Aad bent a piece of tubing to create the raised backbone that will be welded on top of the existing backbone. After bending he cut the tube section in half with an angle grinder. The radius of the front part was too tight to bend without distorting the tube, so Aad machined a ring from a solid chunk of steel and cut out the part he needed. As always it helps alot to have a fully equipped machineshop next door! After the new backbone was mounted we found that the gap between frame and tank was a little bit uneven so that took a lot of welding and grinding to fix.....