93 Carbed 302 T5 DIY no JB Weld or Duct Tape
 

I purchased my 93 Miata with a blown engine and equally bad convertible top. I did not plan on doing a conversion but the only engine I could find for it was being sold by a very shady dude who could not read an odometer. No Thanks.

After several days of research I was still on the fence. Then I found this forum and saw how helpful everyone is so I am going to do it! Tomorrow, I will officially be at the point of no return when I buy a used T5 setup for the 5.0 that I built a few years ago (never even started it, long story).

The Miata's engine block has a hole in it and one piston's connecting rod was feeling a little disconnected. Never seen anything like it - see pictures.

This is definitely going to be a very low budget build because I'm putting a kid through college. My 13 year old son will be helping so I think it is a good father son project.

Looking forward to seeing your progress.

Spent a few hours driving around to buy parts. Scored a complete T5 setup for $450 that is a little dirty but in good condition.

Didn't get as far on dismantling the Miata as I hoped. Some things were a real pain. The exhaust was the easiest I have ever removed though.

I hope to have a picture of the empty engine bay to post tomorrow. Wish me luck.

Oh you are a lucky man for sure Jack. I would love to build a car with my son and some day it will happen.

I really appreciate you doing this thread and am excited to see how you guys tackle things. Good luck! :sign0058:

Thanks Jim.

My 18 year old son helped me on several projects, most notably, the engine build on our 05 Mustang GT. It was my first tuning, forged internal, and turbo install. It was big success - we achieved 500whp and 24mpg. It's a blast and honestly, I couldn't have done it without him.

My 13 yo son is starting to be a really good helper. It's making the project more enjoyable since it's a good time for us to catch up on life.

Got the engine & trans pulled and realized that I am really just at the beginning of the project where the modifications and fabrication start. Got lots of new cuts and bruises but my spirits are still high.

Attachment 7438

It took a while but I was able to get the clearance cuts roughed in.

Attachment 7437

I don't know if everyone else did this but I just had to see if it would fit in the car. It fits!!! I am just about as amazed as if I had just seen bigfoot!

The engine has been sitting about in the garage for quite some time. I am going to spiffy it up and make it look nice as time allows.

Attachment 7436

I spent a lot of time in the U Pull It lot this morning. Mainly looking for a rear differential. I found several Thunderbirds and Cougars with axle codes Y (3.08) and 5 (3.55) - no lockers :( and no Lincoln Mark VIIIs either.

I did notice that the 3 02 Ford Explorers had IRS and it looks like an 8.8 with an Aluminum housing. Checked the codes and two of them were D8 which is 3.73 Locker. I haven't seen anyone recommend them but it looks like it would work since I'm going to be making my own mount anyhow.

Here is a link for removal which has a ton of picks:
How to: 3rd Gen Aussie Locker Install - Ford Explorer and Ranger Forums "Serious Explorations"®

What do you guys think?

A couple of thoughts: What are you doing for axles? Some of the Explorers have 31 spline axles which is a problem if you want to use the FFR axles, as they are only 28 spline. Not a problem if you go a more custom route.

Also it appears to me that the rear mounting scheme takes up a lot of room right where you might want to run exhaust. I haven't actually tried an explorer rear, but I have seen a post where they actually cut the mounting ears off and used a bolt-on mount. I suppose you could use the rear cover from a T-bird if you had an extra.

Mike

Thanks for responding.

I haven't started researching the axles. I thought, worst case, I use the 8.8 shaft cut and spliced to the Miata shaft. Was planning to use a steel sleeve (that matches the two shaft diameters) welded to the ends of the shafts to join the shafts together. I don't know if the Miata section is going to be strong enough though.

After I posted, I found a company that makes a kit that uses this rear. It is a very unusual setup that uses the 3 mounts. I'm not very fond of it, I'll do something different for sure.

Thanks Again!
Jackie

Front mount looks about the same but the back mount is a concern. If it would clear the rear part of the frame to tuck up you would be golden.

Everything is different inside and the part # for the axle seals are different too so I doubt Martins axle shafts would work. You'd have to run the numbers both ways but my guess is it would be cheaper to pick up a bird diff on car-part.com or on tccoa.com and use Martins shafts than it would be to build custom stuff for the Explorer. I got my 8.8 3.27 locker for $100 shipped and I could have run it as is if I didn't want to swap to 3.55 gears.

Speaking of gears 3.73 is pretty tall for a T5 trans and you would be spinning near 2500 rpm on the hwy with them. Most guys run 3.27s with T5s.

Any GOOD salvage yard should be able to locate what you are looking for. I opted for a 7.5 open 3.27 differential & installed a new limited-slip carrier as well as all new bearings & seals. If you can locate a used locking assembly, chances are it will be worn out & need new clutches anyway.

As far as the 8.8 Explorer differential goes, I have had the pleasure of rebuilding hundreds of them. It appears that the aluminum case expands with age, causing the backlash to change, thus making them whine like crazy. The only short-lived repair would include a new ring & pinion.

Welcome! This forum really does have some super helpful and skilled builders. What area of the country/world are you located?

Thanks for all of your responses and help!

Charchri4: I was thinking the 3:73 would not be good for cruising. It's good for drag racing but that's about it. I want my car to be able to cruise too. Right now, I can find 3.08 or 3.55. Will have to look on Car-Part.com for the 3.27. What RPM are you running at on the highway?

tbone: I was curious why I saw some Explorers with missing axles. Thanks, I'll stay away from them. It looked like a PITA to mount it anyhow.

I live in Eastern NC near Greenville. I need to add that to my information.

try call Factory Five racing
I am 90% sure they have 31 spline axles for 01-04 cobra diff
i assume those will fit in the explore

please report back

Based on the previous responses, I am going to stay away from the Explorer rear diff. Just gonna keep it simple with the Tbird 7.5 and put a locker in it later. There are a lot more builds with it so it looks much easier to mount.

1600 at 60 but keep in mind I'm running a T56 with the .5 overdrive 6th gear. Fun to see the 4cyl guys freak out at this shot...

Attachment 7431

Charcri4: That's a nice overdrive. My T5 is jealous!

I did manage to get some work done on the car over the weekend. I got the rear rear diff dropped and the rear subframe wire brushed for painting. I hope to be able to do all the differential mounting mods without dropping the whole thing but that remains to be seen.

Oh man it's only 6 bolts to drop the thing and very well worth the time to drop it. Even empty the diff housing weighs 30 lbs and sooo much easier to not fight gravity or weld laying on the ground.

You've seen this post right? Jim and Jenna build diary, Miata LS1 Conversion: The other half of the back half

BTW it's really handy to be able to drop the gas tank down a bit to and run the fuel lines to it and the subframe has to be out to do that.

[QUOTE=Jack Sprat;7636]Thanks for all of your responses and help!


tbone: I was curious why I saw some Explorers with missing axles. Thanks, I'll stay away from them. It looked like a PITA to mount it anyhow.

The most likely reason is that people came to get the rear knuckle assemblies (the hub bearings are another area known to have issues, are a PITA to replace without special tooling) & did not have a 36mm socket to remove the c/v nut, so they took the axle with them.

It has been a great day. Hauled off some scrap stuff to raise project capital since my investment request was denied by management (wife).

Went to junk yard and found a factory ford aluminum intake manifold for $28 and some GT40P heads for $115. Didn't have my tools so I'm going to go back asap. The part finds helped me make my final decisions.

5.0L, carbed with ported Ford AL intake
m-6250-e303 CAM (282° 282° .498 .498)
GT40P heads -requires Speedway Motors block hugger Headers:
Small Block Ford Block Hugger Tight-Fit Headers, Plain - Speedway Motors, America's Oldest Speed Shop
Trans - T5 with 3.35 First .68 OD
7.5 Open Diff (at first) with 3.08 (or 3.27 (not sure yet)) gears
Quiet exhaust (no droning) with cutouts for racing

Picked up the intake yesterday. It is a factory Ford 4 barrel from an 84 Mustang GT. The ports are tiny so I started porting it today so it would match a GT40P head.

Been hard at work porting the intake. Tomorrow I order the headers. I have decided to try the Speedway headers. They said they would take them back if they don't work and I don't damage them.

Be sure to check for spark plug accessibility with your headers installed. I think that one style of GT-40 head had a different spark plug mounting angle, causing the plugs and/or wires to hit the tubes.
Good work on that intake. Hog it out!

Yeah the GT-40P heads have the straight plugs that won't work with most headers. They work with the Speedway Headers but that is about it. I'm concerned that they are about 1" wider than other block huggers.

I was going to do the mismatched Hedman headers but they are 50% higher than just a 3 years ago. It's the principle of the matter, well and $100 too.

Thanks TBONE. Once I learned the secret to keeping the AL from loading up the bit, it went much smoother. Still got to polish them but that will be after tomorrow's junk yard trip!

Get you some of this: https://www.fastenal.com/web/product...%20Fluids%22|~

Thanks Tbone. I had read that WD-40 will do it and I tried it. Works great to cool and not load up. The stuff from Fastenal is probably much better to extend tool life.

I have decided to go Super Low Budget so I can enter this contest:
Grassroots Motorsports $2014 Challenge: Grassroots Motorsports

I'm already getting closing in on the $2014 limit so I'm going to need some real deals on a clutch, rollbar, and top. I'll probably even have to shorten the drive shaft myself.

I ordered the headers! They should be here tomorrow, then the subframe cutting will commence. :eek4dance:

Intake is ported and needs to be bead blasted.

Got headers. As expected, they aren't going to fit. Got a lot of cutting to do on the subframe. I think I'm going to make pockets and reinforce the internals with gussets. I want it to drop in real nice like. LOL

LOL that $20xx challenge is on my bucket list too Jack! No question a converted Miata would be my first choice but in many hours of pondering I think the only viable way to do it is to use an engine that you can leave the stock Miata rear end in tact. That and find a very cheap Miata with a torsen in it already.

This is now my favorite thread and I am rooting for you all the way!!!

Thanks Jim. I'm glad that I'm building something with a chance and I'm going to need some moral support. Got a lot done tonight even though I was exhausted when I started.

I am not familiar with the torsen rear diff. What models did it come in? Can you identify it from the outside? Will it handle a V8 with 300-400 ft lbs of torque?

Thanks!

There have been a few builds that have left the diff and with a low power small block it might hold together. It would be fine for the event but you would not want it on the street. The gearing in them is like 4.05:1 and you would scream that V8 down the road with one.

A torsen is the way car makers have been doing posi for the last 15-20 years or so. It's a slick set of gears that wind around each other to work their magic. I don't think a lot of NAs had them but it was an option. I really have no idea how to tell them apart because I know very little about normal Miatas. But I do know there will be guys who read this that do!

By the way my sons idea was to weld the inside of the tbird shaft to the outside of the miata shaft and just be sure to get it straight. The apple didn't fall far from the tree...

Thanks to you, I was motivated to get something done tonight. See picture above.

Funny, about the cv shafts, I'm very sure I'm going to do what your son suggested even if I have to make a sleeve to adapt the two. I've done it before with DOM tubing and it turned out great.

I'm thinking worst case, $150 for the entire rear end. No choice but to keep it cheap if I'm getting it under $2k.

A Good Night.

More progress tonight. I got enough of the subframe cut that I can see how everything is going to fit. The doubting (will I be able to do this) about the project is over. I am 100% sure I will make the headers work, the bellhousing will fit (with the tranny) and I will have enough metal left to make the motor mounts work. I even see how to box it for strength. A lot of work to do but now I know for sure that it is doable.

Thanks for all the help!

Attachment 7354

More progress. I found a big shoe horn and managed to get the engine sitting in with the headers bolted on both sides. Oil pan is on too.

Got tons more to do but this was victory that I stopped to celebrate.

Haven't painted the manifold or engine yet. I'm going metallic graphic on the engine and still deciding on the intake.

Picked up a pair of Anchor 2235 motor mounts for less than $10 (total) at Advance Auto Parts. Score! :smilie_daumenpos:

While looking over Factory Five's install instructions for the 8.8 IRS. I finally realized why I am so excited about this build. I am essentially building an AC Cobra with pop-up headlights. Since I would never be able to own a Cobra replica, in essence this car will be as close to a dream come true as I will get. I'm good with that, really good with that.

And a real top, and side windows that actually roll up and down.

Mike

Yep, that's about the size of it. Best thing is you don't have to put up with all the Boy Racers everytime you stop. And the stealth factor is FUN. Of course if you drive around with the hood off the Miata you do get some Cobra like attention. I drove mine to town a couple times recently hood-less, it was certainly a conversation starter.

Good Luck!
RR

Click and enjoy Jim and Jenna build diary, Miata LS1 Conversion: Is the V8 Miata really a modern day Cobra?

True, CVX_20. It is a real car on the inside.

5.0MX5 Good idea. I'm sure it would get stares everywhere without the hood. I'll have to try that.

Jim, I checked out your link. Excellent job on the comparison. I had no idea they were that close. Back in the 80s I read a magazine with the Cobra 427 specs and was blown away. Can't wait to finish my car!

Made the mistake of buying a roll bar, then found out it is a style bar. I'm going to reinforce it with some DOM tubing then wrap it in carbon fiber.

Attachment 7337

I would suggest selling the style bar & getting a roll bar. The roll bar really stiffens up the chassis, especially if you incorporate some door bars.

+1 ^^ for sure! Unless it blows the 2014 budget then I would just make my own start to finish.

If you want to go cheap and use a kit this is what I used. http://www.rhodesracecars.com/90-98-...A_c_10658.html

It is quite a bit of work to fit and if I was going to do it again I'm not sure I would.

BTW If you do the kit don't use the duplicolor roll bar paint everyone says is great. John Deere Blitz black tractor paint is way more durable and half the cost.

I agree. I hate the (don't want to) Roll Bar. I got it for $70 and I need it at that price for my GR 2014 Challenge. Drove 2 hours to get it and should have just drove home empty handed. The website didn't have anything about style on it, got home and saw it in the instructions.

Charchri4: How hard was it? How long did it take?

This is the way it comes,
Attachment 7329

If there was a bend about half way down each leg of the main hoop it would be so much easier to work with. With out that bend it either has to tip backwards about 15 degrees or you really limit your seat travel. I just cut the thing off and put it in the way hard dogs are done because even with a bender it would limit seat travel to take the legs to the floor of the car.

I'm on the road and have a lot more photos at home I can send you but there is a little on the first page of my blog here
Jim and Jenna build diary, Miata LS1 Conversion: Weekend 1 the journey begins.

For me it was the first time I ever pulled the trigger on a welder so that had a big impact on how hard it was to do. I had no idea welding the diagonals to the center of the hoop would warp it so much. Also I did not make it like the factory cuts with the bar going side to side but did diagonals instead.

As far as the kit goes it is good stuff. It is the proper NHRA and SCCA tubing that weights a ton and they give you plenty of it. I bought the 8 point version to have extra tubing to practice welding on but if I did it again I'd just do the normal 4 point. BTW if you buy it check on on ebay. With the ebay bucks back it is a little cheaper than the web site I posted. I'll be home next week and can put up more photos for ya.

Wow, that looks way better than my stainless steel exhaust pipe 'roll bar'. In fact, I think I'll cut it up and use if for my exhaust. I'd have a lot of Jbends. LOL. Maybe it could mount to the mounting bases once I cut old roll bar up.

Jim, if it's not too much trouble, when you get back home could you upload some more pics.

Thanks!

Nice Rear!
 

After 2 hours of wrenching in the mud, I scored a 3.27:1 geared 8.8 aluminum diff and half shafts. Thanks to my son, Jake it wasn't that bad - two hours start to finish. Cool thing was that we were able to remove the shafts without going into the boots and they popped out of the diff with no problems. :yippee:

Got to clean it up but I'm stoked to have found one!

[IMG]http://i324.photobucket.com/albums/k...ps1c178436.jpg[/IMG]

Gratz! What did you pull it out of?

Thanks!

It was hard to find but we pulled it from a 1998 Lincoln Mark VIII with 120k miles. It cost me $150 but it was worth it due to the low miles and having the exact gear ratio I wanted.

Based on others' feedback and my calculations, 3.27:1 is the best gear ratio for my application.

There is a Mark VIII with a 3.07:1 ratio (unknown mileage) in Wilmington NC at Cape Fear Pick N Pull if anyone needs one. Their inventory is posted online so check before you go.

Cape Fear Pick N Pull

Well, I had no luck getting the hub broaching done locally so I contacted Martin at Monster Miata. He is a great guy and has given me some really good advice. I am going to have him broach my hubs for me. He also talked me into the 7.5 hubs which will save me some trouble with shock mounting and will be plenty strong enough for my car.

Buying some .120" wall 1 1/2 in. tubing from Summit Racing and a hydraulic pipe bender. I am planning to make my own roll bar and exhaust. I hate I wasted $70 on the style bar but at least it won't go against my total.