Need help understanding C3 storage compartment lock cylinders and cases

[Gary B.]

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[Gary B.]

Re: Need help understanding C3 storage compartment lock cylinders and cases

To add to my confusion, here is a photo of an NOS lock case GM #8869811.

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[John S.]

Re: Need help understanding C3 storage compartment lock cylinders and cases

Gary, here’s a couple shots of the original compartment lock from my ‘73 including my original key. It looks like the housing matches up with the one in your photo but it looks to me like the lock barrel itself is the shorter one you labeled as ‘68 only.

Hope this helps, let me know if you need any further information or pics.

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[Gary B.]

[John S.]

Re: Need help understanding C3 storage compartment lock cylinders and cases

Gary, glad to help out, it was a good reason to take mine apart for some overdue cleaning and lubrication. I agree the 81717639 could be a service replacement, just an ugly one.

[Joe L.]

Re: Need help understanding C3 storage compartment lock cylinders and cases

It’s my understanding that the GM part number for an uncoded storage compartment lock cylinder for ‘68 is GM 7778996. And the part number for the uncoded storage lock cylinder to service ‘69-‘82 is GM 8717639. Examples of each of those is shown in this image.

[ATTACH=CONFIG]124129[/ATTACH]

The ‘68 lock cylinder is 1.0” over length.The ‘69-‘82 lock cylinder is 1.24” over length. This suggests to me that the respective lock cases for those two cylinders must also be a different length. And the fact that the stainless steel cap on the ‘69-‘82 cylinder is longer than on the ‘68 cylinder also suggests to me that the push button protrudes further out of the lock case on the ‘69-‘82 lock. Can anyone confirm that my two suppositions are correct?

Does anyone know the GM part numbers for a ‘68 lock case and for a ‘69-‘82 lock case?

Thanks,

Gary

Gary------


The 1968 and 1969 cylinder cases were the same----GM #8869811. The uncoded lock cylinder for 1969-82 was specified in SERVICE to be the 8717639 from the very beginning in 1969 until it was discontinued without supercession in November, 1991. However, I do not believe it was ever used in PRODUCTION or that it even ever was the correct SERVICE part. For this cylinder to work properly, it would have to be installed in a door that was thicker and configured differently than that used in earlier C3's. It might work for later C3's with plastic compartment doors, though.

With these lock assemblies, it's impossible to correlate PRODUCTION parts to SERVICE parts because the PRODUCTION assembles included case and cylinder and were never available in SERVICE.

I believe the GM #7778996 was used well after 1968 and, in fact, was catalogued as the SERVICE cylinder for 1972-75. The cylinder and case installed in my 1969 is the same as John's. Plus, the 7778996 was available in SERVICE until January, 1987 when it was replaced by GM #1154261.

In my experience, GM SERVICE parts information is about 99.5% correct. But, there is that 0.5% when it's not.

[Gary B.]

Re: Need help understanding C3 storage compartment lock cylinders and cases

Joe,

For service of model years that don’t use a D keyway, GM 7778996 is inconvenient because it has a D-restricted keyway. GM 1154261 is a better choice since it it has a universal keyway, i.e., it can accept any letter key. That’s not ideal for for judging (and should fail a PV), but at least you don’t need a 3rd key with the 1154261 cylinder.

Gary

[Joe L.]

Re: Need help understanding C3 storage compartment lock cylinders and cases

Joe,

For service of model years that don’t use a D keyway, GM 7778996 is inconvenient because it has a D-restricted keyway. GM 1154261 is a better choice since it it has a universal keyway, i.e., it can accept any letter key. That’s not ideal for for judging (and should fail a PV), but at least you you don’t need a 3rd key with the 1154261 cylinder.

Gary

Gary------


If that's the case, then, apparently no functionally correct "H" coded keyway lock cylinder, as used for 1969, 1973, 1977, and 1981 was ever available in SERVICE from GM.

[Gary B.]

Re: Need help understanding C3 storage compartment lock cylinders and cases

Gary------

If that's the case, then, apparently no functionally correct "H" coded keyway lock cylinder, as used for 1969, 1973, 1977, and 1981 was ever available in SERVICE from GM.