Warning: this involves the modification of a seatbelt mounting point, if you are not confident or competent, leave it alone. Neither I or the forum shall he held responsible for any injury or loss of life resulting in the following modification!
I did this with tools the everyman should have laying around. Namely a drill, hacksaw, file and spanners. Although I did use an impact gun for speed.
Parts required were a small sheet of 3mm steel (I had an a5 sized piece but there was lots left over), 4 m8x30 10.9 flange headed bolts, 4 m6x30 8.8 standard bolts, nyloc nuts for the above and 4 standard m8 nuts for spacers. A longer seatbelt bolt with nut and spacer would have been better but I didn't have one in my collection so I repurposed the factory bolt and cut the nut off the original mount.
The pictures tell the story but the gist of it goes like this:
Remove seat from car, take plastics off seat base.
All the seats have the hinge at the front for raising and lowering the seat but they lack the rear hardware.
Measure between rail and seat base.
Drill out the 4 rivets, 6mm at the top and 8mm at the rail.
Cut the piece of metal out.
Push the rail towards the base, I went with 25mm closer, it makes you feel like you're sat in the car not on it.
Make new steel plates after making a cardboard template.
Slide in M6 bolts, don't forget your washers, add 1 plain m8 nut or other spacer material to the bolt then slide the plate on. Washers and nyloc nuts on the back. Do not tighten.
Install M8 bolts through the plate then through the rail, washers and nyloc nuts on the back.
Tighten everything.
Cut down plastics to clear the rail, flip seat on its side and work out where your seatbelt bolt will go through.
Drill a 12mm hole and bolt your seat belt clip back on. My method of reusing factory bolt and nut required slight bending of the clip.
Bolt seat back in, swear because you lost the handle, go inside and ask wife to dress the wounds sustained from the unbelievably sharp underside of the seat.
