shtbxr22 Posted May 13, 2009 Share Posted May 13, 2009 better yet, is there an LSD for 3.90? Link to comment Share on other sites More sharing options...
Guest Posted May 13, 2009 Share Posted May 13, 2009 Front LSD has nothing to do with ratio. Ratio is determined by ring and pinion gears that are separate pieces. Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 13, 2009 Share Posted May 13, 2009 Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 13, 2009 Share Posted May 13, 2009 so you can just swap your original ring gear onto it? Link to comment Share on other sites More sharing options...
HAMMER DOWN Posted May 13, 2009 Share Posted May 13, 2009 ^^^ Yes Mileage:331487 Retired/Sold Link to comment Share on other sites More sharing options...
whitetiger Posted May 13, 2009 Author Share Posted May 13, 2009 so you can just swap your original ring gear onto it? yes. the LSD i got will fit your trans perfectly. Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 13, 2009 Share Posted May 13, 2009 sell it to me! or, can you give me the part #? Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 13, 2009 Share Posted May 13, 2009 hmmm.......I wonder where I can get a 3.90:1 rear LSD diff? Link to comment Share on other sites More sharing options...
Guest Posted May 13, 2009 Share Posted May 13, 2009 hmmm.......i wonder where i can get a 3.90:1 rear lsd diff? 07-09 LGT 5mt (viscous) 04-05 STI 6MT (clutch type) if you want entire diff. Otherwise you can transplant LSD unit from any 5MT LGT or OBXT, WRX, etc. I believe OB 2.5i with "winter package" has rear LSD unit as well. Link to comment Share on other sites More sharing options...
whitetiger Posted May 13, 2009 Author Share Posted May 13, 2009 the ratio does not matter. you keep your old ring and pinion gears. the part# for the front lsd is in the first post of the thread. if you want a rear LSD, you can use the factory LGT one, prolly the cheapest way. Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 14, 2009 Share Posted May 14, 2009 Thanks. I think the final drive on the GT is 4.11:1. i'll have to look up ratios. at least for the rear. i'll buy a front LSD, and i'll just bastardize a rear diff from some other car. I want my speedo to stay the same, so no full GT swap. Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 14, 2009 Share Posted May 14, 2009 RST-1903? from where? it doesn't sound like a subaru part #. Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 14, 2009 Share Posted May 14, 2009 never mind. rallispec. ha! i'm a dumbass. thanks for tolerating me. Link to comment Share on other sites More sharing options...
Xenonk Posted May 14, 2009 Share Posted May 14, 2009 the REAL fun is getting all the Cusco Diffs.. running a limited 1-way mechanical LSD of any sort will be a dramatic improvement over an open-diff any day.. of my many miles of tracking the GT, you come to learn how to 'cope' with the open diff (all it really means from a driver's learning curve/standpoint is that you change your driving to match that part). In case of an open diff to get fast lap times, you have to commit to a late apex and clip the apex deep so that you can unwind the wheel ASAP. Open diffs require you to spend less time turning AND flooring the throttle to get through the corners. Throw in a 1-way diff, then you really can abuse the car and get away with being sloppy through the corners because now the car will actually pull through the corners rather than spin that inside unloaded wheel. Take another step with the Cusco tarmac center diff (split is 35%/65%) and you'll really start to make the car feel more like a RWD car going into the turn with harder throttling. Let's go all-out and run a 2-way rear LSD where you get lock-up during trail braking.. talk about a late apex action early on the turn-in point.. (aka drifting the car or a faint simulation of a e-brake turn-in, depending on the ramp profiles on the LSD). Overall, any mechanical setup will do and be a huge gain in response and behavior over an open diff/viscous diff mix. That is why the Evos still come with helical diffs which makes them handle well on tarmac. Subaru at that time of the 05's STi opted to not go with a dedicated tarmac setup or even bother to one-up Mitsubitshi on that one simply that the car will handle differently on loose pavement. While it's fun to run with more mechanical diffs, selecting the correct combination to match your road conditions is what everyone should think about. I think most of us drive on tarmac, so talking about driving in mud or dirt is kind of moot. Although having a full mechanical system and running in the dirt sure looks cool with all 4 wheels kicking up 10 feet high rooster tails. Hopefully by then, you will have a rally-inspired side-brake that can disengage the center diff and still be able to be on full throttle to spin the front two tires to pull you out of the muddy corner rather than under-steering into the ditch. Ah, the fundamentals of rally knowledge. Keefe Link to comment Share on other sites More sharing options...
Guest Posted May 14, 2009 Share Posted May 14, 2009 Thanks. I think the final drive on the GT is 4.11:1. i'll have to look up ratios. at least for the rear. i'll buy a front LSD, and i'll just bastardize a rear diff from some other car. I want my speedo to stay the same, so no full GT swap. 07-09 5MT LGT is 3.9 05-06 is 4.11. Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 14, 2009 Share Posted May 14, 2009 f-ing good to know! i love this site!!! Link to comment Share on other sites More sharing options...
Guest Posted May 14, 2009 Share Posted May 14, 2009 Keefe, saying "mechanical diff" is vastly imprecise. I suppose you're refering to clutch type differentials. But then you mention helical (e.g. Torsen). There is a big difference between them. the REAL fun is getting all the Cusco Diffs.. running a limited 1-way mechanical LSD of any sort will be a dramatic improvement over an open-diff any day.. of my many miles of tracking the GT, you come to learn how to 'cope' with the open diff (all it really means from a driver's learning curve/standpoint is that you change your driving to match that part). In case of an open diff to get fast lap times, you have to commit to a late apex and clip the apex deep so that you can unwind the wheel ASAP. Open diffs require you to spend less time turning AND flooring the throttle to get through the corners. Throw in a 1-way diff, then you really can abuse the car and get away with being sloppy through the corners because now the car will actually pull through the corners rather than spin that inside unloaded wheel. Take another step with the Cusco tarmac center diff (split is 35%/65%) and you'll really start to make the car feel more like a RWD car going into the turn with harder throttling. Let's go all-out and run a 2-way rear LSD where you get lock-up during trail braking.. talk about a late apex action early on the turn-in point.. (aka drifting the car or a faint simulation of a e-brake turn-in, depending on the ramp profiles on the LSD). Overall, any mechanical setup will do and be a huge gain in response and behavior over an open diff/viscous diff mix. That is why the Evos still come with helical diffs which makes them handle well on tarmac. Subaru at that time of the 05's STi opted to not go with a dedicated tarmac setup or even bother to one-up Mitsubitshi on that one simply that the car will handle differently on loose pavement. While it's fun to run with more mechanical diffs, selecting the correct combination to match your road conditions is what everyone should think about. I think most of us drive on tarmac, so talking about driving in mud or dirt is kind of moot. Although having a full mechanical system and running in the dirt sure looks cool with all 4 wheels kicking up 10 feet high rooster tails. Hopefully by then, you will have a rally-inspired side-brake that can disengage the center diff and still be able to be on full throttle to spin the front two tires to pull you out of the muddy corner rather than under-steering into the ditch. Ah, the fundamentals of rally knowledge. Link to comment Share on other sites More sharing options...
Drew888 Posted May 14, 2009 Share Posted May 14, 2009 Ok, very interested....you've got my attention. So, being a 2008 Spec-B... I simply hit up the parts dept and ask for an LSD from say...an 06 STI and it's that simple and being a 6spd I'm saving on the labor because they don't actually have to split the case? What would you suspect the labor to be? Thx! Another thing, how to qualify a shop in SoCal to install it correctly? If I don't know how to ask the right questions I will never know until it's too late. [URL="http://legacygt.com/forums/vbpicgallery.php?do=view&g=1586"VbGallery/URL] Link to comment Share on other sites More sharing options...
VTGT Posted May 14, 2009 Share Posted May 14, 2009 the REAL fun is getting all the Cusco Diffs.. Keefe is the man! Anyway I can get the Cusco Diffs for the 5eat Link to comment Share on other sites More sharing options...
Guest Posted May 14, 2009 Share Posted May 14, 2009 I have SpecB tranny in my wagon with 06+ STI's front LSD. Cost me around $850 installed. $500 part + $350 labor. Labor seems simple (no need to split the tranny, just pull the bell housing) - however what is not simple is setting the bearing preload and gear backlash. Link to comment Share on other sites More sharing options...
shtbxr22 Posted May 14, 2009 Share Posted May 14, 2009 it's simple if you know "the trick" Link to comment Share on other sites More sharing options...
Gator GT Posted May 14, 2009 Share Posted May 14, 2009 Drew, you're going to have to rattle some cages in your local regional forum to see who has the expertise in differential work. It may or may not be a dealership. I live in NH and traveled to NJ to RalliSpec to have mine installed. A few Subie Sport issues back, they did some diff work and mentioned the shop they did it at, which, iirc, was on the west coast. "If we are to guard against ignorance and remain free, it is the responsibility of every American to be informed." - T. Jefferson Link to comment Share on other sites More sharing options...
Drew888 Posted May 14, 2009 Share Posted May 14, 2009 Funny thing, I'm excited to soon get my VF52 but I'm more excited about upgrading the front diff... Weird... [URL="http://legacygt.com/forums/vbpicgallery.php?do=view&g=1586"VbGallery/URL] Link to comment Share on other sites More sharing options...
Gator GT Posted May 14, 2009 Share Posted May 14, 2009 it's simple if you know "the trick" pray tell sir...pray tell. "If we are to guard against ignorance and remain free, it is the responsibility of every American to be informed." - T. Jefferson Link to comment Share on other sites More sharing options...
whitetiger Posted May 14, 2009 Author Share Posted May 14, 2009 i think its joke. Link to comment Share on other sites More sharing options...
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