Filler rod for motorcycle casings

[garththefacebiter]

I've got a cheapo (but functioning) AC/DC TIG welder, a full bottle of pure Argon, and a large quantity of British and Japanese motorcycle casings that need minor repairs.
Nothing massively structural, mostly broken lugs which had threaded holes in them (and got snapped off by ham fisted mechanics)
Now from experience I can tell you that the British motorcycle industry used a very different Aluminium alloy in their castings than the Japanese.
Japanese alloy castings have a very high zinc content in comparision (or so I was always told)
Filler rods that work well on British castings will throw up a load of porosity when used on Japanese case.
My instructors at college (about 20 years ago) reckoned that high silicon content rods were the answer, but they didn't make much difference TBH.
So now I'm looking to find both the correct filler rods for British, and also the correct rods for Japanese aluminium alloy.
I'm not sure where to start TBH, but I'll take the advice of welders more experienced than me, and then progress by trial and error.
Any advice would be appreciated.
Thanks

 

[minimutly]

I've got a cheapo (but functioning) AC/DC TIG welder, a full bottle of pure Argon, and a large quantity of British and Japanese motorcycle casings that need minor repairs.
Nothing massively structural, mostly broken lugs which had threaded holes in them (and got snapped off by ham fisted mechanics)
Now from experience I can tell you that the British motorcycle industry used a very different Aluminium alloy in their castings than the Japanese.
Japanese alloy castings have a very high zinc content in comparision (or so I was always told)
Filler rods that work well on British castings will throw up a load of porosity when used on Japanese case.
My instructors at college (about 20 years ago) reckoned that high silicon content rods were the answer, but they didn't make much difference TBH.
So now I'm looking to find both the correct filler rods for British, and also the correct rods for Japanese aluminium alloy.
I'm not sure where to start TBH, but I'll take the advice of welders more experienced than me, and then progress by trial and error.
Any advice would be appreciated.
Thanks

High zinc? Maybe, but equally it could be anything, whatever would help in the die casting process I guess, and if this material gasses off it will cause porosity nomatter what rods you use. Maybe you need to practice on some sacrificial casings to see what happens - cleaning methods, preheat, yes high silicon rods, but what else is there?

 

[123hotchef]

what filler have you been using? do you pre heat the casings first?

 

[ronan]

Same experience here, old British castings are not much of a problem, but the Japanese stuff is a nightmare. I'd get the castings as clean as possible with acetone and a wire brush and see is it a help.

 

[outofthefire]

When we first got an acdc tig at work I had a play with rover v8 rocker covers (one of my bosses wild ideas, you wouldn't believe how many we've got stashed away) I found it was hit and miss with what I guess are general purpose ally rods that came with the welder. What I noticed though was that the castings themselves could be terrible, once you got below the surface some were quite porous and had seemed to absorb oil over time and that really affected the weld.

 

[TechnicAl]

When we first got an acdc tig at work I had a play with rover v8 rocker covers (one of my bosses wild ideas, you wouldn't believe how many we've got stashed away) I found it was hit and miss with what I guess are general purpose ally rods that came with the welder. What I noticed though was that the castings themselves could be terrible, once you got below the surface some were quite porous and had seemed to absorb oil over time and that really affected the weld.

Thats the problem with die cast alloys....they are all porous, some more than others. There are also loads of different alloys, sometimes down to properties but mostly down to personal preference and good/bad experiences. They are a nightmare.
Zinc was mentioned....as far as Im aware they are not "high" in Zinc but some contain more than others. I think the maximum is 2 or 3% so not what I would call high but still enough to make a difference.
They are also prone to collapsing....often they are near to eutectic composition (solid melts straight to liquid..no mushy zone)....so get them just slightly too hot and they collapse.

 

[Popcorn]

ER4943 welds cast alloy like a dream, trouble is you'll have a hard time finding it here. I got mine sent from Arc Zone in the US.

ER4943 - Aluminum / Silicon TIG Welding Rod - 1lb. Pack

Achieve precise welds with our Aluminum/Silicon TIG Filler Rod. Perfect for high-quality welding in aluminum and silicon materials.

www.arc-zone.com

 

[TechnicAl]

ER4943 welds cast alloy like a dream, trouble is you'll have a hard time finding it here. I got mine sent from Arc Zone in the US.

ER4943 - Aluminum / Silicon TIG Welding Rod - 1lb. Pack

Achieve precise welds with our Aluminum/Silicon TIG Filler Rod. Perfect for high-quality welding in aluminum and silicon materials.

www.arc-zone.com

I believe the reason being that its designed to be higher strength than 4043 and 4643. In Europe the higher strength is usually dealt with by using the Mg types 5356, 5556 and the 4943 is generally considered to offer no benefit welding wise....Therefore there is no market for 4943........You obviously consider it welds better than 4043 so you may have discovered something but i would suspect that market is pretty small.

 

[lchris21]

I used 4043 on this. Sometimes you've got to be brutal and remove the rot.....good luck

Cafe Racer dreams..............rusting wreck rescued from the spiders???

Nice job on the paint finish :cool: still not sure about the "speed blocks" will have to see how it looks when finished.

www.mig-welding.co.uk

 

[Munkul]

I wonder if, on finding a die-cast alloy too difficult to TIG weld, would it make sense to try those low-temp alloy rods and oxyfuel brazing instead? Since they are mostly zinc based filler anyway.

I've tried the process once in my teens and thought it impossible, but I'm not so sure now... with the right cleanup... anyone have a good experience with it?