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.