Hi Guy's
The top subframe cast mounting, is just a hearth brazed sleeve over the tube. best way to remove it is to cut very gently with a 4'mini grinder nearly through the casting on both sides horizontally . then heat with oxy gas welding torch until the braze starts to melt now give the casting a sharp tap with hammer and chisel and the two parts of the casting should fall away. Heat and wire brush away the remainder of the brazing residue.
You will not effect the tube by heating as long has you do this before cutting out the bottom tube (if you are going too)I have found that the tube is 14 gauge ERW??
Pictures on the bsaotter web site.
The bottom hearth brazed lug does hold the seat and bottom tube run.
Sump shield ?? I would make your own 4-5-6 mm alloy sheet
Regards Charlie. www.bsaotter.com
