2005 legacy gt transmission interchangeability

[Slammed05]

I have a 2005 legacy gt 5 speed that has a whine to it in 3 gears. So I am looking into replacing it in the near future.

 

What I am looking for is what other Subaru (year/model) transmission will drop into a 2005 legacy gt WITHOUT ANY MODIFICATION OR SWAPPING OF THE REAR DIFF

 

I can't seem to find any sort of thread or anything about this topic, so I'm hoping I can find some info here

 

Thanks

[whitrzac]

05-07 legacy gt.

[GEE-OTTO]

I have a 2005 legacy gt 5 speed that has a whine to it in 3 gears. So I am looking into replacing it in the near future.

 

What I am looking for is what other Subaru (year/model) transmission will drop into a 2005 legacy gt WITHOUT ANY MODIFICATION OR SWAPPING OF THE REAR DIFF

 

I can't seem to find any sort of thread or anything about this topic, so I'm hoping I can find some info here

 

Thanks

 

http://www.rallispec.com/downloads/T...art_Public.pdf

[Max Capacity]

There's a sticky up top with that info if I recall.

 

http://legacygt.com/forums/showthread.php/transmission-gear-ratios-and-final-drives-229267.html

 

 

quickly looking I think you want a 05-06 2.5GT 5mt.

 

Or find a good tranny shop that does a lot of work for the local circle track and race car guy's. They will tend to be the better shos and have more of a clue about these.

[whitetiger]

05-07 legacy gt.

 

no, only 05-06, since they are the only ones with the 4.11 FD ratio. really you can do any late model 5mt(or 6mt ) but you'd have to find the matching rear diff with the correct FD ratio for the trans.

[Rhitter]

Do you need a new transmission? Or do you just need to change fluid? These transmissions are noisy.

[Max Capacity]

http://car-part.com/cgi-bin/search.cgi

 

search that site with your zip code, see what you get.

 

http://car-part.com/cgi-bin/search.cgi

[Slammed05]

I would assume new transmission, it whines pretty good in 2nd, 3rd, and 5th, not in first and fourth, and I'm already changed the fluid

[oODanKNesSOo]

no, only 05-06, since they are the only ones with the 4.11 FD ratio. really you can do any late model 5mt(or 6mt ) but you'd have to find the matching rear diff with the correct FD ratio for the trans.

 

So the downside of the 05-06 is the dual mass flywheel, but a positive is the 4.11 FD ratio right?

[Dujo]

You can change out the dual mass flywheel and use a single mass flywheel from an 06 WRX. Not a drawback anymore. The main drawback to the 5MT is that it isn't as strong as the 6MT.

[oODanKNesSOo]

Haha ya definitely love the sexyness of the 6MT, and brembos... ahh maybe one day!

 

My point was more that, having the 5mt (for all its glory!-or not) that having an 05-06 is most desirable, after changing the clutch and ditching the dmfw. Once the smfw is installed it's a "better" setup then say an 08', due to the 4.11s vs 3.88s, right?

[Dujo]

The higher the final drive ratio, the more it skews toward acceleration and torque and away from top speed. 4.11 should be quicker off the line than 3.88, but you will cruise on the highway at a higher rpm. Mileage is better on the lower final drive, acceleration is better on the higher final drive. Sure, I'd say that's "better". (Note: I personally don't know which Subaru final drive differential matches with which Subaru 5MT, but I believe that's the theory anyway).

 

^ Not an expert. Here's your grain of salt with my info. Enjoy!

[oODanKNesSOo]

I hear ya... top speed is lower but acceleration is quicker. Thus higher rpm on highway and worse mpg.

 

Seeing how I never have topped it out, nor do I have any desire to, I'll take the quicker vs faster limit.

 

For the 1/4 mile finding the balance would be key.. if you can get up to 170mph (figuratively speaking) but you cross the 1/4 mile at only 90mph, then I'd rather the gear ratio that gets me to the finish line quicker, say 120mph with a Max mph of 140.

 

Seems most forms of racing these cars would face, track, lap, drift, quicker acceleration would be preferred over Max speed

[Dujo]

Sounds right to me. Even more so on the street as far as I'm concerned. Now, keep in mind that it's the final drive in each gear. So yes, of course, in 5th, the final top speed (which we should never be approaching on the street) would be lower with the higher final drive ratio. But it's also true in fourth, and third, etc. What that means is that you are reaching redline at slightly lower mph in each gear ... which again seems like not such a bad thing to me. But now we're getting into more esoteric arguments about final drive and gear ratio and it's a little above my pay grade. I'd say, yes, higher final drive is better as long as we can agree that it's not better in all cases. Just the cases we care about.

 

On the track, the truth is that you want the gearing ratios that keep the engine in it's best band of power production as much as possible for what you're going to use. So on a circuit, you might want a really tall 1st and 2nd since you won't be using 'em that much with a super short 3rd and 4th where you'll spend most of your time and then a tall 5th to get you all the way up to top speed. On a drag strip, you might want shorter 1st, 2nd, and 3rd and who cares what 4th and 5th are 'cause you're not reaching them in a 1/4 mile in an LGT. Of course, the final drive ratio in the differential will then always be a multiplier, but you get what I'm saying here. There's the simple answer ... and then there's the really complicated true situation. Somewhere out there, there's a thread where boxkitta is discussing the perfect drive ratios for the Subaru MTs for a racecar. Something about 1st and 2nd from and LGT and then 3rd and 4th from an STi and then 5th from a Forrester (or something like that ... I don't remember the exact details of what he was saying.)