aluminium/alloy welding

[RED1]

OK - way out of my depth here. I have a set of motorcycle crankcases, parts of which have had holes drilled in them

Three holes, each approx 7mm diameter into approx 4mm thick alloy (the crankcase material).
I want to fill them - can they be welded ? Should i use some epoxy stuff? Is it easy enough for me to weld ?(unlikely) Should I junk 'em and buy replacements:full Should I give them to an "expert" for repair?

advice much appreciated
iain

 

[Airweld]

Hi, Your crank cases should be ok to weld but you will need to use a TIG set with AC setting, also the aluminium must be spotlesly clean, for the thickness you have quoted I would think you would need around 80 to 110 amps. Good luck
Paul.

 

[fingers99]

Depends what equipment you have access to. They should TIG fine, but as you're asking, I'd guess you've never done it.

Mig, maybe. Again, it won't be easy.

Epoxy is fine if the holes have not reduced the strength of the cases.

Lumiweld does a pretty good job, but on big crankcases you'll need to put in a lot of soft heat.

Depending on how many holes there are, (and how difficult replacement cases will be to get) I'd get someone to TIG it. With careful re-finishing no one will know the holes were ever there!

 

[runnach]

A lot depends on the alloy type? If zinc dye-cast forget it, unless you have dye-cast rod and experience of welding this rubbish.But fair to say, most bike casts are repairable depending on age of castings, TIG is the way to go! Another but, even if scrupulously clean, oil (if it runs around the casting) will still ooze out.

Cheers.......

 

[Weldingartisan]

Bit of a steep learning curve to start ally welding on old crankcases. Clean well with solvent (I use brake cleaner), countersink the hole for good penetration, pre-heat with propane torch and clean again (oil will be released during the pre-heat).
I would use a 5% mag filler on about 120amps, colour match will not be exact but a lot of people seem to spray older casings with ally paint anyway. W/A

 

[peterd51]

Hi,

how about tapping the holes and screwing in a bolt with loc-tite, araldite, etc, under it?

Regards
Peter

 

[shenion]

I would probably go with alum brazing rods like Alumiweld, lumalloy etc. Must be real clean. These rods take practice but are not difficult. As you are not melting the crankcase it is a bit easier to control the heat.

The rods tend to flow like water so a SS backing plate usually helps.

When filling holes woth brazing rods, Iusually tap them first; that makes them mechanically stronger in case there is not perfect fusion.

 

[aametalmaster]

I mig weld lots of motorcycle cases of all brands. I use my spoolgun and 4043 wire but it must be clean. If its a non critical just expoxy it. If its a large hole just back it up with a piece of steel like a hammer face...Bob