Bill Ball

I was complaining earlier today and asking for help with a hatch lock that would unlock but not lock the hatch. It simply would not turn in the counterclockwise direction. Here is what I found on dissection.

First, here is the hatch upper latch mechanism removed from the car and partially disassembled.


Below is the detailed anatomy of the lock. I don't show how to disassemble it, but I will just say you have to first remove the tongue from the latch housing by drilling out the flared end of the pivot pin to get the lock out of the latch housing. Then drill out two tiny pins you will see in the lock's black dress ring. This is somewhat hard due to the tiny size of the pins but I managed by bracing my Makita and going at it. The dress ring is a tight fit even with the pins drilled out. Once that is off, put the key in, and the tumbler will slip out.

What I didn't see even after removing the alarm contacts, gasket and base plate, was the alarm lock tumbler - the source of the problem. It was hidden in grease inside the lock. It has two additional blades.


This shows what should happen when a key goes into a tumbler - the blades or whatever they are called are retracted flat with the tumbler surface so it can turn in the lock barrel. This is the main lock tumbler - it works fine. What about the alarm lock tumbler?


I cleaned out the grease and fiddled with the alarm tumbler and key. It was stuck in the lock body, but finally came out. Here is why it would only turn one way. One of the blades stayed proud when the key was inserted due to wear to the other side of the blade inside the lock.


Earlier I mentioned the passenger door lock exhibited the same behavior. Here is a photo of the end of the lock with the alarm electrics and base plate removed and the grease cleaned out. Note the two blades locked against the lock barrel. THIS IS A DOOR LOCK, not the hatch lock, so don't let that confuse you, but it illustrates the problem with blades that do not fully retract flush due to wear. The green arrows point to the two blades capturing the boss on the inside of the lock body so the lock will not turn. That's good with the key out.


Now look at the lock with the key inserted. Hah! One blade did not retract fully. So, the lock will turn one way (opening the door) but not the other (locking the door).


The solution is to take the lock apart and file down the protruding blades.

Bill Ball

Here is why the hatch lock would not disable the alarm upon opening the hatch even though the key turned easily in that direction. These are the alarm electrical contacts that fit on the end of the lock body, shown here AFTER I cleaned them up. One of them is badly eroded. However, it did work after the clean-up.


Here are the door lock electrics - CLEAN. It still disabled the alarm as it should when opening the door.

Landseer

Exceptional post. Thank you very, very much.

Chris

Bill Ball

Well, it took filing of almost every blade to get the action to be smooth, not just the one obviously high blade. The others almost all had high edges that caught on the inside of the lock barrel. The tolerance inside the door and hatch locks are much tighter than in the gas cap lock. It did not require nearly as careful or complete filing. For the door and hatch locks you want not even the slightest edge of a blade protruding, so remove them and file them so they are very slightly below the tumbler face. Check with the key in both ways. Check with the some turning force on the key in the tumbler to make sure the blades do not **** slightly and protrude as you turn the key.

ANYBODY HAVE CLUE HOW THE CENTERING SPRING GOES BACK IN? I can't seem to find the magic spot.

Bill Ball

Aha! I was puzzled by how the spring goes in. It finally dawned on me after some trial and error.

Here are the parts: tumbler, spring, lock barrel


Here is the spring just layed in its location on the tumbler for starting the install. It needs to be wrapped around the post so that the tang pointing right ends up on the other side of the post, putting tension on the spring.


Here it is wrapped around the post:


Finally the tumbler is installed so the post goes in the center of slot in the lock barrel. The spring tangs will engage a similar post inside the lock barrel in the center of the slot.

6mil928

Excellent post!!!!! Super info. I've got a lock that is not unlocking anymore with the key. Have any feeling on what may be causing it after looking at the internals? How tough do you think it would be to rekey one? Thanks, Jason

Bill Ball

Well, that's basically what I did here. The lock needed to be "rekeyed" so that it would turn in both direction and not just one. This is done by examining the tumbler blades with the key installed, noting any blades that are high, removing the key, pulling out those blades one at a time, filing the proud side, reinserting and checking whether they are still proud when the key is inserted.

If you are installing a "new" lock and want to key it to your current key, the filing is only for fine tuning. You do as much as you can to rekey by swapping blades and getting them as close to flush as possible before filing.

The steps for getting the lock mechanisms off the car and getting the lock body out are not entirely self-evident. I will add more pictures about that later.

Ron_H

[QUOTE=Bill Ball;4610853]

Below is the detailed anatomy of the lock. I don't show how to disassemble it, but I will just say you have to first remove the tongue from the latch housing by drilling out the flared end of the pivot pin to get the lock out of the latch housing.

Bill, they must have changed the retention method in the later cars. I didn't need to drill out anything to get the lock out of the housing. I had to remove a tiny set screw in the housing that retained the lock and kept it from rotating in the housing.
Once that was removed and stashed in a safe place, the lock could be removed by twisting. That makes me think the locks for various years are not interchangeable.

6mil928

Ron I had the same set screw. Bill that burn out looks awesome!!!! The sharks in the park looks like it was a lot of fun too. Where was the park at? Jason

Bill Ball

Ron: Even with that screw removed, the lock was trapped by the tongue. This is only true for alarm locks. Non-alarm locks will come out. Now, with a little wiggling and prying, maybe the lock will clear the tongue, but it wouldn't on this car.

6mil: That's Tilden Park in the hills above Berkeley, CA.

PortlandTom

I was able to just slide the lock tumbler past the tongue, but my tongue may be a little worn (on the lock, that is).

I couldn't get the trim ring off the tumbler, though. I didn't drill out the two little pins, because I thought they must just push in. My question now is, what did you replace those two little pins with?

Tom D.
'93 GTS, 5 sp., AMazon Green

Ron_H

JB Weld

6mil928

I punched my pins in also. please explaing how you used JB to replace them. Thanks, Jason

Ron_H

When you grind the pins down to free the cylinder, you will need to secure it in place when you replace it. Just fill the indentation where the pins were ground away with JB Weld epoxy and finish it off flush with the surface of the cylinder housing so it will slide into the latch housing. I had to file mine down flush after curing. Mine lasted around 21 years and about 190,000 miles so I'm not too concerned with replacing them again anytime soon. When I do, I can simply grind down the JB Weld plugs. I got this idea from 928 International which is who rekeyed my locks.

6mil928

Ok Ron I got it great idea. Jason