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Old 02-16-2011, 08:29 PM   #176
FuJi K
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Old 02-18-2011, 04:21 PM   #177
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Quote:
Originally Posted by FuJi K View Post
I just found out that the '08 WRX uses the LGT gears and runs a 4.111FD. I wonder if it is the same tranny.... more likely.
Can you change this in post #3 please?
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Old 02-19-2011, 02:26 AM   #178
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Originally Posted by roadtrip1098 View Post
Can you change this in post #3 please?


corrected info. The final drive a 3.900
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Old 02-21-2011, 04:16 AM   #179
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Man, TONS of great info on here. If I had a wrx or sti...

Last edited by Jagular1785; 02-23-2011 at 05:09 PM.
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Old 02-23-2011, 02:28 PM   #180
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Originally Posted by FuJi K View Post
corrected info. The final drive a 3.900
Did Subaru make a mistake?

http://www.driveperformance.subaru.c...x_spec_dim.asp

Using these figures on the gigantic link below http://www.teammfactory.com/gearcalc...ission+1+%26+2

Yeilds nearly identical top speeds for the WRX and STi of 181 and 182 respectively. I know this is not accurate for the WRX. Mine is pushing about 165ish around 6500-6800 mark. It also does about 65 in second when pushing close to redline - not the 71 MPH stated by the calculator.
In fact the Speed vs RPM in my WRX matches perfectly with the gears listed, but a 4.1 final drive. To me it makes more sense mathematically and practically if the WRX has a 4.1 FD and the STi has a 3.9.

Last edited by roadtrip1098; 02-23-2011 at 04:36 PM.
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Old 02-23-2011, 04:46 PM   #181
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Did Subaru make a mistake?
Simply put, no. In a lossless situation, your car should hit 169mph at 6500RPM. However, keep in mind that you're driving a car with aerodynamic qualities that are less than optimal, to put it nicely. Counting in wind drag, I'd be surprised if you're only losing 4mph at those speeds. The 181mph is a purely theoretical number, meaning it takes no mechanical losses, drag, or or power limits into play. In a real world situation, hitting 165mph at 6800RPM is pretty spot on.
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Old 02-23-2011, 08:50 PM   #182
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The speedo isn't spot on. It always tends to be around 2mph more than what the car is actually going. I run the JDM DCCD 6spd with STi cluster, 235/40/17 tires and it read 3mph faster than what I'm going.


I've always wondered what the FD was on the '08+ because when looking at the rear diff part numbers, it shows a 4.111, but i specs says a 3.900FD. Only way to find out and to go under, spin the driveshaft so many turns for ONE tire rotation.
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Old 02-23-2011, 09:13 PM   #183
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Simply put, no. In a lossless situation, your car should hit 169mph at 6500RPM. However, keep in mind that you're driving a car with aerodynamic qualities that are less than optimal, to put it nicely. Counting in wind drag, I'd be surprised if you're only losing 4mph at those speeds. The 181mph is a purely theoretical number, meaning it takes no mechanical losses, drag, or or power limits into play. In a real world situation, hitting 165mph at 6800RPM is pretty spot on.
Even if drag is causing the vehicles actual speed to be lower, the output on the transmission itself should show the theoretical speed. If the clutch isn't slipping, and you don't have broken teeth in your gear box then there isn't going to be any loss between the engines number of rotations and the driveshaft rotations off the transmission, so the speed sensor on the transmission should be showing your theoretical speed not your actual speed.

The wind resistance shouldn't have as much of an effect at much lower speeds so why is the 2nd gear a 60-65MPH gear rather than the low 70's you should see with 3.90?
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Old 02-23-2011, 09:15 PM   #184
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The center diff could have a multiplier on it, similar to how 5-speed bugeyes are--3.90FD, 1:1.1 center diff, 3.545 rear end.
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Old 02-23-2011, 09:15 PM   #185
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Quote:
Originally Posted by FuJi K View Post
The speedo isn't spot on. It always tends to be around 2mph more than what the car is actually going. I run the JDM DCCD 6spd with STi cluster, 235/40/17 tires and it read 3mph faster than what I'm going.


I've always wondered what the FD was on the '08+ because when looking at the rear diff part numbers, it shows a 4.111, but i specs says a 3.900FD. Only way to find out and to go under, spin the driveshaft so many turns for ONE tire rotation.
I know mine reads about 2-3 over versus the GPS
I'm throwing my official vote that it has 4.11's and SOA dicked up when they put out the stats on their website.

Tell ya what, providing it's not raining or freezing this weekend I'll jack up my car and we'll have a real no BS answer as to what the 08+ WRX has, I'll even take a video and post it.

Last edited by roadtrip1098; 02-23-2011 at 09:31 PM.
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Old 02-24-2011, 06:43 AM   #186
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Originally Posted by RossLH View Post
The center diff could have a multiplier on it, similar to how 5-speed bugeyes are--3.90FD, 1:1.1 center diff, 3.545 rear end.
Going to climb under it on Saturday so we'll all know for sure. This is my first Subaru, but I've had it long enough to know that they make just as many mistakes as any of us.
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Old 05-05-2011, 01:36 AM   #187
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whats the mpg drop if any from an 07 wrx 5speed to an 04 sti 6speed tranny ?
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Old 05-05-2011, 01:45 AM   #188
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If anything, I'd say the 6-speed will give you better mileage because you'll be able to stay in the optimal RPM range that much more often. Highway mileage will not change.
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Old 05-05-2011, 01:41 PM   #189
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well thats music to my earns. Hey why i have you have you hand any experience with rallysped directs 04 6speed up grade
http://www.rallispec.com/prod_trans.htm
gives a 4.44 final drive
worth for it for street use
note the set im talking about is just about the short shifters for sale
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Old 05-05-2011, 02:16 PM   #190
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That post is next to impossible to decode, so I'm going to answer the only question I could possibly extract from it.

A 4.44FD is usable on the street, but I'd recommend against it with '04 STi gearing. Highway cruising speed (70-75mph) leaves you at almost 3500RPM, which I've done before (JDM STi 6-speed). The ratios are fun as hell, but highway cruising SUCKS. I got better mileage in the city than I did on the highway.
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Old 05-05-2011, 02:39 PM   #191
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sorry for that man the droid txting is anoying at times
yeah it said it have longer gears for top end but i see were your comming from 4.44 FD for street use
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Old 05-05-2011, 05:03 PM   #192
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lol yeah, pros and cons for 4.44 gearing
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Old 05-05-2011, 06:59 PM   #193
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agreed
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Old 05-05-2011, 07:46 PM   #194
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If anything, I'd say the 6-speed will give you better mileage because you'll be able to stay in the optimal RPM range that much more often. Highway mileage will not change.
I completely disagree. There is absolutely NO way he will not see a decrease in mileage both in the city and on the highway going from a 2007 5MT to a 2004 6MT. That amount cannot be predicted, but I can promise you it will be lower. I've installed a half dozen 6MT's in 5MT cars and observed this every time.

The number of gears is absolutely NO indication of mileage, economy or performance. Ratios are everything. The STi ratios are short which means you are shifting frequently and in higher RPM's more often.

Quote:
Originally Posted by emsbuff124 View Post
well thats music to my earns. Hey why i have you have you hand any experience with rallysped directs 04 6speed up grade
http://www.rallispec.com/prod_trans.htm
gives a 4.44 final drive
worth for it for street use
note the set im talking about is just about the short shifters for sale

4.44 with the 04 6MT would be stupid short. Enjoy an absolutely useless 1st gear and a sky high RPM cruising on the freeway.




Look at these charts and try to place your driving on them. (all done with a stock sized tire)

02-05 & 08+ WRX:


06-07 WRX (your ride):


04-06 STi:


07+ STi:


Rallispec High Speed Ratio for the 6MT (07+ 2nd, 3rd, 4th, & LGT Spec-B 5th, 6th):
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Old 05-05-2011, 07:50 PM   #195
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Believe me when I say I loved my JDM STi 6-speed (3.9FD, 0.842 top gear), but I drive upwards of 20K miles a year, including several 600+ mile trips. You gotta be prepared for a 25% loss in highway mileage, and if your exhaust didn't drone before, well it will. I would have put the gearbox in my current car, but with a 2.0L and TD04 (as opposed to the preceding 2.5L and FP Green), gas mileage would be even worse--if the wind blows the wrong way, the car would be at full boost.
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Old 05-05-2011, 07:55 PM   #196
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I completely disagree. There is absolutely NO way he will not see a decrease in mileage both in the city and on the highway going from a 2007 5MT to a 2004 6MT. That amount cannot be predicted, but I can promise you it will be lower. I've installed a half dozen 6MT's in 5MT cars and observed this every time.
Highway mileage wont change when the top gear and final drive dont change. And I dont care how many 6MT swaps you've done, I'll say from personal experience that my car got better gas mileage in the city with a 6-speed than it could ever hope for with the 5-speed. This effect can be proven mathematically, but not only am I way too lazy to do that right now (or ever, for that case), at the end of the day it depends on the driver.
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Old 05-05-2011, 08:06 PM   #197
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Highway mileage wont change when the top gear and final drive dont change. And I dont care how many 6MT swaps you've done, I'll say from personal experience that my car got better gas mileage in the city with a 6-speed than it could ever hope for with the 5-speed. This effect can be proven mathematically, but not only am I way too lazy to do that right now (or ever, for that case), at the end of the day it depends on the driver.
But the top gear is different between the 07 5MT and the 04 6MT. On the order of 250rpm to 300rpm at highway speeds.

And it really cannot be proven mathematically because as you indicated, the driver/style is the biggest factor and it's an unknown variable. I threw out the number of swaps I've done because that adds to the data points I've personally verified which adds anecdotal evidence. You have your single point (I assume) and that may be correct. I on the other hand have 6 data points (more or less from myself driving these swapped cars) and then 5 more data points from the owners telling me their experiences as well. Who is more correct? We don't know, but I have a lot of experience.
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Old 05-05-2011, 08:20 PM   #198
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On closer inspection, I had forgotten the '06-07 had the 3.70 rather than the 3.90. My mistake.

However, all your experience with 6MT swap tells me is those who drive said cars are heavy on the throttle. I had no problem getting 28mpg average (meaning upwards of 30mpg highway, 22-24 city) with a hybrid block and FP Green with an MFactory 1-4 short ratio set if I wanted to save my bank account a little. With the JDM 6-speed, a stretched tank of gas would get me 25mpg city and 22-23 highway.

It is all very subjective, but given a driver who knows how to save gas, I can promise you the 6-speed will be better in the city. By assuming the driver isn't lead footed, the calculations will show in favor of the 6-speed for city driving.
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Old 05-05-2011, 11:46 PM   #199
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im not that high in the hp department 293 whp and 326 torque wheeled i only going to do an up-pipe inlet and little bigger injector retune and call it a day in the engine department. But dont you have to factor in wind varriables and how areo dynamic your car is? i mean you said you saw a decrease in mpg but that could also be accounted in for drag on your car.
I've heard sti putting 500whp getting 30mpg on the highway because they are more aero dynamic. mainly because the car is so lowed no air can get under the car, and it has several other key features that alows for better air flow over the top of the vechicle
I know the STI wing in the 04-07 years wasnt just for looks but for down force too.
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Old 05-05-2011, 11:49 PM   #200
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But dont you have to factor in wind varriables and how areo dynamic your car is? i mean you said you saw a decrease in mpg but that could also be accounted in for drag on your car.
Thats just another testament to my results. I had roof rails with a ski rack on them year round, and I still got better mileage than just about anyone I've seen.
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