I've been doing a bit of gearbox work on my old '84 Tenere and made a bit of a strange discovery.

There has been quite a bit of welding done to re-fix the pillar that has the stopper arm for the gear selector drum - I have another gearbox that has this very same pillar missing (looks like it has been snapped off).

I'm guessing this is a bit of a weak spot with the early engines???

I've looked at both sides of the repair and it looks like it is good but how reliable are welded repairs to cast metals???

I have a third gearbox casing (greedy eh?) that I might use but I wanted to keep the engine/gearbox numbers to match - what should I do???

Tom

I would have posted photos but I can't find my USB lead.

I'm sure it will turn up - I hope

Provided it was done correctly the weld will be stronger than the parent metal. You dont need to be an expert welder to spot a good weld either.
Because the material is somewhat porous (all casts tend to be more porous) it will have absobed oils. If it has been cleaned enough to give a good looking weld you can be sure the welder was proffessional enough to have an acetone bath...this bodes well for you.
Look for good penetration, a nice fishscale bead and no warpage of the joint and any surrounding parts. Look for any hairline fractures immediately either side of the weld bead.

Chances are it is good.

Weld looks good - it must have been done by someone who knew what they were doing.

It has been machined too to replicate the correct profile.

Fingers crossed - I'll build the gearbox and everything should be good.

Tom

Welding into cast aluminium is easy and safe. This is routinely done to Enfield engines when converting them to 750cc. The main bearing housings are welded so they can be re-machined to take bigger main bearings. I had a 500 Triumph once that threw the primary chain through the chaincase ( faulty qualcast clutch hub) the welded repair was not noticeable afterwards.

I dislike welds into cast iron, somehow they never seem to be any good.