Hey LockDoc...

[davepl]

Three questions for you that might be of broad enough interest that I'll post as a thread rather than bugging you in a message.

First, why are GM locks so hard to pick? My locksmith friend (20 years ago) said they had a "slider" that prevented it. But then why wouldn't all locks have that?

Second, any idea how many pins and how many depth options there are? Like if there are 5 pins of 6 possible depths that's about 15000 possible different keys.

Lastly, my Dad had a 1961 GM key (the older style head) and he said that just by the luck of the pin depth setup on that key it had about a 25% chance of opening other cars if you jiggled it.

I don't think he was talking about a bump-key style approach but do you have any idea what he might have been talking about?

Thanks!

[LockDoc]

Originally Posted by davepl

Three questions for you that might be of broad enough interest that I'll post as a thread rather than bugging you in a message.

First, why are GM locks so hard to pick? My locksmith friend (20 years ago) said they had a "slider" that prevented it. But then why wouldn't all locks have that?

Because they are what is known as a "sidebar" lock. When you try and pick them you have to put turning pressure on the cylinder plug and when you do that with a sidebar lock it actually puts the lock in a bind and prevents it from being picked. GM has been using this same Briggs & Stratton lock since 1935

Second, any idea how many pins and how many depth options there are? Like if there are 5 pins of 6 possible depths that's about 15000 possible different keys.

The GM locks actually use flat wafers instead of pins. 5 depths and 6 spaces for the single sided keys. There are a lot of different factors that enter into that equation, like you can't have a #5 cut and a #1 cut next to each other on the key and you can't use all one number for all of the cuts. Those two alone eliminate a lot of possible key combinations. See post #22 in this thread

http://67-72chevytrucks.com/vboard/s...d.php?t=630654

Lastly, my Dad had a 1961 GM key (the older style head) and he said that just by the luck of the pin depth setup on that key it had about a 25% chance of opening other cars if you jiggled it.

I don't think he was talking about a bump-key style approach but do you have any idea what he might have been talking about?

If the key is worn and the lock is worn that may be possible. Some have even mentioned on here that their ignition lock could be turned with a screw driver. You also have to remember that many years ago people didn't remove the keys from the cars and trucks like they do now and some of the wafers would stick in the unlocked position even with the key removed. If that happened there was a good chance that another key would turn the lock....

Thanks!

LockDoc

[davepl]

Thanks! I was wondering if there was a transition limit (like going from a 1 to 5). Not hard for the computer of the day to pick, I suppose, about 10 lines of code.

Any idea why all locks aren't sidebar? Seems like an important security feature, and if its from 1935, the patents are long since expired...

[LockDoc]

Originally Posted by davepl

Thanks! I was wondering if there was a transition limit (like going from a 1 to 5). Not hard for the computer of the day to pick, I suppose, about 10 lines of code.

Any idea why all locks aren't sidebar? Seems like an important security feature, and if its from 1935, the patents are long since expired...

I don't know how long patents last but Ford went to the double sided key in '65. I think Chrysler used a few sidebar locks in some of their higher end cars. Most of the problem was that the sidebar would only work with wafer tumbler locks and everyone except GM used pin tumbler locks.... The Ford locks were made by the Hurd Lock Co. and the Chrysler locks were made by the Yale Lock Co..

LockDoc

[04sshd]

good info, I've encountered some of those worn lock cylinders that would allow any GM key to turn a door or ignition lock.

[PanelDeland]

I actually had a key that would start a B I L's car back years ago. Then one day it suddenly wouldn't. He claimed he hadn't done anything to the ignition but lube it. Maybe that released one of the wafers that was stuck.

[LockDoc]

Originally Posted by PanelDeland

I actually had a key that would start a B I L's car back years ago. Then one day it suddenly wouldn't. He claimed he hadn't done anything to the ignition but lube it. Maybe that released one of the wafers that was stuck.

I'm betting that's what happened. I have taken a lot of them apart that had tumblers stuck in them.

LockDoc