1950s Interchangeability of 51' differential center chunk?

[Mowerhoarder]

I just recently found out that some Cadillacs were offered with an optional 3.07 rear gear ratio??? I know it only came in some years but can't seem to get a solid answer. Does anybody happen to know what years they came in as options, and also if those would fit into my 51' series 62? I'm not talking about the whole rear end, just the center chunk with all the meat and potatoes and such.

[Jay Friedman]

According to my 1935-1955 Master Parts List 1952-55 Series 62 and 60S used a 3.07 differential. It may be that 1956 was the same but my MPL only goes to '55.

[dn010]

The interchange book says the axle/carriers are interchangeable from 1941 through 1955. While other years may have it, a look at the 1952 shop manual shows the 1952 series 52/62/60S has the optional 3.07.

[Mowerhoarder]

I figured it'd be something like that with the 52'. Seems like they were pretty much the same car from 50-53 other than some minor styling things. I guess I'm on the hunt for a 52' rear diff with 3.07 gears then!

[Mowerhoarder]

It seems like there's a 57' differential on ebay right now for a pretty reasonable price, any ideas on if that would work? Seems like it has different brake drums but maybe everything else is the same? Or maybe I should go with a vintage quick change rear end? Pretty tempting for the price plus there's a few near me.

[Warren Rauch #4286]

         The 1957 Carrier Assembly  will not likely bolt up to the 1951 housing. The gasket is new in 1957.
        Hollander says 1941-1955 the carrier was the same. And notes 1956  will interchange,but doesn't explain why it has a different Hollander number. It does note that the axle shafts are not all the same. The 3.07 ratio was available form 52-56.  To ID ,they will be stamped "3" . Or just count teeth and divide.

Warren

[Mowerhoarder]

Sweet! I guess not so sweet that the 57' one won't work but I'm sure I can find another way to get one. I think there's a junkyard near me with a couple really old ones like that, gotta check I guess.

[Jay Friedman]

From 1941 to 1955 (and maybe 1956) the differentials are interchangeable although ratios are different depending on the model and different transmission.  For example, in 1949 in Series 60S, 61 and 62 if a car had a manual transmission like mine a 3.77 ratio is used; with Hydramatic a 3.36 ratio is used.   

From 1952 to 1955 a 3.07 ratio differential was used in Series 60S and Series 62.  So you can use a 3.07 differential from any one of those years. 

[Mowerhoarder]

Ok, that makes a whole lot more sense. I thought it was only an option through those years, not a standard issued thing. Should make it easier to get though! I guess I'll look for something through those years then.

[dn010]

If you've got enough time, tools, skills and knowhow, you could always swap the entire rear end out for the 1957 3.07. Lots of cutting and welding required. 

You could also surf ebay for parts cars and see if the sellers are willing to identify, remove and sell you the rear end or carrier. I have had good luck doing this.
https://www.ebay.com/itm/123897486004

[Mowerhoarder]

I think I might just swap my whole rear end for one out of a 52' or 53'. Mine already has a badly leaking axle seal but it also has new bearings and stuff for the axles. I guess it wouldn't be that much work, plus I could sell this one and make some dough back. Sounds pretty tempting right now but price will decide. Getting the car ready for a trip to Tennessee here in a few weeks so it'll probably happen after that. I would like to have it done before may though for the trip to Kansas so I can cruise 70 comfortably.

[Jay Friedman]

Is a leaking axle seal the only thing wrong with your rear end?  If so, axle seals are easy to replace.  If I understand your problems correctly, you just need to change the differential (chunk) and one or both axle seals.  Why swap the whole rear end which is a big job?  In any case, when you remove and replace the entire rear end, it makes it a lot easier if you remove the heavy differential from the rear end beforehand. 

[Mowerhoarder]

Sorry, I guess I should've clarified. I've replaced both axle bearings and seals but the passenger side still leaks, I put 2 seals in it and both leaked so I'm assuming it's something with the axle itself. By the time I get another axle and another seal, it might just be easier to get the whole new diff in there as well. I'm planning on doing the bushings back there too so it should be a little bit easier to do with all that outta the way, plus easier to run brake lines and such.

[Jay Friedman]

The axle could have a burr or some other imperfection on the surface that the seal rubs against. In that case the easiest solution is to replace the axle or have a machine shop fix it.

[Mowerhoarder]

I assumed that and took the axle back out, everything looks perfect and no issues with it. I measured the OD of the shaft and ID of the seal so I can match it up with the other side but I never did