this is the lock-picking lawyer and what
i have for you today is a master lock
model 875 combination padlock this is a
relatively new lock only about four
years old I believe and the mechanism in
it is completely different from the
superficially similar master lock model
175 which has been a mainstay of the
product line from master lock for
several decades now this new mechanism
appears to be poised to replace the old
and can already be found in the M 175
the 875 which is this lock and the 975
which is the brass version of the 875
now the 175 has a number of
well-documented design flaws that master
lock seems to have tried to fix in the
875 in order of severity this lock can
be bypassed relatively quickly with a
tool like this in fact it can usually be
done faster than actually dialing the
combination and as you can see that was
pretty darn quick next the lock can be
decoded with this same tool simply by
reaching in between the dial and the
lock body and feeling for the code wheel
on the side and the flat surface on it
the final flaw is that a tool is
required to change the combination and I
see this as a problem because everyone
seems to lose this tool very very
quickly so what did they fix on the 875
most importantly this lock is no longer
by passable I've seen a couple of videos
on YouTube suggesting that it's not by
passable because you can't fit a tool
all the way back into the mechanism and
that's actually inaccurate this lock
couldn't be bypassed even if there was a
huge hole in the side that let you
access every bit of the mechanism let me
show you why that is
now this lock is held together by two
pins one on each side so I took another
one of these locks and I drilled those
pins out when I do that it slides apart
we then have a zinc clamshell on the
inside that's held
together by two rivets so I ground the
heads off of those rivets and after we
do that we should be able to simply open
this up okay let me zoom in on this just
a little bit so you have a slightly
better look at it now if you look at
this mechanism you can see that the only
way for this shackle to be lifted out of
the lock body is for these rollers to
move inward and the only way for these
rollers to move inward is for this fork
to move downwards the only way that can
happen is if all of the true gates on
these code wheels are lined up there's
no way we can manipulate this mechanism
such that it will allow the lock to be
opened without these wheels being in the
proper position so bypassing is
completely out next let's talk about
changing the combination because they
have improved that as well it used to be
as I mentioned that you needed a tool
like this to change the combination on
the 175 this is not required anymore on
the 875 if we look at the bottom of this
shackle you can see there is a canned
mechanism on the bottom of the long end
and that is what actuates the change
function so to change the combination of
this lock all we need to do is dial the
correct combination and right now this
is zero zero zero open the shackle
rotate the shackle 90 degrees to the
number one position we then push the
shackle down rotate it another 90
degrees to the two position and then we
can change the combination to anything
we want I'm gonna change it from all
zeros to all ones then we just reverse
that motion and we have the combination
reset it's very easy and most
importantly it doesn't require any
special tools it's a clear improvement
over the 175 okay now we get to the bad
decoding on the old 175 you could decode
it as I mentioned by use
a tool like this and feeling in between
the lock body and the wheels so you
could define the combination you can do
something very similar on the 875 though
master lock did put a tiny little lip on
the side of the code wheel that I
believe is designed to catch your tool
it works a little bit better on on these
sides right here it does make it a
little bit harder but to be perfectly
honest it's not terribly effective if
you put a tiny little Bend on the tip of
your decoding tool you should be able to
reach in there without too much trouble
but I don't think that makes any
practical difference because there is a
far easier way to decode this lock and
it doesn't require the use of any tools
at all if we take a close look at this
mechanism you can see that the beveled
top of the fork makes it such that if
you pull on the shackle these rollers
are pushed into those beveled edges and
that put just pushes the fork and down
into the code wheels once we bind the
fork on the code wheels we can actually
decode this by feel simply by turning
these wheels master lock tried to
mitigate that problem by adding a whole
bunch of false gates in fact there is
one on every single number here but they
made a large mistake in using false
gates that are much narrower than the
true gates this allows us to very
quickly differentiate between the false
and true gates simply by feel so let me
demonstrate how we would decode this
lock first I already know the
combination so we need to change this
right now it's all ones so we move it to
the change position
um puts pushing this downward so I can't
see and then I'm just gonna scramble
these wheels once they've been scrambled
enough I'm gonna move it back to one
lift it up lock it up and re scramble it
so right now I have a lock with a
combination that I don't know
the only thing you really have to do is
pull down on here and feel how much each
of these wheels turn so let's get each
of these in a in a gate I'm pulling down
there's only a little bit of motion on
each of these wheels once I determine
that I advance each one by one position
and once I find a true gate I'll show
you the difference between the two I
have not found a true gate yet they're
really pretty obvious
okay I found one on number four watch
let me get closer to the camera and then
watch how much that moves that's quite a
bit now compare it to the number three
wheel that only moves just a little bit
okay let's advance the first three again
okay number three we found the true gate
not on two or one
we must there we go we just got it open
two seven nine two is the correct
combination let's do that one more time
that took probably as long as it has
ever taken me to do that okay let's get
each one of these in a gate to start
with and then just start feeling okay
number three I'm sorry wheel number two
is four and it looks like number one is
correct too so eight four let me advance
just the last two wheels
okay looks like I found the correct for
number three so up there we go and we
got it eight four two two so as you can
see this is a very easy lock to decode
frankly I think it's faster to decode
without a tool than it is when you use a
tool so this master lock model 875 is a
mixed bag when you compare it to the
older master lock model 175 on the
positive side the lock can no longer be
bypassed and you no longer need a tool
to change the combination however you
also no longer need a tool to decode the
lock which means that opening this lock
quickly is within the capability of
anyone with a little bit of knowledge
that's all I have for you today if you
do have any questions or comments about
this please put them below if you like
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have a nice day thank you