Please help ID

[Flamingo 5]

It’s supposed to be a 2002 

3:64

thanks 

[coloincaalpine RIP 2021]

On the side of the nose,drivers side, there is a stamped #.   Sometimes very faint.

[jireland2002]

Show us a picture from the side.  Side cover with 4 bolts and big bolt in center = 2002.  On driver side toward the nose stamped 40  11 = 3.64 ratio.

[PaulTWinterton]

You can rotate both output flanges forward 360 degrees and the input shaft should rotate 3.64 times to confirm it's a 3.64.

Edited June 24, 2020 by PaulTWinterton

[Conserv]

Paul’s method, above, recognizes that the gears installed at the factory 50 years ago may not remain in the differential today. So I also would recommend his method. Nonetheless, a majority of differentials retain their factory gearing, and it’s nice to know what that was, as mentioned above and illustrated below, from the left front side panel of the housing:

 

Below is a 3.64 differential (11-tooth pinion, 40-tooth gear, designated by “11” and “40”). It’s also a limited slip unit (designated with an “S”). And it was manufactured May 1978 (“5” over “8”, stamped below the pinion and ring teeth numbers).

 

Regards,

 

Steve

 

 

 

Edited June 25, 2020 by Conserv

[Flamingo 5]

[Conserv]

Yes, it was originally, and probably remains, an open 3.64 differential, manufactured October 1978 (“10” over “8”). Double-check with Paul’s test. The rear cover is the later, finned-version of the ‘02 differential cover; I call the finned version the “square taillight rear cover”, but I don’t know for certain that the changeover coincided precisely with the first 1974 model ‘02’s.

 

I’m slightly hazy as to precisely when the e21 differentials switched from 4-bolt side covers to 6-bolt side covers — I believe it was with the 1979 model year (approximately September 1978). Your example suggests that approximately September 1978 could be the changeover. My May 1978 diff. has 4-bolt side covers (first and second photos below). Your October 1978 example has 6-bolt side covers (third photo below). None of this affects this diff’s suitability for an ‘02. It will bolt right into the short-nose ‘02 subframe.

 

Regards,

 

Steve

 

 

 

 

 

Edited June 25, 2020 by Conserv

[Flamingo 5]

Given its design would it be possible to

create a limited Slip using it ?

[jimk]

10 hours ago, Conserv said:

I’m slightly hazy as to precisely when the e21 differentials switched from 4-bolt side covers to 6-bolt side covers — I believe it was with the 1979 model year (approximately September 1978)

A pretty good indication as to when can be found in RealOEM.  In the E21 lookup, enter 1978 and go to the diagram for a 6 bolt cover.  It will respond, not that car.  Try the next year, same results.  It takes quite a few years to get a parts listing for a 6 bolt. I don't have the answer as to when the changeover in parts listing happens, but when I need to look up  parts, I've gotten accustomed to just going to the latest year.

[mgben]

You definitely can go limited slip, you have the preferred 6 bolt side covers. 

Contact Aceandrew as well as read up on it.  

It all just takes money, 

 

[Flamingo 5]

3 hours ago, mgben said:

You definitely can go limited slip, you have the preferred 6 bolt side covers. 

Contact Aceandrew as well as read up on it.  

It all just takes money, 

I’m not up to the job but, I’d love to know what to expect it should cost.

anyone been quoted a number ?

 

[TobyB]

Late E21 case with a late 2002 cover.  

 

Beyond that, well, I can't tell the diff...

 

t

 

[PaulTWinterton]

12 hours ago, TobyB said:

Beyond that, well, I can't tell the diff...

 

Wah!

[TobyB]

Oh, Paul, that'll never work...

 

What's odd is that it's stamped 3.64 but has 6 bolts.  

The 320 trans, engine and diff all changed at about the same time, so

almost all of those have 3.91 gears in them.  It's unusual to run across

a 6- bolt case from a 4- speed car (3.64) OR it's from a 323.  Which is also

unusual in this country.

 

t

 

[PaulTWinterton]

1 hour ago, TobyB said:

Oh, Paul, that'll never work...

 

Oh no!

 

The 3.45 has been in my car since last year.  It was sent to me by a rebuilder in CA with the predrilled flanges and long bolts.  All I did was switch covers.  I put the newer cover on the 3.64 just to keep it closed and for storage.

 

Far as I can tell the 3.45 is doing its job.  Am I misunderstanding something?