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Repairing aluminium casting
cliftyhanger - 5/3/19 at 11:04 AM

I have a "bit" of gear linkage housing (old Triumph gearbox) that has broken. Made of cast ali, so I can't mig it.
Has anybody tried the Lumiweld/aluminium brazing rods that are sold? Experiences would be very welcome.
The part is not massively stressed, but does get the occasional whack if a gear change is aggressive. So it is not just a a cosmetic repair required.

And I have seen epoxy resins/putties that claim to be "stronger than the base metal" but again, anybody got experience?

TIA
Clive

rusty nuts - 5/3/19 at 11:19 AM

Probably better to find someone to TIG weld it, maybe cheaper as well?

Mr Whippy - 5/3/19 at 12:12 PM

I've used the aluminium brazing rods before and you need a lot of heat to get them going and very clean metal, they do work but the balance between soft and pliable to running all over the place is tricky. It hardens very quickly so crystals tend to be big and the part brittle. Used JB weld a lot too and it's good for repairing cracks, hose fittings etc but not for what you are talking about

I think I'd opt for getting it tig welded.

JAG - 5/3/19 at 12:26 PM

I've used Technoweld for Aluminium brazing. It works but does need a lot of heat as the Aluminium parts conduct the heat away from the joint.

Anything with any mass, say thicker than 3mm or so, will be hard to get hot enough and keep hot enough; unless you have a suitable Oven!

I'd get someone local to TIG weld it for you

[Edited on 5/3/19 by JAG]

theconrodkid - 5/3/19 at 02:24 PM

https://www.mig-welding.co.uk/

have a word on ^^^, should be someone local that would tig it for you

gremlin1234 - 5/3/19 at 04:41 PM

quote:
Originally posted by cliftyhanger
I have a "bit" of gear linkage housing (old Triumph gearbox) that has broken. Made of cast ali, so I can't mig it.

I assume its the gearbox top cover/extention


https://rimmerbros.com/Item--i-GRID005689

if so the top is relatively flat, and you may be able to bolt on an external reinforcement

cliftyhanger - 5/3/19 at 05:53 PM

It is sadly the rarer, and very tricky to find, overdrive later gearbox. Last linkage I saw was over £100 (for the linkage) so I don't think I will get lucky.

As I suspected, the magic fixes don't work. I have a lead on a local TIG welder, will get in touch.

Thanks all.

James - 5/3/19 at 11:42 PM

At Mclaren they use Devcon for repairing all sorts of bits of tools and equipment.

I would certainly consider using it for something like this.

fazerruss - 6/3/19 at 01:30 PM

These are the kind of jobs I do in my spare time (TIG). I'm.not local though so it would need to be posted to me.

Do you have any photos of the damage?

http://www.mig-welding.co.uk/forum/threads/motorcycle-crank-case-repair.85103/

[Edited on 6/3/19 by fazerruss]