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Single-Use Lock Nuts on Compressors

pottsf on Mon August 20, 2007 9:32 PM User is offlineView users profile

Year: 1966
Make: Chevrolet
Model: Corvair
Engine Size: 164CID
Refrigerant Type: R-12
Ambient Temp: n/a
Pressure Low: n/a
Pressure High: n/a

The compressor in question is a Delco A-6 and the nuts in question are the one at the front end of the shaft that holds the clutch hub on and the four at the back that squash the whole compressor into the shell on its o-rings.

What I want to know is, can any of these nuts EVER be re-used under any conditions (e.g., compressor never put in service, nut recently new)? While o-ring leaks on this compressor aren't rare and might be attributable to loosening lock nuts, I don't know if I've ever seen or heard of a clutch hub working loose. The answers I'm looking for, of course, would come from extensive experience.

Now, I've been buying nut kits for this compressor (the five nuts mentioned) for about $14 plus shipping, which I find a little steep after a few units, especially if all I want to do is the one at the front (3/8-24 thread, distorted-thread FLANGED). If I could source a supplier of either or both of these nuts in bulk (say, quantity 100), I would spring for that and make it up on volume, as they say. I have worked the Internet raw trying to source these, and have done no better than the nut kit mentioned above at a similar price. Can anyone identify a supplier?

Of course, I'd use a known-reliable substitute or replacement if I could identify one, so I'd appreciate any pointers down that line, as well.

CorvairGeek on Mon August 20, 2007 11:42 PM User is offline



-------------------------
Jerry

pottsf on Tue August 21, 2007 11:40 AM User is offlineView users profile

Wow! Now THAT's an eye-opener (and problem-eliminator)! Thanks so much, guys! I'll just keep using anything I think won't spin off (including generic locknuts, thread-lock fluid, etc). Never heard of a (deliberately) bent key - I'll be more-thoughtful in evaluating the first one I see, too (Look! That key's all BENT!). You guys are likely well aware that, in their lock-nut kit (Delco #15-234, which on Delco's Web site is NOT shown as applying to our compressors), Delco replaces the original shoulder lock nut with a flange lock nut AND advises removal of the spacer and snap ring originally put in their hubs. Such MYSTERY . . .

An A-6 I took apart recently displayed about 1.0 degrees free rotation versus the shaft, and it HAD its key, no spacer, and an old-style (shoulder) lock nut. Still worked OK (except for a bad shaft leak), but I eliminated the free play somehow before I put that one back into service.

Now, is there any chance you folks could similarly enlighten me about the four single-use nuts at the BACK of the compressor? On that very compressor I mention above, an o-ring leak has developed that seems to have resulted from loosening of those nuts (I've retightened them to the specified torque). New nuts for this application don't display any attribute that I can even associate with a locking feature (they're just a funny reddish color). All I know for sure is that the Shop Manual says to replace these nuts with new rather than re-use them.

NickD on Tue August 21, 2007 12:20 PM User is offline

Aren't we comparing an 60's A-6 with a late model HT-6, that shaft nut on the A-6 did keep the hub from falling off. A 3/8-24 thread with a 9/16" hex nut is not exactly a rare item, can make your own by tapping on the the threads with a pointed punch and a ball peen hammer. Some styles have a piece of nylon in the threads, others are acorn type with the nylon in the rim, while others have like a rectangle stamped in one of the flats. I did recently purchase some self locking nuts recently from my local True Value store, in stainless steel no less, was for an airport ground antenna that has to be adjusted, could have used the $1.99 a pound variety, but after a year to two would be so badly rusted, couldn't loosen them to save my soul. Ha, I worry more about taking a nut off rather than it falling off.

pottsf on Tue August 21, 2007 12:40 PM User is offlineView users profile

NickD: first, thanks for the correction. My A-6 is indeed Vintage 1966.

3/8-24 FLANGE locknuts appear to be unobtainium. On the other hand, there are twelve 3/8-24 flange nuts (not locking) on every Corvair (my car) engine. GM advises replacing these after removing them, too, but obviously not with respect to any locking feature (they're subject to very high heat). Distorting their threads DOES seem as though it could be done. So I guess I'll try that.

Now, about those four on the back.

- Joe

NickD on Tue August 21, 2007 3:07 PM User is offline

Know the feeling, recently had to pay about 30 bucks for a couple of caliper bolts when the caliper itself was only 12. Seems they like to get you on the small stuff.

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