walkingspanish

Hello All,

I had been looking to buy my girlfriend's daughter her first car. I was going to buy her a Miata that needed some work, and then make her fix it up (with help of course). It seems like a perfect first car to both learn how to wrench and learn how to drive.

Anyways, when searching through CL, I saw an ad for a "modified miata" with the following text:
1997 Miata MX
302 Motor .030 over
HD C-4 with Shift Kit
Ladder Bar Rear Suspension with Coil overs & Panard Bar 8"
Mustang Rear End
Aluminum Rad, with 2 large electric fans.
Auto with override switch.
Running gear is EXCELLENT
Power Brakes (disc front) power windows , mirrors & steering. Subframed
AM & FM Cassette track
3:00 to 1:00 Rear end Ratio

There were no pics, so I called, and I spoke with the PO's widow, who was selling the car. She had dropped the price, and so I took a ferry ride across the water from Seattle to Port Orchard and checked out the car.

It was rough, but it started up, and ran well and I was able to drive it home.

Suffice to say, I still need to keep looking for a regular NA miata for my girlfriend's daughter. ;-)

Here are some initial pics of the car:

Just picked her up.



Ah, it was a bit of a mess when I first opened the hood.



It's all homebuilt, no kit.

I bought it from the PO's widow, so I don't have a lot of information to go on, but I know the PO was a Ford factory drag racer in the 70s in the Pacific Northwest.

Really, honestly, this is a restoration project. Everything that holds fluid is leaking, there is a bit of corrosion (PO lived near salt water) and some of it is just plain jacked up (both rear springs were broken).

But I am having a ton of fun fixing it up. It's really cool to work on an old muscle car engine.

jrmotorsports55

Very cool project, look forward to the updates.

walkingspanish

First things first, I pulled the driver side brake drum to find the wheel cylinder leaking. When i went to check the passenger side brake, the pad retaining pin broke and so the spring and clips were loose and torn up. So now I'm rebuliding both brakes.

I also noticed the rear diff was leaking, so I pulled the rear end, cleaned it up and noticed that both brake backing plates were severely worn on the pad contact points. The part is a Bendix 313355-10, but I can't find a comparable replacement part online.

If I can't find replacement backing plates today, I'm going to go ahead and order a disc replacement kit instead and get back on the road..

Also, when I drained the diff fluid, it was black, like carbon black. Boy, she needed love.

I think I'm going to call around and see if I can find someone to take the diff, clean it, rebuild the third member if needed, replace the wheel bearings and seals and give it back. I have to work this week, but I really wanna drive it, so off to the professional this will go.

New suspension arrives soon, so new springs and coil overs are coming, too.

Here are some pics:


Pulling the rear end.



I think the PO tried to lower the springs by heating them., because they are pretty messed up.



As you can see the pad contact points are badly grooved.



Best decision of the day was taking the rear end to a car wash and blasting the road grime off.

Thereelbiged

This is awesome, I have almost and identical build but using a chevy

walkingspanish

I dropped off the axle at a recommended mechanic and learned that I have an 8" diff, not a 9", and it was a pain to get the right gaskets and seal. Additionally the driver side axle seal wouldn't seat properly. It took a week to get the axle back.

I needed to move shops, so I just put the axle back on, and put it together enough to roll it onto a flatbed. I moved to this place: www.theshopclubs.com.




Now that I know I had an 8" rear end, I decided to go ahead and swap back to the original miata rear end, so I picked a complete rear subframe off CL and cleaned it up:




I then popped the Miata on the lift:




Dropping the original rear was pretty easy, I just supported it on a jack. I then loaded the subframe on a metal table and then lowered the miata onto the subframe. I forgot to take pics. :/




The end result! She sits like a Miata again!

walkingspanish

Updating the thread, she moves under her own power again.

I couldn't find any radiator hoses that worked for my routing, so I had to fabricate some elbows to get the radiator hoses hooked up. I also swapped the wheels and started installing roll bars.




I found a driveshaft flange that I could use to connect the stock miata diff to my 1310 driveshaft, and now it runs and drives again. (Though the ignition is always on right now, it's not connected to the key. So I have to disconnect the battery to turn it off. The wiring is a mess, so that is the last thing I need to figure out before I can take her back out on the road again.)

The transmission is offset horizontally a lot though, but it'll work well enough for moving the car around the shop and maybe going around the block. I'll be installing a Ford 8.8 this winter.




And finally I've been collecting parts for a winter rebuild, including a Tunnel Ram, a BorgWarner T5 and a Ford 8.8 rear end. I still need to buy axles, so that is where I am now. I can't decide if I'll get a custom axle shaft machined or if I'll buy Martin's axles or v8roadsters. Any axle recommendations are welcome!

walkingspanish

Well, I reinforced the diff a little and it broker in the first drive around the block. Lol.

Good thing I have the Ford 8.8 waiting to install...




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walkingspanish

Honestly, this seemed like a challenge, it broke too easily and I read in another thread about the notch. So I decided to weld the ear back on, and reinforce it, to see if I can keep it drive-able for another few months.

I've nearly finished collecting all the parts for a complete rebuild, including new custom k-frame, new cam, heads, tunnel ram instake, t5 manual and ford 8.8 diff.

Until then, I've managed to weld the ear back onto the diff, and it still fits! Now I need to block in all the webbing and add some reinforcement. I can't decide if I'm going to pull the open diff and weld it locked. I can't decide if that would be easier on the diff, or if it's hard on the diff when one wheel spins out and suddenly catches traction again. I'm probably going to weld it locked.

BGordon

After seeing what you have done so far I sure hope you bought it cheap.

walkingspanish

I paid 5k for it, which seemed cheap at the time, and in retrospect, a pretty fair price.

I'm keeping that frugality moving ahead, I'm buying everything off CL / ebay and doing all of the work myself.

For instance, I've paid so far:
Hood scoop - 90
Tunnel ram intake - 300
GT40 heads - 300
t5 transmission - 140
t5 bellhousing - 250
Ford 8.8 IRS diff - 100
99 miata complete rear end - 400
new wheel and tires - 500
roll cage - 700

I've also purchased about $200 in steel and aluminum so far, and add probably another $500 in random auto parts store receipts. I imagine I'll spend at least double those amounts before I'm done.

Also, this is going to become my track car, so I'm going to be seam welding it, adding .125" frame rails and tying in the front subframe, frame rail and rear subframe, etc. But all of that is cheap, shielding gas, welding wire and mild steel, as cheap as anything gets with cars.

I'm hoping to keep total costs under 10k by the time I'm done, and I'm on track do that, right now. Right now I'm under budget by about two grand. The only open question for me is rear half axles and hubs. I'm leaning towards Martin's axles / hubs. That would give me enough cash for a new cam!

I've always wanted to do a build like this, so even though I'm rebuilding the whole thing, I'm totally happy to do so. I enjoy using all these skills.

BGordon

When it is done I am presuming it will be a fairly radical street legal drag racer since it will have a tunnel ram sticking out of the hood.
Maybe 2100-2200 lbs.
Perhaps a bit of nitrous to keep things interesting.
Should be deep into the 11's after you get everything dialed.

walkingspanish

I'm hoping for 300-350 with an NA tune and cam and then adding a moderate 150 shot of nitrous to bring me to the 450hp range, and get me to high 10s.

I've heard many stories of ford 302 blocks cracking down the middle at 500hp, so I'm gonna keep it under that until I decide to upgrade the block.

Once I upgrade the block, I'm going to go with twin sequential turbos. But that is a whole different ball game.

BGordon

Not sure where you are at on your Ford 8.8 differential but I remember on another thread that some are electric lockers.
I have been keeping that in mind because if/when I do another Miata swap that is the rear end I will be utilizing that style.
It would be killer to have a good street limited slip and then have a locker with just the flip of a switch.

You might look on YouTube at a build series by Taylor Ray.
He utilizes the cheapest option that he could find for 8.8 axles.
It involved some amount of assembly but saved him a few hundred dollars over buying axles ready to install.

cvx_20

Taylor used the Monster Miata LS swap kit that uses the 8.8 and Martin's axles. The kit includes the front subframe and is somewhat less expensive than V8Roadster's.

walkingspanish

Thanks for the tip about the electric locker! I'd heard about pneumatic lockers on old trucks, I didn't know they had electronic versions.

I've watched a fair bit of the Taylor Ray build. As noted, he used Martin's loose axle kit.

Martin uses the outboard cvs from a ford 7.5 rear diff, but using stock hubs. The hubs on Miatas are kind of failure prone anyways, so I'm not keen about machining out more material and making it weaker to fit a stronger CV. So that's why I haven't gone with martin's kit yet. I want something with upgraded hubs, too.

walkingspanish

oh hey, shout out to cvx_20!

I really enjoyed reading your blog! your blog inspired me to do my own custom front sub-frame.

walkingspanish

The side exhaust arrived today and I had to mock up the car with the hood scoop and side exhausts.

BGordon

Supposedly the electric locker 8.8 differentials come in a bunch of the newer Ford SUV's.
They can come as open diff or limited slip so you gotta be careful when buying one.
You might check out the builds in the GM build section as I seem to remember it being in one of those.
It seemed like it was the build thread with the NC and turbocharger.
That car is awesome and has a 9.4 second quarter mile pass in a youtube video.

I like the side pipes.
Old School.

MX-Brad

Wtf.....? Nice collection in the background. Yours?

walkingspanish

No, I am a member of a place called "The Shop" in Seattle. Those are other member's cars. Quite the background though, eh?

walkingspanish

I went ahead and make little cardboard templates of all the blocking to fill in the differential ear webs:



I then fitted them:





Then I welded them in, skipping around to help prevent distortion:





And finally, I welded a 1/4" 2"x3" angle across the whole top.




I reinstalled it back in the car and took a drive around the block. It didn't break, but the whine from the diff reminded me that I emptied it and didn't refill it. So on go the hazards and a very slow drive around the block back to the shop.

Filled it up with gear oil and went back around the block, this time it went great. It misfired really bad above 4.5k rpm, but I shifted up and down and nothing broke.

Finally, I installed new points and condenser and set the gap and took it again.

Now it revs out to 6500 rpm and I kept getting deeper and deeper into the throttle and the diff was fine.

I finally gave it full throttle from a stop and it burned out through second gear. I took my friend for a ride and his comment was "ok, that scared me a little"...

I have to admit, it scared me a little too. :P

My next step is to take it to a dyno, to get a baseline before I do any mods.

walkingspanish

One more update for the weekend, I picked up rx8 front control arms / knuckles / discs / hubs from the local junkyard.

The knuckle is taller, but I'm building a custom k-frame, so this actually gives me an opportunity to drop the steering rack for better oil pan clearance, and probably lower motor positioning, too.

I might get much better choice of brakes for the front end (I hope). And 4x4.5 bolt pattern. This will match the cobra hubs I'm going to try and use for my rear end.

I really only went back to get the driveshaft flange from the Thunderbird I got the 8.8 diff out of. But it was only $90 for the everything, so it was an easy impulse buy, and still on budget!

walkingspanish

I might have blown my budget, but it looks good.

walkingspanish

I went by a local shop called Carburetor Connection to get a baseline dyno run. My guess was 120hp and 200ftb of torque. This being a 1971 ish motor with questionable internals.





The tech guessed 160, and he was near dead on!




The runs were really consistent and they all ended around 5k rpm. I'm hoping to roughly double the HP and maybe a 50% increase in torque, once I rebuild the engine.

This was the last thing I wanted to do before I started the rebuild in earnest.

Now I need to finish designing an updated suspension that uses the new front and rear uprights, then I'll pull the motor / driveline and begin fabricating the new subframes and suspension components.

stng_96

So, how are you stabilizing the front of the miata diff? Figure the PPF is cut in your pictures so is it just mounted using the two ears? If so I'm saying that has a lot to do with why it broke so quick.