LS1 Miata Build Thread by fourwhls

9 minute(s) of a 124 minute read

I wasn't able to do much this weekend, but I was able to clean up the tunnel and get some primer on it.

I still have a few spots I would like to clean up better, but overall it turned out OK.

2/28/10

This week/weekend was somewhat productive....

I was able to get the engine and transmission mounted and installed together for the first time. Then I was able to mount, drill, and bolt in the frame rails and transmission cross member.

I mounted the RX7/929 differential for the first time. This gave me the chance to get a measurement for the drive shaft and measurements for the front differential mount. I still need to pull it all back down and install the LSD, but it was nice to see it all in the car.

Steering column came next. Being that I am not re-installing the stock dash, I had to come up with a mount for the steering column. Here's a picture of my steering column mounted with adjustable height settings. It's hard to tell what is right when sitting in the garage. The adjustment will allow me to make changes at the track if my initial setting wasn't correct.

Here's where things got creative/interesting. I have been mulling over ideas to somehow tie the front of the car into the roll cage. After some serious thought and brainstorming with friends, here's what I went with. (Note: everything is just mocked up, no final welding has been done yet)

The two 45deg tubes will be welded to the firewall support shown in the next picture.

Here's a support plate that I built to reinforce the top of the firewall. The area of the cowl under the plate was cut out so the supporting tubes are welded directly to the plate. This is all designed to support the triangulated strut tower bracing that I will build later. (Yes, there is clearance for the wiper arms. Mere thousandths of an inch, but clearance nonetheless.)

I plan to build a brace that is bolted to both the firewall and strut towers. I may even continue forward of the strut towers to the frame rails, if space allows. That's a task for another weekend.

3/27/10

I was able to spend a few hours out in the garage today. I wasn't super productive, but I was able to get a few things accomplished.

I bought a wrecked '04 MSM a while back and parted it out. I decided to keep the rear sub frame and bracing for my car. It is quite beefy.

I went ahead and stitch welded the sub frame while I had it out. I primed and painted it this afternoon, and hope to install it tomorrow.

I also worked on mounting my seat a little lower. I cut out the stock mounting humps and welded in some angle with some adjustment for my race seat. I'm pretty happy with the outcome.

I finished up the day adding the AN fittings to the fuel tank and fuel filter. Still lots of work to do, but it's a start.

3/27/10

I took some measurements earlier this week and modeled up my custom dash concept. I will mock it up out of cardboard and check my design before I cut any metal.

I would like to hear from those of you that track your car. Can you suggest any changes or additions?

All my switches will be mounted at the top of the window frame in a custom switch panel, so they are not going to be anywhere on the dash.

I do plan on installing my brake bias adjuster and fire system release somewhere on the dash, but I'm not sure where right now.

9/27/10

Finally got back out to the garage this past weekend and got some work done.

I fabricated and welded in the mounting points for the front of the differential. I'm sandwiching the diff ears between two poly bushings. I test fit everything, but pulled it all back out before taking a picture (Doh!)

You can see where I stitch welded all the seams on the subframe. Everything should be pretty solid.

I rebuilt the RX7 LSD and installed it in the 929 differential. I didn't bring the tools home to set the backlash and bearing preload, so I wasn't able to button everything up. I will bring the tools home from work one day this week and finish it up. I ended up with right around 70ft-lbs of static lock up, should be close. It's amazing how much difference a 0.5mm shim makes.

Then I jumped into making the MSM rear subframe and bracing fit my NA. This was highly recommended by a friend of mine, Tim, which built Jim's LS6 NA. Tim had a lot of trouble with wheel hop that was all but eliminated with a brace similar to what comes stock on the MSM.

The subframe bolted right in, but the bracing was another story. The NA doesn't have provisions to bolt the bracing into the body tub. My initial thought was to drill through and bolt it from inside the car. That's when an easy situation became difficult. When I drilled through, it didn't go into the cab. It went into a void between the cab and fuel tank which is not accessible. So my fix was to weld some nuts to a plate, drill clearance holes for the nuts, then weld the plate to the tub. It worked out pretty well. A lot more work than anticipated, but I'm happy with the final product.

I was also able to build a bracket to use the stock Miata throttle cable with the LS1 throttle body. I finished this late last night, so no pictures. It was a little tough to get the throttle pedal linkage to fully open the throttle body, but after some massaging of the floorboard with a BFH and some bending of linkage here and there, it all works.

I hope to finish up the diff one night this week, then jump into building the dash and putting together the interior. I did install the seat, steering wheels, and shifter to feel out the ergonomics and gauge/switch locations, but I still have ton of work to do.

10/24/10

I was able to spend the day out in the garage today and did get a little bit done.

I started out with the easy stuff and finished up the diff. The rear end is pretty much done. Drive shaft and brakes are the only things left back there.

Fuel Tank / Fuel Filter

I planned on using -6an fitting at the tank, but didn't order enough hose connections, so I took the cheap route for the time being. FI hose clamps will be purchased to replace the ones shown in the picture.

You can see that I mounted the Corvette fuel filter next to the gas tank. It fits nice and snug in there. I weld a nut to the fuel filter bracket and bolted through the sheet metal. I plan on dumping my exhaust before the diff, so I wanted as much space as possible under the car.

Dash

I mocked up my dash using cardboard. I think everything is where I want it. I modeled everything up in 3D tonight and will send the drawings out to the fab shop in the morning.

It will end up being 4 different pieces bolted together using PEM nuts. I wanted to be able to build the wiring / panels on the bench, then bolt them in.

Oil Hoses

This is where I am stuck. Evidently I didn't give myself enough room to run the -16an hose from the oil pan to the dry sump pump. I need to look for some different fittings, possibly even hard lines.

This one kinda stumped me, and was a good breaking point.