Retrofitting FAQ

[Numbchux]

Intro

Alright, I just noticed that I can edit old posts. So I'm starting a FAQ post. I will try to keep on this to keep it updated. My plan is basically just a list of useful thread links, specifically for things that are hard to search for (my first thought is 5-lug swap stuff...). If you come across a particularly useful thread or link (does not need to be something posted on the USMB), whether you are the original poster or not, post it up.

 

I envision this to be a retrofitting-specific FAQ. Focused on using parts from/for one car (usually Subaru model, but not necessarily) on a Subaru. Be it for some sort of upgrade, or just parts availability.

 

I also think this will lean a little more towards old-gen cars (my specialty was EA82s, so it will start very heavy in that department). New-gen retrofitting stuff is usually pretty well documented on other sites like NASIOC and others.

 

 

 

 

 

 

 

 

First place to look, is the Ultimate Subaru Repair Manual. It's current configuration (as another section on the forum) is easier to host and maintain than others, but it does sort of blend in with the rest of the forum. This has been around for about 15 years at this point, so there are more than a few dead links, and outdated information, but it's a great start.

http://www.ultimatesubaru.org/forum/forum/30-ultimate-subaru-repair-manual-the-knowledge-base-of-usmb-complied-posts-and-writeups-to-common-problems-and-projects/

 

 

 

EA to EJ swap manual. This was written 10 years and a couple months ago, so it's a little dated, but hopefully still useful.

Current sources:

http://wordpress.suberdave.com/wp-content/files/EA82/EA2EJ.pdf

https://lib.store.yahoo.net/lib/mroseusa/EA2EJ.pdf

http://offroadingsubarus.com/downloads/EA2EJ.pdf

 

This thread is extremely useful for finding people here who have done these swaps. You might find someone who's done the same or similar combination that you are, and you can search for their posts....

http://www.ultimatesubaru.org/forum/topic/80134-ej-swap-whos-who/

 

Modified flywheel pictures:

http://www.ultimatesubaru.org/forum/topic/79328-todays-project-ej-ea-modified-flywheel-pics/

 

 

SPFI EA81 write-up by General Disorder

On 7/5/2017 at 4:13 PM, Crazyeights said:

The SPFI conversion file is here in my Dropbox;

 

https://www.dropbox.com/s/k4kdbpaclc6sko4/EA81_SPI_guide.pdf?dl=0

 

Until it isn't 

 

 

I think the 5-lug swap is one of the next most important projects that should be in here. It can be hard to search for, and there are so many ways to do it.

 

Very old post in the USRM: http://www.ultimatesubaru.org/forum/topic/47998-5-lug-conversion-list-plus-tips/

Anything in there that refers to "GC8 Impreza", can actually be any 5x100 EJ-chassis car.

Not to many details on the setup, but many pictures of my first swap: http://www.ultimatesubaru.org/forum/topic/76502-frankenwagon-suspension-build-up/

 

FYI, XT6 or EJ knuckles use a larger diameter stud on the tie rod end, the EA82 rod ends will not seat correctly. With XT6 knuckles, just use XT6 rod ends. EJ knuckles are shaped differently to change the Ackerman angle, and require a shorter tie rod. Ea81 rod ends work perfectly for this.

 

 

Shock/Strut options. After the 5-lug swap, you can run almost any EJ front strut, which gives you a myriad of options for performance options. But, KYB Excel-G is about the only option for the rear that's at all stiffer than stock, and that's just barely. Luckily, "NB" ('98-05) Miatas use a VERY similar shock. They have less travel than the EA82s, but come in 2 different lengths for your ride height preference. Fronts are very close to stock EA82 length, and rears are about 4" shorter. The Miata uses a larger diameter spring, so you will need to use a coilover sleeve kit. Pictures of that install here. This is with the longer front shock, but the upper mount flipped upside-down to lower a bit. I later switch to the standard upper mount, Miata rear shock, with a bit more preload on the spring.

http://www.ultimatesubaru.org/forum/topic/75933-holy-grail-of-ea82-rear-shocks-found/?p=741734

 

 

 

Coilover sleeves

These are pretty handy, as they allow the retrofitting of a very universal 2.5" ID spring to almost any strut, with adjustable pre-load (ride height) for fairly cheap. EA82 rear springs are 2.5" ID already, so these kits fit very easily on the rear. I used a kit that was designed for a "GC" Impreza for many years on my Loyale, both in 4- and 5-lug configuration. I later bought a Ground-Control set that was specifically designed for EJ struts in the front and Miata in the rear. Here's some information on that, cliff notes: I would just order for an Impreza in the future

http://www.ultimatesubaru.org/forum/topic/75933-holy-grail-of-ea82-rear-shocks-found/?p=739855

 

 

Complete Coilovers

This is a completely new strut/spring assembly, typically tuned specifically for the chassis for which they were designed. '00-'09 Legacy/Outback have a very similar rear shock design to an EA82, and there are some coilover options for the '05-'09 in particular. I believe WJM (RIP) was the first to do it, but Suberdave was the first to document Tein Flex coilovers in an EA82 body:

http://wordpress.suberdave.com/?page_id=54

 

'08+ Impreza, '09+ Forester, all Tribecas, all BRZs and '10+ Leg/Outback have a still-different rear suspension design, but uses a very similar rear shock. Nico has used these ('08-'12 STi to be exact):

http://www.ultimatesubaru.org/forum/topic/126559-retro-gl-10-turbo-build/?p=1227259

 

Others have been used, but it requires putting the EA82 upper mount on the coilover, so the exact fitment will depend on the specific brand and model of coilover, not just the application.

 

 

Driveshafts

EA82 4WD 5MT transmissions are all the same length (driveshafts are interchangeable), including XT6.

EA82 4WD 3AT transmissions are the same length as the EA82 5MT

4WD 4EAT transmissions are longer than the 5MT (require a shorter driveshaft).

EJ AWD 5MT transmissions are longer than EA82 5MT, but shorter than 4EAT.

STi 6MT are the same length as the 4EAT.

 

All EA82 chassis have the same wheelbase, so driveshafts will interchange between body styles (same transmission).

EA81s......What should be mentioned RE: EA81 driveshaft length?

 

All Subarus use the same slip yoke where they slide into the transmission (Possibly with the exception of the BRZ)

 

93-07 Impreza 4eat driveshaft just happens to be the perfect length for an ea chassis with an ej awd transmission. The one I used is from a 99, and I had to swap the pinion flange on the 1st gen legacy rear diff because somewhere through the years they changed to a larger bolt pattern than the earlier r160s used. Also had to make carrier bearing mounts, but perfect length, straight out of impreza into ea81 car.

 

No EA82 or newer Subaru is designed to have serviceable U-joints, they're staked in. But it's been done, there are 2 driveshaft shops here in my town that can rebuild them, so it's fairly common.

https://www.ultimatesubaru.org/forum/topic/168456-driveshaft-ujoint-replacement/

 

 

Axles

EA81 front axles at the transmission are all 23 spline

EA82 turbos and XT6s are 25 spline, all other EA82s are 23 spline. 5MT stubs can be swapped, but require splitting the transmission

'93-'94 FWD 5MT Imprezas are 23 spline

All other pre-'05 EJs are 25 spline

After '05, EJs all switch to male splines on the axles that fit into the transmission. Interesting, the stub axles from an earlier 4EAT will pop right into these transmissions, though.

 

EA81 front axles are shorter (narrower track) than EA82

Early EJ ('90s for sure, probably others) are a bit longer than EA82/XT6 axles, some have reported issues...

GD Imprezas ('02+ Impreza Sedan) have a wider track, and therefore longer axles.

 

86BratMan posted his recipe for the ball joint reamer he used to modify EA control arms to accept EJ ball joints, and the EJ inner and outer joints that he was able to slip onto the EA81 shafts to use EJ transmission and EJ knuckle with EA81 track width:

http://www.ultimatesubaru.org/forum/topic/162269-converting-4x140-to-5x100/?p=1350309

 

Transmissions

I'm not going to get into the minute differences between stock replacement transmissions over the years. Here's a really good chart with gear ratios and stuff for EJ transmissions, with transmission code (printed on the bellhousing near the starter):

https://www.rallispec.com/downloads/Transmission ID Chart_Public.pdf

 

As far as major differences for swapping (mainly talking manual transmissions, as autos introduce a considerable amount of complication with wiring), axle spline counts and driveshaft differences are a major concern. Also, there are a few different transmission mount options...

 

EA81s had a unique transmission mount situation, and basically any swap will require some sort of custom crossmember

 

EA82s changed transmission tunnel in '87.5. The mounts on the transmission didn't change, but the crossmember did. Manual transmission XT6 got a 3 piece crossmember like most EJs, the front and rear XT6 crossmembers will bolt up to the center EJ piece, and allow an EJ transmission to bolt in (custom driveshaft still required....but...)

 

STi 6-speed will fit in a '87.5+ transmission tunnel

http://www.ultimatesubaru.org/forum/topic/97346-will-a-sti-6-speed-fit-in-an-88-gl-yes-pics-inside/

 

And, of course, rear diff ratio has to match. With the exception of the STi and BRZ, Subarus have all gotten the r160 rear diff. Axle splines and gear ratio are really the only thing that effect interchangeability.

 

Putting an r180 in an EA82:

http://www.ultimatesubaru.org/forum/topic/111035-goodbuy-r160-hello-r180/

 

 

EA82 vs EA81 flywheels:

http://www.ultimatesubaru.org/forum/topic/163014-ea82-flywheel-in-a-ea81/

http://www.ultimatesubaru.org/forum/topic/162986-a-few-questions-on-swapping-to-a-dual-range-tranny/

 

 

 

EJ Modified-MacPherson rear suspension under a Brat

http://www.ultimatesubaru.org/forum/topic/93247-build-thread-off-wrx-pickup/

https://www.ultimatesubaru.org/forum/topic/165430-1982-wrx-brat-swap/

 

 

A new creative way to do it:

jdmleggy97 torched the old bearing out, and welded a new face onto the EA82 trailing arm to mount an '00-'04 Outback rear hub/bearing/brake assembly onto the EA82 arm. Now he can use off the shelf rear axles.

https://www.ultimatesubaru.org/forum/topic/168379-writeuptread-loyale-rs-ej-5-lug-hub-fabrication/

If I were to do it, I *might* look into using '08+ Impreza, '09+ Forester, or '10+Leg/OBK parts, as I think that would give more axle options (and therefore diff options). But that's splitting hairs.

Edited June 20, 2023 by Numbchux

[Numbchux]

Reserved for future expansion

[Numbchux]

Another one reserved

[Numbchux]

One more just in case

[silverhelme]

Nice write up. I am probably one of the few who care about the 3at and am currently running one behind an EJ22. I am pretty sure the drive shafts are the same length as the 4 speed shafts on EA81 cars and the same as the 5 speed shafts EA82 cars

[86BRATMAN]

The 3at and 4sp ea81 driveshafts are indeed the same length. But they're also made with serviceable u-joints, only ea82 and newer platforms have staked u-joints.

 

In a few of my posts I have given links to aftermarket inner and outer cv's that will fit the 22 spline ea81 axle shafts to allow a DIY 25 spline ej axle for a 5 lug swapped ea81. As well as a link to a ball joint reaming tool that has the correct taper for ej/xt6 ball joints that will eliminate the need for xt6 control arms.

Edited March 11, 2017 by 86BRATMAN

[Numbchux]

Thanks guys!

 

Do you guys know how the EA82 3AT compares length-wise? Is it the same as the EA81 3AT?

 

 

 

Bump! I added a few things, but I'm looking for more! I think the EA81 SPFI write-up would be good, but I can't seem to find a good link for it. post it up if you find it!

Edited April 11, 2017 by Numbchux

[86BRATMAN]

The ea82 4wd 3at is shorter than the ea81 version, by how much I don't remember. The difference is in the output shaft and housing.

 

 

I also have a breakthrough in the driveshaft department for 5mt awd trans swapped ea cars. I'll post it up though when I have it finished, haven't been able to get under the car since I injured my leg. But I'll be back at it soon.

[The Pink One]

can someone tell me what is the best way to adapt from a 05 d/r forester gearbox (25 spline) to an ea brumby driveshaft (23 spline at the inner cv or doj) please?

[86BRATMAN]

Look at the link in the first post under the Axles heading. The inner cv (doj) I posted in the linked post are one option you can use.

[86BRATMAN]

No good pictures at them moment. But I'll rectify that when I get my car on the lift at the exhaust shop.

 

But... 93-07 Impreza 4eat driveshaft just happens to be the perfect length for an ea chassis with an ej awd transmission. The one I used is from a 99, and I had to swap the pinion flange on the 1st gen legacy rear diff because somewhere through the years they changed to a larger bolt pattern than the earlier r160s used. Also had to make carrier bearing mounts, but perfect length, straight out of impreza into ea81 car.

[Numbchux]

Awesome, thanks man! I thought I looked at that when I did it, but I never actually tried it. Do you know if the carrier bearing spacing is the same as the EA82? Or would that mount have to be moved on those (cheaper and easier for most than driveshaft modification)?

 

 

Updated the first post with everything in here, and a couple more things. Keep it coming! I still think the EA81 SPFI manual needs to be in here!

[86BRATMAN]

I honestly don't know about the ea82 cars and their carrier bearing location. I'll dig up one of my fsms and see if we can figure it out from there.

[LittleLoyaleMan]

This all looks so useful, I just pulled my EA out of my 92' Loyale and am planning out an EJ20 build for it. I don't have much money, so ideally I'm trying to do a majority of the work myself. Thank you for providing resources and shortening my search of information

[BioPunk]

I've got an EA81 that, if no one buys it, I'm looking to turn a bit bonkers when I can better afford to (starting off in the short term with some frame restoration and reinforcement)

 

It's a 2WD and also the hatchback, so double-removed from most EA82s! But it'll make a great little sleeper if i can overhaul it

[Jhowey]

So I've seen quite a bit about people swapping newer engines into older Subarus like brats and what not, what do they do about the ecu? Do they flash it so that it works with the older system? Or do they buy new computers meant for these swaps? Also how do these newer engines work with the older mechanical gauges?

 

Edit new to subies for the most part, I've maintenaced them but never modified one or tried to swap one

Edited March 3, 2018 by Jhowey

[Numbchux]

On 3/3/2018 at 5:47 AM, Jhowey said:

So I've seen quite a bit about people swapping newer engines into older Subarus like brats and what not, what do they do about the ecu? Do they flash it so that it works with the older system? Or do they buy new computers meant for these swaps? Also how do these newer engines work with the older mechanical gauges?

 

Edit new to subies for the most part, I've maintenaced them but never modified one or tried to swap one

Sorry, I just noticed this post....

You bring the ECU and related wiring from the engine donor car. This is the biggest job of the swap.

Since the gauges are mechanical, you just splice them into the appropriate signals (sometimes with the addition of resistors or even whole sending units to get them to read correctly).

 

The specifics will depend on the specific combination, but that's a general idea...

[subarujim01]

I am considering adding a fuel injection system to my 1978 brat with a EA71 engine.

Holley has a new 2bbl EFI kit available "Holley Sniper EFI 2300 self-tuning master kit",

with a adapter plate that will fit unto the Weber plate I added when I upgraded to that from the orginal carburetor.

Has any one tried this already?

If so what issues did you run into.

I have added a AC system the Brat but when I tried to use it last summer here in Tucson

the current draw on the engine is too much , unless I change the electric chock to a manual unit on the weber carb.

[Numbchux]

1 hour ago, subarujim01 said:

I am considering adding a fuel injection system to my 1978 brat with a EA71 engine.

Holley has a new 2bbl EFI kit available "Holley Sniper EFI 2300 self-tuning master kit",

with a adapter plate that will fit unto the Weber plate I added when I upgraded to that from the orginal carburetor.

Has any one tried this already?

If so what issues did you run into.

I have added a AC system the Brat but when I tried to use it last summer here in Tucson

the current draw on the engine is too much , unless I change the electric chock to a manual unit on the weber carb.

Very good question, and sounds like a great project. I've seen one of those Holley kits used on a domestic V8 and it seems like a really cool option. I have not seen one used on a Subaru.

 

As such, I'd recommend starting a new thread in this section, it'll get more visibility there.

 

EDIT: just noticed that you already did, I got a notification of a new post here and got ahead of myself. Carry on.

Edited March 6, 2019 by Numbchux

[machthree2]

dmachmer@gmail.com  Dave 

Can we talk about upcoming 86 brat ej ?? tx