If your convertible top has a separated seam, there are two repair options: sew it together yourself or pay someone else to sew it. There is no need to pay someone to repair a separated seam when you can do it yourself. Furthermore, you don't have to wait days with your car in the shop. With a few inexpensive upholstery supplies, you can fix your convertible top faster and cheaper than professional convertible-top repair specialists.
Put the convertible top down. Locate the separated seam, and pull the surrounding folds of fabric away from the separated seam.
Snip off any dangling ends from the original thread.
Pull the two edges of the seam together. Pin them together with some upholstery straight pins. Place the pins about 3 inches apart.
Cut a 2-foot length of upholstery thread from the spool. Thread the upholstery needle, pulling the thread far enough through the needle to prevent it from coming out while sewing.
Insert the needle through both edges where the seam is still intact. "Back stitch," or run several stitches in the same place, to secure the thread.
Sew over the existing stitching, and continue down until you have completely repaired the seam. Make your stitches close enough together to keep airflow or rain from permeating the seam. You may need to replenish the needle with upholstery thread during the process.
Back stitch at the end of the new seam to keep the thread from unravelling. Snip off any loose ends.
When shopping for upholstery thread, look for a colour to match your convertible top or the existing thread in the top. If you can reach the separated seam only with the top up, use a curved needle to repair the seam.