1962 Rear axle Identification, ratio tag?

[Dino L.]

Referencing the new 1962 judging guide, I am confused on the rear end ratio ID tag, I have a 3:55 which I thought was a solid disk ( there should always be one hole to mount it), but the JG says it should have a single round hole (this means a total of two holes) in it which I thought was 3:36, any original car owners with 3:55 gears that can clarify for me?

[Mike E.]

Re: 1962 Rear axle Identification, ratio tag?

The JG is correct, the info the vendors had (supplied by GM, ironically) is wrong. Disc with one hole is 3.36, two holes is 3.55.

[Dennis C.]

Re: 1962 Rear axle Identification, ratio tag?

In addition to what Mike has said, this has been discussed before. Tom Parson's has indicated this error by the vendors several times. Here a link to one discussion:


https://www.forums.ncrs.org/showthre...ght=ratio+tags

Dennis

[Mike E.]

Re: 1962 Rear axle Identification, ratio tag?

And by the way, the repros I have seen are the wrong diameter. Originals were regular steel, not stainless. Other than that, the repros are great.

[Dino L.]

Re: 1962 Rear axle Identification, ratio tag?

Thanks everyone for the clarification!!! What is the correct diameter?

as I mentioned that new 62 JG, will Make a lot of top flight cars drop a notch !

[David B.]

Re: 1962 Rear axle Identification, ratio tag?

In the recesses of my old dormant files I found the blueprint on the rear axle tag PN 3714716 drawn 4-16-54 showing it's dimensions along with another blueprint PN 3737071 referred to as "axle identification tag chart" drawn 3-7-56 which shows ratio imprint dimensions etc.. I know it is correct for the 56-57 years and possibly much later. I recall years ago reading I believe in the 56 production parts ledger that it was merely a slug punched out of some kind of shipping crate and reused for rear axle I D purposes. At the time I read this I thought it was really interesting and ingenious (also economical). Do not quote me on this one since my reference sources went with the sale of my 56 Sebring car in 1997. I would attach the blueprints if I could figure out how. With my limited computer skills I cannot figure out how to attach it to these threads or get past the test forum.

[Gary C.]

Re: 1962 Rear axle Identification, ratio tag?

Attached are a couple of ratio tag blueprints

Gary
....

Ratio Tag 3767632_12-08-1958 (Small).jpg 55 Rearend dwg w-ratio tab (Small).jpg 3767632 Ratio Tag BP_120858.jpg

[David B.]

Re: 1962 Rear axle Identification, ratio tag?

Gary,
Your prints work, especially the second one which primarily shows where Tag 3714716 should be placed. Can't read dimensions on the first print so can't tell if the same as the actual 3714716 tag print.
Maybe now is not the time to open a whole new can of worms BUT HERE GOES:
1. Is there a part # and print for the 2 hole version?
2. If the 2 hole version is correct for the 3.55 ratio what about all the other ratios.
3. Looking at an OLD black book it appears RPO 203 ratio 3.08 does not show any quantity does NCRS currently show anything?
4. Not being an expert on anything, I would guess that up until at least the date of your 1st print all tags were the same with the ratio listed on the surface.
5. A quick look at 62 production quantities in this black book and an old NCRS pocket spec guide list 14,232 RPO 675 (posi) equipped 62 Corvettes. If this number is still currently listed as correct I think this number should be researched again.
6. I found 1,110 62 Corvettes were equipped with RPO 203 which was not positraction thereby making the 14,232 quantity suspect.
7. Did not mean to get off the tag thing but one simple question often leads to bigger issues.

[Mike E.]

Re: 1962 Rear axle Identification, ratio tag?

Dave,
I have found that 62 number for posi-equipped cars suspect for ages. There is no way that few were open-rear equipped. Glad you agree.
GM's documentation on the 3.36 vs 3.55 tags has been interesting as well. I don't know if the 3.36 tags ever were double-hole, but every 61-62 car I have documented over the past 40 years with an original-code 3.36 has a single hole.

[Gary C.]

Re: 1962 Rear axle Identification, ratio tag?

Dave,

In my original post I added a zoomed on the dimensions. Hope you can read those.

As I recall and believe Tom Parson has corrected this many times, that the "double hole" tag was strictly 3:55 ratio. I've attached a corrected chart from 2007, but can't recall the source.

Gary
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Rear End Tags-Corrected Reference.jpg

[David B.]

Re: 1962 Rear axle Identification, ratio tag?

Gary & Mike,
Can now read your enlarged print #3767632 Gary, Based on upper right notations it appears print was redrawn on 12-10-58 and again on 2-26-63. In comparing with my print of tag #3714716 it appears 56-57 & 58 cars had a tag diameter of 1.78 which "might " have changed when redrawn on 12-10-58. Your print #3767632 shows a tag dia. of 1.68/1.44. The punched hole diameter of .39 to fit the axle housing stud is the same. It appears this punched hole was enlarged to .45 on 2-26-63. For discussion purposes one can draw the conclusion this particular tag was 1.78 round for all 56-57 & 58 cars and was slightly smaller 1.68/1.44 for all cars from 59 thru 62. That takes care of this tag now what about the picture of all those other tags you show. It makes a lot of sense to use different configurations to ID the ratio easier. I seem to recall this subject was discussed years ago in my former life, SOooo is there a blue print or official part # describing the use of these tags? I note the "unofficial" picture mentions a diameter of "approximately" 1 1/2 ". Do not want to belabor this issue but there must be something more concrete and official. LEAD ME TO THE WATER GUYS.

[Gary C.]

Re: 1962 Rear axle Identification, ratio tag?

Dave,

IMHO, the ratio tag attached to the rear end housing would only be shown in a completed assembly drawing; pumpkin, housing etal, which I do not have.

Originally, the tags were ink stamped, but the ink quickly wore off and thus the differently cut tags started being used approximately 1957 VIN 3700.

Gary
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[David B.]

Re: 1962 Rear axle Identification, ratio tag?

Gary,
Let me play the devils advocate for a moment. We both have GM blueprints regarding the round tag that supposedly went away in favor of the cut versions. I am aware of the ink stamp (if that is what it is) showing the axle ratio on the 3714716 tag and as previously mentioned I have the "axle Identification tag Chart" PN 3737071 which lists all the ratios that might be applied showing where they should be put on the tag. This print not only lists the ratios but also assigns a part # for each even though it notes N D (no drawing). NOW, why does this round tag continue in existence and in fact be redrawn twice if it was replaced sometime around 1957 vin 3700? Someone out there must have some solid GM document showing this change and I am sure it would be in the form of part numbers for each tag even if there is N D . They may very well be on the lay out print for the axle assembly as you indicate but it would still have a part number assigned to it and in all likelihood have a Chevrolet print showing all these ratios by assigned part number. I would also bet there is a print for each tag which would also help pin down when they were starting to being used. I like the clear picture of the cut tags and they make sense and probably came into existence whenever but I would personally love to see some Chevrolet document.

[Gary C.]

Re: 1962 Rear axle Identification, ratio tag?

Dave,

I've shared with you the BP's I have. The Axle identification Tag Chart BP 12/10/58 3767632 Notes: Items 1 thru 5 were original part numbers prior to the 3767632 BP. The individual ratio tag part numbers are listed in the Part No. column and there are ND (no drawings for any of those part numbers).

The cut ratio tags appeared on 1957 Bowtie cars along with the introduction of the 4 speed transmission.

Documentation would have to come from Ken Kayser or Art Armstrong.

Good luck. Let us know what you find.

Gary
....

[Gary C.]

Re: 1962 Rear axle Identification, ratio tag?

Did find this that Roy Braatz published in the old C1 car club magazine years ago.

Rear Axle ID Tag.jpg