Differential Ratio Tag

[John T.]

Looking for correct ratio tag for a C-1 with 3:36 gear. I have 2 sources so far. One says "round tag with one hole" and the other says "round tag with two holes".

Any information will be appreciated.

John

[Dennis C.]

Re: Differential Ratio Tag

Looking for correct ratio tag for a C-1 with 3:36 gear. I have 2 sources so far. One says "round tag with one hole" and the other says "round tag with two holes".

Any information will be appreciated.

John

John,

Tom Parsons has written about this several times. I just looked for his post and the link and photo he had in his posts are gone or don't work any longer. Check the 61-62 Chassis manual, I believe we have it correct in there.

From memory, I believe 3:36 is one hole.

Regards,

Dennis

[Mike E.]

Re: Differential Ratio Tag

John,
To ask for "C1" isn't specific enough. For some strange reason, GM changed those between 58 and 61 (I don't know exactly when). For 61-62 a 3.36 was only one hole (for mounting).
Mike

[Harry S.]

Re: Differential Ratio Tag

John, found this in my files.

[Harry S.]

Re: Differential Ratio Tag

Also found this.....

[Mike E.]

Re: Differential Ratio Tag

Harry,
You are right on, and you have them sequenced correctly. When did the change take place--that's what I don't know.

[Tom P.]

Re: Differential Ratio Tag

I do not know what prompted me years ago to start lobbying to get the ratio tags changed. I have been working on and rebuilding early Chevy (55-64) rearends and early Corvette (56-62) rearends for 50+yrs. In the process of removing original CHEVY and CORVETTE rearends, I started paying more attention to those little tags. As the years passed by and I paid closer attention to the ratio tags, I observed that the tags on BOTH Chevys and Corvettes for a 3.36 ratio had ONE hole for attachment and the 3.55 tags had two holes. I also inquired with many Chevy/Vette owners who had 3.36 or 3.55 rear ratios, and without exception, ALLLLLLLLLLLL of them (who still had tags on their rears) said that their 3.36 rear tags had one hole and 2 holes for a 3.55 tag. SOMEHOW, SOMEWAY, one (or several) vendors made repo tags for the different ratios, BUUUUUUUUUUUT, they had the illustrations for the 3.36 and 3.55 reversed. As I said, I tried multiple times to get this changed (correct as seen above). So far, ONLY, ONLY, ONLY NCRS has now acknowledged and illustrates in the manuals that the above ratio tag illustrations are correct.
So far as I know, NONE of the vendors have changed their illustrations of the tags in their catalogs. For example, I just now went onto a Corvette vendors online catalog (I suspect I should not name the vendor, but it is one of the biggest names) and they STILL show the 3.36 tag with 2 holes and the 3.55 tag with one hole!

Now, with all of that said-----------------and this is bssed on the information In Key Kayser's fuel injection book--------------until 1957, ALLLLLLLLLL ratio tags were round and had only ONE hole. The pre-57 tags were ink stamped with numbers for the ring and pinion teeth (the ink eventually wore off and only a plane round tag with only one hole was on the rearend). Then, beginning in 57, the ratio tags were round discs with different sections removed or different holes.