I recently replaced the rear window on my 94 vert. It was a pain in the a** and required 2 people for a lot of the job.
https://members.rennlist.com/frisbee91/ ... ir_DIY.pdf
This guy made an excellent guide about how he replaced the window in his Porsche. A lot of what I ended up doing was inspired by him.
I tried multiple methods but the only way I got the thing to look decent was by sewing the replacement window. In order to taughtly hold the replacement clear vinyl in place, I actually ended up making holes in the convertible top and using nuts and bolts to hold the clear vinyl in place and then sewing it in. I bought a "Speedy Stitcher" along with some sewing machine needles and used what i believe is called a lock-stitch to sew the window. For a lot of the sewing one person would have to be inside to feed the thread through the look and the other person the outside with the speedy stitcher to puncture and pull the needle. Once my partner and I got a rhythm down it only took a couple sessions to get the whole thing done.
Prior to sewing I completely removed the old window and removed most of the old thread that held it in place.
I tried to sew the vinyl to where the original window was attached everywhere I could. I ran into the problem that the fabric from the convertible top covers from the outside where the original window was stitched so I had to sew through the convertible top fabric on the two sides and top (from a distance does not look that bad, can barely see the black thread on the black convertible top. The bottom edge I sewed about 4 cm lower than where the old stitches for the original window were. After the sewing was complete I put a bead of clear silicone between the fabric and vinyl to try and help seal everything better. I stitched outside the bolts all the way around.
At first I tried to glue the new window to the outer edge of the old one, did not work. One of the biggest problems is getting the vinyl tight enough that it doesn't have any wrinkles. My vert's top isn't in the greatest shape so I had no qualms with putting several bolts through it to hold the vinyl tight. I tried ordering super powerful magnets to hold the vinyl in place, did not work.
I have a bunch of wrinkles in the top part because I first attempted to attach the top edge with velcro. I sewed a strip of velcro to the piece of clear vinyl and sticking it to the top, did not work out well and unfortunately I had already started sewing the top before I used bolts to hold the vinyl in place.
I will admit it does not look super clean but it is so much better than the cracked and opaque remnants of the old rear window.
I have not removed the bolts yet, still trying to come up with a clever way of patching those holes.
Also, some tips if anyone want to stitch their own rear window. The speedy stitch is a must and you will break needles. I always attached a second need to the loose thread end of the string to make it easier to pass through the loop that the speedy stitcher makes when it punctures the fabric. Having the inside of the car well lit will help a lot, feeding the needle through the loop is tedious. I used some sort of black vinyl thread I bought off of amazon that was supposed to be good for the outdoors.