which tranny for 03 wrx???

Discussion in 'Modifications & DIY how-to' started by mokinbird87, Oct 8, 2007.

  1. mokinbird87

    mokinbird87 Active Member

    i know that there are many options out there for a replacement transmission, but i wanna know which one would be the most suitable for my preference. some of the things i`m looking for in the new tranny are

    1. reliability
    2. economy (as far as how much it cost, what kind of gas mileage i would get)

    3. user friendly (if it is loud, i dont want it.. also a more direct shifting feel compared to my stock 5-speed would be nice, and it would def. please me if the damn 1st gear and the rear gear will go in willingly)

    some of the questions i have are:

    1. will 6-speed get me better gas mileage than the 5-speed?
    2. is it economical to have shorter final gear ratio? (i`m guessing probably not)
    3. if i dont need the DCCD, which tranny is a better choice bet the sti and the legacy 6-speed? (because of its taller gears)

    i dont drag race, but i drive my car hard sometimes, so i dont neccessarily need a 5-speed tranny, but i have a feeling that 6-speed tranny will be more vulnerable to the 1-2 shifts when you launch.

    decisions decisions... i`m leaning towards the RA gearset for its price and reliability.
     
  2. Demo24

    Demo24 Member

    1) I doubt it. 6spd has shorter ratios on the first few gears(not sure about 4-6) thus requiring more shifting to get to speed.

    2)can never remember the terms, but if your wanting to put in a early model forrester xt rear diff, then no.

    3)not really sure if it matters, sti is likely easier to source.


    not sure why you consider the 6spd more vulnerable, I would say its definitely the other way around.


    RA gearset has mixed opinions. Some say it helps, others say it's generally not much of an improvement over the 05+ gearsets.


    The cheapest method however is to get some legacy gt gears in there. They replace the 1-2 gears, which are most likely to go. Slightly different ratios that apparently work better. Course you could do a full swap, but it requires some work with the speedo to do.


    Shifting feel would benefit from more synchros. However I dunno if it's even possible to add more to this transmission. Would like to know about improving this though.
     
  3. techlord

    techlord Active Member

    RA gearset will be somewhat like the 1-4 STI...actually you can run them slightly higher 3-4. I have the full set and love them, 5th on the hwy is not the best (keep your stock 5th if you need economy) even still I got 22mpg going to Florida on several occasions playin a bit with meth and all.
     
  4. nicad

    nicad Yes I am a troll

    I've done a 6MT in my bugeye, here's my thoughts:

    the 6MT 6th gear ratio is a .756 vs a 5MT .738. you aren't going to see much difference in cruising RPM or gas mileage as has been my experience. reliability of the 6MT is unquestionable, it is a great transmission and leagues above the 5MT. it might be ever so slightly louder than the 5MT, but I can't really tell (and it's been so long).

    you aren't going to be able to get anything other than a 3.90 (easily) in a 6MT, so the gear ratios are a non issue. the 6MT from a LGT has a .707 6th, so you'll see lower cruising RPMs and slightly better mileage.

    6MT will be better for 1-2 launch IMO, since 2nd gear is much better suited to keep engine RPMs up and allow you to get back into the boost sooner. you will have to shift into 5th for the 1/4 mile, however.

    if you find a 2007+ 6MT, you can reuse your R160 (3.54 ratio) from your WRX and not have to switch to a 3.90 rear end, thus saving the cost of the swap.

    hope this helps!
    -justin
     
  5. mckenzietj

    mckenzietj Member

    good info, i will be heading down this road in the near future as well
     
  6. Cool_____

    Cool_____ Banned

    A 2006+ 6MT is a direct drop in from the rear end view.
     
  7. papatel

    papatel Member

    6MT FTW, so much abuse has mine taken, never does it complain
     
  8. Deke

    Deke Active Member

    Just based on the one sti I've driven, I'm not a huge fan of the 6-speed. I find the ratios to be annoyingly short. I'm sure it's just a matter of getting used to the extra shift, but my first impression wasn't great. I've heard the legacy gears are longer, so IMO that would be the way to go.
     
  9. Jake

    Jake Active Member

    i dropped a complete '06 WRX tranny into my '02. noticed no major difference other than i can put it into first gear whenever i want. you would have to change your rear end as well since the 06+ use a different center diff ratio. as well as a different clutch and flywheel. but that was the cheapest replacement i could find at the time when my front diff blew in my 02. bought it off ebay for less than 2200 shipped and had it installed at SOG for like 800ish (maybe less, can't remember been a while)
     
  10. johnswrx

    johnswrx Member

    yeah i have a legacy spec b transmission in my 03 wrx and i love it no complaints
     
  11. slowwrx

    slowwrx Supporting Member

    How much power are you planning on making?

    A 5 speed ppg box is a way better drag race box than a 6 speed but it cost more.
     
  12. Cool_____

    Cool_____ Banned

    How much is just the Spec B transmission and needed parts? I can install myself.
     
  13. nicad

    nicad Yes I am a troll

    yep, I mentioned it in my post ;)
     
  14. johnswrx

    johnswrx Member

    WJM did the install. I would ask him any ? about it. I think it cost about $9200 though. but im sure you would save money if you did it yourself.
     

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