WRX's rear diff????

[mbtoloczko]

the 160 in R160 is the diameter of the ring gear in mm, so it would be interesting if you measured the diameter of the SVX rear diff ring gear and that of the one in the other rear diff that you have. If you could snap a comparative pic of the SVX diff internals and the internals of the other diff, that would be cool too.

[Phast SVX]

i have one in my garage, ill try to get to it tommorow
phil

[alex_umn]

Would anyone have the ring gear out of the case right now? Otherwise it might be hard to measure what with the clutch packs (I think) in the center of the ring...

I'll take a look tomorrow, too I guess...

Wow, there's a whole lot of bad information in this thread!

Let me get you guys sorted out. Here's the easiest way to tell the difference between the R160 and the R180 is to measure the distance between the upper two and/or lower two bolts on the aluminum cover. On the R160 the two bolts are about 2 3/8" apart and on the R180 they are about 3 1/4" apart. The R180 is wider but not really taller. Also the plastic vent on the top of the cover partially blocks one of the bolts on the R160 and you have to remove it to gain access to the bolt. On the R180 you can just sneak a socket past the plastic vent so you don't need to remove it to get to the bolt.

As far as the "R160" referring to the ring gear as 160mm in diameter I guess that's the general idea but the ring gear isn't actually 160mm in diameter. It's actually less than 150mm at it's widest so I guess that 160 is a nominal designation. So why don't they call it R150? I dunno. I haven't measured a R180 ring gear so I don't know how that compares.

As Mychailo points out alex_umm has a few pictures of rear diffs in his locker. The pictures of the two rusty ones on a piece of cardboard clearly show two R160 diffs. The lower one is an earlier unit with the splined axle stubs sticking out of the case. These used the same kind of driveshafts as the front with the "female" inner ends.
In another folder there is a few pictures comparing the diff that alex took out of his SVX, which is clearly an R160. Next to it is the obviously larger R180 which, I take it, came from a USDM STi. Alex is in error refferring to both diffs in the picture as R180's.

To use the R180 diff you must also use the knuckles and axles that go with it. The driveshafts for the R180 are larger in diameter as are the splined shafts that slide into the differential on the inner end and into the hub on the outer end. They are only about a couple of millimeters larger in diameter but the wheel bearings are larger, too. So you couldn't use R160 driveshafts with an R180 because they would be too small. You wouldn't want to anyway because part of what makes the R180 setup stronger is that the axles are stronger and so are the wheel bearings.
Did you replace the knuckles and axles on your SVX with the STi pieces as well, alex?

As far as I know the 2004 USDM WRX STi is the first Subaru model in the U.S. to get the R180 rear end. Legacies did not get them, not even WRX's got them. Heck, in the rest of the world even standrd WRX's and Sti's didn't get them, they were only available in the STi RA versions. And, of course, in the SVX everywhere else in the world but here, apparently. Which is why I thought they might but Mychailo and I already figured this out a few weeks ago when I had him measure the bolt spacing on his rear diff. R160, bummer! And the pictures in alex_umm's locker also confirms it.

To address some other comments/questions:

alex_umm, the rear diff that came out of your SVX is the same as the one from the '91 Legacy, both R160.

svxsubaru1, the R180 is twenty stronger than the R160.

jamesy, the WRX diff (non STi) is just as strong as the USDM SVX diff. They are both R160's.

alex_umm, yes, the ring & pinion gears from an R160 can be put into an R180 case. You can also put a Geo Metro engine into a Kenworth truck engine bay but that doesn't mean you could actually bolt it up to anything and make the truck move! That's an extreme example but I think you get the point. It ain't gonna work.


Oh, and just by way of introduction because I realized you guys could be thinking, "Why should I listen to him, he could be some wanker, too." I build and maintain rally cars for a living. I've built several Subarus, including national and divisional championship winning cars and I was part of the Subaru Canada Rally Team in 2001. So I've been around this stuff a little bit. Not trying to sound high and mighty, just giving some credentials to lend validity to what I stated above.

-Dave Clark

[svxsubaru1]

Thanks, i was wondering why subaru would put a r180 in a 135 horse 1 gen legacy.

[Subafreak]

OK then Mr. high and mighty What the hell is the little rear diff with the screw in bearing caps that i'v been told about but never seen? an R140?


Did you say that every other SVX came with an R180 but the USDM's?

Originally posted by Subafreak
OK then Mr. high and mighty What the hell is the little rear diff with the screw in bearing caps that i'v been told about but never seen? an R140?


R160, just older, like from a Loyale.




Did you say that every other SVX came with an R180 but the USDM's?

Apparently so.

[Subafreak]

I'v had as old as a 77 Brat and it still had bolt in rear caps. I'm begining to think this mystery rear does not exist.

[oab_au]

Using your measurements, the Euro/Australian version has an 3.7:1, R160 diff.

Harvey.

Originally posted by Subafreak
I'v had as old as a 77 Brat and it still had bolt in rear caps. I'm begining to think this mystery rear does not exist.

Well I agree, I don't know that I've ever seen a Subaru rear diff with screw in bearing cups. The front, of course, is like this.

Certainly the older diffs have the splined stub shafts like the front.

BTW, the R160, R180, R200, etc. diffs are made by Hitachi and came in a number of different vehicles, mainly Nissans (and Subarus, of course). 280Z's had R200's , some had R180's. I'm not a Nissan guy so I don't really know exactly what came in what. But if you got an R180 out of a Z car it would physically bolt into a Subaru. Whether the gear ratio would match up or the axles would fit is another matter...

-DC

Originally posted by oab_au
Using your measurements, the Euro/Australian version has an 3.7:1, R160 diff.

Harvey.

Well that's pretty interesting because it was a supplier of mine in Australia that thought that the SVX's (down there at least) came with R180's. I guess "thought" was the key word.

-DC

[svxsubaru1]

Dosent the rear diff say on the pice of plastic on the rear cap weither the diff is a r180, or r160?

Originally posted by svxsubaru1
Dosent the rear diff say on the pice of plastic on the rear cap weither the diff is a r180, or r160?

Piece of plastic? Do you mean the decal on the rear cover that is sometimes there, more often not? I found an older diff with a decal but it just listed the part number and the gear ratio. Most diffs don't have a decal. Otherwise the only plastic part on the diff is the vent breather and there are no markings on that.

Anyway, I already outlined how to tell the difference above.

-DC