THE Transmission Thread 2.0, Now with Pictures

[Ironhydroxide]

If you haven't had some previous experience with transmissions before. Go to THE TRANSMISSION THREAD FOR DUMMIES first, and then return after reading up a bit.

I've been seeing a lot of Misinformation and hearsay about Subaru transmissions going around. I've decided to do this writeup to clear this up, and keep it in an easy to read/understand format for all, newbs and OG's. that said, i am human, i do not know everything there is to know about Subaru transmissions, so if theres something i've missed, please let me know. if something is wrong, also let me know.

and lastly, this is INFORMATION, not a debate on if/what gearsets are strong enough to hold the power. All i'm going to say on the subject of power and gearsets is, I ran an EJ18 1994 Transmission (thinnest gears available) on my 2000 RS with an EJ20G (about 320 BHP with the mods I had), and I autox'ed it as well as Drag raced it with NO issues.

What you need to know about Subaru Transmissions

• Every Subaru Transmission has a Transmission code, this code tells what gears the transmission had stock, and what it came in stock.
• There are 3 Different Styles of transmission
  
  • Phase 1 5 Speed
  • Phase 2 5 Speed (CANBUS info Here)
  • STI 6 Speed (also Legacy SpecB)
• STI 6 Speed (and Legacy SpecB) will not work for the 818 currently. (dont ask here, there's other topics about this, like this one )
• There are 3 different Clutch/flywheel setups for 5 Speed Transmissions
  
  • Push Style clutch
  • Pull style WRX clutch
  • Pull style STI clutch
• If you use a Phase 1 transmission, get a Phase 2 center diff housing.
• Final Drive can be changed in Subaru transmissions (though options are limited)
• A Limited Slip can be added to the Front (our rear) differential
• Specific gearing in the gearsets can be changed, though is much more indepth than just changing final drive.

[Ironhydroxide]

subaru Transmission Codes

Transmission identification codes start with a "T" and an example would be:

TY754VN2AA

"T" = transmission code

"Y" = that it is a manual awd gearbox

"75" = the transmission classification...in the case of manual gearboxes this number indicates the gear shaft spacing in millimeters. 6-speed transmissions use an 85mm shaft spacing while the current generation of 5-speed transmissions use a 75mm shaft spacing.

"4" = some reference to the transmission case. "6" is used for 6-speeds, "4" is used for 8-bolt 5-speeds (phase 2), "2" for 4-bolt Impreza 5-speeds(Phase 1), "5" for Forester 8-bolt 5-speeds(phase 2), "3" for 4-bolt Forester 5-speeds(Phase 1), and "7" for some Legacy turbo 8-bolt 5-speeds(Phase 2).

"V" = transmission specification. "W" is 6-speed, "V" is 5-speed.

"N2AA" = indicates various details about the equipment such as center diff. type, front LSD, etc. and also about minor production changes. In this case:
US Impreza WRX MY02, 1st ratio:3.454, Second Ratio:1.947, Third Ratio:1.366, Fourth Ratio:0.972, Fifth Ratio:0.738, Sixth Ratio:N/A, Reverse Ratio:3.333, Center diff Ratio:1.1, Final Drive (front):3.9, Front differential Type:Open, Center Differential Type:Viscous (4kgf)

• what kind of Clutch the transmission requires (push or pull)
• what final drive the transmission had stock
• what specific gear ratios the transmission had stock
• what vehicle(s) the transmission came in stock
• what center differential the transmission had stock
• what front differential the transmission had stock (yes, there are stock transmissions with limited slip front differentials)
• and sometimes special notes on the transmissions, upgrades, changes, etc.

This spreadsheet has many (i'm trying to keep it updated/find more info) transmission codes and their translation into things we really care about.

Note: If you have a transmission code that is NOT on this sheet above, PLEASE PLEASE PLEASE PM me with the Code and any information you have about the transmission, so I can add it to the list.

[Ironhydroxide]

Differences in Phase 1 and Phase 2 Transmissions

• Phase 1
  
  • 4 Bolt holes (2 for studs 2 for Bolts, 1 for starter with 1 stud for starter mounting) through the bellhousing holding the engine to the transmission
  • 4 Bolt plate on the Center differential, Harder to remove center differential
  • narrower casting down the center split of the transmission case
  • ALL Cable actuated clutches are phase 1, though not all phase 1 is Cable clutched
  
  
• Phase 2
  
  • 8 bolt holes (2 for studs, 6 for bolts, starter now has 2 bolts for mounting) through the bellhousing Holding the engine to the Transmission
  • NO plate on the center differential, MUCH easier to remove the center differential.
  • Wider casting down the center split of the transmission case
  • ONLY hydraulic actuated Clutches
  • All CANBUS systems are phase 2, CANBUS is denoted by the lack of Speedometer Output Shaft on the right side of the transmission case, a plug is installed, these transmissions are the same Phase2 Castings and can have the Speedometer output Shaft and gear assembly installed.

Phase 2 on the left, Phase 1 on the Right



PHASE 1
4 Bolt holes (2 for studs 2 for Bolts, 1 for starter with 1 stud for starter mounting) through the bellhousing holding the engine to the transmission


4 Bolt plate on the Center differential, Harder to remove center differential


narrower casting down the center split of the transmission case




Phase 2
8 bolt holes (2 for studs, 6 for bolts, starter now has 2 bolts for mounting) through the bellhousing Holding the engine to the Transmission, Note, I've installed a stud because I had this transmission mounted to a Phase 1 Engine.


NO plate on the center differential, MUCH easier to remove the center differential.


Wider casting down the center split of the transmission case

[Ironhydroxide]

Differences in Subaru Clutches

Right side is an STI Transmission, but it shows the Pull style, where the fingers actually PULL the throwout bearing
Left side is a WRX 06+ Transmission, with Throwout bearing installed.

• Subaru Hads 3 Styles of Clutch,
  
  • Push Style
    
    • Stamped Steel Clutch fork
    • Pivots on a Ball Threaded into the clutch area of The bellhousing
    • Slave Cylinder Mounting on TOP of the bellhousing
    • flat flywheel (for NON TURBO)
    • Small Stepped Flywheel (for TURBO)
    
    
  • Pull Style WRX
    
    • CAST Clutch fork
    • Fork Pivots on a Steel Pin (like 1"diameter) accessed from the outside Left of the bellhousing, under a plug
    • Slave Cylinder mounts to the SIDE of the transmission BEHIND the starter
    • 6 bolt Pressure plate
    • Flat flywheel
    
    
  • Pull Style STI
    
    • CAST Clutch fork
    • Fork Pivots on a Steel Pin (like 1"diameter) accessed from the outside Left of the bellhousing, under a plug
    • Slave Cylinder mounts to the SIDE of the transmission BEHIND the starter
    • 9 bolt Pressure plate
    • Large stepped Flywheel
  
  
• the Clutch/Flywheel are a SET, and cannot be interchanged Pull to Push style
• The Clutch/Flywheel MUST be matched with the Transmission due to Inherent Casting requirements.
• The STI Transmission (6 speed) CAN be run on the WRX Pull Style Clutch
• The WRX Pull style transmission can be run on the STI Pull Style Clutch WITH MODIFICATIONS TO THE TRANSMISSION HOUSING, you need to clearance the housing to run the STI Clutch.

[Ironhydroxide]

On to the Reason why It matters between Phase 1 and Phase 2. The Center Differential Housing.

Differences in Center Differential Housings Phase 1/Phase 2

• Phase 1
  
  • 4 Bolt plate on top of Differential
  • Two Bolt Oil Catch/director
  • Ball Bearing Rear Output Shaft
  • "L" Style Gear Shift Selector
  • Gets Its Oil Off of the Center Differential
  
  
• Phase 2
  
  • NO Plate on top of Differential
  • Single Bolt Oil Catch/Director
  • Taper Roller Bearing Rear output Shaft
  • "T" Style Gear Shift Selector
  • Gets Its Oil off The 5th Gear

Now those are the Listing of differences, But i'll explain in more detail WHY it matters that we want a Phase 2 Center Differential Housing.
the input shaft of the transmission is NOT oil bathed, rather the gears are oiled by the lower (driven) Shaft of the transmission Flinging oil everywhere. Now this works for most things, including the front input shaft bearing. but it cannot reliably get into the SMALL crevices and bearings of the Input shaft. So the Engineers engineered catch plates to direct oil into the center of the rear part of the input shaft, where it has ports oiling the fifth gear needle bearing and synchro, rear input shaft bearing, fourth gear needle bearing and synchro, and third gear needle bearing and synchro. where these catch plates receive their oil differs between Phase 1 and Phase 2.

The Phase 1 transmissions were designed to get the oil off the center differential flinging oil around (see Photos). this worked fine for Subaru, but when they upgraded the Center differential and Shift selector shaft to the new style that can be removed without releasing the Reverse Interlock, they needed a different place to catch the Fluid, So they used the area around the 5th gear where there was plenty of usable space available.

The fact that the new style does NOT need a center differential flinging oil around, means good things for us. it means we can remove said Center differential, replacing it with a MUCH smaller coupler, reducing rotational mass in the transmission. without having to have an active oiling system installed.

On to the pictures, as they say, the proof is in the pudding. (though you don't want to be eating pudding that smells of Gear lube. LOL)


PHASE 1, WE CAN"T USE THIS STYLE
4 Bolt plate on top of Differential


Two Bolt Oil Catch/director, also Ball Bearing Rear Output Shaft (you can see the ball bearings behind the Oil Director)


Top side of Oil Catch, under the 4 bolt plate (the punch is pointing at the center differential)


PHASE 2, WE WANT THIS STYLE

NO Plate on top of Differential


Single Bolt Oil Catch/Director


another angle of the Catch. showing castings designed to drip fluid onto the catch.


Taper Roller Bearing Rear output Shaft (this really doesn't mean anything to us in performance, but just explanation) you can also see where there is no passthrough on the upper side for the fluid catch/director to go

[Ironhydroxide]

On to Final Drive, and the fun that can come with some slight, fairly simple, changes.

if you don't understand final drive, Feel free to read this next paragraph in blue, if you do. this will be mundane and boooooring

Final Drive, The Last Gear reduction that happens before the power is transferred to the wheels. Taller in ratio means Lower in Number (3.9 is taller than 4.444). Final Drive in the simplest of terms can be explained by this. say you have a transmission with a 1:1 Gear inside, meaning every 360deg rotation of the crankshaft is a single 360deg rotation of the driveline (in our case it will be the center differential eliminator coupler). take this transmission and bolt it to a 3.7 final drive differential. now every 360 Degree rotation requires 3.70 TIMES that rotation in the engine, in this case 1332Degrees. a 4.444, in turn, would take near as makes no difference 1600 degrees of engine rotation.

now this is all good and dandy, we can calculate degrees of rotation and blah blah blah blah. BUT in the real world, a 3.70 means the engine can be turning slower at crusing speed than a 4.444. But everything else the same, a 3.7 will FEEL slower than a 4.444 because your engine will be reving slower for the same speed. and takes more time to accelerate the same amount. if you are looking for a Daily Driver, high fuel mileage item. a 3.70 gear ratio might be your best choice. if you want a "balls to the walls" auto-x machine, where getting through gears FAST makes all the difference, then a 4.444 might be your cup-o-tea.


Subaru Stock Front Differential Final Drives notice, i've left out the 3.545, because it was a REAR differential final drive in the SVX and 02-05 USDM WRX Manual, due to a 1:1.1 Center differential

• 4.444
• 4.111
• 3.900
• 3.700

Changing Your Final Drive
To change a Front Final Drive you Need to have a FAIR DEGREE of mechanical knowledge... It does NOT require any Pressing, but does require cleanliness and a LOT of attention to detal. along with a couple Special tools.

I will explain in BRIEF how to change the final drive, but this is by no means a how-to, and if you attempt to do it off these instructions alone.... well you got bigger balls than Chuck Norris. and i'm not responsible for your expensive learning experiences.

to change a final drive you need to:
First, Remove the center differential housing along with shift selector shaft
Split the case,
Remove the gearset,
Hold the Driven Gearset Shaft with a Special tool, in A CLEAN AREA
Hold the Pinion shaft spline to the Transmission output shaft spline, with a Special Tool. and remove the nut on the end of the shaft
Slide the shaft out of the gearset, mind the bearings and spacers, and order thereof.
slide in new shaft with bearings in correct order.
torque the nut to factory specs, peen in the nut retainers
remove the ring gear from the differential
Install your ring gear with Blue Locktite torquing to spec.
install a matching speedometer gear for your changed Final Drive.
installation is reverse of removal, with One key element. pinion depth.
use the depth tool and the stamping on the pinion to determine shim thickness
set Front differential Bearing preload, and backlash, with the bearing caps on each side of the transmission.

now if your eyes are about as big as your screen right now from the above list, you might want to think about paying someone else to do this, but if you understood about half of what i said, following the FSM (factory Service Manual) you'll be able to fairly reliably change your Final Drive, and if you've noticed, add a Limited Slip

Selecting your final Drive
This CAN BE a highly debated Subject, Though i will try and give you the information to make your decision. also, where to look for what transmission to start your build.

in order to find what Final Drive, one must ALSO be looking at gearset ratios... they work hand in hand, and one cannot say "i need this final drive" before knowing what the range of their desired gearset is as well.

again, in the end it depends on what you want, and what you are willing to do to get it.

on to the fun. and personal research.
This spreadsheet is like the one in the previous posts. but it is organized by Final Drive. Feel free to take that info, and plug the numbers you find into This Website and have some fun. change it up. make it yours.

but lets say you want to know just what gearsets you can get stock, without having to make your own. well here's a list

• STOCK SETS, note, names in GREEN are sets i'd suggest running ie. Stronger sets. Sets in RED are what i'd consider Weaker sets.
  
  
  • 3.083 / 2.062 / 1.545 / 1.151 / 0.825 STI RA 5SPD
  • 3.166 / 1.882 / 1.296 / 0.972 / 0.738 2008-2009 Stock WRX, 05+ Legacy GT, JDM STI 5SPD(non RA)
  • 3.454 / 1.947 / 1.366 / 0.972 / 0.738 2002-2003, 2004-2007 Stock WRX,
  • 3.454 / 2.062 / 1.448 / 1.088 / 0.780 Stock 98-01 RS
  • 3.454 / 2.062 / 1.448 / 1.088 / 0.825 JDM WRX's Phase1
  • 3.454 / 2.062 / 1.448 / 1.088 / 0.871 Some 96-2007 Legacy/Outback, NON TURBO
  • 3.454 / 2.111 / 1.448 / 1.088 / 0.871 Some 96-2007 Legacy/Outback, NON TURBO
  • 3.454 / 2.333 / 1.750 / 1.354 / 0.871 Some 96-2007 Legacy/Outback, NON TURBO
  • 3.454 / 2.333 / 1.750 / 1.354 / 0.972 JDM WRX's Phase1
  • 3.545 / 1.947 / 1.366 / 0.972 / 0.780 93-05 Impreza, NON TURBO
  • 3.545 / 2.062 / 1.448 / 1.088 / 0.780 NON TURBO Legacy GT's, Brighton Impreza's, 02+ Impreza RS
  • 3.545 / 2.111 / 1.448 / 1.088 / 0.780 93-05 EJ22 Impreza, Some Phase 1 EJ25 legacies,
  • 3.545 / 2.111 / 1.448 / 1.088 / 0.825 97-98 WRX Wagons, 95-97 EJ18 Impreza's
  • 3.545 / 2.111 / 1.448 / 1.088 / 0.871 Some 96-2007 Legacy/Outback, NON TURBO
  • 3.636 / 1.950 / 1.344 / 0.972 / 0.780 US Impreza (FWD) MY93-94 (TY752VX3AA)

• NON STOCK SETS
  
  
  • 3.167 / 2.267 / 1.667 / 1.250 / 0.964 Kaaz
  • 3.180 / 1.940 / 1.350 / 0.966 / 0.740 Chalak (now PAR)
  • 3.270 / 2.286 / 1.667 / 1.238 / 0.958 MFactory
  • 3.180 / 1.910 / 1.350 / 0.967 / 0.825 or 0.738 PAR Street Perf.-Drag
  • 2.916 / 1.910 / 1.500 / 1.160 / 0.920 or 0.880 PAR Rally-Track
  • 3.000 / 2.000 / 1.480 / 1.170 / 0.963 Sport Gimmie Gears
  • 3.450 / 1.940 / 1.360 / 0.960 / 0.760 Street Gimmie Gears
  • 3.000 / 2.000 / 1.480 / 1.170 / 0.760 Sport/Street Gimmie Gears
  • 3.454 / 1.947 / 1.366 / 0.963 / 0.738 APS
  • 2.917 / 2.090 / 1.556 / 1.176 / 0.900 Group N Quaife
  • 2.917 / 2.090 / 1.556 / 1.250 / 0.962 Clubman Quaife
  • 3.454 / 2.333 / 1.750 / 1.354 / 0.972 Synchro Quaife
  • 3.080 / 2.150 / 1.350 / 1.050 / 0.738 Andrewtech Automotive (PPG custom)
  • 3.180 / 1.870 / 1.320 / 0.950 / 0.738 PPG SC dog
  • 3.080 / 2.150 / 1.500 / 1.050 / 0.738 PPG HC dog
  • 3.080 / 1.870 / 1.320 / 0.950 / 0.738 PPG SC synchro
  • 3.180 / 1.870 / 1.320 / 0.950 / 0.738 PPG HC synchro
  • 2.916 / 2.090 / 1.555 / 1.176 / 0.900 PPG Groupe N Rally
    

[Ironhydroxide]

Making a custom Gearset

some light reading:
http://www.rs25.com/forums/f8/t10004...ts-ratios.html


Say you aren't happy with the Stock available Gearsets, you want to make one that is YOURS. well you can. but here are some rules you must follow while doing this.

• 1st Gear, 2nd Gear, and reverse are a set. they also determine what phase of transmission case you need. (phase 1 reverse does NOT mix with phase 2 Reverse)
• 3rd and 4th are a set.
• 5th is its own thing.
• Each set needs to have the same "model" Synchros and engagement assemblies ie. shift forks., these DO NOT ALL MIX

That said, you can take any 1st/2nd, throw on any other 3rd/4th, and use any 5th, with any final drive. and there you go, a custom transmission.

What ratios came stock do you ask? well here you go.

• 1st/2nd
  
  • 3.083 / 2.062 (STI/RA)
  • 3.166 / 1.882 (2008-09 WRX, 05+ Legacy GT)
  • 3.454 / 1.947 (2002-07 WRX)
  • 3.454 / 2.062 (Phase 1 WRX, 98-01 2.5RS)
  • 3.454 / 2.111 (NON TURBO, Outbacks, legacies)
  • 3.454 / 2.333 (Phase 1 WRX, Some Outbacks)
  • 3.545 / 1.947 (93-05 AWD Impreza, EJ22)
  • 3.545 / 2.062 (NA Legacy GT, JDM Phase1 WRX, 98-01 RS)
  • 3.545 / 2.111 (EJ18 Imprezas, Early Legacies, Outbacks)
  • 3.636 / 1.950 (FRONT WHEEL DRIVE IMPREZA, DIFFERENT CLUTCH SPLINE COUNT)
  
  
• 3rd/4th
  
  • 1.296 / 0.972 (2008-2009 Stock WRX, 05+ Legacy GT, JDM STI 5SPD(non RA))
  • 1.344 / 0.972 (US Impreza (FWD) MY93-94 (TY752VX3AA))
  • 1.366 / 0.972 (93-05 Impreza, NON TURBO) (2004-2007 Stock WRX,)
  • 1.448 / 1.088 (Stock 98-01 RS, etc, ALL NON TURBO)
  • 1.545 / 1.151 (STI RA 5SPD)
  • 1.750 / 1.354 (Some 96-2007 Legacy/Outback, NON TURBO)
  
  
• 5th (all 5th gears are pretty much the same width, so I find it irrelevant to differentiate by what model for strength purposes... and 5th is usually a cruise/low power required gear)
  
  • 0.738
  • 0.780
  • 0.825
  • 0.871
  • 0.972
  
  

Say you believe any stock gearset, even STI RA, won't be right for you. Well, here's a list of companies who make, OR have made gearsets before (List isn't completely current, pulled from HERE)
Who makes gear sets?
Andrewtech Automotive (PPG custom)
APS (link goes to a retailer as this product is not on the APS website)
Albins Off Road Gears (makers of Possum Bourne gears)
BPM (No longer sells gears)
Chalak gears were named after their designer, Haysam "Sam" Chalak and are now sold under the company he works for, PAR.
FIS
Gimmie Gears (Gears have been discontinued until further notice)
Hewland (makers of Prodrive AKA WRC gears)
Holinger Engineering
Kaaz
KAPS
MFactory
MRT Performance
Modena Engineering
PAR (Precision Automation Robotics)(makers of TRP gears)
PPG (Pfitzner Performance Gearbox)(makers of TurboXS gears)
Possum Bourne Motorsport
Prodrive (apparently they've stopped selling to "road users")
Quaife
S&J Automotive
STi (link goes to a retailer as STi does not have gears on their website)
TRP (Tony Rigoli Performance)
Zero Sports

[Ironhydroxide]

As for Limited Slip Differentials, There are a Myriad of Manufacturers of Limited slip. and the only thing different about the 93-03 and the 04-14 Transmissions are the Seals for the Differential Output. Male Axles or Female axles require their own seal, but you can switch back and forth long as you change the seal in the transmission. THIS MEANS that you can get ANY 5 speed Subaru Front Differential (doesn't matter the year) and put it in, then all you have to do is match the Axles and Seals to the Differential, and you have a runner.

as there are so many options of Limited Slip, and there will ALWAYS be debate on which style of diff is the best. I won't be getting into that debate here. theres too many opinions. and it's all up to the specific person driving the vehicle.

Simply search for Subaru 5 Speed Front Differential on Google, and you'll get enough links to read to your death.


So, now you have a TON of information, what to do with it, is your choice. I will not debate, nor go into the strength of the Gears. I personally feel they will be PLENTY to support my Planned EJ22 W/25 Crank, 9.5:1CR and an M90 on top.


if you see something wrong, let me know, if you find something that needs to go here. let me know. I'm willing to change the info. and keep this updated

*wipes brow* Whew, that was a lot of typing.

[Evan78]

Here's a copy of the previous thread, courtesy of Google's cache. At the top of the page, it says the cached copy is from April 22.

[sponaugle]

For those interested in rebuilding the 5-speed, here are some pictures from a rebuild I did back in 03. This is a WRX 5-speed that had a broken 3rd gear (I have a funny video of it breaking I need to post as well).

[sponaugle]

... continuation of previous post..

[sponaugle]

... continuation of previous post ...

Also, here is a shot of the 5-speed during dis-assembly. You can see the broken 3rd gear, as well as the 3rd gear teeth in the front differential. This failure occured at Portland Raceway during a track day, pushing a little over 400whp.




I would not expect this kind of failure in the 818 use case, given the lack of AWD and the tractive components of that much power delivery. As well, this was a very early 2002 (March 01 build date), and there were some improvements in the gears post this.

Cheers,

Jeff Sponaugle

[Ironhydroxide]

... continuation of previous post ...

Also, here is a shot of the 5-speed during dis-assembly. You can see the broken 3rd gear, as well as the 3rd gear teeth in the front differential. This failure occured at Portland Raceway during a track day, pushing a little over 400whp.



I would not expect this kind of failure in the 818 use case, given the lack of AWD and the tractive components of that much power delivery. As well, this was a very early 2002 (March 01 build date), and there were some improvements in the gears post this.

Cheers,

Jeff Sponaugle

Please tell me that isn't your front diff with bearings on the asphalt

[sponaugle]

Please tell me that isn't your front diff with bearings on the asphalt

Well, there really isn't any other way to get those stress reducing scratches is there?

Remember this was back in 2003 when I was much stupider. Now I would at least put a cardboard box down.

Jeff

[IMPREZvWRX]

I'd also like to add that the 05+ Legacy GT 5-speeds do not have the speedo stuff installed, and they must be split open to add it.

[Ironhydroxide]

I'd also like to add that the 05+ Legacy GT 5-speeds do not have the speedo stuff installed, and they must be split open to add it.

I clarified a note on the CANBUS systems. if someone is going to build a transmission, adding the Speedo stuff isn't beyond them.

[Mitch Wright]

Ironhyoxide, thanks for the transmission information. You touch on adding a limited slip, what's available?

[Ironhydroxide]

Added a snippet about Limited Slips.

[Frank818]

• STI 6 Speed (and Legacy SpecB) will not work for the 818 currently. (dont ask here, there's other topics about this)

I couldn't find that topic, can anyone guide me?
Cuz I need a 6-sp (different reasons why) and I want to understand what I have to change to make one fit. If I can...

tnx

[Xusia]

Main issue is that it's too long (it will protrude past the end of the car). AWD to 2WD conversion is another issue (both electronics & physical). There may be others as well. I doubt we'll know them all until someone tries.

[Frank818]

Well it looks like a project in itself.
After the discussions I had here this morning, I decided to ditch the idea of a 6-sp, STI donor and equal-size twin-turbo engine. loll Not bad, it simplifies my project!

tnx to you guys for helping.

[Frank818]

About gear ratios, applications and whatnot, I found this http://www.rs25.com/forums/f8/t10004...ts-ratios.html

A LOT of options, but I really like the part where it says which ratios and kits to use depending on your power output and application type.

[riptide motorsport]

I'm sooooo confused!

[Ironhydroxide]

About gear ratios, applications and whatnot, I found this http://www.rs25.com/forums/f8/t10004...ts-ratios.html

A LOT of options, but I really like the part where it says which ratios and kits to use depending on your power output and application type.

Added to Links, thanks for the link.

[Ironhydroxide]

I'm sooooo confused!

May i ask what's confusing you?

[Samiam1017]

Wasn't there a few build threads on here. How to convert to fwd and removing the center diff? And I think somebody did a LSD install. They should be linked here if anybody remembers who did them

[SkiRideDrive]

Was thinking about the possibility of a 6 speed again, especially in the wake of the 3rd gear failure at VIR. One thing I noticed was that even though locking the center diff will be much more expensive (people have posted couplers in the 600 to 1,000 dollar range), it seems that the 6 speed already comes with a limited slip front diff, which is a cost saver. Still not sure about physical size and fitment.

[Frank818]

fateo666 wants to check on that (physical fitment), apparently, if I recall his post, he thinks it will fit given minor modifications. But that's all I know, if anything interesting it is.

If it comes with a nice LSD, then yeah that's great.

[FFR-ADV]

Was thinking about the possibility of a 6 speed again, especially in the wake of the 3rd gear failure at VIR. One thing I noticed was that even though locking the center diff will be much more expensive (people have posted couplers in the 600 to 1,000 dollar range), it seems that the 6 speed already comes with a limited slip front diff, which is a cost saver. Still not sure about physical size and fitment.

Given the 3rd gear failure at VIR, I think that the STI transmission is worth revisiting. I plan to hold back on the Quaife LSD I had planned for my 04 WRX transmission until more of this option is known. Hopefully we can find out sooner than later what options we can create. Thanks to all who have contributed so much to this thread and the forum.

Cheers!

[Bob_n_Cincy]

With all the discussion on LSD tonight. I thought I'd try and get an answer to my transmission question.

My Transmission is a 5MT out of a 2006 NA impreza wagon. I'm using a 2004 FTX turbo engine.
I have been told that my transmission is weaker than the units out of turbo vehicles.
What part of the transmission is weaker?

I don't think the 818 will break transmissions. Here are my reason for that.
On a 3200 lbs AWD WRX you have 4 x 215mm tires so 3200 x 4 x 215 = 2752000 btu's
On a 1200 lbs RWD 818 you have 2 x 265mm tires so 1200 x 2 x 265 = 636000 btu's
So you only have 1/4 the propulsion grip in the 818.
So the torque max through the transmission is limited to 1/4 by tire grip in the 818.

EDIT: In higher gears where the tires wont break loose, the clutch must act to protect the transmission. So I won't be putting a crazy clutch in.

the btu's = Bobs Traction Units
Now back to the LSD

[07FIREBLADE]

Why is it 1200lbs instead of 1800? Just wondering.

[Bob_n_Cincy]

Why is it 1200lbs instead of 1800? Just wondering.

That is my estimated weight on the back wheels.
Bob

[Gary Livingston]

Can anyone tell me the weight of the WRX 5 speed transaxle? Thank you.

[Xusia]

http://thefactoryfiveforum.com/showt...l=1#post137798

[Ironhydroxide]

With all the discussion on LSD tonight. I thought I'd try and get an answer to my transmission question.

My Transmission is a 5MT out of a 2006 NA impreza wagon. I'm using a 2004 FTX turbo engine.
I have been told that my transmission is weaker than the units out of turbo vehicles.
What part of the transmission is weaker?

I don't think the 818 will break transmissions. Here are my reason for that.
On a 3200 lbs AWD WRX you have 4 x 215mm tires so 3200 x 4 x 215 = 2752000 btu's
On a 1200 lbs RWD 818 you have 2 x 265mm tires so 1200 x 2 x 265 = 636000 btu's
So you only have 1/4 the propulsion grip in the 818.
So the torque max through the transmission is limited to 1/4 by tire grip in the 818.

EDIT: In higher gears where the tires wont break loose, the clutch must act to protect the transmission. So I won't be putting a crazy clutch in.

the btu's = Bobs Traction Units
Now back to the LSD

from my experience, all NA vehicles have the "narrower" gearsets that were found in the 02-03 WRX transmissions (and consequently all PRE 02 WRX and STI as well, except for the special editions, S201, 22B, RA, R, RA-R)

i personally ran a 4.111 Final Drive "RS" transmission behind an early EJ20G making 280 AWHP and didn't have any issue, and i FREQUENTLY beat on it.

that said, i'm currently in the testing phase of Cryo'd and Shot peened "strengthened" transmissions, I'll mainly be pitching them to the AWD Guys, but building some for 818's is NOT an issue either. SO, if someone wants to test one, PM me and we can work something out. (BTW, this is NOT a sale, if I do get to selling them i WILL be starting a vendor account)


so, in answer to the question: the DRIVE GEARS themselves are weaker, the transfer gears, and differentials, are all plenty strong to hold higher HP.

[longislandwrx]

So you don't subscribe to the "case flex theory" that the gears are fine and excessive case flex breaks all these gears?

[Bob_n_Cincy]

So you don't subscribe to the "case flex theory" that the gears are fine and excessive case flex breaks all these gears?

Thanks Ironhydroxide for the response

Hi longislandwrx..
Let me put on my mechanical engineering hat on.
When you have a engine spinning at 4000-5000 RPM there is a lot of stored inertial energy in the engine, flywheel, and clutch cover.
If the clutch had teeth to grab the flywheel and the car was strapped very tightly to the trailer. When the clutch was engaged, all stored energy would be released instantaneously. TORQUE SPIKE. Weakest link would break every time.

There are 2 protection to prevent this from happening. Tire slip and clutch slip.

My 3 reason transmissions fail.
1. AWD with sticky tires override the tire slip protection.
2. High torque aftermarket clutches override the clutch protection.
3. Aggressive driving fatigues the gear teeth. Three strikes your out.

I believe the gear teeth in the transmission are failing when the torque spike flexes them. With repeated flexing the teeth start to crack and eventually break off. Then all S*** hits the fan.

Bob

[Scargo]

Am I correct to say that an optimal transmission for the 818 needs to be a Phase 2 type transmission (No Plate on top of Differential) and NOT one from a normally aspirated vehicle having the "narrower gearsets" (found in the 02-03 WRX transmissions and all PRE 02 WRX and STI as well, except for the special editions, S201, 22B, RA, R, RA-R)?

I don't think the transmissions listed in the spreadsheet reflect that limited selection. Could those be notated as such or have they been eliminated from the list? In what years/models does the Phase 2 transmission appear?

The gear failures mentioned here, in this thread,... were in the "better" transmissions? What tranny was the FFR car running that lost third gear? In sponaugle's?

[bompus]

I'm looking for a rough estimate on the cost for a competent transmission shop to install a Quaife front LSD and replace bearings / seals in the transmission. I need some kind of baseline to compare against some local shops. If anybody has experience with having this done or knows how much it -should- cost, let me know. Thanks!

[TahoeTim]

Am I correct to say that an optimal transmission for the 818 needs to be a Phase 2 type transmission (No Plate on top of Differential) and NOT one from a normally aspirated vehicle having the "narrower gearsets" (found in the 02-03 WRX transmissions and all PRE 02 WRX and STI as well, except for the special editions, S201, 22B, RA, R, RA-R)?

I don't think the transmissions listed in the spreadsheet reflect that limited selection. Could those be notated as such or have they been eliminated from the list? In what years/models does the Phase 2 transmission appear?

The gear failures mentioned here, in this thread,... were in the "better" transmissions? What tranny was the FFR car running that lost third gear? In sponaugle's?

+1
It would be handy to highlight the preferred rows in green and/or the weak ones in yellow. I seem to be finding a lot of TY755VB1AA for sale but that particular transmission has very little info about it on the net. good? bad?