r.lee89 Posted December 14, 2014 Share Posted December 14, 2014 Hi i have a 08 Legacy Sedan 2.5i SE 4EAT. My rear diff pinion bearing is staring to go so i want to upgrade to a viscous limited slip like on the GT or Outback model. Does anyone know if those rear diffs be a direct bolt on? I see 2 different gear ratios and im not sure what i got. And would the Spec B or STi diff fit? Also is it worth getting a VLSD cause i see alot of bad reviews about them or should i just rebuild my open diff. This car is not going to be a performance car its only a daily driver i just want to have the best traction when im in snow or ice. Thanks! Link to comment Share on other sites More sharing options...
GEE-OTTO Posted December 17, 2014 Share Posted December 17, 2014 You have a 4.11 FDR 4EAT gearbox youll need a 4.11 rear end to match. Since the 5 speed autos are 3.58's you might be stuck with your stock rear end. YOu can find those rear ends at most slavage yards that have a high number of Subarus laying around. Having the viscous over the open with the auto at least isnt much of an upgrade now if you were to change the open center diff you might be on to something Link to comment Share on other sites More sharing options...
SBT Posted December 17, 2014 Share Posted December 17, 2014 G-O is correct. You'll need a 4.11 rear diff with LSD to make it work. There's several older 5MT Subarus with the 4.11 LSD RDiff. Tracking one down shouldn't be too hard. That said, it really depends on when your 08 was manufactured whether a RLSD would work with your sedan. If made before July 2007, then your 4EAT is electronically controlled, constantly varying, front bias (90/10 front rear), and could potentially benefit from a. RLSD. Check your model code If 8AE, then it should be okay. However, starting with July 2007 delivery, model code 8AF replaced the 8AE vehicles and are equipped with VDC is standard. The VDC system comprises a traction control system which senses a loss of of traction and applies the brakes to the slipping wheels to maintain vehicle motion. If you have model code then a RLSD will conflict with the VDC system at worst, or not provide much in the way of additional traction at best. - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
spec.B Dream Posted December 17, 2014 Share Posted December 17, 2014 Why would LSD conflict with VDC? If LSD limits the amount of wheelspin compared to an open diff, how does the VDC cause problems here? Link to comment Share on other sites More sharing options...
SBT Posted December 17, 2014 Share Posted December 17, 2014 Think of it this way. VDC detects slip electronically. It activates the ABS system on that spinning wheel and clamps the brake shut on it, likely before the VLSD can respond. Once the other wheel starts to spin, the VLSD reacts to the now spinning other wheel and attempts to shift power to the other side which is locked. That's where the conflict arises. On the newer 08+ LGTs with VDC and VTD, they've switched to a Torsen rear diff, which reacts differently than the VLSD in the pre 08 LGTs. - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
r.lee89 Posted December 19, 2014 Author Share Posted December 19, 2014 Thanks for the info guys that really helps me out. I know mine doesn't have VDC option and its any early production (03/2007) Upgrading the center diff would be alot of working wouldn't that mean splitting the tranny apart? I guess overall the viscous limited rear diff is a waste of money. Link to comment Share on other sites More sharing options...
GEE-OTTO Posted December 19, 2014 Share Posted December 19, 2014 That is the real point we want you to see its nothing personal. If you had access to a cheap donor I would say go for it never hurts to try something new. If it's any consolation the 4EAT is a great drag racing gearbox! Link to comment Share on other sites More sharing options...
r.lee89 Posted December 22, 2014 Author Share Posted December 22, 2014 I noticed SBT said something 90/10 split it seems kinda low or its that the just what it runs at normally when your not slipping. Feels more like 60/40. Link to comment Share on other sites More sharing options...
SBT Posted December 22, 2014 Share Posted December 22, 2014 On 2.5i non VTD, it's 90/10 Front/Rear until slip is detected, then it transfers power to the axle that needs it. If it were a 5MT, then it would be 50/50 front/rear biased. - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
r.lee89 Posted December 23, 2014 Author Share Posted December 23, 2014 Seems very low to be 90/10 i can launch snow in the air and drift around. Is there any aftermarket companies out there that make rear diffs for this legacy? Link to comment Share on other sites More sharing options...
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