I installed some v8 roadster frame rails to strengthen it up a bit then built this crossmember out of angle iron and square tubing. I also used a section of
pipe from a fence post driver I had laying around for the place where the exhaust pipes go under it.
The same bolts hold the frame rail and crossmember in.

 

I did all of the wiring on my car and used the harness that came with the camaro. Here are some things I learned...

1. Connections that are soldered and heat shrunk are better than twisted wire and black tape.
2. 3M black tape is a lot better than the stuff you get for a dollar
3. You can put all of the orange wires together and hook them to "hot all the time" and put all of the pink wires together and hook to "power with ignition" but how safe is it? If I were to do my car all over again, I would have a fuse panel with separate circuits going to the injectors, coils, 02 sensors etc with very small fuses protecting the small wires.
4. The only wires you need to label before pulling your 4 cylinder motor out are the ones for the starter and the one going to the temperature sending unit. (leave the connector on that one and save the sending unit)
5. I used a dakota box for the speedometer and the tach. It saved me money because I have already used 3 different sizes of tires and didn't need to pay a tuner to make my speedometer accurate.
6. You could leave all of the unused wires in your harness and just have some unused connectors or you could spend many hours removing them and have a cleaner apperance under the hood. Or...you could just cut off the unused connectors and cap off the ends of the wires with heat shrink...that would save a bunch of time.
7 LT1swap.com is an excellent source of info for wiring. There are a couple of LS1 sites with good info too.
8. The PCM uses small amounts of current (sometimes small grounds) to control things like the AC compressor and the fans. You will have to use relays to get enough current to operate these.
9. The easiest way to hook up the gauges is to get a wiring diagram for your car, find the appropriate wires where they hook into the gauge cluster then go from there to your dakota boxes or pcm.
10. GM used the same type of connectors for the Cam Position Sensor, Crank Position Sensor and MAP sensors. Label them and dont get them mixed up...otherwise the car wont start. If your harness is already out of your donor car...trace them back to the PCM pinouts to figure out which ones they are. Again.. LT1swap.com has all of the info you need to do this

I wired mine up and you can too...just be willing to spend lots of time looking up answers and be willing to take a break from it often.

 

Here are some pics of the rear subframe with the 03 cobra 31 spline aluminum differential. Others have described how to do this so I won't go into it other than to say that I put some heavy duty metal into it and burned lots of welding rods.

One huge piece of advice I would give here that I didn't read anywhere else...
The Pinion shaft should not go exactly in the center of the subrame assembly. I didn't know this and centered mine. The differential is made such that the pinion shaft should be about an inch closer to the passenger side...not centered!!!!
I figured this out when my half-shafts came in. One of them was too short and one of them was too long. It took a while to figure this out. When you are finding the right spot for the differential you should either get your half-shafts and install them in the assembly to find the right spot OR you could measure from the hubs to the inside of the differential to that little bar inside where the half shafts go or to the seals that go around the halfshafts.

thedriveshaftshop.com was very helpful and did what it took to get me going...one axle is an inch shorter than what they normally sell and the other is an inch longer. They also made my driveshaft. They do top quality work!!!

 

I promise that the pinion shaft is in the exact center of my car. The back part of the transmission tunnel on the miata is also designed to have the pinion shaft offset one inch. I just had to beat the crap out of that part of the tunnel so the u-joint assembly would not rub. If I had it to do all over again...I obviously would do it with it moved over an inch but by the time we figured out what happened...One of my axles had been shortened so it was easier to lengthen the other one than it would be to get both of them re-made.

 

I used some thin 3/4 inch angle iron to make a radiator frame that bolts to the miata frame rails on each side.
I got a Griffin radiator from Summit. It only has 2 rows in it but it is 3 inches thick! The first Griffin radiator I put in leaked. The guy at the radiator shop said it was faulty from the factory. It was leaking on both sides where the rows go into the tanks. I read online that some folks had a hard time dealing with Griffin. I highly recommend buying from Summit. I called them and they had the replacement on the way before I even got the call tag from them to ship the defective one back.

 

Next I mounted the transmission cooler and power steering cooler.

 

Next I mounted the AC condenser. The dryer didn't work in this location. It hit the bumper cover. I unhooked it then carefully bent that skinny line so that the dryer ended up medial to the driver side headlight. That line was a lot less brittle than I especte but I still managed to get a pinhole in it were it mounts into the tank. The welding shop only charged me $15 to patch it up.

I had some lines made up that were miata on one end and z28 on the other end. I used the stock a/c compressor in the stock f-body location. I did put a new compressor on it and burned it up.

It is important to let the pcm control those stock compressors. (you will have to get a chevrolet pressure switch which can screw into the location where the miata pressure switch was...with an adapter fitting) The GM variable output compressors are not designed to run at high rpm's so the pcm will automatically turn it off to prevent self destruction.

I started out with a toggle switch inside going directly to the a/c compressor. It worked fine for a little while. After replacing the first new compressor with another new one... the toggle switch now tells the pcm to turn on the compressor.

Another mistake we made....when I installed the second compressor...it wouldn't get very cold even though the pressure gauges said freon levels were good. It turns out that we put another can of oil in it resulting in too much oil. To fix it, we replaced the dryer (which was full of oil), charged it up with 2 cans of refrigerant and it was ice cold!!!j

 

I measured and the distance from the outermost part of one fan to the outermost part of the other fan on my stock LS! camaro setup was about 1/4
inch more narrow than the radiator. I had to make it work. Those suckers pull a lot of air. I cut off the part I didn't need, put some duct tape around the edge then started laying fiberglass around the edges. It took a while to do this because I could only do the part that was horizontal. (fiberglass resin runs dowhill before it gets hard). I didn't know about Bondo Glass at this point. If I was to do it all over again, I would use some of that and it would be much easier.

Once it was made, I put it on the radiator, wrapped it in gorilla tape and called it good. I bet it pulls more air than those setups folks are spending hundreds of bucks on and I would say it was free since I already had it with the donor car.

 

Here is how it looks from the top. There is about 1/4 inch clearance between the fan motors and the serpentine belt. I later notched the stock piece of metal over the radiator to allow for an air snorkel. (I guess that is what you call that piece of plastic that joins the MAF sensor to the air filter)

 

Here's that stock piece of metal that goes over the top of the radiator once I notched it. It is needed because it has a couple of holes that hold the front
bumper cover on.

 

I used the snorkel off a corvette that I found on craigslist for a good price on craigslist. The air filter and the T-pipe were purchased on Ebay brand new pretty cheap too.

I ended up putting a piece of 1 inch angle iron behind the air filter connecting both half of the frame. It also allowed me to zip tie the air filters to it for more stability. I also bent and spray painted an old license plate which was bolted to the angle iron on each side and curved up to prevent water from entering the bottom part of the air filters.

 

Here's what it looks like with the hood up....

 

And with the hood down...

The air filter is in that space between the top corner of the license plate and the medial portion of the headlights. They actually protrude into the top portion of the air opening for the radiator about 1/4 inch but I bent up an old license plate and put over the bottom part of the air filter so it won't suck up water if it is being driven in the rain. There is plenty of space between the bent up (spray painted) license plate and the air filter so that it does not impede air flow.

In a future project I will take off the corvette snorkel and make something out of fiberglass that flows more air. I think that pinch point limits the air flow a bit. Maybe not...GM engineers may have known what they were doing when they designed it.

UPDATE!!!!...fast forward to 6/2/15 to see modification.

 

I tried to use the stock fbody shifter but it just wouldn't work with the amount of space I had to work with.

I found this one from a company called Lokar. I like the way the stock shifter works much better than this one but this one looks good in the car and if you just need something to put it into drive, reverse and park...this one works great. If you are wanting to manually shift from first to second, third and 4th... it is very awkward to use and perhaps a ratchet shifter would be a better option.

Attached are pics of the angle iron I cut to mount the shifter to the transmission tunnel as well as the finished product.

I used silicone to attach the boot to the stock plastic ring that goes around the stock shifter...it worked great. There was quite a bit of heat coming in around that area until I took some pillow packing material and filled up that area under the shifter boot. Once I did that ...problem was solved.

 

I bought a piece of heat shield that was about 2 ft by 2 ft and put it in the transmission tunnel. I also purchased some stuff similar to dynamat and covered the entire floorboard. I can't tell you where I bought that stuff because I didn't keep the receipts in a notebook. LOL I wish I would have installed the heat shield material before installing the frame rails because the bolts are covered up. No big deal just not optimal if you need to remove the crossmember later (which I did)

 

My miata had some stock 16x6.5 inch rims. Attached is a pic of the tires I have tried. The far left one is what was on the car when I bought it. The tires were new with about a half inch of tread on them. They lasted about two weeks. The widest tires I could put on those rims was a 245. They gave a lot better traction but even after rolling the finders with a baseball bat...they rubbed when I went around corners fast. The one on the far right is 315 35 17 and they only cost 140 bucks each and I currently have on the car. It handles like a dream and hooks up very well. It required a lot of work on the fenders which I will detail in the next 15 or so posts....

 

I bought some rims off ebay. The fronts are 16x8 the rears are 17x10. I know....this is an "unbalanced set"...well....GM put rims on corvettes that are 1 inch smaller on the front....so I did. They only cost 620 for all four rims.

I didn't like the unused 4 bolt holes so I put some "dummy" bolts in there and now it looks like I have 8 lugs holding my rims on. LOL I just bought some extra wheel studs, did some grinding on them, some countersinking on the wider bolt pattern from the back side then put the "DUMMY" lugs on. Notice the wheel even off the car has 4 lugs on it. Funny huh? Yes...I know...this adds un-needed weight to the car and it probably slows me down another millionth of a second in the 1/4 mile ROFL

 

So this is what the wheel and tire looked like on car. It obviously would not work even after "rolling" the fenders. I would be one pothole away from a flat. Ha Ha

 

So I started by measuring how wide the fender flares needed to be....

 

Next I put some tape on the fender and placed some cardboard in the fenderwell based on the measurements I took.

You should place a black line on the tape where you want the flares to end. You can take a lot of measurements and get each side identical.

 

Next I sprayed on some of the Great Stuff foam that you can get at Home Depot.

It's important to limit your spray to about 1 1/2 inch thickness. Let it cure for a couple of hours then go over again and repeat until you get the thickness you want otherwise the foam below never cures and it is a gooey mess!!

 

Next I cut the foam with a saw blade knife I purchased at Harbor Freight for about 3 bucks. Then I drew some lines on it then started cutting foam away that didn't need to be there.

 

Once you get the rough shape cut...use an orbital sander with 80 or rougher grit sandpaper to shape the foam like you want it. Remember to do the same steps on the other side as you go. If you complete one side then try to do the other side....good luck getting the same shape.

This is what it looked like. I stepped back from it and decided it looked too much like the fenders were stuck on the car and not part of it. It looked a little like I bolted on some dually fenders LOL.

 

I decided that a gradual transition from the flare to the top of the fender might look better.

I drew a new black line on my tape so I could keep both sides the same, sprayed more foam then got the knife and sander after it again.

 

Next I put masking tape over the foam.

Then I put a layer of fiberglass on the tape. I used the cloth type of mat followed by a layer of the mesh type followed by another layer of cloth type. I don't like the mesh type...it gets very messy but I think it adds strength. I found it easiest to put on a bunch of 4 inch by 4 inch pieces otherwise the curves of the fender ended up causing wrinkles with voids under them.

I bought a 50 pack of red solo cups, a box of disposable brushes from Harbor Freight and a box of vinyl gloves as well. That made the process a whole lot less messy.

Once the fiberglass cured...I popped it off the car then took all of the foam out. I wasn't able to get all of the blue tape off the inside but I don't think it really matters.