cheap HM lock hard to pick due to massive core spring tensio

[pillar]

I have a HM padlock.
Its heavy spring loaded on the shackle but on the core too. I need a lot of force to get it open.
Furthermore: When I turn it to unlock position (with key) and then back, I hear some scratching noise when turning back.
I already put WD40 in there, makes no difference.

Question:
Is this hard to pick due to the high amount of spring tension?
I have a few different tension wrenches. Some have a 90° turn to give more area to place the finger on. They are bending quite heavily even to overcome the core spring tension.

Additionally the key has som high/low cuts...


picture:

[GWiens2001]

Have the same problem with an American Series 747 padlock. The high strength of the return spring makes it difficult to get the tension correct to pick it.

As for the shackle tension on the cam, try putting the padlock in a vise and push it down so the shackle is slightly compressed against the sliding bar before tightening the vise to hold it. Then the vise takes the load off the shackle-to-locking cam.

Gordon

[kwoswalt99-]

Have the same problem with an American Series 747 padlock. The high strength of the return spring makes it difficult to get the tension correct to pick it.

As for the shackle tension on the cam, try putting the padlock in a vise and push it down so the shackle is slightly compressed against the sliding bar before tightening the vise to hold it. Then the vise takes the load off the shackle-to-locking cam.

Gordon

Just a note for others, compressing the shackle on most padlocks other than spring loaded pawl ones, won't change the load on the cam or core.