MAZDA MIATA SEATS
When I got my Spitfire, like many Spitfire seats, mine were in serious need of rebuilding. I checked prices for new foam and, after EMS left, I decided that there might be a less expensive option. Doing a search on the web, I discovered the most likely replacement candidate was from a Mazda Miata. Fortunately for me, my cousin Bob Smith from Okemos, Michigan has a Miata. This gave me an opportunity to try them out. The decision was made. These seat would go well in Li'l Brit. I checked some of the sites and discovered that there are many ways of installing them in the Spit. My main concerns were:
1) Would I sit too high and end up looking over the windscreen,
2) Would I be able to adjust them fore and aft so as to be comfortable,
3) Would I eventually be able to install a roll bar,
4) Would there be room for the top to still operate,
5) Would there be clearance for the hardtop to still fit,
6) Would it be possible for the tonneau cover to still fit
7) Etc., etc., etc.
The answers turned out to be:
2) Sort of
3) Probably not
6) Not without some modifications.
I will try to document the steps I took to install them in the Spit. READ THEM CLOSELY A COUPLE OF TIMES AND UNDERSTAND THEM THOROUGHLY BEFORE PROCEEDING.
Here are the old seats out on the lawn. They were in pretty rough shape. Torn, worn, broken down foam. My search for the Miata seats took me to numerous salvage yards and took many weeks. I finally found seats from an unfortunate 1995 Mazda Miata. They were fabric, and though I had hoped to find black leather, they were in perfect shape and had the headrest speakers!
I installed the passenger seat first which gave me more room to work and experiment. The first thing to be done is to remove the seat belt receptacle and the side slide rail. Throw them away, sell them on eBay, or donate them to a Miata owner for spare parts. Next, remove the seat back. Save all the hardware for later. It is much easier to work with just the seat bottom. CAUTION must be exercised when fitting the seat bottom so as to leave clearance for the recline mechanism at the side of the seat back. More on that later.
Remove the linkage that connects the slide mechanisms between the seat rails. This will give you 2 separate rails to work with.
The good news is that the front mount holes align with the floor mount on the passenger side. The bad news is that the right mount needs to be modified to align properly on the driver's side. More on that as we progress.
Remove the seat rails from the seat bottom (2 bolts each rail).
The aft end of the rails have a mount that is riveted to the rail. Drill out the rivets and remove the aft mount.
The front mounts are angled. Some, like Dave West (see Miata seat link on "Tech Tips From Others" page), have fabricated a bracket to match this angle. The problem I saw with this is that it would set me up too high in the seat. I still wanted to see through the windshield, not over it. My solution was to place the front mount in a vice and straighten it out. When this was done, it was still strong and did not require any reinforcement.
Original angle Straightened rail mount
The front of each rail has a pin that I removed. I suppose it could be left on and a hole drilled in the floor pan, but I didn't like the idea of drilling holes in the pan. It appears to be a hardened steel pin, but a hack saw worked well. I also tried a Dremel Tool with a cut-off wheel. Either one will work well.
As mentioned earlier, the right front mount hole of the driver's side needs to be modifed. The mount hole needs to be elongated to allow proper alignment. By placing the seat in the well and fastening the left front mount, I scribed an arc with a marker from the under the car through the mount bolt hole. I then drilled 2 holes next to the original hole to allow for the elongation.
Reattach the frame rails to the seat bottoms and make sure that both rails are at the same slide position (count the slots on the side to the "lock teeth"). Reattach the slide mechanism linkage wire. Fasten the seat bottoms to the car using the original front mount holes and bolts. IMPORTANT!!! Be sure to mount the seat as close to the center of the car as possible. Also, as far back as you can.
The next thing I did was to fabricate new plates for the aft mounting. I used 2" X 1/4" steel bar stock and cut pieces 3" long. Then, with the seat bottom installed, place the plate under the aft end of the rail so that it covers the mount hole. Mark position of the rail and holes on plate.
Remove the seats, drill holes in the plates and attach them to the seat rails. Be sure to remember that you are looking at the seat upside down, so be sure to attach them to the proper side. I used 1/4" X 3/4" hex head bolts and nuts. Anything longer than that would restrict the rail slide movement entirely.
Refit the seats using the front mounts, making sure they are as close to the tunnel as possible. Get under the car, and with a long lead pencil or marker, mark through the aft mount holes onto the aft mount plates.
That done, drill the aft plates slightly larger than the mount bolt.
You're in the home stretch!!
Reattach the seat back to the bottom with the original screws. This next step will require a certain amount of gymnastic/contortionist prowess. It will become apparent why very soon! Place the seat into the well and attach the front mounts loosely. Since the seat rail mount holes are larger than the mount bolts, I used lock washers and fender washers. As the bolt snugs down, it "indents" the fender washer and makes a secure fit. Wiggle the seat to align the aft holes. Use the original seat mount bolts and lock washers. You will notice that a certain amount of "seat sliding on the rails" is necessary during the final assembly stage to allow access to the mounting bolts and holes.
After making them as close to the center tunnel as possible, as far aft as you can, and checking the recline lever clearance when you close the door, torque them down to original specs (9 ft/lbs).
Clean up the mess, slide in, and enjoy. You will still have to connect the speakers to your radio, but that can come another day.
I connected the radio so that the "Front Fade" function goes to the driver's speakers and the "Rear Fade" function goes to the passenger's speakers. Right and Left remain Right and Left of each seat.
I will GUARANTEE that you will get admiring glances from all Spitfire owners you encounter.
I have also seen them installed in an MGB. I assume the process would be similar.