'79 Brat EJ22 Retrofit Build Thread

[mka]

Busy workweek this week - but I got some really wonderful weather today and took the opportunity to get the next notable step dealt with - making the threaded mounting points for the impreza diff subframe.  Also before I get too far into it, a  protip/safety tip:  if someone finds themselves recreating this, or if I decide to do it again - make sure you're using plain, non-galvanized tubing. I'm sure someone has spotted that already and was kind enough to keep their yap shut about it 😅  I used what I have on hand and looking back at it the prep work involved to safely weld this stuff with my setup quickly wiped out any minor cash savings I made by not just going to buy another stick of tubing. I'm sure I don't have to go into details about the dangers of working with galvanized material, but it's worth repeating that Zinc is bad for you in gaseous form and if you're gonna encounter it to take the proper safety precautions. 

With that out of the way - the photo essay goods: 

After everything was tacked up and nominally square - I clamped the new frame in its place on top of the bushings, and marked the first hole location for the threaded inserts ( M16 nuts I'm welding in), then center punched and drilled out the hole. I had access to weld the outer half of the nut since it's pretty close to the end of the tube and I used a technique i learned involving some clever placement of smaller access holes to get the inside faces of the nuts fused in. Like the other channels, this will all get boxed in and closed up when i'm happy with the fitment. After this I continued marking and drilling one hole at a time, using the Impreza subframe as a jig to make sure things ended up where they needed to be. I also drilled these holes slightly oversize so that I have a little wiggle room in their placement. Their final positions were dictated with tacks on the welder and then fully welded off of the impreza subframe so as not to melt or damage the bushings. 

 

After the new weldment and sheet metal subframe were temporarily assembled together, I put the diff back in it, put it on the transmission jack and then bolted the diff to the front mounts under the car.  The original holes and features made for a really handy reference mark and wouldn't you know it, things came out super even. So even in fact, I couldn't help but loosely bolt the lateral links in, prop the trailing arm up, and lean the coilovers (not pictured) up in there without any bolts to get an idea of how things are going to sit. 

I can almost see it on the ground again! (It'll still be a while). I don't know if I'll be able to narrow the rear wheelbase quite as much as I'd have originally liked, though with a quick google having a slightly wider rear track isn't uncommon and can actually help with certain handling characteristics. I might have to flare my rear fenders, as I do not think I'm going to be able to reduce the rear width the full 9" (4.5" on each side) or so I originally measured without some pretty significant clearancing wizardry beween subframe and coil. I'll have a better plan of attack here once I've got everything semi-permanently affixed to the frame but either way what this is telling me is that I'll probably need to refrain from fully welding in this frame modification until I've got the suspension completely located. I'm also eyeballing putting in a set of rear discs rather than these drums, as I'm not a huge fan of drum brakes and well... I'm already really in the weeds so why not just do it from the ground up?

Might get a little more in on this over the weekend, but I'll be playing that by ear. 

Until the next one! 

-M

 

Edited December 6 by mka

[moosens]

Sweet! Little at a time.

 

My first thought on the brakes was wondering if anyone has done inboard disks somehow. That would probably take too much money but I am thinking if axles are cut down maybe they could be adapted at the inner ends to accept a disk. Or an existing setup like from a Lotus etc. as an example. 
 

Pardon my freaky thought in the middle of your hard work. 
 

Inboard brakes at the diff, big bash plate to  shield it all. 
 

Anyways , cool to see as usual and who knows I could maybe copy you or use the knowledge to take a different approach etc.

73 Coupe over the Impreza and just bump out the fenders and quarters with obnoxious looking flares. We’ll see. I’m years away from that project more than likely. But I’d want to keep it thrifty too. 

Edited December 6 by moosens

[mka]

On 12/6/2025 at 1:57 AM, moosens said:

Sweet! Little at a time.

 

My first thought on the brakes was wondering if anyone has done inboard disks somehow. That would probably take too much money but I am thinking if axles are cut down maybe they could be adapted at the inner ends to accept a disk. Or an existing setup like from a Lotus etc. as an example. 
 

Pardon my freaky thought in the middle of your hard work. 
 

Inboard brakes at the diff, big bash plate to  shield it all. 
 

Anyways , cool to see as usual and who knows I could maybe copy you or use the knowledge to take a different approach etc.

73 Coupe over the Impreza and just bump out the fenders and quarters with obnoxious looking flares. We’ll see. I’m years away from that project more than likely. But I’d want to keep it thrifty too. 

Freaky build thoughts welcome here. I don't think inboard brakes are going to fit on the setup i'm planning, but someone wily might be able to make em fit on a closer to stock undercarriage. I'll probably just be swapping the knuckles to add discs on this one once I've got the suspension set up in the back end. 

 

[mka]

Did a little more weekend deathwheel work today - took about an hour to get some access panels cut into the bed floor so I can more easily add some gussets to the subframe while it's bolted to the assembly.

The idea here is that I'm going to use them both to reinforce the subframe and it will give me a locating feature when I go to tack this piece into the car so everything lines back up.

The idea here is that I'm going to use them both to reinforce the subframe and it will give me a locating feature when I go to tack this piece into the car so everything lines back up. I've still got to take things in and out a couple times before this becomes a more permanent part of the vehicle. I'll probably weld the panels back in once I'm satisfied with the subframe and suspension towers, as some of these welds I'm planning on leaving only semi-permanent till I've got all the clearances worked out with the coilovers, so I'll be leaving access until I'm sure I don't need it anymore.

 

This last photo looks real scary but in reality it's just me adding four tack welds to the gussets only on the subframe. I'll be removing it one last time to box everything in and hit it with a bit of weld-through primer. 

Folks with a real professional background in automotive engineering would probably cringe at some parts of my approach, but I got everything measured up as even and straight as a mallet and tape measure would allow. I'm honestly pretty impressed with myself at how evenly I was able to get everything to line up with a couple symmetrical features I used as reference points (a couple bolt holes and a few key bends/seams. I find myself repeating the mantra "perfection is the enemy of progress" a lot on this build, and so far (knock on wood) it's working out pretty good. 

Next up I have a fairly short punchlist to get this subframe on the car in a  meaningful way, and then I'm planning on attacking the lateral links, trailing arms, and locating the strut towers. The more I think on it the more likely it is that I'll probably be scrapping more of the Impreza tower than I'd intended. The rust is pretty deep in the driver side tower and the more I stare at the mockup as it sits the more dislike the way it looks. One way or the other I'll figure out something good. Main goal is to have it back on its own four wheels (again) around the new year. We'll see if I make that goal or if I blow past it for some unforeseen reason. 

 

Hopefully I'll have at least one more update before the New Year, but if you don't hear from me beforehand, have a good last few weeks of the year, everybody! 

-M

Edited 1 hour ago by mka