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No 6 speed is a BIG mistake


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Yes, a 5MT could be used so that the 6MT is seen as another benefit for moving up to an STi version. This was part of the BMW way for quite a while. Now, however, 6MTs are seen across the board. Because of a lack of enough torque off boost, I can see how a tall 6th may not work right on the 2.5T. I think that is one of the reasons that an H6T would work so well. Actually, a 2.5 w/ twinscroll would be awesome. Just look at how the JDM GT peaks its torque at just 2400 rpm. I know it would cost a TON to make the conversion, but a 350hp 2.5 twinscoll would be awesome. That could definitely make use of a tall cruising gear.
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And you could use a nicely larger twin-scroll turbo sized to the 2.5 as theirs is sized to the 2.0L displacement. Ultra response and power through 7k rpm. Better grab the oh shit handle everyone! We're going for a ride. :P Now lets just make sure the drivetrain is strong enough. I think that is the biggest thing that is a holdback for more power. Then again, one driver can drive an AWD car flawlessly on stock tranny forever it seems, and others with a stock RS can break it in 10k miles. A lot depends on the driver.
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Let's face it. The reason why people don't want the 5MT is because they want to modify it, and they guesstimate from the WRX owner's experiences that it won't hold the power. And they are probably right. If you want to play with the Germans, you have to give the impression of solidity and reliability that comes from those cars. Ask Lexus. The 6MT would have made sense, if anything to abate the fears that the 5MT can't reliably hold 250ft/lbs. We all know Subaru dealers will likely blow off all warranty claims on gear or syncro failures on abuse...whether the box can hold all this extra torque or not.
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[quote name='Conduit']Let's face it. The reason why people don't want the 5MT is because they want to modify it, and they guesstimate from the WRX owner's experiences that it won't hold the power. And they are probably right. If you want to play with the Germans, you have to give the impression of solidity and reliability that comes from those cars. Ask Lexus. The 6MT would have made sense, if anything to abate the fears that the 5MT can't reliably hold 250ft/lbs. We all know Subaru dealers will likely blow off all warranty claims on gear or syncro failures on abuse...whether the box can hold all this extra torque or not.[/quote] There are no fears that the 5MT can't reliably handle 250 lb-ft. Look at the real numbers of broken WRX transmissions that just broke, and that weren't abused. I'd bet you'd find them to be infinitesimal. I can think of one that was posted on NASIOC. The worries about the gearbox exist only in the microcosm of tuner/enthusiast boards. In the real world, where people don't beat on their cars, those worries are nonexistent. My '02 WRX's gearbox is just fine and dandy. Goes into first every time, ditto for reverse. And my car hasn't exactly been babied, I can tell you that. As Paul Hansen said in another space, the weakness with the 5-speed for the hammerheads is case flex, something which has been addressed on the new Legacy 5MT box. The reason the STi gearbox is "stronger" isn't because it has magical gears or anything. The case is stronger, and doesn't flex as much, so voila. Further, the 5MT in the WRX is three generations older than the box that will be going into the Legacy. Finally, don't forget that with the same gearbox that we have in our WRXes, but with more power, drivers in Japan aren't breaking transmissions. The only disadvantage to a 5-speed is marketing. Look at the STi fuel economy numbers. Not a big savings there over the WRX, with its 5-speed. You just can't make the overdrive gear in a turbo car that tall. We'll see if the rumors of the lightened 6-speed box for the Legacy are a reality or not. I'll be snapping up an early wagon, to make sure I can still have my one shift to 60 mph. :D Kevin
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[quote name='Conduit']Let's face it. The reason why people don't want the 5MT is because they want to modify it, and they guesstimate from the WRX owner's experiences that it won't hold the power. And they are probably right. If you want to play with the Germans, you have to give the impression of solidity and reliability that comes from those cars. Ask Lexus. The 6MT would have made sense, if anything to abate the fears that the 5MT can't reliably hold 250ft/lbs. We all know Subaru dealers will likely blow off all warranty claims on gear or syncro failures on abuse...whether the box can hold all this extra torque or not.[/quote] The website refers to the 5-speed as "heavy duty". I wonder if they are working some PR spin, or have fixed the durability issues.
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Supposedly it was because of case flex and that has been substantially reduced as I hear. Too bad they didn't say something to the effect already knowing about much of the bad PR some WRXs have caused. Mentioning a more rigid transmission case, yada, yada, yada whatever else sounds good could be really reassuring.
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The transmission is split vertically, I wonder why nobody has come up with some add-on alloy I-beam type things to tie in to the case bolts to reduce flex. Any minimally lost ground clearance wouldn't matter on drag cars. I don't think it would come down any lower than the muffler anyway. When I source a transmission for my project, I'll see if there's an easy (and cheap) way. Steve
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Kevin, you keep making comments as if a 6MT can't get to 60 in one shift and how the STi isn't very different from the WRX. Very true. The problem isn't with the number of gears. It's the ratios used on it which cause it to not really improve mpg and take 2 shifts to 60. The comments about how the only problems with the transmissions is within the tuner group further shows that a "weaker" 6MT should still be sufficiently strong enough. Either one will be strong enough for the general public, so maybe the strength issue needs to be thrown out the window for arguement for or against either transmission. I'd like to clarify that Paul Hansen didn't say that it is a known fact that the casing flex is what was reinforced. What he said/posted was that case flex had been the problem, so he is assuming that reinforcement to that problem area is what was done. I'm not saying that he is wrong at all. It's just that if the case flex wasn't reinforced for some strange reason, no need to say that Paul lied about it or was talking out his backside.
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[quote name='PPower']Kevin, you keep making comments as if a 6MT can't get to 60 in one shift and how the STi isn't very different from the WRX. Very true. The problem isn't with the number of gears. It's the ratios used on it which cause it to not really improve mpg and take 2 shifts to 60. The comments about how the only problems with the transmissions is within the tuner group further shows that a "weaker" 6MT should still be sufficiently strong enough. Either one will be strong enough for the general public, so maybe the strength issue needs to be thrown out the window for arguement for or against either transmission. I'd like to clarify that Paul Hansen didn't say that it is a known fact that the casing flex is what was reinforced. What he said/posted was that case flex had been the problem, so he is assuming that reinforcement to that problem area is what was done. I'm not saying that he is wrong at all. It's just that if the case flex wasn't reinforced for some strange reason, no need to say that Paul lied about it or was talking out his backside.[/quote] Oh no, my only point, Preston, was that everyone is advocating the six-speed so that the first five gears can be short, for performance (which would mitigate against a one-shift to 60 gearing), with an overdrive sixth gear. I thought that Paul Hansen knew for sure that the case had been strengthened. I don't suppose we'll find out what "reinforced" really means until Subaru decides to tell us. Can't wait for the first magazine tests, as then we'll have the details on suspension tuning, etc. Kevin
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For me, the shorter gearing would be like the Spec B gets (same gearing but 4.444 final). This still is a 1 shift to 60mph, but the 5th gear is too short for a car of this "caliber" on US roads and tastes. The point that you have made (very well) about cruising rpm needing to be close to where it can build boost is noted. I am willing to bet that a top gear that was what I would have liked would not have performed that well off boost. About the casing, Paul had told me that the US 2002 transmission was the version from the JDM 2000 model I believe. Then the 2003-2004 USDM WRX got the tranny of JDM 2002 (revision B). Then the revision C tranny of the JDM Impreza is the strengthened tranny in the F-XT. The latest revision D tranny is what is assumed is going to be in the Legacy GT and is what is in Paul's 2002 Legacy RSK. Since that revision is in his car, I am betting that his guess or sleuthing as to what was actually done in revision is probably accurate. If we assume that the case flex issue was dealt with in revision D, then the only assumption left would be that we are going to get the same tranny as the JDM models which I think is very likely. It's just not known as fact yet.
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Oh well, first post - The tranny continues to be a touchy area for people, but the problem is that many are making assumptions. One is that the current 5-speed is not up to par. That, however, is based on the older 5-speed problems. Some checking through NASIOC points towards that no longer being the case, simply because people are not reporting as many problems with newer model WRX 5-speeds, nor the torque-enhanced Forester XT, or Baja. If you went by the common assumptions, the XT would be breaking gearcases right and left. But it's not. So let's move past this one. The newer 5-speed gearboxes, like the one in my car that has a lot more power to deal with than in the USDM WRX, are up to par. And the newest 5-speed in the new Legacy GT is likely even stronger. It doesn't mean you can run 450whp through it and hope to dominate at the drags. It isn't a Camaro or Mustang, or an STi. It has still been built to a cost point that makes it affordable. But if somebody feels a need to have 300whp in it, I think it will do just fine when driven with a modicum of mechanical sympathy. No matter what tranny is in there, it is not a Honda with FWD that has only one or two wheels worth of traction to deal with. Cheers, Paul Hansen
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[quote name='gtguy'] I thought that Paul Hansen knew for sure that the case had been strengthened. I don't suppose we'll find out what "reinforced" really means until Subaru decides to tell us. Can't wait for the first magazine tests, as then we'll have the details on suspension tuning, etc. [/quote] I know it has been strengthened. However, they don't come out and say specifically what has been altered, I think that enters the touchy area of PR and Lawsuit avoidance. It was from talks with somebody else that has been building up subaru trannies for a decade+ to deal with Big Torque (if the dyno sheet is right...680ft/lbs at the hubs) that got me onto the track of case flex. Cheers, Paul Hansen
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