Looking for NOS example of GM #3831588; 63-66 retainer cup for leaf spring

[Gary B.]

Does anyone have or ever seen an NOS example of the early style retainer cups (GM #3831588) used on 63-66 rear leaf springs?

Gary

[Joe L.]

Re: Looking for NOS example of GM #3831588; 63-66 retainer cup for leaf spring

Does anyone have or ever seen an NOS example of the early style retainer cups (GM #3831588) used on 63-66 rear leaf springs?

Gary

Gary-----

I don't have one and have never seen an NOS example. The GM #3831588 was discontinued in July, 1967 and replaced by the GM #3910701. Having been discontinued 53 years ago makes finding one difficult.

[Gary B.]

[Alan D.]

Re: Looking for NOS example of GM #3831588; 63-66 retainer cup for leaf spring

Gary, what about measuring some originals in the mean time? Quite sure many are still around, won't be able to get all the measurements needed but may get a little closer to what they were?

[Joe L.]

Re: Looking for NOS example of GM #3831588; 63-66 retainer cup for leaf spring

Gary, what about measuring some originals in the mean time? Quite sure many are still around, won't be able to get all the measurements needed but may get a little closer to what they were?

Alan------


I think the problem is that installed originals cannot be used to determine the not -installed dimensions of the center section.

[Gary B.]

[Gary B.]

Re: Looking for NOS example of GM #3831588; 63-66 retainer cup for leaf spring

PS. If someone could find and examine the GM engineering drawing that would definitively answer the question as well.

[Joe L.]

Re: Looking for NOS example of GM #3831588; 63-66 retainer cup for leaf spring

Alan,

Yes, and no. I think Joe is mostly right. The collar on the most recently available GM service replacement retainer cups does not have a uniform OD from the base to the tip of the collar. It’s hard to measure the collar OD near the base where it transitions into the base plane of the cup. Part way up the collar the OD gets smaller and then it expands again near the tip. Of course the tip is what gets swaged when installing, and that is really where you’d like to measure the OD. I don’t know why the collar has that wave in the OD. I also don’t know if the earlier style ‘63-‘66 cups had that same wave in the OD, and I don’t have any original cups to measure. If I did have any, I think I’d give it a try to measure in spite if the shortcomings. Also, I don’t think that would definitively answer the question.

Gary

Gary------


I expect that the configuration you describe was a result of tooling wear over time. I expect if you had a 3910701 retainer manufactured way-back-when, you'd find that the configuration was different. Tooling wear and the resultant effect on the quality of the part could very well be why GM discontinued this part. There's no way that GM would invest in refurbishment or new tooling for a part like this.

[Gary B.]

Re: Looking for NOS example of GM #3831588; 63-66 retainer cup for leaf spring

Joe,

There is a difference between old NOS examples from the 60s and recent NOS examples that is unrelated to tooling wear. The first photo attached is a very old NOS example that came with an individual part number tag. I’m guessing it dates from the 60s or 70s. The second photo shows a recent NOS example that came in a box of ten, which is the only way they were sold in recent years by some GM sellers. The top of the collar is very different on the old NOS example. And the collar is not as tall on the old example. The OD is pretty constant along the collar on the old example. The OD on the more recent example is slightly larger up near the top, but not exactly at the top.

Also, the uneven top of the collar on the old NOS example is consistent with the splits seen on original cups on original C2 springs.

Gary
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