Subaru R180 differences?

[nmehdikh]

I bought a 2011 Subaru STI R180 recently with the intention of putting it in my 73 240z. I got the different stub axles, and they fit fine. However when I went to swap the pinion flange from the Datsun R180 to the Subaru R180, I was surprised to fine it doesn't transfer over at all. The Datsun pinion flange bore is much larger than the Subaru, by about .5" in diameter. So it doesn't engage with the splines at all and just rattles around. Am I missing something here? I was under the impression it should just swap over. My solution was to just take the Subaru flange and drill the Datsun pattern on it.

Datsun flange on top.


Subaru flange on the mill

[madkaw]

That’s what I did 

[jhm]

Yes, input flange should be a direct swap -- and it was when I swapped in my STi TORSEN diff (2007, IIRC) into my car.

 

Are you sure that your donor diff is actually from an STi; and even if so, have you cracked open the rear cover to verify LSD?  I suppose someone could have replaced the STi's original differential with a non-LSD R180 at some point in the past?

[nmehdikh]

Yeah I cracked it open. It was as expected a 3.55:1 Torsen diff. Had all the proper markings on the outside as well. It also had the temp sensor built into the fill plug.

Looking through the subaru parts diagrams, the companion flange appears to be the same throughout the model years. Part #38358AA040


Maybe there are differences in the Datsun R180 input flanges through the years?