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Yale V705 combination padlock

PostPosted: Tue Oct 30, 2018 4:33 pm
by MartinHewitt
I do have two of these locks ( https://www.picclickimg.com/d/w1600/pic ... k-Lock.jpg ) and they are showing a strange behavior, which I can't really explain.

I turn the dial left more than three times without pulling the shackle, stop all around and test how W3 (that which is directly connected to the dial) is binding to the shackle mechanism. The binding is between nearly none and at best mediocre.

I turn the dial left more than three times with!!! pulling the shackle. Then I get a very good binding for the complete 360° while I continue to turn the dial. I can easily distinguish true and false gates in W3 because the five false are binding and the true one is all free. That means there is an extremely good binding of W3. Then I release the shackle, turn right nearly a full turn and start to scan W2 by going back to the known gate in W3, than again right to push W2 a bit more and so on. In so far five tries (the first one and the last three) I got open the two padlocks instantly at the beginning of the W2 scan. That means they are open in less than two minutes.

To make this fast opening possible W1 and W2 must have aligned them automagically to the gate and they have to stay there while I turn the dial, even so W3 should turn them with it. I didn't feel any breaking of a pin. There seem also to be no parts loose in this lock.

Any idea what is happening? Maybe I will drill a hole into the back to have a look as I can't turn the dial with an open shackle.

Re: Yale V705 combination padlock

PostPosted: Thu Nov 01, 2018 7:34 am
by MartinHewitt
Not really reliable at the moment, but opening works like this:

Turn multiple times left to clear lock. Pull shackle and turn more left until the second number is reached. Release shackle and turn right to third number. Open lock.

The original combination still works. It might also work with stopping somewhere else than second number.

What is the best way to open such a lock destructively without disturbing its operation?

Re: Yale V705 combination padlock

PostPosted: Thu Nov 01, 2018 9:57 am
by madsamurai
sure does sound like something's broken. Most of the combination padlocks I have have a crimp around the back edge that holds a cover plate on the back side... I've had good success with grinding that crimp off using a little belt grinder and taking the plate off the back to expose the insides. I've done a few this way, and everything stays put and functions fine (the shiny cover is just for shiny). I was intending to cut them out a little further to have as cutaways for study, just haven't got around to it yet.
I've been curious about cracking these little guys, and haven't put any real time into them yet. They each seem to have specific tricks, and I'd be interested to hear how you typically go at them...

Re: Yale V705 combination padlock

PostPosted: Thu Nov 01, 2018 10:43 am
by MartinHewitt
This Yale doesn't have a gap on the backside like the Masterlocks have, but grinding it of might still be the best solution. I don't think something is broken because the real combination still works. Maybe it is a design flaw with the mechanism which changes W1 when the shackle is closed.

This lock is basically a three-wheel direct entry fence lock and can be manipulated as such. Information about how deep the fence sits can be get by feeling how well the fence sits on W3 (no contact with W3 all around -> feeling a few false gates -> feeling all false gates -> false gates are also binding). And the second way to get information is how narrow the true and false gates are. They are getting more narrow when the position of the fence improves. It would also be possible to get information by how far the shackle can be pulled out, but I found this not to be practical. (With this strange behavior I can always pull the shackle out quite far, so it is never far away from opening.) With these sources of information it is possible to do a standard manipulation without any tricks.