ADVICE ABOUT TRANSMISSION UPGRADE
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This is a discussion on ADVICE ABOUT TRANSMISSION UPGRADE within the Transmission & AWD forums, part of the Tech & Modifying & General Repairs category; (highly modded, 2004 wrx) i was going down my drive way in first gear, 5mph, and then i hear a ...

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    ADVICE ABOUT TRANSMISSION UPGRADE

    (highly modded, 2004 wrx) i was going down my drive way in first gear, 5mph, and then i hear a boom... the trans wont go into gear. i have a new clutch (one month) and i feel reasonable normal pressure on the clutch pedal. along with good clutch fluid. i am pushing high boost at 20psi low boost is 15 psi on pro built engine. but i believe the trans is stock...(havent done much to it, but the person before me could have) currently the car (my baby)is sitting at a trans shop awaiting to get started on the fixing process. the trans shop thinks i need to upgrade the gearbox and gears or get an sti transmission... what do you recommend on either or??? i personally want to take the cost effective way and upgrade the gearbox and gears... but does anyone know where i can find reasonable prices on gearboxes and gears???. rallitec.com is my best bet so far..

    any words of input would be helpful

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    zax
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    If you swing it, the STi 6-spd is a fantastic piece of equipment and includes the limited slip front diff and DCCD. HOWEVER, you will need the following equipment:
    1.) STi transmission, shifter linkage and fork, etc.
    2.) STi half-shafts and hubs
    3.) 4EAT driveshaft
    4.) R180 rear diff in the case of 2004-2005 and 2007+ STi donor IIRC. I think the 2006 may be able to retain the R160 rear diff... someone may correct me.

    Exactly what is done to the car (you say "highly modded" but some may consider my car "highly modded" while I do not)? What numbers are you putting down? What numbers do you HOPE to put down? I am interested in torque here. You have a few options here:
    1.) Another 2003-2005 Transmission -- Good for about 315wtq, but depends on driving habits here
    2.) A 2008+ WRX Transmission -- Purportedly contains LGT gears, so it should be good for 350+wtq
    3.) STi RA 5MT gears -- Good for about 325-330wtq, but it seems that the gearing is mostly responsible as the gears are not much physically different from the 2003-2007 WRX gears
    4.) LGT 5MT gears (the LGT transmission will not bolt-up since the rear diff ratio is different) -- Good for 350-380wtq
    5.) PPG (Pfitzer Performance Gearbox) gears -- Top notch, good for 500+wtq, but VERY pricey. At this point, you might be better off with an STi gearbox.
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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by zax
    Exactly what is done to the car (you say "highly modded" but some may consider my car "highly modded" while I do not)? What numbers are you putting down? What numbers do you HOPE to put down? I am interested in torque here. You have a few options here:
    1.) Another 2003-2005 Transmission -- Good for about 315wtq, but depends on driving habits here
    2.) A 2008+ WRX Transmission -- Purportedly contains LGT gears, so it should be good for 350+wtq
    3.) STi RA 5MT gears -- Good for about 325-330wtq, but it seems that the gearing is mostly responsible as the gears are not much physically different from the 2003-2007 WRX gears
    4.) LGT 5MT gears (the LGT transmission will not bolt-up since the rear diff ratio is different) -- Good for 350-380wtq
    5.) PPG (Pfitzer Performance Gearbox) gears -- Top notch, good for 500+wtq, but VERY pricey. At this point, you might be better off with an STi gearbox.
    You also have the option of Albins gearsets; I know MPS uses them in their rebuilds.
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    Subaru Newb MainFrame's Avatar
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    How much wtq are you making? What does highly modded mean? 20psi doesn't really tell us anything, my 2002 will make 450whp at 20psi on pump gas, a stock turbo STi will only make maybe 250whp at 20psi.

    What do you use the car for? Are you planning on drag racing or anything like that?


    The strongest gearset you can get for the 5mt is probably straight cut PPG gears (or MFactory or Albins). Unfortunately due to the design of the 5mt itself they are only rated to 450wtq and could still be broken even with the blast plates installed if you're drag racing. They also whine like crazy, so I wouldn't exactly recommend them for a daily driver. They also make helical gears that aren't as noisy but also aren't rated for quite as much power.


    Back in 2004 I had my gearset swapped out with a cryo treated JDM STi 5mt gearset. My car was only stage two at the time so those gears were just right. I believe they are the same part number as the USDM LGT gearset and should hold around 350wtq. I love the gear ratio, and the first gear dual cone syncro option is a must. This is probably your cheapest route, but it's also the weakest as far as upgrades. If your car is highly modded like you say, there's not much point in replacing the gearset with something else that's just going to break too.. which brings us to option three...


    07+ STi six speed. Great gear ratio, and stronger out of the box than any of your 5mt options (previous years are just as strong, but have a stupid gear ratio IMO). I would feel reasonably comfortable launching the six speed with up to 500wtq (might break axles, but that's cheap and easy to replace). If your car is making a decent amount of power, or you plan on it in the future, to me this is the best option because it will save you money in the long run. I'm currently saving up for a new six speed, and if I had the money back on the other gearset I bought years ago I would be that much closer to owning a transmission I won't be breaking.

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