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Rear end/differential information

A

Anonymous

Guest
In trying to determine what limited slip I could use in my modified 242, I discovered a lot of different pieces of the puzzle. I think I figured out what's going to work, and it occurred to me that others might benefit from my research. Thanks to all of you who helped.

Best I can tell here's the scoop:

1) Seems that 200 series turbo's, diesels, V-6's and some wagons, or anything with gear ratio's 3.54 and above came with the 1031 rear end. Looks like most all 700 or 900 series cars came with the 1031. Everything else should have the 1030 which is the Dana30.
2) Any diff that will fit the 1030 will also fit the 1031. If you're just swapping diffs without replacing bearings, etc., you just need an assorment of Dana30 shims to do the job with either rear end. If you're rebuilding everything, then you need a Dana30 master rebuild kit for the 1030. The inner and outer pinion bearings and races in the kit however, will not work with the 1031 pinion; different one's are required. So, if you're rebuilding the 1031 you'll need the master rebuild kit for the Dana 30, plus the following parts. The inner bearing is part no. 89449 and the race is 89410. The outer bearing is no. 86647 and the race is 86610. All these parts are Timken, however the numbers are from Randy's Ring & Pinion catalog in Seattle. For what it's worth I found them to be much more knowledgeable and helpful than any other supplier.
3) Ways to tell the 1030 from the 1031. Some said they are tagged externally with info that distinguishes. Many of the paper tags on the driver's side axle tube have gone missing over the years. Mine was there, but the part numbers require deciphering - that is, it doesn't actually say 1030 or 1031 anywhere on my unit. However, in talking to folks the following differences seem to be consistent:
a) If the distance from the mounting surface of the back diff cover to the leading edge of the housing casting (pinion side) is 10.125" it's a 1030. If that distance is 10.625" it's a 1031.
b) on either side of the center section there are strengthening ribs or gussets. If the unit has one rib on each side it's a 1030. If it has 2 ribs on each side it's a 1031.
c) If the center housing casting or the ring gear has the word "Volvo" stamped or cast on it anywhere, then it's a 1031.
d) If it's got a 7.25" od ring gear - it's a 1030. If it's 7.75 od then it's a 1031.

Hope that helps - Michael
 
thanks for the summary, Michael...

I would question one thing, however: the ratio does not indicate housing size....I have several 3.91 and a couple of 4.10 rears that are 1030s....

I agree that the decal does not help.

Are you saying that a person can take a carrier (diff) that has a 7.25 ring gear and use it with a 7.75 ring gear? and vice versa?
 
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