Automatic EJ22 Brat swap

[hanyou]

I have seen plenty of threads about swapping manual engines and transmissions into the Brat, but does anyone have a build thread for an automatic?

I am looking to essentially buy an automatic Legacy and swap over the entire drivetrain into an automatic Brat. Is anyone aware of any fitment issues or other trouble to expect or am I mostly looking at a bolt on situation?

 

Any/all speculation welcome! Thanks!

[idosubaru]

the mechanical part will be easy - AT bolts in just like an MT but has different length so the rear driveshaft is a little shorter. other than that it drops in mechanically just the same.

 

computer and wiring is going to be all different and need completely migrated from one chassis to another, so it's just the same wiring circus but much bigger project to get it running via the TCU.

Edited August 24, 2016 by grossgary

[silverhelme]

Your biggest problems will be tunnel fitment and axles. You may be able to get enough clearance for the bigger 4eat by using a big hammer but I think I have read that you need to modify the tunnel by cutting and fitting. The axles are another story.  I don't know of any off the shelf axles that will fit. All the ones I have heard of involve either splicing two halves together or having a custom shaft made and using the correct inner and outer ends.

 

I keep thinking about trying to work this out but the 3at I'm currently using is still going strong after 2 years. The only thing I miss is the OD 4th gear and lock up converter for gas mileage as the 3at only gets about 20 mpg in town and 28 highway with the 2.2.

 

The rest is as Gary said, just don't trim out the transmission wiring when you make the harness for the swap.

[idosubaru]

ah an MT fits but an AT doesn't in the tunnel?

 

spacers between the crossmember and trans mount to push it down enough?

[silverhelme]

If I remember correctly from what I have read ( I haven't yet done this myself ) the 4eat can be put into pre '88 ea82 cars with just some healthy use of a large hammer but I don't know about ea81 cars. The tunnel was enlarged in '88 to fit the 4eat that was used behind the turbo engine.

 

Like I said that is not the biggest problem, it is the axles. In an ea82 you can use the stock axle to swap in pre '88 cars but there is no option for ea81 cars other than cut and weld or have a new shaft made or new spine machined on an old shaft to accept the correct inner joint.

[Numbchux]

Define "entire drivetrain". Just engine/transmission/diff? or suspension and axles, too? With a little swapping of brackets and studs, the rear diff will physically bolt into the car, but you'll have problems with axles (many options there). And with a little grinding, the EJ engine mounts will work in the EA81 crossmember. Nothing else will bolt up. Nothing.

 

 

Yep, the 4EAT is considerably bigger than any 5MT or 3AT, similar in size to an STi 6MT (so fitment challenges are similar). It is true that the '87.5 EA82 tunnels changed, which gives room for the 4EAT. This also means the EA82 transmission crossmembers are different, as the mounting locations got further apart. Doing a lift would probably make it work...

 

I'm not aware of anyone putting a 4EAT into an EA81. You might find an STi 6MT in one, though. Although I can't think of any examples of that.

 

All 4EATs are 25 spline outputs to the front CVs, and all EA81s are 23 spline. Good news, is the MT have the exact same inner spline count, diameter, and length, only difference is the groove for the circlip or snapring. So it's possible to get a pair of 23-spline EA82 5MT axle stubs, and machine a new groove.

 

Here's the before, 4EAT on the left, EA82 5MT on the right:

 

And after, one on the right has been machined for the larger circlip on the 4EAT (This was done to use a Carbonetic clutch-type front LSD in a 5MT, which uses the 4EAT-style stubs). 

 

 

EA81 transmission mounts are completely different than EJ, so any of those options require a custom crossmember. But it is similar to an EJ 5MT, so there is documentation of it.

 

 

Swapping the suspension and such will be MUCH more difficult. A lot of cutting, welding, measuring. Dozens of people have talked about doing it, and I think only one ever actually finished it (A brat in the UK).

[silverhelme]

I knew i'd seen a write up on how to convert to 23 spline some time ago  but my searches didn't turn up anything ( probably wrong search terms ). I've been thinking about changing to the 4eat to get the overdrive and lockup when the 3at goes. Do you have any more info on this or can you point me to the write up?

 

As far as this guy's swap I think there was one in Australia that was finished also.

[hanyou]

Thanks for the info all, looks to be more involved than I care to take on at the moment. For now I think I will just work on getting a JDM Forester to strip for when I move back to the US.