Revamping the Rx7

Well since the engine in the rx7 has shed its moral coil, and i still need to get my rally on, I figured i'd waste some bandwidth on the project at hand. Right now, i have a short amount of time before a deployment, which will help me fund everything while at the same time limit my time to work on the car. My goal is to make the Idaho Rally 2012, about two months after i return home.

At this point i have two main things to accomplish: engine and suspension

The engine replacing the rotary will not be rotary. I am going to remain with a mazda engine as to be compliant with rally america and also to remove any possible contest from Maxattack! rules (since they follow whatever sanctioning body). I am pulling the engine tomorrow in fact so ill continue with that later.

The other thing is the suspension. After getting under the car and poking around i can see i need to give it a good once over and i might as well use the "good" rx7 spares i have for it anyway. The biggest is the 2nd generation rx7 front subframe. A very easy swap and yields better steering, stronger suspension, a normal lug pattern and improved braking. All good things. To make the lug pattern in the front, i will have to change the rear axles out to the GSLSE model axles. These had the 4x114.3 pattern. All of this is temporary because in time i do plan on going with a different rear axle all together but again, time is my problem. Anyway, the axle in the car was a older rx7 axle and had a smaller spline and smaller bearings. The later GSLSE axles would not just go into the housing proper. Had to change out the whole deal. Wasnt too big a problem since i had 4.78 kia sportage 3rd member with an rx7 lsd already in my GSLSE housing.

I have also been looking at strengthening, and rust removal. Woven into this was clearing for the 15" wheels. (lug pattern change...). The car has had some previous rust repair and has made making the rear fender wheels flared and clearanced difficult. Was easy on two previous cars i have done, but this one is less than optimal. That said im making progress.

A few pics to tide over. Will be making updates frequently until i deploy. Also one of shop bunny. Somewhat like a shop cat. Just better tasting.

HAHA! That's funny as hell! My mom helps run the Posion Center (Where Mr. Yuk is from [the green face] )

Nice choice!

I'm starting to see a trend here...

I'll have to start putting pix of my pet spider at the end of picture posts.

Alex - What's your plan for flares?

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Pete
Alex - What's your plan for flares?

it will look exactly like the picture below! Wheels too actually... since i parted that project out to get the rally up to par. (no title shell...) Further progress was made today but the pictures are on my phone so maybe ill get them on here in a few.

Also i have noticed that the bilstein shocks seem to limit how much travel the rear has but a few inches.. they just max out too soon.






Edited 1 time(s). Last edit at 07/30/2011 08:55PM by Gravity Fed.

The remaining portions of the steering was removed today including the steering box and column. The stud that will hit the new subframe were removed and the frame pinch rails notched for clearances. The new steering column was pulled from the parts car as well. Was some progress. Hot as hell today too. Welding tank is getting refilled tomorrow so i can start the finishing the rear flares and the rear subframe studs.

Welded in the rear bolts tonight. Got the axles in the rear end. I also started welding the rear flares back up! I spent most of the day dismounting 34 rally tires. Ill finish up more tomorrow and get pictures.

so now comes the question of "how do i mount this stupid engine." Its seems that frame rail mounts would only work on the passenger side. The Driver's side has the steering in the perfect place to not work. Pics of that are below. I am using the 2" sleeved bushing tube mount (is there a simple word for this??) A friend of mine savvy with machining made me some aluminum inserts to use will mocking the engine and welding. This is so the poly doesn't melt, obviously. Im probably going to build off the sub-frame.

Also, the cam sensor hits the firewall before the front of the oil is clear of the steering rack, to my preference. If i can move the sensor into cutaway into the firewall, then the engine's front can come down since the pan would clear. This would allow me an easy closing hood.

Anyway, here is what im working with...















Edited 1 time(s). Last edit at 08/13/2011 11:25PM by Gravity Fed.

Looking great. I thought about putting a turbo BP into an RX-7 chassis too. My other thought was using the Miata subframes and a-arm suspension too. But keeping a strong rear axle is smart.

-Jon

i think ive put together just about the best combination of mazda parts for a rear wheel drive rally car. The axle may end up getting swaped for the volvo 5 lug dana so i can run the bigger brakes up front without issues and alter the rear geometry. We shall see. thats for another year. Right now she needs to run for 2012.

flares are done! Lots of cutting and welding for clearancing. And battling old rust repairs on the driver's side.

those are awesome!

and functional! lots of clearance. And i already had them so why not.

more progress!

Engine bay was stitch welded as was most layers of metal touching it. Painted over that with tractor paint so i could get the fenders on. Seems as though some of the attachment points have been...rusted and had bolts broken off. Reminds me of home (ohio) anyway.... ill have put some screws into it to hold. But they are mostly on.

Also finished the rear structure welding and coated it all with truck bed liner. I just need two more weldable inserts and the rear mudflaps will be on as well. Engine will be going in soon i supposed. 13b engine i had laying around is the game plan. will be cheaper and i can reuse a lot of parts. Also better for me to learn on!

i also saved 10lbs via removal of the headlamps. also cleared some space and removed some wiring and relays.

car is on four wheels again! Been making a lot of progress! Just need to start buying somethings...

This project makes me very happy...

I've been daydreaming about building exactly this car ever since we saw how cheap and durable a turbo miata engine could be with our Frankenmiata Lemons car.

You know about Miata coolant re-routes, right? I very strongly recommend doing a re-route, as it has made our turbo miata cooing system bulletproof. Now, while the engine is going in and out 10 times a day, is the easiest time to do it.

-Dave

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eyesoreracing
This project makes me very happy...

I've been daydreaming about building exactly this car ever since we saw how cheap and durable a turbo miata engine could be with our Frankenmiata Lemons car.

You know about Miata coolant re-routes, right? I very strongly recommend doing a re-route, as it has made our turbo miata cooing system bulletproof. Now, while the engine is going in and out 10 times a day, is the easiest time to do it.

-Dave

Don't allude, explain, dammit Janet!

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Short version:

Miata engine is based on a front-drive design that had inlet in front and outlet in back of the engine. Miata version put inlet and outlet in front, so coolant flow to the back of the engine sucks, leading to overheating.

Simple solution is to use the FWD parts to put the thermostat on the back of the head and run a radiator hose (pipe) down the side of the engine. You can run it down either side, as the thermostat housing bolts on either direction.

Later (post 2002ish, I think) engines fixed this problem with a new head gasket that forced coolant to the back, but earlier ones really benefit from the FWD coolant flow.

I've got some piccies and stuff if you need more details.

-Dave

Alex was up here in Cleveland this past week, during a whirlwind tour of the country before being deployed, and we talked a bit while I was at the shop shoehorning a Chrysler 300M fan assembly into my RX-7 (pair of shrouded-blade two-speed fans, needs a 40A circuit per speed, maybe this will be good enough finally?) and also so he could poke around and see how I put in the FC subframe and three linked the rear.

Nutshell, he's probably going to just run a stock port 13B just to get the car actually, you know, on the stages. Also probably going to be going for a 4 link because that's a more proven design, and I don't give a rat's ass if the car is squirrely over 80 and he kinda does.

The nice thing about the coolant reroute is, if you get a $300 Protege engine and a $60 eBay Miata intake manifold and $40 Miata oil pan, instead of a $1000 Miata engine which is otherwise the exact same crap, you have the bonus of having had the coolant reroute already done for you...

$1000 miata engine? Shit, my last Miata engine was $50.

Might be California pricing. Might be my preference for 1.6L engines. Might be that I buy busted engines and piece them together, but either way, I think $1000 is a bit much.

-Dave

That's boneyard, 90-day warranty 1.8 engines.

So while we're talking RX-7s here, what makes a 3-link (or your 3-link) squirrely at high speeds?

I've never played that much with solid axles, so maybe I'm being naive here.

-Dave

I have a shit-ton of antisquat, because my concern at the rear is that the rear tires bite when I hit the accelerator, care about nothing else. This isn't a 3 link problem, this is a Pete problem.


I also have fairly high (~200lb) rear spring rates, and the rear roll center is only 2" lower than stock while the front is a lot lower thanks to the poorer geometry of the FC front suspension. So everything is contributing to the car's nervousness at higher speeds, but for me that just means it's responsive. I tried stage rally spec rates and geometry and it didn't bite hard enough and wasn't very responsive, but I'm sure it feels just right on a stage. As it is, the steering does something useful no matter what's going on, and unless I'm going to spin anyway, accelerating makes the car STOP rotating. I countersteer a whole lot less than I used to, which is Good because that means I can place the car within a foot of where I want to even if I fuck up, no more chucking it in at the beginning of a corner and hoping that the arc I chose to carve is where I actually need to go.

We'll see how it works against everyone else in Tulsa. Just got my Mazdaspeed contingency sticker pack in the mail. I fully intend on this trip to pay for itself.



Edited 1 time(s). Last edit at 09/16/2011 03:59AM by Pete.

very nice ride

where did you get the flairs?

they were actually for a 240z. had them for a few years on a few cars now so i can't exactly remember the source.

i love some mystery parts

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Pete
I have a shit-ton of antisquat, because my concern at the rear is that the rear tires bite when I hit the accelerator, care about nothing else.

How does that do for accelerating on a rough, like washboard, surface? Wouldnt a shit-ton of anti-squat tend to remove the compliance from the suspension and cause it to skip over the bumps and lose traction? Just from watching the f cup videos it seems that everything rwd sits down in back when they get on the gas, not much anti-squatting going on. Just curious.

so the rear suspension on the car seems to be less than stock, by a far amount. might be the bilsteins either not having the stroke or something else. ill be testing this out tomorrow. Something i noticed recently... ill measure as well.