I recently (10-1-98) bought a 1991 Red Miata (30,000 miles, not a single door ding or scratch, $7835) and it had a torn and discolored rear plastic window. I looked on the Internet for help and found many articles on replacing the entire convertible top but nothing about quickly and cheaply fixing just the back window.

The back panel of the Miata’s top is designed to be replaced WITHOUT removing the entire top!!! The back panel is the part that unzips and that has the original plastic window inset in the middle. I had to fix mine and I wanted to do it correctly and cheaply.

Mazda sells a replacement back window for $370 and that is just for the clear plastic part, you then need to take it to a shop to have it installed. I did find ads for replacement back panels with a new plastic or glass window but those were also relatively expensive. A catalog sells replacement plastic back panels for $170 and glass back panels for $375. Again you need to have it installed. I see in ads that the zipper half that is on the replacement panel is usually not compatible with the zipper half in the original top, or the zipper comes not sewn on. It is usually required that you remove the zipper from the original back panel and sew it onto the new back panel. What a pain!

I also talked to the local Miata club and they suggested dropping the car off at a specialty/upholstery shop for a rear window transplant. I talked to a few and the prices ranged from $200 to $300. They would remove the top, cut out the window, sew in a new window, and reinstall the top. No one mentioned removing just the back panel but perhaps they all knew how to do it. (I seriously doubt it!!!)

I decided to buy the Miata Enthusiast’s Shop Manual and study it. It includes instructions for removing just the back panel so that the window can be replaced. The advantages are a perfect fit, it’s cheap, the car is not damaged, and it looks as good as possible. If the top is in otherwise good order, this is a great way to fix that broken or brown window.

Please refer to the Enthusiasts Manual for explicit details but I will give you an overview of what to expect if you decide to do as I did. Some steps must be done in a certain order and others can be moved around either a lot or a little. I found the removal took 1.5 hours and the installation took about 1 hour. It was a lot easier than I imagined while reading the manual.

Before I list the steps to complete the repair, I think it would be helpful to give an overview of the convertible top design (this was missing from the manual). The top consists of two pieces; the top and the back panel. Where the top disappears into the body at the back it is attached to a gutter (rain rail) that is used to drain water from the top into drain holes that are in the back corners behind the driver’s and passenger’s heads. This rain rail is a U-shaped piece of plastic and rubber with the rounded part hanging down to channel the rain. Just in front of the trunk is a molding that goes around the where the top is attached. This molding has a rubber flap that hangs down inside the gutter. The back edge of the U-shaped gutter is inserted under this rubber flap so water will drain into the gutter. The top also is inserted into the gutter. All of these pieces rest on and are attached to studs which make disassembly and assembly very easy and straight-forward. Inside the top are three pieces of metal that also push onto the studs, and nuts are screwed on to hold everything in place.

• (EASY) Remove the heavy metal "belt line cover" behind the driver’s and passenger’s heads. There is a bolt on the inside (with a snap top) and a phillips head screw that screws right down from the top. Put them in a baggie with the screws marking which is left and which is right.
• (EASY) Remove a second metal "belt line cover" that is right next to the previous step’s piece. It is attached with a plastic push-on plug. Put them in a baggie with the screws marking which is left and which is right since it is really not obvious 2 days later!
• (EASY) Remove the back window carpet piece. It is attached with plastic push-on plugs and two phillips head screws. To remove the plugs just pry them out using two flathead screwdrivers or using a fork with one tine removed or with a special pry tool. They break easily! They cost $1 each at the Mazda dealership. I have heard that parts stores have generic versions for a lot less.
• (HARDEST ITEM) Lower top. You should see two rivets on each side that hold the cloth onto the frame located just behind the diver’s and passenger’s heads. The manual says to drill these out from the inside with the top up but I say you can drill them out with the top down. I used a small drill that would drill out the center of the rivet just leaving the outside shell for centering. When you drill out enough, use a slightly larger drill and remove the rest of the rivet. Use a SHARP drill so you cut the rivet rather than spin it around. Be careful not to drill through and into the top! Move the cloth from behind the rivets and place an object under the rivets to stop the drill if you drill too far. Use a variable speed drill and go very slow! A variable speed drill is a requirement for this project.
• (EASY) remove the nuts that hold the 3 metal frame pieces that press the rain rail, top, and back panel against the car body. Remove the 3 metal frame pieces marking which side goes up (important).
• (HARD) Carefully and gently remove the top & back panel & rain rail from the studs and lift slightly out of the interior. The rain rail is very fragile. The top and back panel are all riveted (really grommeted) to the rain rail. I found that the plastic will crack easier if the temperature is colder. Do it when the temperature is over 70 degrees Fahrenheit. Be patient here!
• (MEDIUM HARD) With a sharp drill and a slow variable speed drill, drill out the inside portion of the rivets (grommets). They are very small and easy to drill out. Have a helper hold the back of each grommet at you drill. Vary the angle at which you drill to not spin the grommet. If the grommet gets hot, stop and let it cool or you will melt the plastic. Take it slow and be patient and this will be a very easy step. Take the rain rail out of the car and place it where it will be safe. You will not be replacing the grommets! You cannot replace the grommets with rivets since everything must lie flush (and rivets project out). The installation is so much easier. I was worried at this point about putting it back together. Don’t worry, be happy!
• (EASY) The rear panel is riveted to the top piece with two brass rivets (like are on blue jeans). Drill them out so they come apart. You will not be replacing these either (but I did).
• (EASY) Mark with fingernail polish the position of the stays at the two ends of the zipper. Mark a line across the zipper that will allow you to line it up and zip it up exactly as it was. Remove the two metal stays.
• (EASY)Now unzip the zipper and unfasten the Velcro and the entire back panel can be removed from the car.
• Vacuum the back area of the car to get all the shavings from the drilling of the grommets.

• Zip up the window
• Replace the metal stays on the zipper.
• Clean the rain rail and cover all the rivet/grommet holes with square pieces of black plastic electrician’s tape. I covered both the front and the back of each hole. I also covered a crack I made in the rain rail. This is so the holes don’t leak water.
• Insert the rain rail back into the car. Make sure the back edge of the rain rail is placed under the rubber flap where it meets the car body. To say it another way, insert the rubber flap into the inside of the rain rail. This is much easier than removing it but still be careful and go slow, the rain rail is fragile.
• I used an eyelet machine to insert a grommet/eyelet where the brass rivet was drilled out. This eyelet/grommet I installed fastened the top to the back panel. Except for this grommet, every other place where there was a grommet has a stud that will keep everything together correctly. This is optional and the manual doesn’t mention it at all. You could also just tie a loop of string around the two holes to keep them together until you tighten down the metal bracket that will ultimately hold it all together.
• Insert the top and back panel into the inside of the rain rail and onto the studs. Then attach the outside of the rain rail to the studs.
• Put the 3 metal brackets on the studs and hand tighten the nuts. The rounded side of the brackets point upward.
• Make sure the top and back panel are smooth and pretty and in place.
• Put back the outside belt cover with the black plastic plug going through the rain rail and into a hole.
• Carefully tighten the nuts, tightening all a little at a time and then start from the center and work your way to the sides. Give it an hour and retighten, as the fabric compresses. Don’t over-tighten! Don’t strip the studs! Check that the top and back panel are aligned and pretty.
• Put the top up to make sure everything fits well and you are happy with your fixed back panel.
• Put back the inside belt covers and replace the bolt and screw in each one.
• Put the top down and replace the 2 rivets on each side that you removed. These are the rivets that are right behind the driver’s and passenger’s heads. The rivets hold together the top and the back panel to the frame. I didn’t replace mine yet and I see no difference. I will replace them when my friend brings over his rivet tool.
• Replace the carpet.
• Enjoy the rear view.

I hope this helps. I hope I remembered everything. Make sure you get an Enthusiast’s Manual to help you.

Also worth mentioning is the fact that the next time you want to remove the window and replace it, you will be able to do it much faster. Removal in 30 minutes and reinstallation in 30 minutes.

Happy motoring,

Star