1973 RX3 project

[j_man1100]

Hey Guys

Just wanted to share my build here. I know it’s not exactly the status quo around here but I’ve had a lot of inspiration from this forum over the years.

The plan:
I’ve had a lot of Mazda Rotary’s over the years. I bought this car about 14 years ago with big plans for it but never the time or budget. In retrospect, I’m glad because the plans I had as an 18 year old are not what I want now. I’m taking the pro touring approach in keeping it a classic car on the outside but a modern driver. So how to make an old Mazda drive like a new Mazda? Easy. Everything under the body new. Easy right?

Here’s what I brought to Sean at Better Motorsports just out side of Ottawa in Canada. Sorry I don’t have better pics, but that was my jumping off point

172705172706

[j_man1100]

So I bought a rusty miata and scavenged all the subframes and suspension bits. This car was going to see a completely new suspension from a modern car that has enough aftermarket to keep it alive forever. So after some measuring and some creativity, Sean made it happen. It took some problem solving on his end but he ended up making it all fit and look great. The one thing we did that wasn’t originally planned, but worked out great, is using QA1 coil overs in order to not have to build stock shock towers to fit. So that saved some time and headaches. There was also some rust repair he had to do. A surprise to nobody who’s ever had an old Japanese car. 172710172707172708172709

[j_man1100]

At this point I had decided on my motor. A 3 rotor Mazda 20b. They were never available in North America so I bought one from a shop that had it imported years ago. They’re fairly hard to come by and the price reflects that. In stock form they came twin turbo. I plan to run it naturally aspirated but built up a little which should have no problems doing 300-350hp to the wheels. Sean made up motor mounts and got going on the rear end. While the rear was maybe a bit more work he seemed to have a plan for that from the get go. 172712172713172714

[j_man1100]

So nearing the end of the time Sean had it, he closed in the wheel wells, retrofit the miata brake master and booster, and made the steering shaft. The stock one obviously wasn’t going to work but he managed to make it so I could use the stock shaft inside to car to keep the original appearance. He also had to move a section of the firewall back to accommodate the extra length of the 20b vs the stock 12a. 172715172716172717

[j_man1100]

So that’s pretty much where I’m currently at. I’ve not done much work on the car since it came home back in the fall. I’ve moved 500km and the house didn’t have a garage so I bought what’s really just an oversized garden shed. But since this isn’t a long term house, I thought something that was able to move with me or be sold down the road was the best bet. It’s 14x36 so that will do fine for me to work on this project.

Going forward I want to get the flimsy frame rails reinforced and then paint. I’ve been bouncing around a lot of ideas on paint but still undecided.

Wheels have been bought. 15x8 front and 15x9 rears. No tires yet but 225 front and 245 rears will be ordered soon enough. I’ll need those for the body work as I’m sure I’ll need to massage the fenders to fit that much more rubber than stock.

If anyone had any questions, let me know. It’s going to be a long term project but it’s also been a long time coming. 172718

[FLYNAVY53]

Very cool project....I love seeing different stuff on the forum!

[j_man1100]

So just a quick update. Have the new wheels on the car. Have a set of fenders from a car that had raced in a few Canadian series. They look good in the front. Need to flare the back but I knew that already.

Rebuild kit for the motor has been bought and working on options for the trans. I have been considering trying to adapt a c5 rear end. There’s much more room for a transaxle and would help the weight distribution I think. It’s a crazy idea, I know, but wouldn’t it be cool?

Currently waiting for the covid lock down to end so I can get the car out to acid dip. There’s a lot of bondo in spots so I’m thinking instead of trying to sand everything I’ll just go with a dip and know exactly what I have.

Finally, here’s a few recent pics, because who doesn’t like pictures. Some with stock fenders and a couple with the flared fenders.

174601174602174603174604

[ryeguy2006a]

Very cool project! Look into the Z06 that Rob Dahm installed the rotary motor into. I believe that was a C5 and he adapted the stock torque tube to the 13b.

[j_man1100]

Very cool project! Look into the Z06 that Rob Dahm installed the rotary motor into. I believe that was a C5 and he adapted the stock torque tube to the 13b.

One step ahead of you. Haha. I’ve spoke to the shop that’s making the bellhousing to make it all work. Thanks so much though. Glad you like it.

[andrewb70]

Very cool. Looking forward to updates!

Andrew

[slimjim]

This is awesome, I'm surprised there's not more Japanese classics like it here considering they've been doing 'pro-touring' well before muscle cars put a name to it. this will be a great build

[jimco84x]

How did I miss this? I'm dying see where this goes. Down low, fat fenders and 3 rotors at 8000 rpm spitting fireballs on every shift. I can already hear it.

It sucks how expensive 20B's have become. It makes the LS swaps more appealing

Excellent build choice. Keep posting!!!

[Peanut1959]

"And now for something completely different..." right? [emoji12]

This kind of odd rod is right up my alley! Subscribed, for sure.

For color, how about a pewter grey metallic with some distinctive non-metallic orange graphics? Maybe something inspired by the factory AAR 'Cuda appearance (see attached). Just a thought.

Have you seen the "Mongrel" build on YouYube? It's a '59 Ford 100E wrapped around Miata mechanicals, being built over in England. I'm not sure if any of that process will apply to your build, but it might be worth checking out.174626

[j_man1100]

How did I miss this? I'm dying see where this goes. Down low, fat fenders and 3 rotors at 8000 rpm spitting fireballs on every shift. I can already hear it.

It sucks how expensive 20B's have become. It makes the LS swaps more appealing

Excellent build choice. Keep posting!!!

Ya, the 20B’s have got a little out of hand recently. I think I got a decent deal on mine but it was still a bit crazy. But thanks for the encouragement. It will be slow but I’ll keep posting updates as I get more done.

[j_man1100]

"And now for something completely different..." right? [emoji12]

This kind of odd rod is right up my alley! Subscribed, for sure.

For color, how about a pewter grey metallic with some distinctive non-metallic orange graphics? Maybe something inspired by the factory AAR 'Cuda appearance (see attached). Just a thought.

Have you seen the "Mongrel" build on YouYube? It's a '59 Ford 100E wrapped around Miata mechanicals, being built over in England. I'm not sure if any of that process will apply to your build, but it might be worth checking out.174626

Haven’t seen the Mongrel build but I may have to check it out. As for the colour, I’m still really up in the air over it. You could be onto something though. Not sure I’d go with orange on the stripe but something along those lines could look really good. And thanks for the subscribe.

[68Formula]

Love these. Can't wait to see how it comes out.

[454bug]

Great project!

When I was in high school, I had a ‘73 Mazda 808 which was essentially the same car but with a 4-cylinder engine instead of the rotary engine.

I’m looking forward to your updates! :cheers:

[j_man1100]

Great project!

When I was in high school, I had a ‘73 Mazda 808 which was essentially the same car but with a 4-cylinder engine instead of the rotary engine.

I’m looking forward to your updates! :cheers:

Thanks. I actually had a super clean and low mile 808 I’d bought from the same guy this RX3 came from. The 1.6L and 3spd auto made for a boring drive though. I do miss that car. Here’s a pic of it.

174685

[JayinMI]

Haven’t seen the Mongrel build but I may have to check it out. As for the colour, I’m still really up in the air over it. You could be onto something though. Not sure I’d go with orange on the stripe but something along those lines could look really good. And thanks for the subscribe.

The Youtube channel is called "Urchfab" and the dude builds some awesome stuff. Sucks he got screwed by the guy who was supposed to paint it.

Jay

[Pro Touring Store]

What the heck???
This is amazing. Looking forward to the progress! :)

What wheels are those? They look like XXR's but can't read the logo.

[j_man1100]

What the heck???
This is amazing. Looking forward to the progress! :)

What wheels are those? They look like XXR's but can't read the logo.

I appreciate that. And they’re Avanti wheels. From what I can tell they’re the cheap line for Enkei wheels.

[RMMiller]

The Youtube channel is called "Urchfab" and the dude builds some awesome stuff. Sucks he got screwed by the guy who was supposed to paint it.

Jay

It's a cool build and worth watching. He is not as polished as some channels but I think that's one of the best qualities, he's a lot like many of us but with way more talent in my case!

[JayinMI]

I found his channel before he started that build, and it's been fun to follow from the beginning.

[j_man1100]

So a minor update on the car. Have all the glass out and everything from the firewall back removed save the steering column. I was all ready to acid dip the car but I’ve been reading a few horror stories so I’m second guessing that now. Also bought another car. It’s an rx2. But this rx2 was raced to several IMSA RS championships by Jim Downing in the 70s. It’s completely disassembled now but comes with a parts car and will be a project for down the road but figured a few of you here may enjoy seeing it. I’ll put up a picture I got of it when it was actually racing too. Hope to restore it and do some vintage racing with it.

175014175015175016175017175018175019

[68EFIvert]

What a cool build. I am building a Volvo 1800 so I know a little about odd! LOL! I am subscribed to this one.

[JayinMI]

I am building a Volvo 1800...

THAT'S an understatement. You're building the baddest 1800 I've ever seen! lol

Jay

[j_man1100]

Well not a whole lot to report on with the RX3 project. I’ve been busy and not done a whole lot with it recently. I did however have a few cars show up last week. I bought 3 former race cars from Jim Downing and they arrived. Also on the truck with them was another RX3 race car that another friend of mine had bought that was also in Georgia. Pretty handy coincidence to be honest. So the red and white RX3 isn’t mine. The white RX3 another buddy of mine is going to restore and get back on the track with the vintage racing club. The blue and white RX2 I will try to get back on the track for next summer to be a lapping car and learn to drive a lot better. The last car is rough and will be a project for down the road but it has a pile of history and I can’t wait to restore it one day. It was Jim Downing’s personal car. Won several IMSA RS races and was one of the first Mazda’s to see some real success on the track in North America. And I will try to get back to working on the current project soon. Thanks to everyone who’s commented and encouraged my bad ideas.

177251177252177253177254177255

[Vimes]

Your car would probably look good painted like that #32 car, only without the graphics, dark metallic gray instead of white, indigo instead of blue, and maybe a gold pinstripe separating the colors. Or maybe not on the gold pinstripe. Interesting project though. I've always liked the RX cars even if I don't fit well into them.

[GarageToys]

I love those RX-2's like the blue/white #32 in your last pic. My buddy in highschool had one and we used to take it to lunch every day. It had a little buzzer in the tach that would wail at you if you got the R's up to something like 7000.

We hit that buzzer every. single. day.

[Crazy Horse]

Super Subscribed!
One of my racing partners has been racing a 1972 RX-2 since well, 1972 hehe
He had an impressive record with that 2 rotor car until he wrapped it around a tree in the fabulous but dangerous Carrera Panamericana a few years back in Mexico.
He is restoring it to "Museum" specs...or so he says (he will race it again I am sure).
Keep us posted...three rotors will make your car very fast and very loud.

[j_man1100]

Well sorry for not having much to update the build. Summer has been busy and not much real progress has been made. Just getting my ducks in a row to hopefully be able to get the car painted and the motor rebuilt this winter.

I’ve also been working on a much smaller project that’s coming together. Nothing major but I think it’s a little detail that will really make this car pop. Here’s where I’m and with some custom billet hood vents. There were a very small number of factory cars come with hood vents. So running with a sort of modernized and more effective version.

180072180073180074

[j_man1100]

So a patch panel from an ‘81 rabbit just might make a good flare. 180676180677

[andrewb70]

That patch is perfect!

[badbu68]

Very cool, you going to do a big street port on it? I had an s4 fc t2 that had low compression on the rear so I used to park it on a hill and roll start it. I bought the other cosmo motor 13b-re from a place in malaysia but never saw it or my money again.

What EMS are you planning to use?

[j_man1100]

Very cool, you going to do a big street port on it? I had an s4 fc t2 that had low compression on the rear so I used to park it on a hill and roll start it. I bought the other cosmo motor 13b-re from a place in malaysia but never saw it or my money again.

What EMS are you planning to use?

Well I’ve had a bunch of FC’s and miss my last one. Was a 10th anniversary edition and really solid. Wish I didn’t sell it. Too bad you got screwed on the motor. I’m going to go with a big street port. I want to keep it fairly simple and streetable. Going with the higher 9.7 comp ratio rotors though. As for ECU the current plan is a Haltech Elite 2500. Not set in stone though.

[badbu68]

rx8 rotors? I didn't know if you could use those in a 20b. My buddy still has his s5 t2 with a 20b, still has the stock twins even though it's got a street port. It's been sitting for a loooong time. It needed an ems, I let him borrow my haltech e6k for awhile but sold that with the s4. We're going to pull that 20b and check it in the spring. Still dont know what to go with, was looking at ms3pro. I don't think he wants to keep the car, I might end up owning it after I get my project done.

Keep up the progress, love those front ends!

[j_man1100]

rx8 rotors? I didn't know if you could use those in a 20b. My buddy still has his s5 t2 with a 20b, still has the stock twins even though it's got a street port. It's been sitting for a loooong time. It needed an ems, I let him borrow my haltech e6k for awhile but sold that with the s4. We're going to pull that 20b and check it in the spring. Still dont know what to go with, was looking at ms3pro. I don't think he wants to keep the car, I might end up owning it after I get my project done.

Keep up the progress, love those front ends!

Please sell it to me! S5 TII is my favourite rx7. 20b in it is just icing on the cake. But if you want to talk ECU’s send me a message. I’m far from an expert but I can elaborate on what I’m planning and why.

[j_man1100]

rx8 rotors? I didn't know if you could use those in a 20b. My buddy still has his s5 t2 with a 20b, still has the stock twins even though it's got a street port. It's been sitting for a loooong time. It needed an ems, I let him borrow my haltech e6k for awhile but sold that with the s4. We're going to pull that 20b and check it in the spring. Still dont know what to go with, was looking at ms3pro. I don't think he wants to keep the car, I might end up owning it after I get my project done.

Keep up the progress, love those front ends!

Oh, and S5 NA rotors. You can use rx8 rotors with a little work though. Not quite a straight swap.

[j_man1100]

So another piece of the crazy puzzle came home today. While it solves some issues, it creates a few more.

I have been working hard to figure out what to do for a transmission. A lot of options were just too big. I could widen the trans tunnel but that would leave very little foot room. So then the brainwave hit. Transaxle. Looked around at a bunch of options but the obvious answer became c5 corvette. Managed to pick one up reasonably cheap and now I have to figure out him to mount it and it may be a complete custom rear subframe. And some more cutting of the floor. But that’s ok. Should be fun. A lot of cutting and measuring to do but I’m sure it will work. And also have to cut down the torque tube. Seems like there’s several shops that do it, any recommendations?

181567181568181569

[Peanut1959]

Are you familiar with this YouTube build? He's dealing with slightly different components (no transaxle), but it might be useful as you plan your suspension. The entire build is worth watching, and he's doing some incredible work.
https://youtu.be/O0dUbfkHQvk

[j_man1100]

Are you familiar with this YouTube build? He's dealing with slightly different components (no transaxle), but it might be useful as you plan your suspension. The entire build is worth watching, and he's doing some incredible work.
https://youtu.be/O0dUbfkHQvk

I’ve not seen that before. I’ll do some watching though. Thanks!

And does anyone know anything about converting the torque tube to a driveshaft? Not much about doing it. A few people seem to have for the diff when running a conventional trans off the motor. Can’t seem to find much on an outright replacement of the torque tube.

[Vimes]

And does anyone know anything about converting the torque tube to a driveshaft? Not much about doing it. A few people seem to have for the diff when running a conventional trans off the motor. Can’t seem to find much on an outright replacement of the torque tube.

Why would you want to do away with the torque tube? I can think of a several reasons to keep it, but not one good reason to get rid of it. Mind you, I'm not one of those who thinks the factory did it right every time, and love seeing people do stuff their own way, but in this case I can't see a benefit.

[dhutton]

So another piece of the crazy puzzle came home today. While it solves some issues, it creates a few more.

I have been working hard to figure out what to do for a transmission. A lot of options were just too big. I could widen the trans tunnel but that would leave very little foot room. So then the brainwave hit. Transaxle. Looked around at a bunch of options but the obvious answer became c5 corvette. Managed to pick one up reasonably cheap and now I have to figure out him to mount it and it may be a complete custom rear subframe. And some more cutting of the floor. But that’s ok. Should be fun. A lot of cutting and measuring to do but I’m sure it will work. And also have to cut down the torque tube. Seems like there’s several shops that do it, any recommendations?

181567181568181569

I had my torque tube lengthened by Gamel Street Rods. Very easy to work with.

https://gamelstreetrods.com/torque-tube-modification

I’m also using Dobbertin adaptors to install full C5 suspension and drivetrain in my 56 Cameo pickup.

https://rick486.wixsite.com/dobbertinperformance

Don

[j_man1100]

Why would you want to do away with the torque tube? I can think of a several reasons to keep it, but not one good reason to get rid of it. Mind you, I'm not one of those who thinks the factory did it right every time, and love seeing people do stuff their own way, but in this case I can't see a benefit.

Well it was meant to be a simplification. As I get looking further into it, that may not be the case. The stock torque tube will need to be shortened quite a bit. And rebuilt to handle the high RPM. I’d thought it might just be easier to convert to driveshaft. And then I don’t need to pull the whole rear end apart to get to the clutch. Was just a thought.

[Vimes]

No worries, "just a thought" is how some of history's greatest inventions came about. I'd think any driveshaft shop could shorten it for you, but if you want a driveshaft in its place I think you're going to have to move the trans to the engine.

I don't think it's going to be that big a deal on the clutch anyway. That transmission looks like it's bolted to the rear diff the same way the trans would bolt to a transfer case, and it looks like the rear suspension is attached to the cradle as well. When it comes to it, it looks like you could just unbolt the rear cradle, then jack the car up enough to roll the whole thing back a bit to get the trans off the torque tube. It might even make it easier to replace the clutch since you'd be able to get full access to it. This is based off looking at the pics you have.

[Boosted Falcon]

What a fun build, keep going.

[noob5,000,000]

Very cool! I'm a rotary guy myself, currently doing a TII swap in my 2nd gen RX-7. :cheers:

[j_man1100]

Hey Guys

So brief update. The car is mothballed for the winter. I picked up a really nice 1988 rx7 project that I’ll get back on the road as a driver while I work on the rx3 next year. Not to mention the fact that back in July we were able to welcome my son into the world. My wife and I couldn’t be happier with the little guy but it’s certainly lead to a bit less garage time. But not held back any planning. The transaxle fab work will happen next spring and hopefully the 20b will get a rebuild over the winter. But the rx7 is currently out for paint and the plan is to have it road ready come spring. Attached are a few pictures of it coming out of the horse barn it was stored in. Needs to have the interior put back together and obviously a new windshield. Otherwise it’s low miles and rust free.

193359193360

[andrewb70]

The first LS swap that I did was a FC.

[ryeguy2006a]

Love the way that those 20b motors sound!

[Flintstones]

How's the progress been on the build?

[Senek67RS]

Hey Guys

So brief update. The car is mothballed for the winter. I picked up a really nice 1988 rx7 project that I’ll get back on the road as a driver while I work on the rx3 next year. Not to mention the fact that back in July we were able to welcome my son into the world. My wife and I couldn’t be happier with the little guy but it’s certainly lead to a bit less garage time. But not held back any planning. The transaxle fab work will happen next spring and hopefully the 20b will get a rebuild over the winter. But the rx7 is currently out for paint and the plan is to have it road ready come spring. Attached are a few pictures of it coming out of the horse barn it was stored in. Needs to have the interior put back together and obviously a new windshield. Otherwise it’s low miles and rust free.

193359193360

Had an 87 NA and 2 88 Turbos. Loved those cars, a lot of fun to drive.