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Old 10-05-2020, 04:09 PM   #1
poulrais
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Default Help identifying a gear set

I sold a gear set to a TB member in Taiwan but I want to make sure that I'm sending him a part that will fit in his diff. He says he has a 1030 diff and I'm selling him a 3.31 gear with pinion. The ring gear measures 7.2 inches.

From what I've read, this should be the right part for a 1030 diff. Problem is that the guy I bought the gear set from (DET17) says he took it out of a 1041 diff that was on a 1992 Volvo 740 with a manual tranny. Gears form a 1041 and 1031 diffs should interchange but aren't the 1031 equipped with ring gears of 7.562 inches in diameter?

Pictures of said gear set...





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Old 10-05-2020, 06:49 PM   #2
culberro
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ID and OD of the pinion bearings would probably be more helpful in figuring out what it is.
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Old 10-05-2020, 06:58 PM   #3
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These might help
http://forums.turbobricks.com/showthread.php?p=2865196
https://people.physics.anu.edu.au/~a...volvo_dana.htm - see sections 2&3
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Old 10-05-2020, 07:10 PM   #4
poulrais
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Quote:
Originally Posted by culberro View Post
ID and OD of the pinion bearings would probably be more helpful in figuring out what it is.
Pinion gear bearings are:

Inner (differential side): ID = 1.436", OD = 3.00"

Outer (driveshaft side): ID = 1.123", OD = 2.53"
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Old 10-05-2020, 07:47 PM   #5
hiperfauto
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The only bearing that's different is the inner pinion bearing. From the specs you posted above it's definitely a 1031. A 1030 inner pinion bearing would have an OD of 2.8438".
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Old 10-05-2020, 08:01 PM   #6
poulrais
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Quote:
Originally Posted by hiperfauto View Post
The only bearing that's different is the inner pinion bearing. From the specs you posted above it's definitely a 1031. A 1030 inner pinion bearing would have an OD of 2.8438".
Damn...

Is there a 3.31 gear set that exists for the 1030 differential?

Thanks for the info!
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Old 10-05-2020, 09:22 PM   #7
hiperfauto
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I don't think so. I checked the 200 & 700 parts catalogs and it only shows 3.31's for 1031.
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Old 10-05-2020, 09:56 PM   #8
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Quote:
Originally Posted by poulrais View Post
Damn...

Is there a 3.31 gear set that exists for the 1030 differential?
Hmm, I'm almost positive that my 3.31 ring gear measured 7.2" when I installed the True-Trac. Doesn't that make it a 1030? I pulled the whole axle from a 1984 after it had done 20 years of faithful duty; heaven only knows if it was original to that car, but probably was.

To corroborate my memory, I recall being surprised that it was smaller than the 7.25 rear end that Mopar buddies consider notoriously weak. But one of them pointed out the spider gears were the weakest part, and without those, my 7.2 ought to be just fine for normal street use, probably fine even for spirited use.
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