welding old aluminum transmission

[raggededgge]

Hello everyone. New to this forum lots of experience out there looks like.
Need some advice repairing an aluminum transmission housing from a 1929 Indian motorcycle. There is a groove gound into it from where the chain rubbed.
I ground the groove out a bit to clean then I cleaned and cleaned. When I hit it the the tig torch I get some black coming out and lots of porosity forming. I can get a bead layed down I then file it down and repeat. I can't seem to get rid of the little pin holes that keep cropping up.
Using a squarewave machine with ceriated tungsten and a #10 cup and gas lens
I have tried some preheat helps a bit.
Any advice thanks in advance greg

[Craig in Denver]

B_C knows far more about this than myself. But I'll say there's a lot of 'heat-n-clean-heat-n-clean' in your future.

[acwd1950]

What kind of filler rod are you using? What are you cleaning it with? SS wire brush and acetone is what I recommend along with 4043 filler rod. It will take alot of cleaning due to the chain rubbing and grinding against the case. I have used brake parts cleaner on greasy parts. Just my 2 cents. Lets see what BC has to say

Steve

[B_C]

Like most old motorcycle cases yours is made of porous casting and has been soaking up oil for many years....I haven't had a lot of success (Cosmetically) with the older M/C cases...If you can lay down a good base weld it will give you something to work with but it sounds like you have a really dirty casting there that isn't going to weld very well......4043 is what I use for most cast aluminum... But if it's just a
fill job maybe try some 1100 rod?

[raggededgge]

the learning curve

Hi guys thanks for replies
I had been using 5356 filler and cleaning with pure alcohol Tried the acetone and 4043 rod. yikes got worse The 4043 doesn't want to adhere near as well as the 5356. I will try some 1100 but in this town I have to order this "exotic" rod jeez. what is the safe max preheat temp?
Thanks Again Greg

[wldsmke]

welding case

let your tig tourch do the pre-heat. use the high freq to clean your weld, if you are using square wave ,adjust your machine so you have more low cycle ,this will clean better,go over weld area several times before you add filler metal,and wire brush between passes, when your weld area cleans up start adding filler, Good luck. Works for Me.D

[The_Beave]

Bake the part in an oven, preferably not one that a significant other uses to cook food with. Heating up the part to a few hundred degrees for a while should smoke out most of the crap, then wirebrush the crap out of the surface, use some chemical cleaner (acetone and the like), and then wirebrush it again. That should help.

[B_C]

Hi guys thanks for replies
I had been using 5356 filler and cleaning with pure alcohol Tried the acetone and 4043 rod. yikes got worse The 4043 doesn't want to adhere near as well as the 5356. I will try some 1100 but in this town I have to order this "exotic" rod jeez. what is the safe max preheat temp?
Thanks Again Greg

The 1100 filler is used a lot for welding aluminum window frames so keep that in mind.....Also keep in mind that 5356 can be CRACK SENSITIVE when applied to cast.....I think your going to find that the 4043 is going to be your best bet.....Pre- heat temp is when the "Soot burns off"
after you soot it up with OA torch....Can't see you having to pre-heat though...Pretty small part..
You might have to die grind out with a burr the area your trying to weld to get back to clean parent metal.....Not much just skim the surface ....