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Old 02-12-2009, 09:03 PM   #26
Trevor723
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Quote:
Originally Posted by FuJi K View Post
In comparison, WRX STi Ver4 non-DCCD tranny
http://www.youtube.com/watch?v=yiHvWsy27kw
Any idea of the mods on that car?
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Old 02-12-2009, 09:26 PM   #27
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Quote:
Originally Posted by Trevor723 View Post
Any idea of the mods on that car?
That one is a '99 OBS with a EJ22T semi-built shortblock, EJ20R JDM Legacy heads and manifold. TD05H 16G JDM 90* inlet turbo?
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Old 02-12-2009, 11:59 PM   #28
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Here's the NEW VIDEO. MUCH MUCH Better. We used electrical tape to tape the camera onto the steering wheel.

http://www.youtube.com/watch?v=JYNYjc4ZcoU
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Old 02-17-2009, 12:13 PM   #29
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One more for you to add:

MFactory PRO Series Gear Set - 3.454/1.940/1.350/0.958/0.769
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Old 02-17-2009, 03:54 PM   #30
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I've been comparing gear ratio options. and one of the numbers i've been looking at is the difference between one gear and the next. easy way to compare these is to divide the lower ratio by the higher one. you'll notice that with almost all stock boxes, the jump is steadily increasing. each of the 4 gear ratios being about 5% closer than the last. putting a wrx .738 5th gear in with a 1.066 4th makes the 4-5 gap about 5% wider than the 3-4 than the stock .972 4th.

when I get home, I'll post up my numbers.
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Old 02-20-2009, 10:25 PM   #31
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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.
Same exact part numbers for the mainshaft, 1st and 2nd gear idlers. I know because we just installed them in a box today. Though I've always thought it was a misnomer that people call this the LGT swap. These are the same ratios that were in the v4-v6 JDM STi's and WRX sedans. They aren't new ratios, though they are new to the US market, and of course we get them with a different FD ratio than the 4.44 they see in Japan. There's a certain US vendor who has been selling these for years as a complete 5 spd kit calling it v5/v6 STi. Though, they force you to buy all 5 gears in that kit, and you end up with an additional 0.738 5th gear, which you've already got if you drive a USDM WRX. Now, with these in US cars, you are free to just buy the 3-4 gears that you need. We're building a bunch of these boxes.

However, there is one difference with the '08 WRX gears. It's a shorter 5th. They've tightened it up to a 0.780 like were used on the GC chassis 2.5RS and first generation of Outbacks.

Also, there's just a couple of minor errors in your ratio charts. The ratios you attribute to 96-99 WRX-RA/ Type RA/ 22B etc are actually 97-2000 ratios. Also, same for the WRX/STi reference directly under that in the list. Those ratios, which are the ones we are discussing above were for 97-2000 as well. Just a one year shift off of what you've got listed.

Otherwise fabulous thread. When I have more time I'll come give some of my personal input on choosing ratios and applications. Even now with all this new stuff, Subarus are still pretty restricted on what we can do with these boxes. On the Porsche gears I am making we average 12-20 different ratios for each individual gear position. At the same time, on Porsches you are generally only working with 2 final drive ratio options instead of the 3 we have with Subarus. That reduces the number of gear ratios you need to have to reach the same end. Though there's a tradeoff there and if you adjust a final drive it forces you to move all ratios the same percentage at the same time. A shorter R/P ratio that might make your 2-3-4 better might take your 1st and make in pretty much worthless.
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Old 02-21-2009, 11:32 AM   #32
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Can anyone comment about the effect of final drive on the stress the gears see? The way I interpret it is that the higher final drive the less stress the gears will see due to mechanical advantage, but a more technical explanation would be great.
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Old 02-21-2009, 11:39 AM   #33
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The final drive gear is exactly that, the final gear i.e it comes after all the other gears. It doesn't affect the other gears "mechanically", and is basically just a torque converter

A longer final drive (lower numerically) will be more durable than a shorter final drive in terms of the final drive breaking, but causes more radial loads due to the smaller diameter ring gear, and vice versa.

Let me reword that:

Longer Final Drive (e.g 3.7) - More durable, but increases radial loads
Shorter Final Drive (e.g 4.1) - Less durable, but decreases radial loads

Radial loads is what pushes the shafts apart, causing gear mesh misalignment and worn/cracked bearings, ultimately leading to increased tooth wear and/or breakages

Last edited by MFactory; 02-21-2009 at 11:48 AM.
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Old 02-22-2009, 11:51 AM   #34
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Quote:
Originally Posted by MFactory View Post
The final drive gear is exactly that, the final gear i.e it comes after all the other gears. It doesn't affect the other gears "mechanically", and is basically just a torque converter

A longer final drive (lower numerically) will be more durable than a shorter final drive in terms of the final drive breaking, but causes more radial loads due to the smaller diameter ring gear, and vice versa.

Let me reword that:

Longer Final Drive (e.g 3.7) - More durable, but increases radial loads
Shorter Final Drive (e.g 4.1) - Less durable, but decreases radial loads

Radial loads is what pushes the shafts apart, causing gear mesh misalignment and worn/cracked bearings, ultimately leading to increased tooth wear and/or breakages
Thanks

Next question: Is there a way to compare acceleration rates between different gear ratios and final drives? ie 3.166 4.11fd 1st gear in an LGT vs 3.454 3.70fd 1st gear in an 07 WRX. They result in roughly the same top speed. Obviously, power curves effect the real world results, but I assume there's an equation to give a theoretical comparison?
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Old 02-22-2009, 12:00 PM   #35
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Multiply the fd ratio by gear ratio, then multiply by the torque = torque at the wheels

Torque is responsible for acceleration. If both had the same torque curve, then the 1st example would be quicker:

3.166 x 4.11 = 13.01 x lbft = torque at the wheels
3.454 x 3.7 = 12.78 x lbft = torque at the wheels
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Old 02-22-2009, 02:02 PM   #36
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Quote:
Originally Posted by MFactory View Post
Multiply the fd ratio by gear ratio, then multiply by the torque = torque at the wheels

Torque is responsible for acceleration. If both had the same torque curve, then the 1st example would be quicker:

3.166 x 4.11 = 13.01 x lbft = torque at the wheels
3.454 x 3.7 = 12.78 x lbft = torque at the wheels
Thanks again! I decided to go with a jdm wrx transmission based on vehicle speed calcs and general information I've read about a shorter final drive, but numbers make things so much clearer for me. Here's the spreadsheet I put together to help make my decision: google doc The 4.44 final drive, even with longer gears, makes a substantial difference in the torque at the wheels for a given engine torque using the formula above. They only downside I see, on my stock powered car, will be cruising rpm. I figure I can just do the speed limit instead of 80 and it will be about even. It'll just take longer to get places.
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Old 03-06-2009, 10:27 AM   #37
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Old 03-15-2009, 02:53 PM   #38
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Very nice write up so far. This will help many other applications where the vehicle weight and torque and tire size will be different from the suby applications. For instance the 914 midengine suby engine and tranny application that is popular. 2000 lb. midengine, 350 rwd hp 300ftlbs maybe with long street gears or close gears for the track, either with lsd.

Looks like the beginnings of a good sticky.

Last edited by charliew; 08-30-2009 at 05:58 PM.
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Old 03-16-2009, 01:18 PM   #39
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Interesting thread!

I am thinking of rebuilting my '02 WRX transmission with STi RA gear set. I made some calculation and it seems that the ratios with the 3.90 FD will be similar to a STi 5spd 4.44FD (non-RA), except for the first gear that will be quite a bit longer.

If someone have done it before, what's the feeling of it? is the first gear too long when you start from a complete stop, or is it fine?

STi Gears
1st 3.166 * 4.44 = 14,05704
2nd 1.882 * 4.44 = 8,35608
3rd 1.296 * 4.44 = 5,75424
4th 0.972 * 4.44 = 4,31568
5th 0.738 * 4.44 = 3,27672

WRX with sti RA gear
1st 3.083 * 3.90 = 12,0237
2nd 2.062 * 3.90 = 8,0418
3rd 1.545 * 3.90 = 6,0255
4th 1.151 * 3.90 = 4,4889
5th 0.825 * 3.90 = 3,2175
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Old 03-16-2009, 10:27 PM   #40
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Quote:
Originally Posted by Dragon963 View Post
Interesting thread!

I am thinking of rebuilting my '02 WRX transmission with STi RA gear set. I made some calculation and it seems that the ratios with the 3.90 FD will be similar to a STi 5spd 4.44FD (non-RA), except for the first gear that will be quite a bit longer.

If someone have done it before, what's the feeling of it? is the first gear too long when you start from a complete stop, or is it fine?

STi Gears
1st 3.166 * 4.44 = 14,05704
2nd 1.882 * 4.44 = 8,35608
3rd 1.296 * 4.44 = 5,75424
4th 0.972 * 4.44 = 4,31568
5th 0.738 * 4.44 = 3,27672

WRX with sti RA gear
1st 3.083 * 3.90 = 12,0237
2nd 2.062 * 3.90 = 8,0418
3rd 1.545 * 3.90 = 6,0255
4th 1.151 * 3.90 = 4,4889
5th 0.825 * 3.90 = 3,2175
I think You'll like it. It's decent. 1st gear may be long, but most say it's too short. It'll feel like a USDM '07 STi with the 3.900FD with slightly longer 1-2. That's all.

The WRX running the Outback tranny is like the USDM '07 STi running through gears 1-4.
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Old 03-16-2009, 11:30 PM   #41
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I wanna give this gear set a try

3.083 STi RA 5spd
2.062 STi RA 5spd
1.448 '08 Outback NA 5spd
1.088 '08 Outback NA 5spd
0.825 '08 Outback NA 5spd

Have the gears shotpeened and installed with front LSD and a 4.444FD. SO basically just swap out the 1-2 gears on the Outback NA for STi RA and put a 4.444 ring&pinion gears. This will make it Like the STi RA except with a slightly longer 3rd & 4th gear, making the shift into 5th gear not as bad of a RPM drop.

Last edited by FuJi K; 12-20-2010 at 10:30 PM.
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Old 04-24-2009, 07:14 AM   #42
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OK quick one, LGT tranny or the 4.44 fxt tranny for a DD/ rally-auto x. I heard that the FXT 5 speed, is stronger than theimpreza, but where does the LGT tranny fall in?
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Old 04-25-2009, 11:41 AM   #43
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Originally Posted by 04trailsti View Post
OK quick one, LGT tranny or the 4.44 fxt tranny for a DD/ rally-auto x. I heard that the FXT 5 speed, is stronger than theimpreza, but where does the LGT tranny fall in?
I'd say....find a Outback XT 5spd. Geared same as LGT but with a 4.444, which is the same as STi Version 5/6. You'd have to run a push type clutch for '06+ WRX for this application.

The LGT tranny, geared same as JDM STi Ver 5/6 with a 4.111 gives you a little more speed through the gears. The Forester XT tranny will feel shorter. The FXT tranny run the same gearing as the WRX, just with a 4.444FD compared to a 3.900FD and the 3.700FD (ewww). I'd say it was geared that way with the final drive in case folks are looking to TOW, as with the Outbacks and their shorter 5th gear on the NA models and 4.444 on the turbo models. Geared for intended application, see!

For AutoX, people will argue that short gearing is not good, then others will say too long and out of the power band. If you can SHIFT FAST, you are much quick around the autoX course with shorter ratios like the 6spd. The autoX course size matters too. Some places are SMALL, some places are HUGE. I have the JDM 6spd, and it's really nice for what I intend to do with my car. I've driven PPG.... oh that's totally geared for something else, especially running with a 3.900FD... lolz
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Old 04-26-2009, 03:59 AM   #44
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Thanks FK, that gives me another option. would the outback and forester xt tranny be able to hold 300whp or would you be pushing its limits.
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Old 04-26-2009, 04:06 AM   #45
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whats up guys quick question. how hard would it be to put a 07 sti turbo on my 07 wrx??
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Old 04-26-2009, 04:08 AM   #46
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where could i get some work done on my car also. i live in the orange county/ la county area and am looking at upgrading my turbo. if anyone has any suggestions i would appreciate it.. thanks
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Old 04-27-2009, 03:16 AM   #47
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i could be mistaken but this thread is about gear ratios/ transmissions

Last edited by 04trailsti; 04-27-2009 at 09:35 AM.
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Old 05-07-2009, 08:08 PM   #48
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post #4 added with videos. I'll try to get a video of the JDM 6spd runing through the gears and also the PPG one of these days.
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Old 06-07-2009, 02:06 AM   #49
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Quote:
Originally Posted by MFactory View Post
One more for you to add:

MFactory PRO Series Gear Set - 3.454/1.940/1.350/0.958/0.769

Sweet, I have an 02 WRX, what will these be going for ? $$$$
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Old 06-22-2009, 12:22 AM   #50
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wow why didnt i know about this thread before. so ill throw my two cents in real quick, i want to be able to handle 375whp/tq or better, and have similar 1-4 gearing like that of the 07' STi.

so Fuji which would be the best/cost effective option?

MFactory pro gears?

STi RA's? (which i hear arent that much stronger...?)

07' STi 6 speed? (which i would love to have but will take the LGT Spec B if it has less parts but still works and can miraculously fit into my budget lol)


help a man out. im upgrading to a 7cm TD05H 18G soon and want to actually turn the wick up with it and not completely grenade my tranny in the process.
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