Corrosion Avoidance - Lower Chassis Longitudinal Area

[Jim 123]

I am sure that others have been down this path before, but until Jonathan corrects me, I can't find anything in the archives  : )

During blats in rainy conditions, water collects in the engine compartment where the aluminium skin wraps underneath the chassis longitudinals inside the engine bay.  The main areas of entry are the lower wishbone rear mount apertures in both side skins, plus the bodyside exit aperture for the exhaust primaries.  Parking up recently, I noted that the volumes of collected static water can be surprisingly large, and no doubt that acceleration and deceleration helps distribute the water all along the longitudinals-to-body skin interface, including into the grot trap.

I know that cavity wax in this area is a good deterrent, but water tends to get into places that even hot wax does not penetrate, particularly where the underside of the longitudinals are riveted to the skin.

I am looking at making small diameter drain holes in underside the ally skin just outboard of the chassis longitudinals.  Current thinking is one hole fore and one aft of the soldered joins in the body skin at the wishbone lower entry points.  Ditto a couple of drain holes holes on the left and right of the car, and these will be fore and aft of the position of the aperture for the exhaust primaries.

Before I fire up the drill, I'd appreciate feedback from anybody who has done similar.