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First time poster, keen to keep a record of my rebuild in the one place as well as access collective knowledge from around the world! Forgive any formatting errors, I haven't posted on forums like this before. Also, my dad is definitely the brains of this project, I'm no mechanical guru.
As the title suggests, 1982 S2 Australian RX7. Goal is to rebuild to (mostly) stock with the 12a and Nikki it was born with and have it to street on the weekends and eventually attend the occasional light track day. Performance plans only really include an extend port, hotting up the stock carby or going aftermarket, exhaust (came with rotaflow system) and suspension upgrades.
I picked up the car from my dad around Mid 2018 and this is what it looked like. Pretty tidy, a few little rust spots to be dealt with down the track, but overall a clean package. Interior is the very 80s red that I've grown to love, with the normal sun damage in vulnerable areas. Dash has cracks as well as the A-pillar pieces that are essentially crumbling to nothing. Overall a good base to start from I think!
We got to work performing the manual conversion just to get it running and driving. Long story short it did run, but was a little 'sick', which we already knew. I drove it around for a little on a historic registration and ended up putting it back in the shed until I could afford to do a full engine rebuild and make it purr smoothly once again.
Pulling the engine down we found the issue/s pictured..
Everything else in decent condition. Decided to get the plates faced and a conservative extend port done but stopped short of having the rotating assembly balanced and rotors clearanced.
13b housings were sourced and ground down to 12a width, exhausts ported also (pictures still to be taken of these).
After sourcing a full rebuild kit (all OEM Mazda kit for stock 12a), having the bearings pressed for the rotors and stationary gears (Chris Milton Engineering taking care of this), rebuild of the Nikki Carb (including welding up mechanical secondaries), we're now up to the present day - prepping the rotors and then assembly.
My short initial to do list, and some questions for anyone following along - especially if you can foresee any issues I will likely run into along the way.
- Suspension refresh - considering aftermarket coilovers for all four corners as a more future-proof option.. In Australia, anyone recommend shocks and springs for a sporty, but not bone-rattling, setup? Any advice on coilover setups that you'd recommend?
- Bushing kit - was going to just source a SuperPro set of polyurethane bushings and press them myself.
- Rust prevention - the plan would be to do a full body rust repair down the track down to bare metal, cut and weld etc.. but for now I'd just like to keep it from worsening as best as possible, any tips?
- Body/window seals - Can source a kit for this, just a matter of time and money.
Thanks for following along if you are, just wanting to have this to compile the journey more than anything else.
Your 12A rotors appear to be in really good shape. How many miles/kilometres on the engine?
I'm not entirely sure, I'd have to ask dad, he had it for a while before I got a hold of it and has a better understanding of its history. Off the top of my head, maybe 120000kms?
Glad you all like the wheels! The problem is that the wheel centres are quite chunky and the current wheel nuts don't have a heap of purchase on the hub. Putting them on is a bit of a process! Haha.
I'm not entirely sure, I'd have to ask dad, he had it for a while before I got a hold of it and has a better understanding of its history. Off the top of my head, maybe 120000kms?
Glad you all like the wheels! The problem is that the wheel centres are quite chunky and the current wheel nuts don't have a heap of purchase on the hub. Putting them on is a bit of a process! Haha.
You may want to change to screw in studs and get the lug nuts.....
Just picked up the stat gears and rotors with newly pressed bearings. Hoping to get at prepping the rotors this weekend and then rebuilding in the next few weeks. See how we go.
Well it's been quite a long while with COVID getting in the way of everything. We've made significant progress especially in the last few months. Writing to try and remind myself of all the little issues we ran into and how we worked our way through. It's been fairly painless so far, just takes some time as the car is stored at my dad's place about 40mins away. At any rate, here's the blow-by-blow of what we've managed so far!
First job that needed to be done to prep for engine rebuild was assembly of the rotors. This was tedious but painless. Cleaning, clearancing, honing side seal and corner seal grooves. Found out that the guy who put together the rebuild kit for me didn't include new oil control rings. Thankfully my dad had an Atkins 13b kit so we stole them from that. Some pics below. Clearancing side seals Side and corner seals complete - oil control rings yet to be installed Small honing/cleaning tool my dad made for the corner seals out of a welded on corner seal
Here's a shot of the engine bay before we ripped out most of the front end (steering and suspension components) and gave most of it a lick of paint. Dad is very handy with a spray gun so he whipped up some 2-pac and got to work. Lots of surface rust but nothing significant. Also put a coat of paint on the housings and plates. Wire brushes, bench buff and a lot of prepsol later it was prepped and ready to go. Went with Jet Black for most of the undercarriage, Heatproof Aluminium for the housings and Cast Iron for the plates. Engine bay looking a bit greasy and dusty All out in one go - suspension has to go! The Pro at work
Pulling apart the underside we found the original rubber bushings in disrepair (not surprising), so these were all replaced with new poly bushings in the front - rears will be left as is as they weren't in a bad state anyway. Front shocks and springs were replaced and we don't recommend anyone do it this way, but we did it the backyard mechanics way: playing russian roulette with some ratchet straps and a rattle gun. In the end there wasn't a whole lot of pre-load on them and they came off without incident. Standard KYB shocks and 'Low' King springs front and rear should only drop by around 1 inch from stock height. Old shocks were completely blown. While we were on the front rotors we re-packed the front wheel bearings with grease. Out with the old.. All front bushing replaced with new poly bushings Don't do this. All installed. New tie-rod ends, all steering components aside from the steering box were replaced. New ball joints pressed into the lower suspension arms too. This is where we hit our first issue. Dad had gone wild painting everything up in the black 2-pac and when we installed the lower ball joint on the passenger side we believe that painted surface on the underside of the knuckle arm gripped the dust boot and consequently tore it as we steered from one side to the other. This didn't happen on the other side for some reason, but we decided to clean up that surface and use some rubber grease on initial install to stop it from happening again. Hardest part here was trying to find a dust boot that suited this ball joint! Impossible, as it turns out, and in the end I think we went with something that was close enough - I'll have to see if I have pics of that.. big headache for such a small component. At any rate, it all got bolted up and torqued down and we're moving ahead.
Old and crusty New and shiny! First issue of the rebuild.. Proposed solution..
Next up was the rear suspension and rebuilding the brakes. With a bit of wrangling getting the shocks and springs out was relatively easy. Rebuilding the rear brakes was a little more complicated, however. Interesting to see the handbrake mechanism at work, it was just tricky to have the sprung bar slide in over top of the loose yoke that actuates the piston. Anyway, with a bit of swearing and a few hours to figure it out the first time, it was done! Leak in the rear of the diff needs solving, but the plug is just rounding, so we may need to become a little more 'persuasive' in our approach - will likely need to re-thread and install a new plug.
Had no idea what I was looking at here.. Cleaned up so we could inspect Pin removed All painted up with braided line installed after new seals put in and re-greased with fresh stuff Diff leak, yet to be solved..
Replaced the fuel filter while I was messing with the central braided brake line (HEL Brake lines used, very pleased with how these look!), also installed the lines up front and refreshed the sway-bar bushings.
Old fuel filter - also drained gas tank while we were here. HEL Braided brake lines up front Fresh bushings up front for sway-bar
We had also found that the passenger side rear brake rotor was warped, so I'm waiting on new rotors to arrive, they'll go on as soon as they get here and that's basically the front and rear end complete!
The day finally arrived! Time to assemble. Quite nerve-wracking for me as this is the first engine I've ever rebuilt, and certainly the first rotary. Dad has experience with them and we had plenty of material to help us through, so we felt confident to give it a go. Was just praying that in the end it would turn over and give us some indication that we had some good compression. I'll let the pictures do most of the talking, no major issues here, was fairly straight forward! Finicky dealing with the apex seals and springs, but mostly because the corner seals were just rotating and blocking them from dropping all the way to the face of the plate below.
No fancy engine stands here, just a bench with a hole that can fit a bottle jack underneath for when the intermediate plate goes over the e-shaft. Worked a dream! Raised it 25mm and the plate slid over real easy, then lower it together to seal.
One thing that we had to do (I may have mentioned it before) was have the housings machined down from 13b housings, and the seal channels were then CNC'd in. One of the pictures shows that the seals didn't sit very proud of this channel, but at this point there was no going back - hoping this doesn't come back to bite me, but I wasn't about to stop and find new housings based on a hunch. See how we go when we try to start 'er up!
All new seals everywhere, all Mazda OEM except for the control rings which came from the Atkins kit my dad had lying around. Not sure if I can upload videos but I have a vid turning it over by hand and I was pleased to feel almost too weak to get it around smoothly - lots of compression. Fingers crossed this is all looking really good! Used a syringe with hylomar on the large seal grooves to ensure there wasn't too much in there/ have it 'smoosh' out or kink when we started torquing it up.
Bottle jack below the cutout for the e-shaft - our ghetto setup instead of a proper stand All progressing smoothly The master at work All together! Really like the way the paint turned out.
Another small job we did was block off the coolant passage to the intake manifold. Was already blocked on one of the housings (cast in) and I've read that it's not necessary.
Larger water seals in, and not sitting very proud of the machined grooves. Not sure if anyone can advise on this - certain I had put them in the correct way!
