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Technical GM Door Lock Code?

Discussion in 'The Hokey Ass Message Board' started by blowby, Apr 20, 2016.

  1. blowby
    Joined: Dec 27, 2012
    Posts: 7,554

    blowby
    Member
    from Nicasio Ca

    Is there a hidden code to cut a key for a GM door lock hidden inside this? How does it come apart? Locksmith wants $50-$75 to pick it.

    0420161702.jpg
     
  2. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    Those old one-sided key locks only had like 14 different keys. My cousin had a string of keys and he could unlock any GM car made, up to the time they started making the double sided keys.
     
  3. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    On my old Chevys I just take out all the tumblers and use any key that will fit the hole. Nobody knows about it, who would ever try using a random key?
     
    54fierro likes this.
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 48,789

    squirrel
    Member

    there are a whole bunch of different keys, way more than 14. There should be a 4 digit number stamped on the side of it, which is the key code.

    http://selectric.org/manuals/locks/index.html

    If the lock has been replaced with an aftermarket lock, then it might not have the code number on it.

    It comes apart by destroying the bezel...or at least bending it...
     

  5. blowby
    Joined: Dec 27, 2012
    Posts: 7,554

    blowby
    Member
    from Nicasio Ca

    Got it apart, still no numbers. I bought a blank key awhile back, if I knew what to do...

    0420161831[1].jpg
     
  6. you look at the pins, you can put them in any order, then file the key to where each pins sit flush. this allows the barrel to be turned with your key in it. Any other key and it will push the pins to high to turn.
     
  7. F&J
    Joined: Apr 5, 2007
    Posts: 13,223

    F&J
    Member

    The row of slots are for the "wafers". The points on the key move all of the wafers flush at top, so the tumbler can turn.

    tiny spring on each wafer...easy to loose

    Each wafer is made different, to go with the high spots of each tooth on the key

    My kid kept losing my car door keys after I spent $30 on cracking the key code....so I just use one working wafer in my doors and rear lid.
     
  8. squirrel
    Joined: Sep 23, 2004
    Posts: 48,789

    squirrel
    Member

    the link I posted tells you how to work on those locks....yes, it requires lots of clicking and reading.

    Usually we just buy a new lock assembly.

    You can key the lock cylinder to match the other locks, if they use the same key blank. This is easier on the older cars that use the B10 blank, which was used from 1935 to about 1965.

    You might need more wafers to change the keying. I have parts from several old locks I've taken apart over the years, they come in handy when I need to make a lock cylinder match the rest of the locks on a car.


    Have fun!
     
  9. blowby
    Joined: Dec 27, 2012
    Posts: 7,554

    blowby
    Member
    from Nicasio Ca

    Thanks guys.

    I better wait until morning.

    I do have the other side so would like to match.
     
  10. Not exactly the way these GM side bar lock cylinders work.

    The wafers don't directly prevent the lock core from turning in the case. And when properly assembled the wafers never extend beyond the outside diameter of the core. The wafers have to be lifted to specific and various heights to allow the side bar (shown extended at the bottom of the lock core pictured above) to retract into the core so it clears the lock groove on the inside of the outer case. It's an ingenious design and makes these locks very difficult to pick by conventional methods.
     
    turboroadster likes this.
  11. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,727

    oldrelics
    Member
    from Calgary

    I work in a GM parts department, too bad your not closer I could help you, they are easy to decode and cut keys for. Did you check your local GM dealer?
     
  12. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    the wafers are sold as a seperate kit if you want to build your own locks , it was sold thru forney ( the saw sharpening school ) but I have seen them on e bay once and a while , the whole kit was like 80 but it had bezels and wafers and springs to do 20 locks
     
  13. 54fierro
    Joined: Jul 6, 2006
    Posts: 493

    54fierro
    Member
    from san diego

    I would take the wafers out and identify them first
    [​IMG]
    [​IMG]
    Find a key already cut. Maybe match the ignition key if it fits the cylinder. Identify the cuts on the key
    [​IMG]
    [​IMG]
    Put the wafers back with the cut on the key that matches. If you're short the correct wafer, find the correct one or leave the slot empty.
    [​IMG]
    ...or just leave all the wafers out and any key will work like was already mentioned. :) Good luck
     
    henryj1951 and turboroadster like this.
  14. jlckmj
    Joined: Oct 28, 2008
    Posts: 59

    jlckmj
    Member

    There were about 60 different codes from 1932 to the 60's for GM.
    A lot of the older door cylinders had the code stamped on the tail piece, look for it there.
    I owned a locksmith service for 15 years, and worked in the trade for about 25.
    If the code is there, about $10. If not, it should only cost you about $20-$25 to get one made.
    Usually the chrome cap comes off and then they decode and replace the cap.

    Jim
     
  15. Thanx 54fierro! Those are the kind of pics I was looking for to add to my previous post, but wasn't having much luck doing a quick image search. The side bar locks are much easier to understand with these illustrations rather than just trying to explain how they work. ;)
     
  16. saltflats
    Joined: Aug 14, 2007
    Posts: 10,750

    saltflats
    Member
    from Missouri

    The code is on the cylinder in the pass door.
     
  17. squirrel
    Joined: Sep 23, 2004
    Posts: 48,789

    squirrel
    Member

    yeah, I suppose....but why are there 5 more pages just like this in the list of GM key codes for 1935-65 cars?

    [​IMG]
     
    ClayMart likes this.
  18. blowby
    Joined: Dec 27, 2012
    Posts: 7,554

    blowby
    Member
    from Nicasio Ca

    Thanks. What info would my local dealer require? I do have the donor vehicle ('83 Chev)

    Figures.. I have the other lock but it looks like I did take the pass lock apart. I will check again.

    Other than that, I need to digest all the diagrams and info posted and give it a go. Thanks for that.
     
  19. 35WINDOW
    Joined: Jul 7, 2005
    Posts: 454

    35WINDOW
    Member

    I don't know if Chevy Dealers still do it, but back when I worked for Chevrolet ('70-'78) I regularly took these apart and recoded them for Customers-we had a Block fixture that the Cylinder fit in, and you could recode and check the operation on it, along with (of course) the hand held key cutter-
     
  20. squirrel
    Joined: Sep 23, 2004
    Posts: 48,789

    squirrel
    Member

    if it's a "late model" 1983 lock, then my knowledge is not much help...sorry
     
  21. blowby
    Joined: Dec 27, 2012
    Posts: 7,554

    blowby
    Member
    from Nicasio Ca

    Went to the Chevy dealer yesterday. Parts man tried looking up the VIN for key code, that only goes back 15 years. He said he could cut me a key if he had the code. Then I went by the locksmith, who happened to be a Chevy guy. First thing he said was "Ugh, side bar lock". Said it would take him 60-90 minutes to pull it apart and make a key. Said there is a gizmo that goes into the lock and tells you what the code is, unfortunately they don't have it.
     
  22. squirrel
    Joined: Sep 23, 2004
    Posts: 48,789

    squirrel
    Member

    just what exactly is the lock from?
     
  23. blowby
    Joined: Dec 27, 2012
    Posts: 7,554

    blowby
    Member
    from Nicasio Ca

  24. I have decoded this style of lock cylinder at work many times. But you have to be patient and work carefully.

    With the core removed from the case, use a thin bladed screwdriver to carefully pry up the ends of the spring retainer. It's staked in place on the ends. Pry up a little at a time on both ends, from both sides of the retainer, to slowly "walk" the ends of the retainer out of the core. If you get in a hurry and break off the ends of the retainer the core will likely have to be replaced. Try to use just the end tip of your screwdriver to avoid damaging the tumbler springs under the retainer.

    With the retainer removed, take out the six tumbler springs and set them and the retainer safely off to the side for reuse. Now remove the tumblers (wafers) ONE AT A TIME starting from the key-slot end of the core. Cover the last five wafer slots in the core with your finger, invert the core and gently tap it on your work surface to knock out the first wafer. If it doesn't just drop out you may have to use a pick or a paperclip with a small 90 degree bend on the end, inserted into the key slot, to push the wafer out. Once removed, usually the wafer will have a number, 1 thru 5, stamped on it. Write this number down for key cut position #1.

    Then repeat the above procedure uncovering the next wafer slot in the core, one at a time, until you have all six cut numbers in order (from the head to the tip of the key) written down. With this information most GM dealers or locksmiths should be able to properly cut your blank key. But then there's the matter of reassembling your lock cylinder. It will likely need to have a new end cap crimped on it and maybe a new spring retainer installed and staked in place. You might just want to have it assembled wherever you go to have the key cut. Hopefully for less than $50!

    Also note that with this vintage of GM cylinder, this procedure only works with most door lock cylinders. With the end cap pried off of the cylinder assembly the core can be easily removed from the outer case. With trunk cylinders however, unless you have a working key for the lock, the cylinder won't come apart without damaging the core and/or case beyond reuse.


     
  25. blowby
    Joined: Dec 27, 2012
    Posts: 7,554

    blowby
    Member
    from Nicasio Ca

    Thanks ClayMart. Got it apart, broke the spring retainer. I'm better with big stuff like bumpers. Think I have a code figured out and ready to have a key cut. I'll let you know how it works.

    0423161629[1].jpg 0423161631[1].jpg
     
    Last edited: Apr 23, 2016
  26. 54fierro
    Joined: Jul 6, 2006
    Posts: 493

    54fierro
    Member
    from san diego

    I broke the retainer on one of my cylinders and bent up one of the springs while prying it out. I cut a retainer out of some scrap sheet metal and just left out the one wafer that I did not have a spring for.
    Even though it's a later model cylinder looks like the same idea. Youre halfway there.
     
  27. LOL! Yep... I've broken a few retainers over the years too. :oops: The main difference is that I had either a new cylinder in stock or enough spare parts to cobble something back together. ;) You're right, it's not like taking off a bumper. I guess it's a bit more like being a watchmaker.

    Couldn't see any numbers on your tumblers. If I had to guess I'd say your cut numbers were 544353. Make sure to test the new key in any other cylinders you're hoping to use with it.


    (edit to change my guess :rolleyes:)
     
    Last edited: Apr 26, 2016
  28. blowby
    Joined: Dec 27, 2012
    Posts: 7,554

    blowby
    Member
    from Nicasio Ca

    Just got back from the Chevy dealer. I hadn't noticed your guess on the code, same as mine! Tension mounted as I sat there listening to the key punch tool clicking behind the curtain. Did I get the code right? Did I read it from the correct end? Seemed like forever when he emerged with the key. Put it into the assembled lock from the other door....it works! 6 bucks all in! Now all I have left to do is get the other lock back in one piece and fumble a retainer as 54fierro mentioned.

    Thanks guys!
     
  29. HA! I usually hate second guessing myself :( but the more I looked at the pictures the more something didn't look right to me. Glad I took the time to give them a second reading. If the old tumblers weren't numbered I'm impressed that you took the time to figure out how to read them. That's one of those cases where you have to do a little "inside out" thinking. :rolleyes:
     
  30. I would find another locksmith for future problems. I had a local one here cut me a key for a lock I took him. He charged me $12.
     
    slack likes this.

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