You have to determine the extent of rot and so begin by thoroughly cleaning the floorpan/chassis assembly top and bottom. Be quite brutal when probing for rot (use a pointed panel beaters' hammer), because a sound‑
looking spine can in fact be very weak if it has rotted out from within, and floorpans covered with sound-looking underseal can be heavily rotted underneath that layer of underseal. If rot is found to extend up into the chassis spine then perhaps it is best to scrap the chassis and either use a new one (available from Autobarn) or to take one from another Beetle.
The decision whether to patch repair or replace the floorpans should be taken according to the extent of the rot and, more importantly, according to whether you wish to have to repeat the repair at some time in the future! If you patch it, then sooner or later more patching will be required. Bear in mind that repaired panels usually rot out first along welded seams and, if you elect to turn the floorpans into a kind of welded patchwork quilt then they will rot all over in double-quick time! Replace the lot, properly rust-proof it and the floor should last as long as the car itself.
If the engine has been stripped from the chassis (as it should) it is little problem to turn the chassis onto its side so that you can get at the underside of the floorpans —drain the transaxle oil firstly on swing axle cars. If money is very tight and repair is the only option, begin by cleaning both floorpans back to bare metal so that you can find every trace of rot. If possible, make use of proper repair panels and, for the sake of strength, use an overlapped joint continuously seam welded both top and bottom. Rot most frequently occurs at the floorpan outer edges, for which complete, front or rear half repair panels are available.
looking spine can in fact be very weak if it has rotted out from within, and floorpans covered with sound-looking underseal can be heavily rotted underneath that layer of underseal. If rot is found to extend up into the chassis spine then perhaps it is best to scrap the chassis and either use a new one (available from Autobarn) or to take one from another Beetle.
The decision whether to patch repair or replace the floorpans should be taken according to the extent of the rot and, more importantly, according to whether you wish to have to repeat the repair at some time in the future! If you patch it, then sooner or later more patching will be required. Bear in mind that repaired panels usually rot out first along welded seams and, if you elect to turn the floorpans into a kind of welded patchwork quilt then they will rot all over in double-quick time! Replace the lot, properly rust-proof it and the floor should last as long as the car itself.
If the engine has been stripped from the chassis (as it should) it is little problem to turn the chassis onto its side so that you can get at the underside of the floorpans —drain the transaxle oil firstly on swing axle cars. If money is very tight and repair is the only option, begin by cleaning both floorpans back to bare metal so that you can find every trace of rot. If possible, make use of proper repair panels and, for the sake of strength, use an overlapped joint continuously seam welded both top and bottom. Rot most frequently occurs at the floorpan outer edges, for which complete, front or rear half repair panels are available.
