Here is my $0.02 on welding these parts: The casting is often referred to as "pot metal". Not sure where the term came from, but it basically means that instead of being pure Aluminum, these castings are high in Zinc and Sulfur. The Zinc and Sulfur are added to ease mold release. These elements also give the casting more strength than pure Aluminum, while still enabling the casting to be easily machined. The lister who mentioned that his welder said that there was a lot of "air" in the casting was not far off. What was really happening was the Zinc and other trace elements were turning to a gas at the elevated temperatures required to turn the Aluminum to a liquid (melt). This material is weldable, but will not look nice, like a tig welded aluminum motorcycle frame does. Instead, it will be porous, as the escaping gas leaves bubbles in the Aluminum as it is trying to freeze. Your best bet if you must weld it is to use a product called Kirksite rod (www.crownalloys.com). This product works best if you use a propane or acetylene torch as your heat source, rather than a tig welding torch. I've used this product to weld broken clutch and brake levers on my dirt bikes. These levers are cast out of the same "pot metal".
If you aren't feeling up to the job of doing the welding yourself, contact your local Lincoln Electric representative (www.lincolnelectric.com). They are good people (I worked with them for 10 years) Explain your application and they will connect you with a competent weld shop in your area. Now, if this doesn't have everyone running to Ace hardware for a tube of J-B weld, nothing will. Good luck, Matt Atwood AccuBilt Automated Systems Inc. 2365 Research Ave. Jackson, MI 49203 517-787-WELD 517-787-0783 (fax) 517-206-9218 (cell)
