Learning to Choose your Gear Sets/Ratios

Discussion in 'Tech, Tips, Newb Info' started by FuJi K, Feb 1, 2009.

  1. FuJi K
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    FuJi K Well-Known Member

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    Information is subject to change as more information comes.

    I have a ’05 WRX and I have NOW upgraded my turbo to a decent TD06H-20G-8cm^2, FMIC, EWG with ported heads, 272* cams, 9.0:1CR pistons, Cosworth rods/bearings and running 110oct. What I’m afraid of is breaking my transmission now. The car was tuned to 22psi up top and we push 364whp and 331wtq. I don’t know what gears I want to hold the power. Some were saying go PPG’s and others were saying ’07 STi 6spd.

    WELL…. The MOST important question is, what are you going to be doing with your car? Gearing is determined by the car’s use. A person who drag races a car has much different gearing compared to a person who does circuit/lapping days. The stock gearing on the car is much different from BOTH of the guys who does the 1320 and track races.

    A drag racer much rather prefer rolling through 1-2-3-4 on a typical 5spd tranny with an average 280-450whp. Gear ratios are much longer and further spread out. Less shifting means more time for acceleration. First gear for get up and go, second gear for gaining ground when there’s not enough wind drag yet, third gear to pull through with the power made, and forth gear to show “wassup†about TOP END.

    A track racer much rather prefers rolling through 2-3-4-5 on a typical 5spd tranny with an average 280-450whp. Gear ratios are much shorter and closer to each other. Staying in the power band even after a shift means power on the tap 99% of the time so you can zoom out of a corner faster. Second gear is usually for slower turns, third gear to get you to the next corner, forth gear for that high speed turn, and fifth gear to pull through the back 1000ft straight. An autoX guy will like a nice short 2nd gear and 3rd gear, more like the STi 6spd 2nd gear and 3rd gear.

    Now the Daily driver much prefers being able to go through all gears on a 5spd with an average 280-450whp. Gear ratios are much wider in the first 3 gears and shorter as they go up or get shorter as they go up to 4th and 5th gear would be a little longer. Less shifting in the lower speeds means more concentration on the ROAD, closer ratios from 3-4 means staying in the power band and NOT using a lot of gas, and a nice low ratio 5th gear for that NICE hiway cruising engine speed.

    Now you should have an idea what you want now. Remember that these are the KEY POINTS in choosing the gear ratios that meets your needs. Don’t expect the Daily driver gearset to keep you IN THE POWERBAND all the time and don’t expect it to give you MAXIMUM acceleration getting up and going from a stand still on the side of the hiway.

    This is where it gets technical. There are final drive numbers on each tranny can vary on year. Also are your engines’ powerband and window of RPM operation. The gear ratios will determine how much gap in engine revs there are between shifts and some speed. The final drive ratio will change the overall SPEED of each gear and how much overall speed once in top gear. Sometimes a tranny will have a short 4.444 final drive ratio, but its speed carried through the gears given the engine’s rev limit is really close to the same as one with a 3.900 final drive. The ’95 WRX STi Ver.II 4.111 tranny(3.454 2.062 1.448 1.088 0.825) and ’99 WRX STi Ver.VI 4.444 tranny(3.166 1.882 1.296 0.972 0.738) would be a good comparison; STi VerII 60mph@2880rpms and STi VerVI 60mph@2785rpms both in 5th gear.

    Typical Subaru’s with an average 280-450whp will rev up to 6500-7500rpms. Most gear ratios out there will work fine with the factory final drive ratio given the engine’s rev limits. One would put STi RA 5spd ratios(3.083 2.062 1.545 1.151 0.825) in a ’06 WRX tranny(3.700FD). It’ll give you decent acceleration and still a forgiving 5th gear hiway gear running 60mph@2590rpm and 80mph@3455rpms. Putting the same STi RA 5spd ratios in a ’05 WRX(3.900FD) would mean a bit quicker running through the gears, however a slightly higher engine speed; 2730@60mph and 3640@80mph both in 5th gear.

    Those who are running the PPG gears have all out acceleration performance through the straight with an average 280-450whp with up to 7500rpms rev limit. Let us look at these ratios; 3.08 / 1.87 / 1.32 / 0.95 / .738(OEM) with a stock final drive of 3.900 on ’02-’05 USDM WRXs. Running through first gear you’ll get to approx 41.3mph, second gear starting at about 4200rpms carrying speed to 68.1mph, then third gear starting at 4900rpms and carrying speed to 96.4, forth gear starting at 5000rpms and carrying speed to 134mph, then fifth gear starting at 5400rpms and carrying it up to 170mph if given enough straight shifting at about 7000rpms. You can carry enough speed through the quarter mile in 4th gear giving you plenty of time to accelerate shifting only 3 times for the drag racers.

    Now when you put in aftermarket gears, you have a variety of ratios available. Knowing what YOU are going to do with the car will allow you to make the right choice in selecting the right ratios for you. You can also consult with a shop that specializes in rebuilding transmissions and they can help you narrow your gear sets down to the one that suits your application.

    Now what about the 6spd? Oh when you go with the 6spd you are jumping into a whole different ball game. You have LSDs, DCCD, rear biased, and short gearing. The 6spd was made for track driving and was NEVER intended for 1/4mi use, however it will put a decent time. They come with and without DCCD depending if you get JDM stuff or USDM stuff. In Japan they have non-DCCD 6spds for the purpose of owners’ preference. DCCD 6spds will always be rear-biased except very few models and the newer models; 35:65, 41:59, & 45:55. The strength is also very incredible. You will be able to run the tranny hard and don’t have to worry about breaking gears with the average 280-450whp.

    Gearing is changed a little bit for certain countries. For example the JDM 6spd is much shorter than what’s offered here when looking at ’07 models. For the ’04 STi that first came here in the USA, we had the same gearing 1-4 as the JDM 6spd, but with LONGER 5th and 6th gears. This was changed out for the ’07 models using longer gears that are the same as the Legacy Spec B 2-4th gears while retaining the same 1st, 5th, and 6th gear ratios. The USDM Legacy Spec B 6spd ratios are like the USDM ’07 STI, but with much longer 5th and 6th gear evening the spacing out.

    For the guys who run and average of 280whp-450whp, the 6spd will get things done well for most applications. The gearing is short enough so you don’t have to worry about long gears when you run at the track. They are also long enough to enjoy rolling through the 1320. The longer ratio ’07 STI tranny is will suit those who do the 1320. The ’04-‘05 STi tranny will suit those who autoX and do circuit. The JDM STi 6spd will suit those who are doing PURE time attack and road course events. If the car has HIGH HP, the Legacy Spec B ratios will suit them better for its longer ratios.

    Now selecting the ratios does go hand in hand with the amount of power as well as window of power with engine speed. For example would be if I wanted a QUICK & FAST street car running 540whp revving to 7500rpms on a built 2.5L, I would definitely do a 6spd and have Legacy Spec B 2-6 ratios installed. The car would have enough power to push through the longer ratio gears. The longer ratios also help because of the lower engine rev compared to the JDM models with the 8000rpm redline. If I was to have JDM STi 6spd I would run out of gearing so fast that I wouldn’t have anytime to use the power for acceleration. There’s just too much shifting with shorter ratios where you can have longer ratios to gain more ground accelerating. If it was a pure short/medium track or rally machine where top speed isn’t a factor but more so acceleration, the JDM ratios would fit right in. Anytime out of a corner power would be on TAP.
     
    Krunk Fu likes this.
  2. FuJi K
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    FuJi K Well-Known Member

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    General Idea of Gear Set for type of application

    1320ft / Wangan

    280whp-450whp or more


    5speed transmission
    PPG gearset
    3.18 / 1.87 / 1.32 / 0.95 / OEM - Synchro 1st-4th Helical Cut Gear Set
    3.08 / 1.87 / 1.32 / 0.95 / OEM - Synchro 1st-4th Straight Cut Gear Set
    3.08 / 2.15 / 1.50 / 1.05 / OEM - Synchro 1st-4th Helical Cut Gear Set from Andrewtech
    3.18 / 1.87 / 1.32 / 0.95 / OEM - Dogbox 1st-4th Straight Cut Gear Set
    3.08 / 2.15 / 1.50 / 1.05 / OEM - Dogbox 1st-4th Helical Cut Gear Set

    6speed transmission
    Subaru
    3.636 / 2.235 / 1.521 / 1.137 / 0.891 / 0.707 - Legacy Spec B/Rallispec High Speed 2nd-6th Ratio Conversion
    3.636 / 2.235 / 1.521 / 1.137 / 0.971 / 0.756 - USDM '07 STI+

    PPG
    3.080 / 1.880 / 1.350 / 0.960 / OEM / OEM - Drag 4 Gear Subaru 5MT Dog Gear Kit


    Short Track / Road Course / Time Attack / Autocross
    280whp-450whp or more


    5speed transmission
    PPG gearset
    2.916 / 2.090 / 1.555 / 1.176 / 0.900 - GC8 Group N 5 Gear Subaru 5MT Dog Kit
    3.08 / 2.15 / 1.50 / 1.05 / OEM - Synchro 1st-4th Helical Cut Gear Set from Andrewtech

    KAAZ
    3.167 / 2.267 / 1.667 / 1.250 / 0.964 - MCF2050 Close Ratio Gears

    MFactory
    3.270 / 2.286 / 1.667 / 1.238 / 0.958 - Close ratio Gear Set

    6speed transmission
    Subaru
    3.636 / 2.375 / 1.761 / 1.346 / 1.061 / 0.842 - JDM STi
    3.636 / 2.235 / 1.521 / 1.137 / 0.891 / 0.707 - Legacy Spec B/Rallispec High Speed 2nd-6th Ratio Conversion
    3.636 / 2.235 / 1.521 / 1.137 / 0.971 / 0.756 - USDM '07 STI+

    PPG
    3.636 / 2.375 / 1.761 / 1.346 / 1.062 / 0.842 - GroupN 6 Gear Subaru 6MT Dog Kit
    3.333 / 2.284 / 1.750 / 1.333 / 1.040 / OEM - Group N 5 Gear Subaru 6MT Dog Gear Kit


    Budget Daily Driver
    up to 375whp or more if you are willing

    Subaru
    3.166 / 1.882 / 1.296 / 0.972 / 0.738 - USDM '05+ Legacy 2.5GT & JDM models
    3.083 / 2.062 / 1.545 / 1.151 / 0.825 or OEM - JDM GC8 WRX/STi RA Version 3-6






    http://www.rallispec.com/prod_trans.htm
    http://www.kaazusa.com/partinfo_gearsets.html
    http://www.teammfactory.com/products.php?category=Close Ratio Gears
    http://spda-online.ca/modules/tinycontent/rewrite/tc_28.html
     
  3. FuJi K
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    FuJi K Well-Known Member

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    Factory Gear Ratios for Reference

    All-Wheel-Drive 5-speed Transmissions
    USDM
    3.454 / 1.947 / 1.366 / 0.972 / 0.738 / 3.900FD - '02-'05 USDM WRX
    3.454 / 1.947 / 1.366 / 0.972 / 0.738 / 3.700FD - '06-'07 USDM WRX
    3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 3.900FD - '08-current USDM WRX
    3.454 / 1.947 / 1.366 / 0.972 / 0.738 / 4.444FD - '04-'08 Forester 2.5XT
    3.454 / 2.062 / 1.448 / 1.088 / 0.780 / 4.111FD - '04-current Forester non-turbo
    3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 4.111FD - '05-'06 USDM Legacy 2.5GT
    3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 3.900FD - '07-current USDM Legacy 2.5GT
    3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 4.444FD - '05-'09 USDM Outback 2.5XT
    3.545 / 2.111 / 1.448 / 1.088 / 0.780 / 4.111FD - '98-'01 USDM Impreza 2.5RS
    3.545 / 2.111 / 1.448 / 1.088 / 0.780 / 3.900FD - '96-'01 USDM Impreza L/OBS
    3.545 / 2.111 / 1.448 / 1.088 / 0.780 / 4.111FD - '96-'99 USDM Legacy 2.5GT
    3.545 / 2.111 / 1.448 / 1.088 / 0.871 / 4.111FD - '96-'99 USDM Legacy Outback
    3.454 / 2.062 / 1.448 / 1.088 / 0.871 / 4.111FD - '00-'07 USDM Outback
    3.454 / 2.062 / 1.448 / 1.088 / 0.825 / 4.111FD - '08-current USDM Outback
    3.454 / 2.062 / 1.448 / 1.088 / 0.780 / 4.111FD - '02-'04 USDM Impreza 2.5RS/'05 Impreza 2.5RS Sport
    3.545 / 1.947 / 1.366 / 0.972 / 0.780 / 4.111FD - '93-'94 USDM Impreza 1.8L
    3.545 / 2.111 / 1.448 / 1.088 / 0.825 / 3.900FD - '95 USDM Impreza 1.8L

    JDM
    3.454 / 2.062 / 1.448 / 1.088 / 0.825 / 4.111FD - '93-'96 JDM Impreza WRX/STi
    3.454 / 2.333 / 1.750 / 1.354 / 0.972 / 3.900FD - '93 JDM Impreza WRX RA
    3.454 / 2.333 / 1.750 / 1.354 / 0.972 / 4.111FD - '94-'95 JDM Impreza WRX RA/STi RA
    3.454 / 2.062 / 1.448 / 1.088 / 0.825 / 4.111FD - '93-'00 JDM Impreza WRX Wagon
    3.083 / 2.062 / 1.545 / 1.151 / 0.825 / 4.444FD - '97-'00 JDM Impreza WRX RA/Type R/STi RA/22B STi
    3.166 / 1.882 / 1.296 / 0.972 / 0.738 / 4.444FD - '97-'00 JDM Impreza WRX/STi


    All-Wheel-Drive 6-speed Transmissions
    3.636 / 2.375 / 1.761 / 1.346 / 1.061 / 0.842 / 3.900FD
    - JDM Impreza WRX Spec C/STi/STi Spec C RA/V-Limted/S202/S203/S204/Spec C RA-R
    - AUS Impreza WRX STi

    3.636 / 2.235 / 1.521 / 1.137 / 0.971 / 0.756 / 3.900FD
    - USDM 2007-current Impreza WRX STi

    3.636 / 2.375 / 1.761 / 1.346 / 0.971 / 0.756 / 3.900FD
    - USDM 2004-2006 Impreza WRX STi
    - UK/Europe/NZ Impreza WRX STi
    - JDM Legacy 3.0R Spec B

    3.636 / 2.235 / 1.521 / 1.137 / 0.891 / 0.707 / 3.900FD
    - USDM 2007-current Legacy 2.5GT Spec B
    - JDM Forester STi



    Calculators for Speed and RPM
    http://www.car-videos.net/tools/speedrpm.asp
    http://www.teammfactory.com/gearcalculator.php



    http://spda-online.ca/modules/tinycontent/rewrite/tc_28.html
    http://www.ausubaru.com/wiki/index.php?title=TRANSMISSION
    http://www.rexnet.com.au/forum/index.php?showtopic=29168
    http://www.cars101.com/
     
  4. FuJi K
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    FuJi K Well-Known Member

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    Videos of various gearing combination's


    3.636 / 2.375 / 1.761 / 1.346 / 1.061 / 0.842 - 3.900FD
    '01RS Ver.VI swap, USDM '02 WRX ECU/harness, JDM V7 6spd non-DCCD , 7000rpm shifts



    3.08 / 1.87 / 1.32 / 0.95 / 0.738(OEM) - 3.900FD
    '02 WRX, PPGs straight cut 1/2, helical cut 3/4, OEM 5th, 7000rpm shifts



    2.111 / 1.448 / 1.088 / 0.871 / - 4.111FD
    '03 WRX, '97 Outback NA 5spd, '01RS VLSD 4.111FD R160, 7000rpm shifts



    3.166 / 1.882 / 1.296 / 0.972 / 0.738 / - 4.444FD
    '99 CANADA OBS EJ20G swap STi Ver.IV tranny



    3.636 / 2.235 / 1.521 / 1.137 / 0.891 / 0.707 / - 3.900FD
    '07 USDM STi 6spd BPU



    3.454 / 1.947 / 1.366 / 0.972 / 0.738 / - 3.900FD
    '02 WRX stock 5spd BPU


    ...............
     
  5. fobiawrx
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    fobiawrx Fabiola

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    reserved for when im not drunk....

    oh and that's allot of words...
     
  6. Musashi
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    Musashi Well-Known Member

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    I'm reading it right now! Will follow up with a phone call for a discussion. Good stuff none the less!
     
  7. Paul Revere
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    Paul Revere BANNED

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    Fuji can we get some OEM gear ratios for comparison?
     
  8. Soupboy
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    Soupboy Well-Known Member

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    Homie please... Cease the spoon-feeding.
     
  9. Paul Revere
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    Paul Revere BANNED

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    I know where to find them I just wanted him to post them with the rest of his information.
     
  10. SubeN'Siren
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    SubeN'Siren Well-Known Member

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    I agree, that would be helpful for easy cross reference...
     
  11. FuJi K
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    FuJi K Well-Known Member

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    Gear ratios added
     
  12. Shane86
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    Shane86 Well-Known Member

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    Fuji,
    What does it take to change out final drive in the gearbox? is it just swapping out the ring gear on the front diff, to one that matches the ratio of the rear diff?
     
  13. FuJi K
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    FuJi K Well-Known Member

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    Yups, that would be it. For your WRX, if you wanted 4.444, you can get it from the Forester XT, have a tranny shop put it in. Swapping FD in the tranny requires a teardown of the tranny. eekkKKKK!!!

    The rear diff you can pick up a matching on from a few cars that already have it. Just swap over the VLSD you have or get a real clutch LSD or your preference and put it in with the 4.444.
     
  14. Shane86
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    Shane86 Well-Known Member

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    How about external markings, indicating which transmission is which, or at least the case...? Where are they? Is there a list of which set relates to what case numbers?
     
  15. piddster
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    piddster Lone Wolf

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    It does not require a complete teardown of the transmission. You do not have to dissassemble the input or driven shafts to do it. Splitting the case is the easy part.

    Keep in mind that with a WRX transmission you have a 1.1:1 reduction in the center differential so swapping straight 4.444 front and rear ring/pinion sets would spell trouble.
     
  16. FuJi K
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    FuJi K Well-Known Member

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    thanks for pointing that out, but still splitting the tranny though. :O:O:O
    . Must get transfer gears that are 1:1; found in NA trannies and a few newer turbo trannies like FXT, '06+ WRX, LGT.
     
  17. piddster
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    piddster Lone Wolf

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    ^ No prob. It's a lot of bolts, but not too bad.
     
  18. Musashi
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    Musashi Well-Known Member

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    1: So can someone help explain in lames what these numbers mean as far as ratio?

    2: When does weight become a factor when selecting gear, if at all?

    3: How will wheel size effect your gear ratios? I saw the link, but can you explain further?

    4: What gears would you recommend for those interested in performing on loss surfaces?

    5: Will you notice WHP changes from changing the final driver gears?

    6: Is there a good way to select gears based on power band delievery?

    7: How can knowing your gear ratios help you better utilize your engines power for improving your performance on the track?

    8: Can aftermarket LSD change your gear ratio?
     
  19. piddster
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    piddster Lone Wolf

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    Give me some time to dig into my gear ratio program, and I can have some more qualitative answers for you.

    Tire/wheel size plays a part in your gear ratios. Tire size has an across-the-board effect on lethening or shortening your ratios.


    Weight is a factor in selecting gear ratios. It all depends on how far you want to nit-pick.


    As far as loose surfaces, I don't have the experience to elaborate on that. Different ratios will affect how easy or difficult it is to spin your tires. This can play a part is the ratios you choose and why you choose them.

    As far as whp goes, when tuning a car on a dyno, you try to do your tuning in the gear that has the closest ratio to 1:1 as possible, meaning your tires spin one revolution for one revolution of your crankshaft.


    Power delivery is a factor in choosing gear ratios, and I hope to learn more on how that affects said decisions in the near future.


    Knowing your gear ratios in itself doesn't necessarily help your performance on the track. Knowing how your powerband is delivered can have more effect on your times. Having proper gear ratios is just the icing on the cake that lets you maximize the power you do have. For instance, with my old heads, I had a wad of torque at 4-4500rpm. The heads fell off by 6k rpm, so my car was fastest by short-shifting the car by 6k. Slightly longer ratios could have helped that situation.


    Lastly, and LSD in itself does not affect your ratios. That is in your ring and pinion, in the diff. In theory, someone could have taller ratios due to excessive wheelspin with an open diff, but usually people eliminate the open diff before getting serious with gear ratios and final drive ratios.


    I need to play around with this software that I happen to have which takes most of the factors into consideration. Don't ask me for a copy;)
     
  20. FuJi K
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    FuJi K Well-Known Member

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    1. 3.636 on first gear means, the engine rotates 3.636 times to spin the output shaft form the tranny 1 time. The Final drive number means how many times the out put shaft spins to turbo the wheel 1 time. So for first gear on an STi 6spd with w 3.900FD, it takes the engine 14.1804 rotations to rotate the wheel 1 full rotation. yah?? hahha

    2. Weigh does become a factor at a certain point. The engine's power also plays a role as well in power and engine's rev range. Semi trucks have much shorter ratios as they need to haul heavy trailers. This also means they need more gears so they can get more top speed on the hiway.

    3. Wheel size affects the gearing the same way changing the Final Drive does. You just can't see it in the speedometer.

    4. It really depends on the engine's rev range, and power output. It also depends on the speed of which your application calls for. Rally dirt course you want come decent short gearing because there are many turns and low speed turns. The surface doesn't matter. For drifting, you want a decent not too short gearset because you want a wider range of RPM so you can get more wheel spin to induce more oversteer. Too short and you run out of revs unless you gotta sequential gearbox like Team Orange's D1 cars.

    5. Engine torque does get multiplied onto the ground depending on gearing. I won't notice any gains aside from better acceleration because you stay and get into the powerband quicker with a shorter final drive than the Original. With a longer Final drive it'll take you a little longer to get into the powerband, however you can carry more speed staying in the powerband longer.

    6. lower reving engines need slighter longer ratios than higher revving engines if where looking at the same power outputs. The more power the engine has, the longer the ratios you can get too to mach the application if you're shooting for acceleration. Track racing you always want to have a decent short set to allow you to stay in the powerband after shifts and while exiting corners. If the engine has decent power/torque, you can go with a longer ratio set if you find yourself needing to shift.

    7. knowing is one thing, having the right set to match the engines rev range and allow decent speed for the engine output. I do the touge/track style. I have chosen the JDM 6spd for its shorter and better spaced 5/6th gears compared to the USDM. They are a bit short for 7000rpms but work very well. They allow you to stay in the powerband all the time after upshifts, and even downshifts when you're 4500-7500rpms.

    8. LSD doesn't change the ratio. It just changes the car's character when you're on and off the throttle. Also allows better traction out of turns, from a dead stop, and can also provide stability while engine braking into turns.

    correct me if I'm wrong.
     
  21. FuJi K
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    FuJi K Well-Known Member

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    Transmission codes are on the driverside of the tranny on the side where the starter bolts onto.

    This provides most ratios that are for most trannies
    http://spda-online.ca/modules/tinycontent/rewrite/tc_28.html
     
  22. FuJi K
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    FuJi K Well-Known Member

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    NEW VIDEO!!! The outback tranny!!

    [youtube]JYNYjc4ZcoU[/youtube]
     
  23. i_subie
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    i_subie Well-Known Member

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    Is it just me or are their more and more gear ratios missing on those transmission charts???!!!

    Good info Fuji...but will read tomorrow. Too tired...*yawn*
     
  24. Musashi
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    Musashi Well-Known Member

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    Now that we've watched the video, can you tell us the differences and why it would be beneficial to go with an Outback tranny instead?
     
  25. FuJi K
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    FuJi K Well-Known Member

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    This Outback tranny has it's own benefits and draw backs. It's shorter in ratios compared to the WRX through all gears. This is a good benefit for track drivers who wants to be right in the powerband when they get on the gas. The RPM sweeps right into the powerband when you get on the throttle out of a corner. The RPM gap between shifts are also not too long and allows you to stay in the meat of the powerband even if you short shift. The gearing is what's most beneficial in this case. Gear strength is questionable.

    Being shorter ratios, this also means more shifting and also higher rpms at freeway speeds. You can see just shifting at 3000rpms I shifted a little bit more to get to 30mph. A regular WRX will hit 30mph by 3000rpms before going into 3rd gear. Also if you noticed the engine speeds are higher than average when cruising in 5th gear at 60mph and 70mph. This can hurt fuel mileage for those who are looking for better mpg.

    For HIGH HP cars, these ratios may be a tad short for them. Those who drag race that trap up to 120 this gear set will be fine if they run 7500rpms rev limit. Strength wise these gears may break if you go beyond 250whp. Track driving they may handle it because there are constant launches more rolling through gears.
     
  26. 25iguy
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    25iguy New Member

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    Am i able to throw a wrx lsd in my 07 2.5i
     
  27. Shibbs
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    Shibbs The Daywalker

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    Which transmission?
     
  28. FuJi K
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    FuJi K Well-Known Member

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    That the WRX LSD out of the carrier. Take your Open diff out as well.... swap over ring gears and install the WRX LSD back into your diff carrier. Your axles will work.

    This is assuming it's the VLSD out of the '02 USDM WRX and 00-01 2.5RS. non VLSD axles will work with VLSD diff. IF Old skool that's questionable.
     

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