Hier mal am Beispiel E34, DIY Bilder
www.bimmerboard.com/forums/posts/707946/
www.bimmerboard.com/forums/posts/708718
Beschreibung: To try and answer your questions in one post...
1)I had never sewn or stitched leather or anything else in my life before. I borrowed a 20yr old conventional Elna sewing machine from my mother and practiced with offcuts. I discovered one can turn it by hand doing literally one stitch at a time and get very straight lines this way. I used a Pizza cutter to score straight lines on the back of the leather as a guide and then glued the two pieces together on the visible side with contact, stitched it and used thinners to remove the contact once it was stitched. (The thinners did not harm the leather surface at all surprisingly)
2) The leather is about 1.2mm thick and the back was folded over both sides and glued down after stitching, used an old Coke bottle to flatten it. Leather compresses very well and stays that way when the glue dries.
3)The centre vent, upper vent, both speaker covers had to be sanded smaller with a belt snader and resprayed to fit the holes, wasn't too much of an issue. The cluster, I used an old one shoved in with leather offcuts and then heated the plastic dash with a hot air gun, this enlarged the hole enough that the cluster fitted the leather covered hole afterwards.
4) Gluing straight lines, used heaps of wet contact on the back, this gave me about 5 min to massage the leather into place allowing me to get perfectly straight lines and flat surface before the contact glue dried.(The trick is not to use it as contact, just a kind of setting slime)
5)I had a few dashes lying around, destroyed the first by trying to cut the surface off to give more space didn't work, second one (the one I used) I sanded with a handheld belt sander with 60 grit sandpaper to give a rough surface for the glue and even things out. I had eight door linings and destroyed about four trying to get them apart, found out lots of Acetone allowed me to get the vynyl off and then used the wet contact technique to shape the leather onto the panel. I did the sills first and then the door lining working top downwards. The front doors were Hell where the pockets are and took a few attempts. Fortunately one can drench the leather with thinners and retry.
All the separate little bits were all glued together before stitching and cleaned up with thinners afterwards. The door linings use two different types of foam rubber as the backing to get the surface flat. Special nylon thread was used. The leather was purchased from a local supplier called Woodheads. I used grain corrected leather (the grain is stamped on) as this hides any uneveness in corners.
If anybody wishes to try this for themselves I am more than happy to share my new found knowlege via email. If I can do it, you can! Just took lots of common sense thinking and a few retry attempts. No it wasn't easy, but if you refuse to give up, you will eventually get it right. (I gave up and got desparate a few times, had bits of car interior all over the house, and thought many times "Damnit I can do this, some guy in Germany or Italy did")