Bugeye Rear Diff

Discussion in 'Modifications & DIY how-to' started by wrxin8or, Aug 15, 2009.

  1. wrxin8or

    wrxin8or Mullitt Staff Member

    Last week while changing the rear diff fluid, I noticed quite a bit of metal and a few teeth stuck to the magnetic drain plug. That, coupled with the fact we couldn't break the fill bolt loose, I parked the car for a week while I figured out my next step.

    I posted up looking for a rear diff, and Liquid_Force posted up that he had one and got Techlord to deliver it this morning when we were starting to tear it all down. So, after a few trips to home depot due to some missing tools, we got cracking at tearing everything apart. We got to the point were we started to pull the axles out of the diff, and ran into another problem. 2pt5rs called the best Subaru tech in town and Kingwrex showed up about 30 minutes later to show us what was up. In about 30 seconds he had the axles out of the diff (we forgot to pull the lateral link bolts out which allows the axles to fall) and we got to work on the diff. About an hour later, we had the old diff out, and the new diff loaded up in its place. Took us another hour and a half or so to bolt everything back up and get the fluid changed out for new Extra-S.

    Car is running so much better than it was, and I cant thank King, shiringles and alex enough.
     
  2. nicad

    nicad Yes I am a troll

    should have put a LSD in there
     
  3. Matt

    Matt Think before you post Staff Member Supporting Member

    doesn't a stock WRX rear diff come with an LSD?
     
  4. nicad

    nicad Yes I am a troll

    viscous
     
  5. baddriver

    baddriver Active Member

    Doesn't that rear diff take 75w90 gear oil?

    Didn't think Extra-S went anywhere but into the transmission / front diff assembly.
     
  6. Davidwrx

    Davidwrx Member


    I am about to need to chage mine too. I think Extra S is very close to 75w90. Anyone know the definitive answer to this.

    Seems like I read once on NASIOC that about anything would work. But then again, that was on NASIOC.
     
  7. nicad

    nicad Yes I am a troll

    I wouldn't sweat the fluid in the rear diff too much. it's just a rebadged nissan unit. just match the weight and be sure you use a formula for limited slips (if you have a mechanical diff)
     
  8. Alex

    Alex Community Founder Staff Member

    Wirelessly posted

    Extra s is 75w90. Check out my site for addition info: jpmusa.com. Look under subaru -> fluids.



    Subsru LSD is highly recommended for the STi rear diff, not wrx.



    Both diffs are approx 1qt
     
    Last edited by a moderator: Aug 16, 2009
  9. FACE

    FACE Active Member

    Glad to hear all went well!

    Hail to the KingWrex! :bowdown:
     
  10. wrxin8or

    wrxin8or Mullitt Staff Member

    Yep. Now, where do I get one of those Built by Kingwrex stickers;)
     
  11. Davidwrx

    Davidwrx Member

    So for a wrx diff, Extra S isn't thick enough, but any 85w90 would work?
     
  12. wrxin8or

    wrxin8or Mullitt Staff Member

    :squint:

    The WRX diff needs 75w90, which is what extra s is, and is what is recommended by subaru to put in the rear diff.

    The subaru LSD gear oil is only recommended for the STI diff.
     
  13. Jake

    Jake Active Member

    Yeah from what I understand Nissan makes all the rear diffs for all Japanese auto makers. Kinda like Mitsubishi makes all the turbos over there (except ihi vf series), has to do with the fact that there isn't a whole lot of land over there so they work with what they got. And yeah that Subaru LSD fluid is only for the sti. Extra s is fine for non-sti rear diffs.
     
  14. Alex

    Alex Community Founder Staff Member

    I guess I will repeat my post for the sake of better understanding.

    If you own a WRX
    Your diff works with just about any 75w90 gear oil. This includes Subaru Extra-S. Many, many, many WRX owners have reported excellent results when using this fluid in their diffs AND in their transmissions. It is expensive, but it is OEM and it does work. Several master techs recommend this fluid for your vehicle.

    If you own a STI
    The only fluid that comes highly recommended for our rear diffs is the Subaru LSD fluid (approx $24.00 per 1l). There is no real need to try any other fluid as this has been proven time and time again to work well since 2003. For the transmission I definitely recommend Subaru's Extra-S. I have yet to drive a 6MT with a "cocktail" in it that feels and shifts smooth/correct.

    Hope this helps!
     
  15. Cool_____

    Cool_____ Banned

    Alex you ever drive a 6MT with Motul in it? Heard it's better than the Extra S.

    Oh btw I need drain and refill mine.....can I pick some up from you when I head to Atlanta this week on either Wednesday or Thursday?
     
  16. MrCoffeeATL

    MrCoffeeATL Member

    Glad to hear the swap went well.
     
  17. blindfold

    blindfold Active Member

    just to be clear 07 STi rear diff uses extra S, not the LSD weight oil. You will know when your diff binds with the incorrect fluid
     
  18. blaster

    blaster my other ride is your mom Supporting Member

    Glad to hear it (eventually) went well.
    Wrxin8or is back on the road! Everyone, watch your bumpers.
     
  19. nicad

    nicad Yes I am a troll

    no need to put some crap "cocktail" in a 6MT. it's a real transmission. hell, I would bet you could put crisco in the damn thing and it would work fine

    as for the sti rear diff, I'm with the opinion that subaru's $$ rear diff fluid is no different than a quality gear oil with limited slip additive.

    I've run it in mine for years, and my diff is over 10 years old. (from a Ver 3 STi)
     
  20. wrxin8or

    wrxin8or Mullitt Staff Member

    Hey now. Alex is the ne who hit my car, not the other way around
     
  21. kingwrex

    kingwrex Supporting Member

    now you just need to get that clutch replaced
     
  22. techlord

    techlord Active Member

    Let me guess it happened at the house/church? Only took me 10min to get the truck out of the driveway without taking out the bridge.

    NICE PLACE THOUGH!
     
  23. Matt

    Matt Think before you post Staff Member Supporting Member

    nah this was about a year ago or so....
     
  24. Kokopelli

    Kokopelli Active Member

    I want my garbage bag back.
     
  25. wrxin8or

    wrxin8or Mullitt Staff Member

    I have an even better garbage bag for you (well, maybe not better...). Want to meet over in Norcross this week? I have the garbage bag in the car
     

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