Conversion Products from Subaru Gears
About the product
Standard 1999 WRX TY754 transmission in its normal state................................and with flipped differential
With standard ring and pinion the flipped diff gear do not mesh. With the reversed ring and pinion the gears mesh.
The Subaru 5 speed gearbox is a modern, lightweight, compact transaxle designed for a front engine car. Mostly used in WRX and Liberty sedans, this gearbox holds up to 206kw (280hp) in factory STi form.
With a set of aftermarket gears these boxes will handle approx 500kw (650 hp). This makes them a great choice for high turbo race applications as well as everyday vehicles.
The reversed ring and pinion allows all the gears in the transmission to rotate in the same direction as factory, ensuring long life and silent running as designed.
Limited Slip Differentials (LSD's) of all kinds will work with the Subarugears reversed ring and pinion.
This product is compatible with all 4WD Subaru TY752, TY754, TY755, TY758 5 speed transmissions, produced from 1990 and still in production today. The serial number is on a sticker on the bellhousing. The 4WD transmissions are modified to become 2WD transmissions.
The bellhousing pattern is the same on EJ18, EJ20, EJ22, EJ25, EZ30, ER36, EG33. So the fit WRX, Impreza, Forester, Liberty, Legacy, Tribeca, Outback and SVX.
These transmissions suit the EJ, ER, EZ and EG series of engines, both in 4 bolt TY752 (1990 to 1998) and 8 bolt TY754/755/TY758 (1999 on). The transmissions and engines are all compatible with each other.
It is not possible to use this product with the Subaru FWD/2WD transmissions as the gears are different.
It is not possible to use this product with earlier EA style engines or transmissions as the bellhousing pattern is different and the transmission design is different.
This product IS NOT compatible with TY transmissions that have HI/LO range unless you lock the input shaft into direct drive and lose the HI/LO range. The split input shaft and gears in these transmissions interfere with the flipped ring and pinion gears.
This product IS NOT compatible with the larger STi 6 speed transmission TY85…..which is a different design to the TY75…. series.
This product IS NOT compatible with the Automatic transmission.
Modify the right side case to fit the flipped crown wheel. Clearance for the differential carrier, crown wheel and crown wheel bolts should be checked by progressively fitting each part to the right side case. It's finished appearance should be similar to the left side case when complete.
Subarugears machined case ..........................................Customer hand ground and finished case
If you are using the transmission in it's 4WD state then that is the extent of your case modifications. Move on to fitting the Subarugears ring and pinion and differential set up.
Shortening the 4WD case to a 2WD case for Beetles, Kombis, Vanagons.
As we are only using the 2WD part of the transmission, the casing can be shortened to 565mm length (plus 80mm length of shifter support tube that is placed over the top of the torsion bar).
This should be performed on the later style center differential housings from 1999 onwards ( 8 bolt or TY754/755/758)
Earlier style center housings (4 bolt TY752) are difficult to shorten effectively. These are identified by their square panel on top of the center differential case. Newer center differential casings are interchangeable with older side casings.
Mark out the cut line
9cm (3 1/2 inches) from the end with the cast bosses for the mounts. Do not mark all the way around - leave the base of the shift rod support tube unmarked and uncut.
Carefully mark above and below the shift rod support tube. The castings are left thin there so are easy to cut through.
Be very careful - there is a bolt just to the right of this round plate (gearshift interlock) that holds a ball and spring in place. Do not grind off the bolt. Do not grind down the flat mounting surface for this bolt or the tension that the ball and spring places on the interlock will be incorrect.
Rough cut complete....Back................................Right hand side.............................................Left Hand Side
Note there are three holes to fill :
1) Large hole with Subaplug
2) Hole on inside of shifter support shaft, filled with TIG weld, threaded plug, Devcon or Silicon
3)Weird shaped hole on right hand side, filled with TIG weld, Devcon or Silicon
After some finish grinding and flap disc work plus holes filled with Subaplug, threaded plug, TIG weld.
Complete shortened Subaru transmission casing
Here is the driven shaft after being pulled from the trans case:
On a front drive Subaru, or any other front drive longitudinal transaxle, the gears would be mounted directly to the pinion shaft.
This Subaru setup uses a concentric shaft layout and sends a slender front driveshaft through a hollow driven shaft to drive the front differential.
This shaft has the pinion gear on the end of it and is the one that will be replaced.
After the 27mm retaining nut, some washers and a bearing are removed from the end of the shaft so it can be pulled out.
Comparison shot between standard pinion shaft and reversed pinion shaft—note the reversed gear cut on the top one.
The main bearing that the driven shaft rotates on is mounted to the pinion shaft. If your bearing shows no signs of wear you can elect to re-use it.
The bearing itself is not a press-fit, the collar that holds it on is. The main bearing does not run on its own internal race, it runs directly on the shaft.
Installation of the collar can be done with an arbor and press. This shows a quick arbor made from aluminium pipe.
With the main bearing and collar in place, reinstall the smaller surface bearing that allows the vertical surfaces to move against each other.
For 2WD applications, install the Subaspool in place of the splined adaptor, 2 x washers & 1 x surface bearing at the rear of the pinion shaft.
Completed 2WD assembly with Subaspool installed, 27mm retaining nut torque and peened over.
If you have the Subaru factory tool available, set the pinion depth :
Fit the driven gear assembly to the right hand (modified) gearbox casing and torque the retaining plate up. Fit the Subaru factory tool over the gearbox casing with the dowels. Slide the gauge between the end of the crownwheel gear and the plate. This will show you how close your pinion gear depth is to ‘zero’. This picture shows that the clearance is 0.5. The tool can be ordered directly from here.
Adjust the pinion depth with various shims fitted between the shaft retaining plate and the housing. We re-fitted the two original shims to set the pinion depth close to 0.18mm, factory specs.
Next up, set the crownwheel mesh into the pinion gear by adjustment. Assemble both halves of the gearbox, with crownwheel and pinion in place. Screw both side bearing covers in and out as per the factory manual. The pinion shaft should turn easily with a tiny amount of slack when engaging the gears. Once you have met factory specifications, you need to double check the gear mesh with a physical test.
Disassemble the case again and smear bearing blue onto all surfaces of the pinion bearing. Smear bearing blue onto 4 teeth on each quarter of the crownwheel gear. Assemble the gearbox again and turn the pinion shaft a number of full rotations in both directions.
Carefully disassemble the case again and inspect the meshing patterns of the gears, using the factory specifications and illustrations as your guide. Make adjustments as necessary.
The meshing pattern on each gear should slide along the majority of the gear, engaging and disengaging before the ends where the teeth are weaker. Ensure the depth of gear mesh uses the majority of the tooth but doesn’t bottom out.
Mounts - Beetle
Shortened transmission required. Kombi CV's and axles required.
Order:Reversing kit with type 2 Subaflanges standard length.
Quad cam engines require extended Subaflanges & shortened axles to lower the engine under decklid.
Engine / Transmission mount example:
Material used was 6mm steel plate with 65mm x 35mm steel tubing, MIG welded together.
The bolts used are Hi Tensile 12mm x 1.25 x 100mm long with no thread on the are of the shank that the bushes locate on. The bushes are Superpro suspension bushes (SPF2092BK) or in the U.S.A. Pep Boys (Prosteer SL100) which keep the steel plate 'captive' with their raised edge.
Which Subaru transmission should I use?
The latest model, lowest mileage one you can afford, and most closely matched to your engine i.e. turbo / aspirated.
TY752.... from 1990 to 1998 can be used. If you need to shorten & seal the TY752 trans you will need a TY754 or later center differential housing. Their slightly different design makes them ideal for shortening, they bolt up to the TY752 split case housing.
Non-turbo TY752 transmissions used a push clutch which allows you to retain the VW cable clutch and pull the top of the clutch fork away from the engine. These are not suitable for turbo engines.
Turbo TY752 transmissions used a pull clutch which features a hydraulic slave cylinder to push the top of the clutch fork towards the engine.
Non-turbo TY754 transmissions produced from 1999 to 2004 generally used a push clutch with a hydraulic slave cylinder of a different design that pushes the top of the clutch fork away from the engine.
Turbo TY754 transmissions used a pull clutch with hydraulic slave cylinder like the turbo TY752.
TY755 and later from 2005 generally all used a push clutch for non-turbo and turbo applications. These featured a hydraulic slave cylinder to push the clutch fork away from the engine.
TY755 and later transmissions generally have a pop-out stub axle and cv joint as 1 piece. In order to use the Subaflange, a retrofit to the older ty752/ty754 circlipped stub axle and older seals is required. Please note this on your kit order and we can supply.
Are all the bellhousings the same?
The TY752 bellhousings are a '4 bolt' bellhousing and the TY754 and onwards are an '8 bolt' bellhousing. They simply have 4 more bolt holes fitted, the pattern is the same. They can be mixed and matched.
Will the gearshift work the correct way in my vehicle?
Yes the gearshift will work correctly in your type 1 Beetle and your Split Kombi/Bay Kombi. You simply have to join your shift rod to the Subaru shift rod via bolts or universal joints. The forwards/backwards direction and left/right direction will be correct.
In the T25/T3/Vanagon/Syncro/Bulli you will need to modify your shifter at the front to have a ball and socket like the Beetles & Kombis have. This corrects the direction of the shift.
What about the dipstick?
You cannot use disptick anymore since it interferes with the flipped crownwheel. Use a rubber cover such as a chair leg plug and a hose clamp to securely close off the dipstick tube. For a great finished look, use a -12 hex hose finisher :
You can choose to drain the entire 3.7 litres of transmission oil every time you want to check the levels, or simply drill all the way through this hole/boss already cast into the case (circled in orange). Simply fit with the correct size bolt and you can check the correct transmission oil level by undoing this bolt when in the vehicle.
My transmission has different CV's / Stub axles
Transmissions manufactured from around 2006 (TY755, TY758) use a 'push in' stub axle and CV joint that is one unit. The circlip on this unit is smaller to allow the unit to be pushed in and pulled out of the differential.
Old style separate CV joint ------- New style 1 piece CV joint & stub axle
In order to use the Subaflanges, these newer style differentials need to be fitted with the old style stub axles, using a larger circlip to permanently hold the stub axles in the differential. Older style oil seals must be fitted to the transmission case to match up with the size of the older style stub axles.
Good used stub axles and new older style seals are available for purchase in the products section.
We are proud to be partners with Subarugears.com, developer of Subaru Conversion Products for classic Volkswagen, Porsche and Kit Car applications.