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Howdy, all - We just picked up a GSL SE chassis (carcass?) with intent to swap the 9182 FB into common lug pattern and rear disc brakes. The car is/was an LS swap, but the previous-previous owner windowed the block, so the previous owner bought the complete car for the brackets and driveshaft and other accessories. So it's literally an empty void in the engine bay, just a big hole under the hood. However, I noticed the rack n pinion steering and thought "hey, maybe just swap the whole subframe and steering?" But apparently there are "differences" in mounting the 12A onto the 13B subframe.
What I have derived so far: the GSL SE front subframe will bolt onto the FB chassis, and struts will mount into the same location same/same.
A 12A will bolt to a 13B (GSL SE) front subframe when using the 12A front crossmember (engine mounts).
Power steering: the 84-85 GSL SE has a pump (and some kinda electronic compensator doohickery). We don't have the pump or the hoses; we have a complete steering wheel->steering box->rack. I don't know if the GSL SE PS pump will mount to the 12A without a couple of animal sacrifices and whatever other black magic is required.
Subnote to PS pump: I'm investigating an electric pump option, but having a stock-ish setup would be cool. And sorry to all, but my daughter really wants PS, not because she's a girl, but she's just getting into driving a stick, and power steering makes her more confident actually getting out and driving.
Please critique my statements above and let me know if I am choosing the hardest path possible. It's my daughter's project car, but I have a fatherly responsibility to make sure that I don't end up with two inanimate RX7s in my garage, thereby relegating them to "dad's new project cars."
First off; welcome aboard. Secondly, I read your post 3× and I'm still not sure what you're trying to accomplish. I think you're trying to install a 12a from somewhere (???) into a previously 13b chassis, and the engine mounts will be different. You can use a stock 12a engine mount - if you have one - or Mazdatrix sells the Racing Beat version for 12a mounting. The subframe is the same, to my knowledge. Maybe another member can chime in. Here's the mount, for visual reference; https://mazdatrix.com/product/front-...ate-79-85-12a/
Note that the engine mount plate attaches to the front housing of the engine with 4× bolts. Not knowing what's in the engine bay of your SE host, maybe you can post some pictures to show us more.
As to the PS on an SE, the system uses a pressure regulator to detune power assist at speed to make the car behave better on the highway. Aside from that, the PS pumps, rebuild kits, hoses and most other parts are NLA today. The SE will require the left side engine bracket to mount a PS pump to the front housing and line up the drive belt properly. These are heavy, cast iron and add a ton of weight to an already heavy corner of the car due to the battery location.
How are you set for the other driveline components? Unless you have everything off of a 12a donor car ready to bolt-up, you're biting off a lot of work to get this up and running. Other SE differences off the top of my head; driveshaft, fuel lines (*feed & return), Fuel Pumps & Injection Filter (*could be made to work for a 12a carb), Brake Master Cylinder (*larger swept volume for rear disc brakes), and exhaust system - as the block is 20mm longer with wider gap between the exhaust ports, and then there's the Oil Cooler orientation, plumbing, and such for the front-mount SE to a bee hive 12a.
Is your 12a donor also an FB? That might simplify a few things,
Last edited by LongDuck; Sep 21, 2025 at 07:43 PM.
Oh yeah, sorry. I can claim that it made sense when I wrote the post, but that's just a diversion. Let me try again...
My daughter has a very straight 1982 FB ith the (semi) original 12A that runs great and has zero issues (wobbly steering box, soon to be remedied). She got an idea to swap in GSL SE rear end and front hubs to access more wheel options. We picked up a roached 84 GSL that previously held an LS1, but that engine and accessories are long gone. What's left is the entire rear end, plus the entire front end with the entire steering chain from wheel to rack. The remainder of the GSL would then go to the wrecker or to someone who needs a VIN and title along with 1982 FB front and rear suspension and hubs.
(Here's where the original post was supposed to lead) I was curious if the complete front subframe, with steering rack, would swap into the FB chassis and still allow us to use the current 12A, assuming that we can install a power steering pump (probably a remote one like the Volvo pump). It appears that yes, this should work as long as we swap just the subframe (and steering and hubs) and use the current engine mounts.
If you want them GSL-SE front and rear lug pattern and brakes, you can swap the rear end over as a whole and for the front, swap in the front spindles from the SE into the 82. No need to swap over the front crossmember and mess with engine mounting points. You will want to use the SE brakes booster and master cylinder, as well as the proportioning valve. You will also need to use the SE parking brake cables as well.
As for swapping in an aftermarket steering rack, I'm not entirely sure how you would do that or which rack is even in the SE. There are options available, but nothing is just plug and play really. You would have to see which kit or rack is in the SE and go from there. Perhaps post some pictures of the setup thats currently in the SE and we can better assist you on that part.
so you're asking if you can swap an FB subframe into an FB?
the only difference between the GSL-SE subframe and every other 79-85 12A car is that the engine mounts are 20mm further forward for the longer 13B
Here are a bunch of pics. Upon further examination the hub installations look sketchy. This engine bay used to contain an LS1, so I'm not surprised if this is a "custom" install. Also, I'm extremely ignorant of what a typical front sub would look like as I have only looked at the '82 with everything in place. But the steering installation seems...
What we were told: This is a 1984 GSL SE that used to have an LS1. What happened between the Mazda factory and my driveway is between the previous owners and their creator. I can try to answer questions, but again, my info comes from a place of shallow information.
What thoughts do you all have on this? As long as the rear end is in good shape we can still source front hubs, but this rack and pinion steering, if this installation is safe, would be pretty sweet.
Looking down from driver door Looking scross from right headlight Looking across from above right front wheel Left hub Looking from in front of left wheel
At this point I'm sure what I have. I know that I have a set of GSL SE wheels bolted to the hubs. I figured out that it's an FC subframe, and swapping that into the FB chassis shouldn't be the worst project I have undertaken. The two glaring items that I see are the fact that I have 4X114.5 (not 4X114) front hubs grafted onto an FC subframe, and the fact that the struts appear to be welded to the knuckle. The combination of those two things means that I really need to evaluate whether it's worth it to swap that subframe and steering rack into the FB or just have my daughter get a set of GSL SE knuckles and hubs.
The 1984-1985 front struct assemblies are the same regardless of model. The only difference for the GSL-SE is the backing plate, rotor, caliper. With this said, GSL-SE calipers are hard to find.
The 1984-1985 front struct assemblies are the same regardless of model. The only difference for the GSL-SE is the backing plate, rotor, caliper. With this said, GSL-SE calipers are hard to find.
What about FC struts? I'm aware that FB struts are FB struts regardless of trim level, but the parts under the tin on this car appear to be FB struts welded to FC knuckles, with GSL SE rotors on the FC spindle (which is possible according to bearing numbers for certain years). I'll take some time this weekend to perform a postmortem, but something doesn't look right to my untrained eye.
Those aren't FB struts. FB struts don't have a bolt on hub. The FB rotors won't fit on the FC hub. If they did it would make it a lot easier for us FB folks to get the 5x114 wheels.
Everything about that front suspension and steering is janky as HELL. Unfortunately, that's what can be expected from most of the non-purist, LS-swap crowd - and the pics above prove my point. I would be looking at your daughters existing car and seeing what it needs, because this SE (*just what we can see) is an awful mess. Who knows what else is held together with bailing wire and prayers?
Everything about that front suspension and steering is janky as HELL. Unfortunately, that's what can be expected from most of the non-purist, LS-swap crowd - and the pics above prove my point. I would be looking at your daughters existing car and seeing what it needs, because this SE (*just what we can see) is an awful mess. Who knows what else is held together with bailing wire and prayers?
Seriously, dude. That's not safe,
Thank you for validating my concerns. I was hoping that it was shoddy workmanship, and not "eh, everybody does it." I was holding out hope that it was salvageable, but I see that I was being Pollyannish along with a sprinkling of sunk cost fallacy etc.
The shell has a title so we can get rid of it in a legal manner. And the rear end is GSL SE with discs, so we are halfway to the finish. Or a quarter, I guess, because half is getting the parts, and half is doing the work? I dunno.
"79-82 pinion flange is threaded, so bolts go strait through the drive shaft flange and thread into the pinion, while the 83-85 pinion flange is an untapped hole, requiring 4 slightly longer bolts that go through the 2 flanges and nuts on the back side to tighten the two together."
"79-82 pinion flange is threaded, so bolts go strait through the drive shaft flange and thread into the pinion, while the 83-85 pinion flange is an untapped hole, requiring 4 slightly longer bolts that go through the 2 flanges and nuts on the back side to tighten the two together."
GREAT info, thanks! Again, more shopping. I'm glad it's my daughter's money and not mine. It will be my knuckles that get skinned, but wounds heal faster than bank accounts. I guess that my skin in the game is physical, her skin in the game is financial, and I'm okay with that.
You've only shown us the engine bay, but if it were me, I'd pull anything remotely usable off of the SE shell and set it aside. These cars (*your good 82 and the SE) will have many interchangeable parts mechanically, and these parts are hard to find these days, as every Pick-A-Part has long since moved on. This includes any header panels, straight fenders, windshield, wiper rack & motor, basically anything that's in usable shape. You never know what you might need, and you're looking at it right now - might as well save what you can. Glass, too. Good choice,
