Had a round track buddy give me a Winters magnesium centre section from his sportsman car that has a little damage to it that needs welding up. I don't think that will be the problem. The problem I see is that there is a certain amount of corrosion present on some of the gasket surfaces. Can these spots be welded as well as long as they are ground out to solid metal? Is there a way to stop the already present corrosion from starting again? How about protecting the magnesium surface of the rest of the centre section from starting to corrode? I love the weight savings and the look of the mag. centre over an aluminum centre (have the option of buying that one if I can't save the mag. one). Please tell me I can save it instead of hanging it on the wall as art!!
I can't comment on the welding, but Gibbs brand is your best bet for cleaning and sealing the magnesium from moisture and corrosion. Here's a good write up with some good examples including a mag quick change.. http://www.roadsters.com/gibbs/
Tig is very effective for welding magnesium. Get it clean, clean, and clean then make sure that purge gas covers the weld affected area, including the back side of thin areas.
Cleanliness is the key to welding. If you attempt to weld this be sure not to breathe the fumes. Could (will) be harmful to your health.
DON'T USE BRAKE CLEAN TO PREP FOR WELDING. It gives off VERY deadly fumes. Use soap and water, then dry with acetone.
Thanks for the replies guys. Anyone offer any experience on welding up the corroded gasket flanges? Just grind to good metal and have at it?
Magnesium can corrode in a vacuum. That means it is possible for the part to corrode from the inside out. ***uming the part doesn't have corrosion issues, the weldability of magnesium depends on the alloy of the metal, and the quality of the casting.
It is especially important to clean the mag before you weld. Use a co**** carbide deburring tool and then clean the area with acetone. Preheat the casting to at least 275 degrees and use AZ101 filler rod. Set your TIG welder to the same settings that you would for aluminum welding. Better practice a bit first before you s**** your high dollar rear end. In racing "Every Ounce Counts" Scott Fab Manager Welders360.com
Keep the info coming guys. Still wondering about how difficult it would be to weld up the corroded gasket areas? Some parts are almost a quarter inch deep? Anyone have a source for reasonable filler rod? I don't need 3 lbs!! My one source has AZ92T60 for 3 bucks a stick, would this rod work?
If it were me, on gasket surfaces, I wouldn't weld them back up. I'd use a two part epoxy type filler they use for corroded cylinder head repair. Fills in the pits and just sand smooth. Easier than welding, machining or grinding.
Got pictures of the damage? Welding = distortion on some level. I'd consider epoxy repair of gasket surfaces as safer, to avoid distorting and mis-aligning bearing bores, etc. re: corrosion protection. Magnesium is the at the very end of the "galvanic series". http://www.talle.biz/images/Galvanic Series.gif If two metals are in contact with some salty water around then the "less noble" one corrodes. Magnesium even loses to zinc, which is used to sacrificially protect steel.
I'd do what Modifieddriver says for repair,or just silicone the halfs together opon ***emblie If it's really that bad there's probably not that much life left in it anyway, Next thing you'll find is the bolt holes are rotted out and even helicoils won't hold nice Tony
......... or re-machine the surfaces flat and make a spacer to correct for the amount removed. That gets everything back to where it was originally, and eliminates the distortion issue already mentioned. With 1/4" of material corroded away that is an indication of what could be a part that corrosion has already re-claimed. It is very possible that you are seeing the tips of corrosion that goes a lot deeper into the casting. If that is so, getting to the good metal needed to do a proper weld repair could be impractical or impossible. Another consideration, magnesium isn't very strong to begin with. A part that is badly corroded will be even weaker. I hope this works out for you, but realize there is a chance this part's life is over.
Digging with a pick, 1/4 " deep is the worst in only a couple of spots, most is just a little corrosion. Where bearings mount etc, all looks solid, corrosion mostly in the edges of gasket surfaces, plus the damaged spot that I must weld first to try and salvage the centre section. The centre was free to try and fix so I'm not scared if it doesn't work. If unsuccessful I will buy his aluminum centre section (but it weighs about 3X's as much) plus it isn't magnesium (fetish).
I wouldn't weld up the gasket surfaces at all. Clean the hell out of it and if you want to make it smooth use JB Weld to fill the pits then file flat. The more you weld the more you chance you have to warp things. the more you warp things the more machine work you have to do.
I wouldn't' worry about the weight differance on a street car. A local welder around here retired from ALCOA. This guy is a real master welder. He welds alum, mag anything you give him. anyway hes' too far for you. But I seen early Halibrand solid knock offs he welded for a customer, (the pit holes) then the guy machined in a big lathe, and was selling them for big money after polishing. Ago
here's some ****ty pics of the corrosion. Anyone have a source for filler rod or some they want to sell me? Beg Beg. I know the weight savings doesn't matter for a street rod but Magnesium race parts are just so dam cool!! [/url][/IMG] [/url][/IMG]
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