Kevin's swapped L sedan, 550 robtune td06 20g, 305whp @17psi

[92ss satinsvoice]

yah motors can be expensive to keep fixing, same with the transmission. So far I've been lucky not to destroy a motor.
but ill be really lucky if my tranny lasts after the first pull.

[SILINC3R]

Sticker on the pipe is a nice touch. My have to steal that idea.

[legsportwag]

Well I'm honestly scared to boost around any more. The trans I just blew was a 01 forester trans, close ratio 4.11. Basically the only way to take even more stress off the trans gears would be a baha/fxt/obxt 4.44 trans.. And I'll never find one of those..

Anyways I installed my spare 5speed. This is one I've been saving for a rainy day. Its an 03 foz trans (gear sets and case) with a 88rx 3.9 r@p with the 88rx center diff locker tail section. Complete frankenbox but it was one I have always wanted to build.. (Swapped rear to match 3.9 w/vlsd)

[legsportwag]

Hey look! I think I found 2nd.... Lol (that's just what fell out of drain plug)

[MConte05]

Well I'm honestly scared to boost around any more. The trans I just blew was a 01 forester trans, close ratio 4.11. Basically the only way to take even more stress off the trans gears would be a baha/fxt/obxt 4.44 trans.. And I'll never find one of those..

Anyways I installed my spare 5speed. This is one I've been saving for a rainy day. Its an 03 foz trans (gear sets and case) with a 88rx 3.9 r@p with the 88rx center diff locker tail section. Complete frankenbox but it was one I have always wanted to build.. (Swapped rear to match 3.9 w/vlsd)

The 3.9 will be the lowest stressed transmission, a 4.44 would be pretty highly strung with your power levels.

[Legacy777]

The 3.9 will be the lowest stressed transmission, a 4.44 would be pretty highly strung with your power levels.

I would think that would be reversed since the taller gearing creates more load on the drivetrain components. Am I missing something?

[cj91legss]

That's what I thought too.

[MConte05]

Really depends mostly on the actual individual gear ratios. But the lower the final drive, the lower the torque multiplication basically. There's a reason all the track-based, JDM STI gearboxes with LSD and DCCD are 4.44's, they are extremely short ratio (high torque multiplication) vs the 3.9 or 3.7.

Going from a 3.9 trans in my rally car to a 4.11 and then to a 4.44 was like night and day in terms of acceleration. The 3.9 was dog slow, while the 4.11 really woke it up. 4.44 isn't terribly better than the 4.11 in terms of $/gain.

So if you have a high torque engine, if you have a 4.44 you are more likely to break something since the torque is being multiplied at a higher factor than a 3.9 or a 3.7 like in the USDM WRX boxes. However it'll be crazy fun since the acceleration will be brutal.

Everyone always forgets about the importance of a properly geared transmission and properly selected final drive when it comes to actually putting down the power....

Two legacies, both with 250whp, one with a stock 3.9 and the other with a 4.44? The one with the 4.44 will walk away from the other car without even trying, it'll be noticeably quicker. But at the expense that the 4.44 won't suffer nearly as much abuse before something goes.

[92ss satinsvoice]

ooo those teeth are nice and shinny.

Im really interested to see how my car will act with the 3.90 final, I've always ran a 4.11. really loved the 4.11 for helping the motor with the mechanical leverage. my buddys mkiv supra had a hard time catching me till I was high up in fourth. supra had 450whp

legsportwag, have you swapped in your transmission already?

[legsportwag]

Oh yea the 3.9 diff locker trans is in and happy. I've been keeping boost down but have deff put some power through it.. Not a whole lot diffrent, highway rpm is much better, GPS 75mph I turn just under 3200 rpm. The same gears with 4.11 FD would turn 3550 @75 (stock fox box).

Also today I found some vacuum solenoids and rigged up an on/off switch for the diff locker.. Will test function ability tomorrow

[legsportwag]

Here's a few pics of my diff locker trans from assembly.

[92ss satinsvoice]

hmmm, interesting. this center diff locker assembly, what makes it better then the original center diff that was in the3.90?


I thought most (not all) of the 3.90, 4.11, and 4.44 had locked center diffs at 50/50 power front to rear?

[MConte05]

hmmm, interesting. this center diff locker assembly, what makes it better then the original center diff that was in the3.90?


I thought most (not all) of the 3.90, 4.11, and 4.44 had locked center diffs at 50/50 power front to rear?

In a manual most all (95% of them) have a viscous limited slip center. Great when new, but after 100k+ miles, it pretty much acts as an open diff.

Really curious about the locker setup too. Details!

[cj91legss]

As am I...

[Legacy777]

In a manual most all (95% of them) have a viscous limited slip center. Great when new, but after 100k+ miles, it pretty much acts as an open diff.

The viscous coupling may be worn with 100k+ miles and not as good as new, but I think saying it acts as an open diff is a bit of a stretch. The old 5spd in my Legacy & my current 5spd in the Impreza (both well over 100k miles) both would launch and not spin a single wheel in the rain (which would be the case if the viscous coupling was not working).

[MConte05]

In a manual most all (95% of them) have a viscous limited slip center. Great when new, but after 100k+ miles, it pretty much acts as an open diff.

The viscous coupling may be worn with 100k+ miles and not as good as new, but I think saying it acts as an open diff is a bit of a stretch. The old 5spd in my Legacy & my current 5spd in the Impreza (both well over 100k miles) both would launch and not spin a single wheel in the rain (which would be the case if the viscous coupling was not working).

Put one set of wheels on ice and try it. When all 4 are slipping then it'll continue to deliver power. But if one end is on pure ice and the front is on pavement. You'll probably still get out fine. But the effectiveness will be severely reduced.

Most people never really notice if the center starts to act like an open diff, it's much more noticeable in the front and rear diffs when they are open, or a VLSD starting to act like an open. Harder to really test if the center is still acting like a good viscous unit. In day to day driving it's perfectly fine, and won't be noticeable if it starts to wear out.

Once you have tried driving hard on a proper plated diff, you'll never want to go back!

[legsportwag]

Ill write a better post about this diff locking ej trans later, as im at work, on my cell... lol.
anyways the reason I built a true diff locker trans is mostly because ive burned through 3 viscous type centers (im not easy on them) and because even with a brand new viscous center I still had issues spinning front tires when launching.. diff locker mechanically locks the center and puts true 50/50 to the ground.

[legsportwag]

Much more in depth post about the diff locker trans.. Enjoy!
http://bbs.legacycentral.org/viewtopic. ... 85#p427585

[Legacy777]

Put one set of wheels on ice and try it. When all 4 are slipping then it'll continue to deliver power. But if one end is on pure ice and the front is on pavement. You'll probably still get out fine. But the effectiveness will be severely reduced.

Most people never really notice if the center starts to act like an open diff, it's much more noticeable in the front and rear diffs when they are open, or a VLSD starting to act like an open. Harder to really test if the center is still acting like a good viscous unit. In day to day driving it's perfectly fine, and won't be noticeable if it starts to wear out.

Once you have tried driving hard on a proper plated diff, you'll never want to go back!

We very rarely get prolonged ice in Houston, probably the best I can do is mud.

[legsportwag]

Monster power slide vids coming soon

[legsportwag]

Finally tore down my old trans.. Exactly what I was expecting.. No 2nd.

[legsportwag]

Today was dyno day! Set a record (As far as I know) for the "robtune" ecu. 305.6whp/265.1ftlbs @ 17psi. The dynos name is "ball buster" (dynocom dyno) as it reads about 40hp less then a dynojet dyno or mustang dyno.. I was only able to get 17 psi as there just wasn't enough rolling resistance to spool my td06 20g journal bearing turbo. We could of used the eddy brake but the dyno is so new we decided not to.. On the open road I have no problem spooling up to 22psi as seen in earlier vids of this post.

[legsportwag]

Nice finally having a semi local awd dyno.

[jessman1942]

Finally tore down my old trans.. Exactly what I was expecting.. No 2nd.

ha your 2nd looks like my first dam these weak transmissions! Im wondering if anyone would know?? say i where to open up a 4.11 cable 5 speed legacy/impreza trans i have could i swap all the internals over to my 91 hydro case and benefit from the shorter gear ratio yet still retain my hydro clutch setup just a thought would it even fit ?

[jessman1942]

BTW dam your making some nice power out of that car im jelly