have in your brake tool arsenal!

As for the rotors, I have all sizes of micrometers (as I'm sure most of you
do too), where my normal one-inch mic usually works best but your point is
well taken that most micrometers don't necessarily have a "deep" enough "C"
shape to get any deeper than about an inch or two over the rotor.

As for my dial gauge, I have a block mount on a bar, a magnetic mount and
the weird looking "S" shaped clamped mount, where I generally clamp that
S-shaped rod to the springs and measure runout on the rotor that way.

As you noted, the tools are NOT what a professional mechanic would use, but
they are, I posit, better than what I think most shade tree mechanics use,
as I've heard too many times on forums the oft-asked question...
o *How do I know when to replace my drums and rotors*?
Which seems, in retrospect, to come from those with no mics or calipers.

Also, I've heard the similar question often of...
o *Do we replace the rotors after every brake pad or every second pad*?

That question seems to be most often asked by the same people who claim
that their rotors "warped" (which is almost impossible to actually happen
in a passenger vehicle, even under extreme circumstances, due simply to the
temperature required to melt steel being almost impossible to attain,
AFAICR).

In summary, I appreciate and agree with your statement that even my
calipers and mics are not the right tools that a professional will use for
a typical brake job; but I maintain that these tools are more than most
will use (in my experience on the automative forums).

I made a few drum and rotor tools over the years. Extended jaws for
calipers and deep frames for mics. These days even the cheap digital one
from harbor freight is better than most of the older tools that were
sold back then.

--
Steve W.

On Sat, 14 Mar 2020 07:18:42 -0000 (UTC), Arlen Holder wrote:

It's shocking, actually, how long the rear brake shoes lasted on that SUV,
where I replaced the clutch twice in the time that I did the shoes just
once, and that rear drum had plenty of meat left for another 180K miles.

BTW, is this about right for what you might think under "normal use" where
I know there's no such thing as a defined normal use... but anyway...

a. The clutch lasted less than 100K miles (say, oh, about 80 or 90K).
b. The rear shoes lasted less than 200K miles (say, about 180K or so).
c. The front pads lasted less than 50K miles (say, oh, about 30 or 40K).
d. The front rotors went about double the pads (about 75K miles or so).
e. The rear drums are gonna last about double the shoes (about 350K).

While every "normal" is different, how do those estimates sound if someone
were to ask you "how long" do these things last under normal use?
--
It matters for what you plan your maintenance and parts stocking for.

Arlen Holder wrote:
On Sat, 14 Mar 2020 07:18:42 -0000 (UTC), Arlen Holder wrote:

It's shocking, actually, how long the rear brake shoes lasted on that SUV,
where I replaced the clutch twice in the time that I did the shoes just
once, and that rear drum had plenty of meat left for another 180K miles.

BTW, is this about right for what you might think under "normal use" where
I know there's no such thing as a defined normal use... but anyway...

a. The clutch lasted less than 100K miles (say, oh, about 80 or 90K).
b. The rear shoes lasted less than 200K miles (say, about 180K or so).
c. The front pads lasted less than 50K miles (say, oh, about 30 or 40K).
d. The front rotors went about double the pads (about 75K miles or so).
e. The rear drums are gonna last about double the shoes (about 350K).

While every "normal" is different, how do those estimates sound if someone
were to ask you "how long" do these things last under normal use?

That depends entirely on how the person operates the vehicle and what
the vehicle is.
In city stop and go, you are going to use up the brakes and clutch
faster than highway driving, usually by a large margin. However if you
drive like one of my relatives you will wipe out the brakes far faster.
She likes to drive fast, then climb on the brakes rather than down shift
or use any engine braking at all. She goes through at least one full set
of pads and rotors in about 30K or so. Calipers at every second swap.

Then there are cars like my wife has, it's AWD and has a VERY balanced
braking system. It had all new brakes put on by the dealer when we
bought it at 60K and it has 140K on it and the pads and rotors still
look new. I'm going to change out the pads because the caliper pins
stuck on one front and the inner pads in the rear hung up and let the
rotor rust. All related to installer error.

With the description you have given of your driving style and road
conditions you have I would say you did pretty good.
However it wouldn't be hard to double the clutch life and front brakes
on flatter terrain.


--
Steve W.

On Sat, 14 Mar 2020 16:31:56 -0400, Steve W. wrote:

That depends entirely on how the person operates the vehicle and what
the vehicle is.

Understood.
It's a 2WD suv driven by a relative as a daily drive on these roads:
https://i.postimg.cc/wxf5CyS6/mount42.jpg

Rough estimates for that 2wd SUV are (in increasing miles):
o Tires 30K miles
o Front pads 50K miles
o Front rotors 75K miles
o Clutch 90K miles
o Rear shoes 200K miles
o Rear drums 350K miles

However it wouldn't be hard to double the clutch life and front brakes
on flatter terrain.

Yes. The problem for the clutch is the terrain, and, this particular driver
doesn't comprehend the concept of being gentle on the clutch either.

Even so, the hills eat the tires:
https://i.postimg.cc/G3HWPtQg/mount39.jpg

Xeno explained why in the past as 'camber scrub':
https://i.postimg.cc/8zVxVHVx/mount40.jpg

Which is an amazingly complicated set of affairs:
https://i.postimg.cc/YqHVb5gY/mount33.jpg

Resulting in wear of the front inside edge that you can't believe:
https://i.postimg.cc/g004XCLW/mount37.jpg

Which is palpable after even as little as a few hundred miles:
https://i.postimg.cc/pT71cQZG/mount41.jpg
--
Usenet helps all of us improve our technical skills by sharing with others.

On Sat, 14 Mar 2020 19:57:50 +1100, Xeno
wrote:

On 14/3/20 6:18 pm, Arlen Holder wrote:
On Sat, 14 Mar 2020 17:04:31 +1100, Xeno wrote:

It tells you what it does in the description. It measures clearance
between the brake lining and the drum.

That doesn't explain how to use it, but that's OK as the way I do the
shoe-to-drum clearance is I adjust that by a friction fit and then back it
off a few notches, and then I engage the self adjusting mechanism once it's
all put back together.

BTW, do you radius grind brake shoes when fitting them to an oversized
(worn or machined) drum.

Here is something for you to cogitate on. You have a drum that requires
machining. You do that and it is now *oversize*. You now go out and buy
a set of new shoes. What you will find now is that the diameter of the
shoes no longer matches the diameter of the shoes. When you adjust the
shoes up, as you describe above, the linings only contact the drum in a
small section at the centre of the length of the lining. Both ends of
the lining will not contact the drum. That means that, as you are
bedding in your nice new brakes, only, say, 25% of the linings contact
the drum. Guess what that does to brake efficiency?

There are 3 solutions to this issue.

The first is to radius grind the new shoes so that their arc matches the
arc of the drum. Used one of these radius grinders in the 70s.
https://www.youtube.com/watch?v=afuwxWqBBa8
Just need to be sure the dust extraction and capture system works and it
looks pretty absent on the video.

The second is to replace the drum rather than machining it. In fact, a
lot of manufacturers don't recommend drum machining these days.

The third is to get new shoes with thicker (oversize) linings to match
the larger diameter of the drum.

Some say all linings should be matched to the drum diameter - oversize
or otherwise to ensure an efficient and rapid bed in. Like this one;
https://www.youtube.com/watch?v=WQhnTidoJEM

Anyway, just something more for you to think on.



Luckily, nowadays, very few vehicles I've worked on have drum brakes, where
that specific drum was on an SUV that went something like 180K miles on one
set of rear shoes (and there was _still_ meat on those rear shoes but I
replaced them anyway because I didn't want to have to take it apart again).

It's shocking, actually, how long the rear brake shoes lasted on that SUV,
where I replaced the clutch twice in the time that I did the shoes just
once, and that rear drum had plenty of meat left for another 180K miles.

The reason the VAST MAJORITY of repair shops no longer have drum
lathes. (and the rear brakes on my 96 Ranger were just replaced for
the first time at 360.000+ km - and the drums were NOT machined or
replaced - - - -

On Sat, 14 Mar 2020 19:57:50 +1100, Xeno wrote:

The second is to replace the drum rather than machining it. In fact, a
lot of manufacturers don't recommend drum machining these days.

Hi Xeno,
I love that you brought up points of additional points of finesse, which
is, after all, what learning on rec.autos.tech is all about!

One thing I have observed, which I'm sure you'll understand, is that living
in the Silicon Valley, where shop rates are commonly around $200 an hour,
_any_ machining of basic parts isn't going to ever be cost effective.

As an example, when I replaced the flywheel of the SUV, the cost for
machining it was almost the price of a brand new flywheel at the auto parts
stores (but far less than a brand new dealer-supplied flywheel).

Even though the flywheel could have been machined, it wasn't worth it given
the cost of labor here in the Silicon Valley.

I suspect machining shoes and drums would have the same economics, unless
we bought the tools to do ourselves.

I think throwing away parts instead of machining them is kind of sad
because we throw out a lot of useful parts simply because they're cheaper
to replace than to machine.

On 15/3/20 10:14 pm, Arlen Holder wrote:
On Sat, 14 Mar 2020 19:57:50 +1100, Xeno wrote:

The second is to replace the drum rather than machining it. In fact, a
lot of manufacturers don't recommend drum machining these days.

Hi Xeno,
I love that you brought up points of additional points of finesse, which
is, after all, what learning on rec.autos.tech is all about!

One thing I have observed, which I'm sure you'll understand, is that living
in the Silicon Valley, where shop rates are commonly around $200 an hour,
_any_ machining of basic parts isn't going to ever be cost effective.

Given that, on many cars, the disc is considered a wearing component
just as much as the pads, machining is likely not intended. For sure,
there are some marques where you cannot machine the discs at all. But
then, replacement discs are inexpensive.

As an example, when I replaced the flywheel of the SUV, the cost for
machining it was almost the price of a brand new flywheel at the auto parts
stores (but far less than a brand new dealer-supplied flywheel).

If the flywheel has hard spots, machining is not always successful. The
cutting tool rides over the hard spots leaving high points. In these
cases, surface grinding is the better/only option.

Even though the flywheel could have been machined, it wasn't worth it given
the cost of labor here in the Silicon Valley.

Yes, costs always figure into the equation.

I suspect machining shoes and drums would have the same economics, unless
we bought the tools to do ourselves.

If you have, or have access to, a lathe, you can do most machining
yourself. It won't be as *efficient* as a dedicated brake machining tool
but it will get the job done. I used to use these;

https://www.youtube.com/watch?v=ICRRIUhwOJE

Very quick and efficient. Even at $200 per hour, I could make machining
operations cost effective with this machine. If you had ever used one,
you would know why.

I think throwing away parts instead of machining them is kind of sad
because we throw out a lot of useful parts simply because they're cheaper
to replace than to machine.

That is the way of the world.

--

Xeno


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