Rally Revival: 1973 Mazda RX3 Rally Car

After much debate and measuring and random thoughts, it was time to give up on my RX8 ideas. It just didn't make sense and was going to cost way too much money. So I managed to sell the rolling shell...

a truck with a winch is a godsend, time to swap trash for trash. SWMBO won't let more yard cars stay there so only 1 inop at a time means rx8 had to go bye bye. 

 and associated parts along with some spare Rx7 parts to come up with enough cash to save this car:

it was conveniently located near my parents house in the Chicago area so being that is thanksgiving week and I was already coming here with my truck, it made sense to drag the trailer along for the ride as well, in the end it only cost me a little bit of gas money however this car has no title so there is going to be some interesting things that will need to happen to get that resolved and registers but we are far from having this on the road so that will wait. 

It is in rough shape and as far as I can tell it hasn't been rally raced since 2003. It is in dire need of rust repair inside but has some redeeming features being the rear end of the car is in good shape, doesn't appear to have been rolled (yet), front has some 

tiny gas tank but looks to be very intact, unlike the floor:

passenger area is held together by paint, inner and outer rockers are gone, you can see air through them:

engine bay looks to be fairly solid but lots of paint flaking off

lots of work ahead, no real time table but should be fun as these were 2000lbs in original trim so several hundred pounds lighter than the current rx7 and if we can put together a 160-200hp motor for cheap this should scoot pretty good but before we get there it needs a floor and preparations for a suspension overhaul. 

Ideally the stock welded diff axle on 13s isn't going to work great as we cant fit brakes or cant find tires but some fabrication and various FC parts for the front end will work as will a shortened 8.8 ford solid axle and convert it to a 4 link, ideally I can find some Ford Econobox rally parts and adapt it, we will need to do a lot of modification to the floor to fit ourselves in this small car but that has been done before and will be done again, if we had to cut the floor out anyways this makes for a nice opportunity as this car basically fell into my lap. 

the bolt together cage parts are pretty laughable, safety has come very far for Rally since this has hit the stages but still has some ways to go given the immense challenges of the sport. 

Key project goals:

• install Floor
• Title (if no title, I can't register it then it will just become a rallycross car versus a stage rally car)
• map out history
• Performance/Rally Readyness

fidelity101 said:

 

 

Finally someone will have a rally car older than mine :) Yeah, I know there are a few others running ARA, but not many! I'm excited to see this build :)

I cant make an fc 500lbs lighter but this should be

so some quick digging and comparison:

so the ideas are floating around now

IRS or 4 link rear?

AWD or RWD? 

Boost or N/A?

Cheapo Deluxe or go home and go broke?

or the ultimate frankenstein spare parts car? (part rx8, part subaru, part FC rx7)

either way everything requires a lot of fabrication 

4 link, RWD, NA, Cheapo Deluxe

Another option to consider if you want to retain a smaller diameter wheel is a Datsun truck rear end. My dad had one in his 73 Corolla and it measures 50" drum to drum IIRC. It was sourced out of a Datsun 520, thick axles, aluminum 3rd member. You just need to change the PCD and mounts.

An RX3 can work.  Back in the paleozoic Rod Millen won the New Zealand rally championship with one before he went to the UK, then to the US.  I think some people ran Mk. 1 Ford Econobox rally suspension in them.  Back in the 70s and 80s when I was competing (in Corvairs!) there were a couple in California and the Pacific Northwest.

EvanB said:

4 link, RWD, NA, Cheapo Deluxe

why do I need two rx7s rally cars though, granted the rx3 will be far lighter (likely) thats the existential problem I have. I had issues when I had my turbo rx7 and the rally car, both were too time consuming so I sold the tubo car to cover the costs of a title chase in 2019. 

If you swap out the rear axle, lmk and I'll take the RX3 one off your hand. Swapping to an 8.8 and RX7 front struts will also get you a 5x114 bolt pattern which opens up wheel options from the stock 4x110.

Can't wait to see this build progress!

Yeah this is a stock Rx3 rear axle, it has a welded open diff in it currently, regardless of what I am gonna do with the car, I don't see this rear axle staying in the car. 

In reply to fidelity101 :

For my GLC any RX axle was an upgrade. I bent the RX2 axle in it when I flipped it. I'm almost 100% sure the RX2 and the RX3 axles are the same. I've also got a welded open diff as well as a few other diffs for it.

What do the regulations say?

Looking at the MkI/II Ford Econoboxs, Volvo 240 and other things successful in rallying, a well setup live axle in a 4-link seems to be a good bet. But that is dependant on having access to suitable live axles.

For an IRS a Miata swap sounds like something to consider?

therealpinto said:

What do the regulations say?

Looking at the MkI/II Ford Econoboxs, Volvo 240 and other things successful in rallying, a well setup live axle in a 4-link seems to be a good bet. But that is dependant on having access to suitable live axles.

For an IRS a Miata swap sounds like something to consider?

RWD (open 2 wheel drive)has the best regulations:

the IRS idea is 2 fold, I would only do it if I went AWD. Just doesn't make sense RWD given how easy an Ford Econobox 4 link setup is. The problem with that setup and AWD is I can't find 4.444 gears for it as I would plan to use subaru parts to make it AWD. 

this is where the IRS comes in to play, I have so many FC spare parts and access to even more should need be. I can use just that rear suspension system - its not the greatest but it does work and I have lots of spares and all the rally part of it figured out.

the big issue with this rear suspension, which I have discovered with the rx7, is the diff - I blew the diff on old all seasons so the pinion is weak but I can rectify this with a s1 rx8 diff which is widely accessible, possibly axles too but I have demonstrated that FC axles spline into the Rx8/miata hub.

since the diff wont be the long pinion most of the subframe in the middle is dead space 

if AWD it can be STI front so I can keep 5x114.3 bolt pattern and off the shelf rally parts, rear is already pretty sorted and if I move attachments around I don't see why I cant get 8+" of travel out of the rear whereas I already 7 or 8" right now in the FC.

Minimum weight becomes an issue (2900lbs) but thats only ARA's problem because they need to subaru competitive (shots fired) whereas NASA is 2375lb based on the displacement.

therefore I need 250+HP and NA would be tough to move that much mass around and add more drive axles to the mix 

just kinda spitballin now likely situation is FC front end and 8.8 4 link rear, sorting out title stuff now so I dont get carried away, otherwise I'll just slap together a carb'd 13b and put a cheap floor in it and tow it to rallycross because if I can't road legal it, it doesn't matter. 

good news everyone, we have a title!

• For it to be a rally car it needs to be road legal
• for it to be road legal I need to register it
• for me to register it I needed a title
• for me to get a title I needed to:
  • Form of ownership (MI)
  • Form/witnessed by police officer (VIN verification)
  • Surety bond ($100)
  • Certified Michigan Appraisal ($385)
  • pay tax on the value + title fee ($137)
  • wait 2 weeks for title to get mailed 
  • Bill of sale from purchase

This only works on cars valued under 2500, this is more common on pleasurecraft things like bikes/ATVs/boats etc apparently but still feasible. 

project is a go!

fidelity101 said:

good news everyone, we have a title!

<<>>

This only works on cars valued under 2500, this is more common on pleasurecraft things like bikes/ATVs/boats etc apparently but still feasible. 

i did this process to get MI title for my '61 corvair station wagon.  the cop was kind of a car guy, and commented something to the effect of "no worries with being under the value cap here!"

In reply to AngryCorvair (Forum Supporter) :

yeah unfortunately since I bought it out of state they needed the verification value anyways which was a pricey appraisal for someone to overvalue my car for a quick google search of the only other rx3s for sale but whatever it was what was needed and I got the job done. I dont think I needed the surety bond for this but i didn't want to go to the SoS office a 4th time...

the cop that verified the VIN for me was a local cop and thought it was funny, " you want me just to sign this and fill this small section out? okay!" he was also giving me E36 M3 for "does your SWMBO know about this??" haha

okay well its time for an update, its about a year later and I am finally "started"

the idea was; tear into it and come up with some sort of plan of attack. 

throw out a lot of zip ties and general trash/debris inside the car, remove the fuel tank and gut the engine bay as I'm sure none of this will be retained and I really needed to see what good metal I have to work with. 

that helped highlight the plan, I need to get a good 3d scan of the floor and chassis space and I can get tubes and sections fabricated as I rebuild the car. I'm not that great of a welder and this will be beyond my comfort of safety zone, IE building a whole car so I will do my best to get things in place and prep then call in reinforcements when needed. However with the rx7 repair ahead but for me to get the floor/engine bay area I need to remove everything - maybe I will get myself something nice for christmas to solve this then.

luckily there are still some cab corners with metal and the firewall has a lot of clean good metal as does the trans tunnel and rear tower area which is promising. 

so right now I am working on removing the dashboard and associated pieces, the fuel tank has been removed and maybe shortly the rear axle is going to come out then it will be ready to scanning or hold off on scanning until I can add some rocker material on which will get tied to the cage and ultimately help build the car around. once I have a few hard points in place it will be easier to math up the round and square tubes needed and get local shops to supply some components and put the jigsaw in place as I cut away at the rust and rot.

The current cage is far from legal or safe and will be removed eventually but right now its handy giving it rigidity to hold things in place while I work from and possibly anchor to. 

see? there is metal. I want to add some structural rockers from square tube and use the ends as pin stands then I can get the car on car casters w the pin stands and begin working on the middle/rear and remove the old axle/suspension setup prior to 3d scanning. 

next to real metal is a lot of this though...

but honestly after looking through this, seeing the rx7 cut up, seeing new cars and section cuts. Its very visible to see the progress in how we have built automobiles over the years. We have come a long way, this looks fairly straight forward whereas there are a lot more overlapping pieces to the FC to build the structure its no wonder everyone got really hurt in old car crashes and cars got mangled easily. there is a lot of evidence of 'offs; with this car but holy cow every bolt under the dash is spotless and came out effortless, even the steering box bolts came out and still showed plating, it was nuts how much was so rusty and so much other was perfectly fine/great condition. 

The diff tunnel, top of the driveshaft tunnel, and the cross bar piece are solid and have some strength that can help hold this car together. the whole gas tank area is good as are the structural part of the rear wheel tubs and shock towers but the spare tire wheel well is pretty rotted and misc corners of the body. 

engine bay is mostly gutted and soon I can mockup a dummy block and trans and see what room I have to work with. 

the beauty of this car being so similar to the UK Ford Ford ES COR T (why does it keep changing it to econobox) coupes this solves some of my fabrication needs:

I can rebuild the rear of the car to suit my needs with these parts basically, the middle will be a variant of a floor drop, the front will be drifty boi special of trailer fenders and tubular front end to cut out the rot and hold up the body panels/cooling/lighting functions and round out the engine bay. 

Glad to see you digging into this.

¯\_(ツ)_/¯ said:

Glad to see you digging into this.

me too, I needed to know what I was really working with to do anything - right now the rx7 is on hold and this costs me nothing but time which is nice because I need to escape to the garage some evenings for some personal papa time lately. 

I will keep preparing this for 3d scan and dolly mode where its safe to work on and focus on an established baseline, when that happens I will probably get the rx7 fixed but I need to visit the potential donor car then have the cage repair/additions completed as i don't budget for one of those likely until the new year. 

I love RX3's.  Following along intently!