95 5MT question

[Wiscon_Mark]

So the 95-96 5MT have the 3.9 final drive ratio. Same as the WRX transmission. My question is, are they the same trannies, and can my tranny handle (potentially) as much as a Rex tranny? Just curious :D

Oh, and a side question, the 97-99 Legacies have the 4.111 right?

[BAC5.2]

So the 95-96 5MT have the 3.9 final drive ratio. Same as the WRX transmission. My question is, are they the same trannies, and can my tranny handle (potentially) as much as a Rex tranny? Just curious :D

Oh, and a side question, the 97-99 Legacies have the 4.111 right?

Here's a few points of note.

1) The WRX has a FINAL drive of 3.90. The rear diff is actually a 3.545:1 with a 1.1:1 center diff reduction. They do this to slow down the driveshaft to reduce NVH.

2) The tranny is not the same. In fact, your transmission is less prone to synchro failure, though the action is not as smooth.

In 1999 they redesigned the synchro engagement hubs, as well as the synchros themselves. The older cars had a more durable synchro setup, but the trade off was smoothness. The newer trannies had a much smoother operation and were more than capable (so Subaru thought) of being durable.

3) Your transmission gears are built in a similar fashion as those used in similar model year WRX's, but the subtle differences made the biggest differences in strength.

The WRX's different ratios allowed for slightly stouter gearing which reduced stress on the the gears themselves. Also, they likely received some special heat treating process to harden them up. Since the Legacy was not the performance minded vehicle, the money wasn't invested.

I doubt your tranny would hold up for long.

4) The 96-99 Legacy's did get the 4.11:1 ratio. The RS did too. The Foresters got a 4.44:1 ratio, which is pretty kick ass, but I wouldn't want it with boost.

In fact, the 3.90 is the best matched final drive with a turbo car. The lower final drive allows you to be in gear for a longer period of time, and when you are in gear you are spooling a turbo. When you shift, you are not. So when you can cross the finish line in 4th gear at 130mph, you shifted a whole lot less and spent more time making power, than the guy who is well inside 5th gear, going slower than you.

The 4.11:1 feels quicker, but you'll get killed by equally modded cars with a 3.90 FD. It all depends on what your particular goals are with the car.

[Huffer]

My 98 Legacy 4EAT is 4.44...

[Wiscon_Mark]

wait, so does 4.44 mean the lowest RPMs? or the highest? I'm confused :(

[Huffer]

At 60mph my tach reads 2,600-2,700rpm approximately.

[Wiscon_Mark]

At 60mph my tach reads 2,600-2,700rpm approximately.

with the 4.44

I have a 3.9, mine reads 2500 at 60mph

[BAC5.2]

My 98 Legacy 4EAT is 4.44...

Yes, the Auto's generally got higher final drives than the manual cars.

4.44 is the highest.

Then 4.11

Then 3.90

Then 3.73

I think that's most of them.

Higher number final drive = higher RPM at speed. Tire size changes RPM at speed too. Significantly too.

[scottzg]

1) The WRX has a FINAL drive of 3.90. The rear diff is actually a 3.545:1 with a 1.1:1 center diff reduction. They do this to slow down the driveshaft to reduce NVH.


So it's not done to underdrive the center diff?

[NewGenSTi]

So a wrx rear diff will not work with a legacy running 3.9?

[gator gt]

So a wrx rear diff will not work with a legacy running 3.9?

no.

Here, this is one of my favorite charts:

http://wac.addr.com/auto/obs/lsd/lsd.html


Mark, the only way for you to get LSD is to get a 1st gen Legacy turbo with a 3.9 LSD tag on the diff cover

-OR-

put in an aftermarket unit.

If you had the 4EAT, you'd have a few more choices.

edit: Also, you've got a different clutch setup. You've got cables, IIRC. The WRX tranny has a hydraulic actuated clutch system; and a PULL system at that. The N/A has a PUSH clutch system.

GGT

[NewGenSTi]

Alright, well how about legacys, were they the same as the impreza tranmission? like the 95 auto legacy would be a 4.11 then? and the 95 manual would be a 3.9?

[gator gt]

Alright, well how about legacys, were they the same as the impreza tranmission? like the 95 auto legacy would be a 4.11 then? and the 95 manual would be a 3.9?

From what I'm seeing? Yes, in the base models. performance models differ (ie: 2.5GT, RS)

95 Legacy 5MT = 3.9 open
95 Legacy 4EAT = 4.111 open

00 Legacy 5MT 'L' = 3.9 open(<- I have the rear diff in storage :-D )

And I know that the 93-01 Impreza 'L' 5MT was also a 3.9 open.

GGT

[Wiscon_Mark]

Alright, well how about legacys, were they the same as the impreza tranmission? like the 95 auto legacy would be a 4.11 then? and the 95 manual would be a 3.9?

these figures are correct. I cannot help you further. GGT also reminded me that i have to remember that the 90-96 N/A tranny systems were cable clutch. The SS 1st gen Legacy was hydrualic as are all 97+ Legacies (& the WRX). So keep that in mind (because your options are limited).

[NewGenSTi]

yeah I know this already. was just looking to see if I needed to pull the rear diff from my parts car as well for my swap
aparently I do

[EXP1787]

Judging by what I have read here, the manual transmission from a 1990 Legacy AWD 5MT would be identical to my 1995 Legacy AWD 5MT, correct? I just want to be sure before I shell out the cash to get my replacement trans from a donor car...

[EXP1787]

Judging by what I have read here, the manual transmission from a 1990 Legacy AWD 5MT would be identical to my 1995 Legacy AWD 5MT, correct? I just want to be sure before I shell out the cash to get my replacement trans from a donor car...

[gator gt]

Judging by what I have read here, the manual transmission from a 1990 Legacy AWD 5MT would be identical to my 1995 Legacy AWD 5MT, correct? I just want to be sure before I shell out the cash to get my replacement trans from a donor car...

not totally sure.

bump for solid answers for exp1787

[Wiscon_Mark]

good question. For sure 93-95 are the same though. Would be a good question to pose on LCO.