r180 diff question

wildacex187 · Post by **wildacex187** » Sun Jul 15, 2007 8:12 pm

are the r180 and 160 diffs the same length? how about the output shafts? i searched but didnt get a definite answer, im thinking of either getting a wrx or sti rear diff.

n2x4 · Post by **n2x4** » Sun Jul 15, 2007 9:27 pm

The WRX and STi have different gear ratios in the rear ends WRX 3.54 and STi 3.90. They're the same size though. If you're gonna use a legacy driveshaft, you'll need to reuse the legacy flange that the 4 driveshaft bolts connect to. Only the r180 will work on a stock legacy because of the gearing.

Splinter · Post by **Splinter** » Sun Jul 15, 2007 10:27 pm

Yes, but you need to change the rear half shafts because of a different design on the stubs.

From what I can tell with my swap (still incomplete), 98 RS25 axles SHOULD work, but I still think you might need to swap the rear hubs for RS hubs

IronMonkeyL255 · Post by **IronMonkeyL255** » Sun Jul 15, 2007 11:24 pm

Splinter wrote:you might need to swap the rear hubs for RS hubs

Or build hybrid CV axles with RS inner joints and Legacy outer joints.

n2x4 · Post by **n2x4** » Mon Jul 16, 2007 3:11 pm

Why would you need to swap the hubs for RS axles? I thought that the spline counts for the hub were the same for legacy/impreza/wrx?

fwiw, WRX axles fit in legacy hubs.

Splinter · Post by **Splinter** » Mon Jul 16, 2007 3:14 pm

I wasnt sure

I knew that RS axles fit on the R180 stubs, but I hadnt checked the other side

Thanks for the info

n2x4 · Post by **n2x4** » Mon Jul 16, 2007 3:57 pm

Interesting find then! I wonder if the WRX guys know about the RS axles fitting on the R180, I've never seen it mentioned over on Nasioc. I did a 05 WRX drivetrain swap into my tleg and did a lot of drivetrain research but that's news to me.

So to sum things up, a R180 will work on a legacy if you reuse the flange that the driveshaft bolts to and get rear RS axles. Cool.

wildacex187 · Post by **wildacex187** » Tue Jul 17, 2007 4:53 am

or wrx axles no? wat about sti axles?

Splinter · Post by **Splinter** » Tue Jul 17, 2007 5:09 am

def not wrx axles

wildacex187 · Post by **wildacex187** » Tue Jul 17, 2007 6:40 am

oh ok so the r180 needs axles from a rs. so the legacy axles no worky?

Splinter · Post by **Splinter** » Tue Jul 17, 2007 7:26 am

Definately not. Not even close.

the stock legacy diff has stubs that stick out, the R180 has a slot you slide a stub into.

Basically, you need to do one of the following:

Put the R180 diff inside the legacy housing
Make hybrid legacy/RS axles
Use RS or STI hubs and RS or STI axles

93forestpearl · Post by **93forestpearl** » Tue Jul 17, 2007 8:12 am

You need to use the STi rear subframe. STi axels, which need STi hubs, along with the Brembo rear brakes which only fit over 17" wheels, which isn't all 17's. Basically you are converting the rear of the car to STi spec.

There is a guy here in MN who is using the R180 and STi subframe in his '98 w/ an STi motor and tranny. He redrilled SVX rotors and backing plates to fit on the STi hubs so he could still use 15 or 16" wheels for the winter. That car is badass. He runs it sans interior and dash, with the STi cluster zip tied to the dash bar. The thing is nuts in the snow/ice.

Splinter · Post by **Splinter** » Tue Jul 17, 2007 8:27 am

You dont need to use the STI subframe.

Ive got an R180 on my legacy subframe

93forestpearl · Post by **93forestpearl** » Tue Jul 17, 2007 8:40 am

Really. This contradicts what I've always been told.

What did you use for axels?

Splinter · Post by **Splinter** » Tue Jul 17, 2007 8:41 am

see above

wildacex187 · Post by **wildacex187** » Tue Jul 17, 2007 2:45 pm

ok so wait, if i put the r180 diff (wrx or sti) inside the legacy housing i can use legacy shafts and axles? is there any other vlsd that would swap in that isnt as hard to find as a r160 vlsd?

Splinter · Post by **Splinter** » Tue Jul 17, 2007 3:29 pm

Making up hybrid axles would be far, far easier than swapping the internals, imo

SemperGuard · Post by **SemperGuard** » Tue Jul 17, 2007 3:37 pm

You can't put an r180 ring into an r160 case.

Splinter · Post by **Splinter** » Tue Jul 17, 2007 3:45 pm

really??

I thought you could

nevermind then

Itd be a stupid thing to do anyway

wildacex187 · Post by **wildacex187** » Wed Jul 18, 2007 8:04 am

Splinter wrote:Making up hybrid axles would be far, far easier than swapping the internals, imo

yea but thats just more stuff to get no? somebody local has a sti diff with no output shafts or anything. getting the extra rs stuff might be hard to come by at the junk yard by me. guess i'll wait it out on ebay/forums

Splinter · Post by **Splinter** » Wed Jul 18, 2007 8:10 am

Rebuilt RS axles are probably going to be about $100 a piece from your local jobber

If you place an ad on nasioc, you'll probably be able to find a pair somewhere for $15 each

So this is what you'd need:

2x used RS axle cores - $30-$50
2x used Legacy axle cores - Use your old ones
4x boot kit - $50? You might be able to do this for less if you are careful removing your old boots, then you just need new axle grease and band clamps.

Shouble be able to do the whole thing for under $100 bucks.

Splinter · Post by **Splinter** » Thu Aug 16, 2007 5:31 am

Just an update on this thread... I was wrong

While RS axles physically fit inside the R180 diff, they don't engage the splines, that is, they wont turn when the input of the diff is turned

STI inner joints are necessary as far as I can tell.

n2x4 · Post by **n2x4** » Thu Aug 16, 2007 1:06 pm

That sucks! Thanks for the update though. Was worth a shot.

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r180 diff question

r180 diff question