Subaru Tri-hybrid FT4WD Transmission (centre locking differential)
The idea behind this was the ability of having AWD while not losing the 4WD advantage. Aussie’s won’t know much about the FT4WD gearbox I am talking about and American’s won’t know much about the dual range (D/R) EJ gearbox either. But I will explain everything here.
Just so you know, I spent 5 months reseaching this before I bought anything or even pulled apart anything for that matter.
The idea spawned from wanting to do an EJ conversion which normally requires an adapter plate to adapt the engines bolt pattern to the gearboxes. Although if you use the EJ gearbox this isn’t needed. But even with the ability to convert the low range in the D/R EJ box to the better EA82 gearing you still have AWD with a viscus centre diff which can allow you do get stuck with only 1 wheel out of traction. Where as 4WD locks the rear and front diffs together so you have to always be turning 2 wheels at a time. After the weeks of research I decided it was time to buy and find out for sure if the EJ D/R gearbox is really just the same gearbox as the old EA82 one only with a different engine mounting and a centre LSD.
I bought my FT4WD (import only here in Australia) from Rising Sun in Adelaide for a very decent price. And I already had the full EJ22 Liberty (known as Legacy’s else where) donor car with the D/R transmission. Plus I had a normal EA82 5sp with the 1.59 to 1 low gear set to go in the EJ casing. So I got stuck into ripping the gearboxes apart. This is a rough guide of the steps I took to pull the box down as much as I needed to:
1. Remove bolts from rear plate and remove rear plate. In the case of the AWD boxes you are pulling the diff off the splines so it may be diffecult.
2. Remove bolts from top plate and remove.
3. Remove bolts from rear casing (holds center diff or 4WD selector gears.)
4. Pull the rear casing backwards off the gearbox, this may require force as some bearings are seated in the gearbox casing.
5. Remove the bolts on the front bearing right behind the clutch
6. Remove all bolts holding the casing together and then pry the gearbox apart only around the outer edge of the bolt holes or on proper prying spots. It will be hard to split the gearbox.
7. When the gearbox splits becareful not to let the front diff damage the seals and do not adjust the side diff bearing load caps.
8. Try and keep the gear sets in each side of the casing as the low range synchros might fall apart. And it’s best to pull them apart so you know how they fit back together.
For putting a 1.59 to 1 low gear set in the EJ box (comes with 1.19 to 1 normally) you will need to change the whole shifter fork, gears, synchros, etc.. Heres how.
Remove the input gear shaft (the one with the low range gearset which is right at the beggining of the gearbox after the clutch) and place it on a bench. Carefully pull the synchros apart so you split the input shaft from the gearset shaft. There are split rings holding the gears on the gearset and input shafts I believe, remove these to remove the low range gearset completely. Also you need to take out the low range carrier shaft from the casing. These use split rings as well and are hard to remove. Try using a pair of pliers over the shaft pushing of both sides of the ring and hammer the pliers. Then pull the shaft out the front of the box and then remove the gears and bearings from the box. Do the same to both the EJ D/R and the PT4WD EA82 5sp. Then install the PT4WD low range in the EJ casing doing the reverse of what I side. When you put the EA82 PT fork in you might want to add a detent to it. The detent is a flat surface with a hole in it for a ball and spring in the casing to push against it to lock it in low range. I have heard this is not needed but if you don’t do it you may expereince low range popping out of gear or even worse the synchros moving to far and falling apart inside your gearbox. To put the detent on the new fork you will need to weld on a patch out the side of the fork and grind it flat. Then using the EJ’s fork to compare drill the hole in the exact same position (important you get it exact.) You may also want to put another patch of weld coming off the fork for the low range light swtich which is in the gearbox.
The reason the EJ transmission has the detent and swtich is because the PT gearboxes have the low range lever connected on a bar to the back casing which holds the detent and swtich. This is so the 4WD lever is for both 4WD and low range. Where as the EJ AWD only needs a low range lever.
Sorry, not finshed yet!
I bought my first Subaru back in 2005, it was a 89 Brumby, flair red. I lifted it, fitted Kumho 27″ MT’s. After a while I swapped the dual carb EA81 it had with an EJ22 bolted on a custom gearbox which used EJ D/R casing, EA82 5sp low range and an RX centre locking diff. Once I sold the Brumby I got a 83 Leone. Converted it to 4WD, put the Kumho’s on it, added a 5sp and drove it like I stole it. I then upgraded to a 99 Outback. It was hail damaged so I repaired it myself. I fitted it out with some storage and a mattress. I now have a 87 Brumby that I’ve resprayed with two pack urethane in Waratah Red. I am planning to fit an EJ with PT gearbox and a little bit of lift. It’s another project in progress.
Phizinza – who has written 50 posts on Offroading Subarus.