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EJ 4EAT transmission into BRAT - any info out there?


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Alright guys, I have a BRAT with an EJ22 swap and a 5 speed D/R transmission. For a while, I've been kind of toying around with the idea of swapping to the EJ 4EAT transmission - I lose low range but I think the torque converter will make up for a lot of that, plus I gain gearing and I won't have to mess with the clutch in low speed offroad situations. I mentioned this idea to my friend, and it turned out he had a 4EAT drivetrain he wanted out of his way, so I ended up with a trans, driveshaft, diff, and torque converter for free. So... I'm going to go through with this idea :)

 

Since I already have an EJ22 swap, the trans will bolt right up to the engine. I retained the TCU wiring on the harness and I still have the TCU from the donor car. I don't drive the car in winter so I think I'll take the time to mod the TCU to work with paddle shifters and mod the trans to give me control of the torque split. I'll I figure I'll have to fabricate a trans support. Pretty much the only things I'm not sure about are the driveshaft and axles. For the driveshaft, I can always have one custom made to length, but I was hoping someone out there has already done this and found an off-the-shelf driveshaft that works. As for the axles, I assume I'll need some kind of hybrid axle that works for the EJ transmission side but EA82 hub side (I'm running a complete EA82 front suspension under my BRAT).

 

I'm sure I've read about people doing this swap before, but I can't find anything right now when I search for it. If anyone can point me to a thread with a similar swap or good discussion, I'd greatly appreciate it.

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Things I thought of while reading your post;

 

Is the 4EAT wider than the D/R?

What spline count on the stubs for the axles?

 

If the auto is wider, maybe use EA81 axles along with EA82 Turbo inner cups to match spline count of trans.

 

Just my thoughts.

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Numbchux has some information here http://www.ultimatesubaru.org/forum/topic/160207-automatic-ej22-brat-swap/ as far as how to get the axles to play nice but you will still have to deal with the problem that the trans is bigger and hits in the trans tunnel. It might be solved with a big hammer or tunnel surgery. 

 

As far as the driveshaft, I think you can use the one out of an '88 or newer GL10 turbo. I think the back of the EJ 4eat is basically the same as an EA82 4eat as far as splines so it should fit.

 

I am thinking about this swap also when my 3at dies just to get the overdrive gear and lockup converter and have gathered most of the parts that I need except the axle stubs for the transmission. I will be following along to see how it goes.

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The transmission will only fit in the tunnel with considerable modification, or a lift.

 

Front diff is not any wider, so that part will not effect axle length. If you are running complete EA82 front suspension (control arms, crossmember, knuckles, struts, etc.) for complete EA82 track width, you can run EA82t front axles. They will have the 25-spline inners and the matched width and outer spline for the EA82 stuff. If you have EA81 track width, you will need custom/hybrid parts to make it work (see the above-linked thread for info on those options).

 

I think silverhelme is correct about driveshaft length. An EA82 4EAT one might work for you, just have to fab a mount for the carrier bearing. Otherwise the slip-yoke splines on your EA81 shaft are the same, you can just have the one-piece one modified for length.

 

Trans crossmember/mount is different.

 

Depending on the donor vehicle, you may need to swap the rear diff, which might create challenges with rear axles. Several ways around it, though.

 

 

My biggest concern is wiring. Depending exactly how the harness was modified/installed, you may want to pull the harness back out and verify that stuff is all connected correctly. There are a lot of small changes between TCU and 4EAT, so you'll have some homework to make sure they will talk to each other.

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Good info! This is what I was hoping to find.

I have around a 4 inch lift with the crossmember dropped 3 inches, so hopefully that's enough extra space to fit the transmission. If not, I'm not opposed to banging the tunnel out with a big hammer, or even cutting a section out and re-boxing it in with some steel plate. And yeah, I have the complete EA82 front end with 2 inches wider track. I think I know someone with a spare set of EA82t axles and probably a driveshaft I could try out, so that's great news. I guess it's mainly the wiring I need to figure out, but I have all winter to work on that. My EJ22 wiring harness still has the original TCU wiring on it, and I still have that TCU, so I figured it would just plug in and all I'd have to do was run a few wires to the transmission, but I guess we'll see.

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  • 4 months later...
  • 1 year later...

Thread dig!

Finnpower, the ea82 engine crossmember doesn't directly bolt into the ea81's position. 

Since Musubk mentioned running a 3 inch lift, I'd say the adaption of the ea82 engine crossmember to the EA81 was done in the lift blocks. Very easy to do it this way. 

Cheers

Bennie

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On 6/15/2018 at 11:39 AM, Finnpower said:

 (I'm running a complete EA82 front suspension under my BRAT).

This got my attention!
What did you modiify in order to make this work?

Do the frame fit bolt on?

 

 

el_freddo is exactly right, it's mostly accomplished via using the lift blocks as adapters. I did it because EA82 replacement parts are a bit easier to find, and the wider stance of the EA82 front end with the strut tops in the narrower EA81 strut towers is effectively like running a camber plate and gives me a couple of degrees of negative camber in the front. Not 'stance' style but just enough to be able to see it. I like it a lot more than the normal positive camber these old Subarus seem to have.

Details on how the front end fit together are in these two videos:

 

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Thanks for the info!
I have just mated my EA81 with the RX-gearbox.
Now Im taking it apart to place restrictions on gear 4 & 5.

I will only be using the lower part of the Leone susp for the Brat.



 (I'm running a complete EA82 front suspension under my BRAT).

This got my attention!
What did you modiify in order to make this work?

Do the frame fit bolt on?

 

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On 2/12/2017 at 11:19 PM, frankenwagon84dl said:

I was able to swap the EJ22 ends on to my EA81 axles to install EJ22 5MT. Use the EA cage with the ball bearings from EJ. I'm stuck on how to get my MT to fit though, it's too tall and even with tunnel mod how would I mount to EA81 bracket? Anyone have ideas?

Could this work for an 5sp?
Then I dont need to change anything else to make the shafts fit.

 

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