Author Topic: Eaton Posi casting number help  (Read 502 times)

x44d80

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Eaton Posi casting number help
« on: January 05, 2019, 02:54:10 AM »
Looking at a posi Eaton 4 series case with a casting date number 297.  What date does this translate to?  Thanks in advance.

ZLP955

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Re: Eaton Posi casting number help
« Reply #1 on: January 05, 2019, 03:31:08 AM »
Would think that's a Julian date code; there's a date calculator here at CRG (you didn't state the year but based on your username I'll guess it's a '69 unit, although not sure if Eaton put a year designation on them): http://www.camaros.org/numbers.shtml#Calendar
Tim in Australia.
1969 04A Van Nuys Z/28. Cortez Silver, Dark Blue interior, VE3 bumper, Z21, Z23, D55/U17, D80, flat hood.
Sold at Clippinger Chevrolet in Covina, CA. Ex-Racer at Lions Dragstrip in Long Beach.

bcmiller

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Re: Eaton Posi casting number help
« Reply #2 on: January 05, 2019, 03:33:12 AM »
Yes that’s a casting date. What are the numbers and letters stamped on the ring gear flange?

Post some pics.
« Last Edit: January 05, 2019, 04:02:03 AM by bcmiller »
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016


ZLP955

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Re: Eaton Posi casting number help
« Reply #4 on: January 05, 2019, 08:11:19 PM »
On that example, the ring gear is dated 11 68 (November 1968) and the carrier is dated 297. I'm not aware if the carriers have any year identifier elsewhere, but if that particular ring gear and carrier were assembled together as OE, then the carrier would've been cast 297th day of 1968 (October 23).
Tim in Australia.
1969 04A Van Nuys Z/28. Cortez Silver, Dark Blue interior, VE3 bumper, Z21, Z23, D55/U17, D80, flat hood.
Sold at Clippinger Chevrolet in Covina, CA. Ex-Racer at Lions Dragstrip in Long Beach.

bcmiller

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Re: Eaton Posi casting number help
« Reply #5 on: January 05, 2019, 10:23:05 PM »
I wouldn’t assume anything.

297 just gives you the Julian date of the casting. No year.

X44d80 send me a pm if you want.
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

x44d80

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Re: Eaton Posi casting number help
« Reply #6 on: January 05, 2019, 10:57:11 PM »
Now it makes sense.  Iv'e seen carriers with casting dates like "93" where the seller is saying it's a 1969 carrier, so I was confused.
 I have been researching the COPO BE carriers and the only difference I can distinguish is the "small" window on the backside.
I don't know if the spider gears were different but it looks like the COPO BE carrier had the same casting number(EDB-30174) as a regular 4 series posi and the 200 pound springs. Not a bunch of information out there on that unique carrier.  Thanks for all your help.

bcmiller

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Re: Eaton Posi casting number help
« Reply #7 on: January 05, 2019, 11:49:38 PM »
Yes COPO carrier has same casting number but is machined differently and has different internals. I have a couple of non COPO 69 carriers. There are small window COPO and non COPO small window carriers.

I have plans to add additional carrier / gear/ other rear end stuff as supplemental info in the CRG pages in the future. Similar to plans to add more Muncie trans stuff.
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

olddragracer

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Re: Eaton Posi casting number help
« Reply #8 on: January 08, 2019, 06:11:43 PM »
I hope I am not being too critical. I believe the part being discussed is the differential case. The carrier is the larger casting that holds the axle tubes, pinion gear and bearings as well as the diff case being discussed

bcmiller

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Re: Eaton Posi casting number help
« Reply #9 on: January 08, 2019, 07:46:00 PM »
There are different ways to describe things. Sometimes over the years different words come to be understood.

The “differential carrier” also called the “differential” we are referring to in this situation is the differential case with internal gears - or the posi unit onto which the ring gear mounts.
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

olddragracer

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Re: Eaton Posi casting number help
« Reply #10 on: January 08, 2019, 09:12:31 PM »
You are right, over the years the word carrier has been used improperly. In my working years I have discussed and diagnosed drive axle problems often. There has been misunderstandings by using the words carrier and differential  incorrectly. The differential carrier is the housing that holds the axle tubes. I am only trying to help correct an area of discussion that has caused me many problems.

bcmiller

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Re: Eaton Posi casting number help
« Reply #11 on: January 08, 2019, 09:38:15 PM »
Not arguing, but here is some more information.  This is how Eaton refers to the posi unit. They call it a "limited slip differential".

In GM parts books, they refer to the posi as "Case, Differential".
The complete axle housing is referred to as "Carrier and Axle Tube Assy., Differential". 

« Last Edit: January 08, 2019, 10:02:01 PM by bcmiller »
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

bcmiller

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Re: Eaton Posi casting number help
« Reply #12 on: January 08, 2019, 10:06:01 PM »
Oh, and olddragracer, it is good to have you here and posting.

I grew up (literally) being at drag strips and dirt tracks.

I have only had my current Camaro about 11 years, but it's an old L78 track car that had 4.88 gears much of its life. So you know how it was being used.
:)
« Last Edit: January 09, 2019, 12:38:01 AM by bcmiller »
Bryon / 1968 Camaro SS 396 coupe - now old school 468 big block
1967 RS/SS 396 coupe L35/M40 - 4 generation family project
Looking for 68 Camaro with body # NOR 181016

olddragracer

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Re: Eaton Posi casting number help
« Reply #13 on: January 09, 2019, 03:45:08 PM »
Corvette and removable carrier vehicles "pot type" just call that housing the differential carrier. I installed many of the 4.11, 4.56, 4.88, 5.12 and higher ratios when these cars were being raced. The setup of the gears is different depending on what type of racing the car was used for. These days those ratios are being removed if the car is being restored or driven on the street. The most often used ratios are 3.73 and 3.56.  As you have I have a 67 RS/SS coupe that I have owned since 1990 and have been restoring for almost 20 years, off and on. I hope to have it finished by this coming summer.