Gearbox drain modification on K series BMW Anyone who's changed the gearbox oil on a K series BMW will know just how messy a job this is. So I modified the drain plug. See the 1st photo. You'll see ( FLTR ) the original plug and sealing washer, an M14 X 1.5 banjo bolt with a square magnet inside it, 2 copper washers, a Ø14mm banjo with a welded on 25mm long extension ending in an M10 X 1.0 internal thread and, lastly, an M10 X 1.0 plug with copper washer. The 2nd photo shows the new drain in position on the bike. No more mess, easy to position a funnel under the drain, easy to undo the M10 X 1.0 plug with the funnel in place. The 5mm X 5mm square piece sticking out of the banjo bolt in the 1st photo is a 15mm long magnet to do the job of the magnet in the original plug, but, of course, the banjo must be taken out to clean the magnet. The magnet is not fastened, it can be removed, but will stay in the banjo because the banjo is steel whereas the gearbox casing is aluminium. The small Alan screw above the drain in the 2nd photo is my plug to see when the gearbox is full, not too successful because the gearbox wall is a bit thin for threading and sealing against the cast gearbox surface isn't easy. I wouldn't recommend it.