Installing a 1999+ Top on a 1990-1997 Miata
By Steve Patterson
Photos By Rich Vatovec
The main difference between the M1(1990-1997) and M2(1999+) tops is the back bow. On the M2
the back bow floats using straps and springs. On the M1, the bow is attached directly to the
soft-top. To install the M2 top on the M1 frame you will have to make the back bow float like
on the M2. I did this by installing a set of straps that holds it in place when the top is
closed. The only thing that you have to deal with after doing the conversion is you have
to manually hold the bow forward while letting the top down. The M2 frame has a set of springs
that does this step for you. It is really easy to do (I even have a Hard Dog "Hard Core
Double Diagonal" roll bar) and is just instinct after a few times. The main advantage of the
1999+ top is that it eliminates unzipping the back window to put the top down. It also gives
you the glass window and still allows you to install a real roll bar.
I won't go over the complete top install process but will give detailed instructions on how to modify the bows to use a '99+ top on a pre-'99 frame. Some of the shop manuals have detailed directions on how to remove and install a top. Also good top installation instructions are found in the November 2000 issue of Miata Magazine and on Miata.net at http://miata.net/garage/miatatop/index.html. Please follow those instructions for removal of the old top. The pre-'99 and the '99+ tops come apart in almost the same way.
There is much debate about taking the frame off the car while doing the top installation. I find that it is easier with the frame left on the car. You may find it easier to take the frame off so you can do the modifications, then reinstall it. There are two Phillips head screws under the last piece of weather-stripping on the top frame near the seat belt mounts. This screw head faces downward and can be difficult to reach with the frame on the car. There is no problem getting to them with the frame off. However, the frame wants to fold up on you attaching the cover with the frame off the car.The tools you will need for the frame modification and installation of the new top are:
The modification is simply to support the back bow and allow it to swing when lowering the
top. You will accomplish this by tethering it between the center bow and the studs on the
After you have the top fabric off the frame (reinstall the frame on the car if you removed it), pull the frame up and latch it. Next cut 2 strips of webbing about 8" long. Then cut 2 strips of webbing about 23 inches long. You can then take the leather punch and punch 2 holes in one side of the 7 1/2-inch long straps for the rivets. Wait until later to punch the other side because some trimming may be necessary. You can also punch 2 holes in one end of the 23-inch straps at this time.
Locate the 2nd bow from the rear. You will need to drill 2 holes for each side in the bow on each side to attach the straps. You will need to drill the holes about 1-1/2 inches from the frame pivot. Take one of the 8" straps and pop rivet it to the frame. NOTE: You will need to position the straps so they go over the frame. (See Pictures) Take the tape measure now and lift the rear bow into position. From the center of the frame, measure the distance between the 2 back bows. The bow should measure 6 inches from the bow next to it. While holding the bow in place, pull the 8" strap back and fold over the rear bow. Locate where you will drill the 2 holes for the rivets for this strap. After drilling the holes reset the bow 6" from the next bow and locate where you will place the rivets in the 8" strap. Install the rivets and trim the excess from the strap. Do the same on the other side of the car.
You are now ready to install the long straps. You will need to drill the holes below the straps you just installed on the back bow. Install them so they flip over the outside of the bows. After you install the tops of the straps, locate the 3rd stud from the end where the back of the top is mounted to the car (rain rail). You will need to make a hole in the strap so that it will fit over the stud. You will need to give some extra room for the metal bar to be installed once the top is installed.
WARNING: Allow the straps to have a little slack in them. I did this install once and didn't leave any slack in the straps. After 4 months one of the straps cut through the top and it had to be replaced again. NOT A CHEAP EXPERIENCE!
You will have to do something with the cables as well. You have 2 options. You can reuse
the old pre-'99 cables that came off your pre-'99 top. You can simply tie the old cable to
the new cable and pull them through the new top. Or, if you choose to use the new '99+
cables, you will have to modify them by turning the springs on the rearward end upside down
and stretching the springs so that you can screw them onto the frame. The long straight part
must go toward the bolt for the M1 or it will not work. It is difficult to rework the hardened
spring steel loop to fit the bolt so if time is not a problem get new M1 cables.
The flaps that are at the corners of the top apron area are not long enough for installation on the pre-'99 frame. You can either leave them hanging (which I have done for over 2 years with no problems) or you can make an extension bracket for them. You will have to add about an inch of material to do this. Some people have fabricated a small bracket made of metal to attach to the flap. We once made the mistake of pulling the fabric to the existing bracket and riveting it down. It caused the top to be over-stretched in the apron area and to pull away from the body at the paint line about 1/4".
While you are installing the new top, you will notice a small tether on each side about halfway on the roof. You will need to screw this to the frame. When you look at the frame it looks like the piece will fit perfectly in a recessed area directly behind the tether. Don't place it there. It will get in the way of the swivel on the frame. Trust me, you don't want to break one off! Simply install a couple of small self-tapping screws about an inch behind the recess. This flat bar is solid steel so it will take a while to drill through it. Sheet metal screws can be used if the hole is drilled right.
You are now done with the modification to the frame. Once you have installed the fabric on the frame, you will attach the back straps on the studs. Then install the metal bar on the back. These directions sound confusing but it isn't that hard. I hope the pictures help.
The last two top bars in the above modification must be moved by hand to drop the top but they are moved by springs on the M2s. For the ultimate finishing touch, we did an experiment to prove the springs could be added. Unfortunately Mazda does not sell these springs separately from the whole top frame! We took 2 springs from a damaged '99 top frame and adapted them to the pre-'99 frame. It is quite a drastic step to add these. First you must remove the bolt and grind off the welded nut at the frame pivot point for the last two bars. We reused the other pivot hardware and connected them with a 1 1/2" long 1/4" diameter bolt, two 5/16" long cylindrical spacers, flat washers and an acorn nut. (See Pictures) It works like a charm. If you have the nerve to take a die grinder to your Miata top frame and hunt through the junkyard for springs then you too could have a 100% equivalent '99+ top!
I know that the Hard Dog Double Diagonal roll bar for a '99+ will work with the factory '99+
soft top. I have one of these installed on my '94 and have no problems with the glass. Kirk
Racing's new style roll bar will fit as well. You must verify the fit with other roll bars
Some people have asked about the defroster. I have mine working using the factory parts on my '94. Unfortunately on pre-'92 Miatas there is no factory wiring for the defroster system. This makes getting the defroster working a bit more of a challenge.
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