Cast welding

[Classiccars]

Hi I have a dynamo that's near new but the bracket has snapped off.Can you weld cast.

[geoberni]

As I understand it, the answer is YES,... and NO.
It all depends on the type/grade of aluminium and the amount of impurities in it, how dense it is etc.
Even the casting process involved when it was made, some casting like sand moulds allow the molten metal to cool slowly which allows gas bubbles to escape, while injection moulding leaves lots of gas pockets in the casting.

What you can do is Braze a repair, where there is more emphasis on the repair being the new metal making the joint, rather than welding where you are reliant far more on the original metal melting to make the joint; if you see what I mean.

[svenedin]

It might be better to swap a good bracket from a scrap dynamo. I sent a dynamo off for overhaul recently (a genuine Lucas C40) and noticed a flaw in the casting. The chap doing the refurbishing agreed to swap it as although not broken it is a point of weakness.

[Classiccars]

Thanks guys yes not an easy one.Think I will ask a repairer if he has one .

[philthehill]

I have to ask the question - why did it snap?
It is most important that there is no strain on the brackets.
Fit the front bracket to the water pump first and then move to the rear bracket.
Adjust the rear bracket so that there is no tension or strain on the dynamo end mount plate.
It is not worth the effort of welding the bracket and I doubt you would have much success. In my opinion the easiest option is to obtain and fit a good S/H end plate.

[Classiccars]

Thank you Phil it was my fault it broke.Live and learn lesson.Just need to find an end now as have a guy that can fit it no problem.

[taupe]

Which end is it as these seem good value and also complete used dynos from £10

https://www.ebay.co.uk/itm/374523582708 ... R6SF5tzOYQ

Taupe

[Grumpy21]

When I used to fly model aircraft we regularly used a product called Lumiweld for repairing cast aluminium crankcases. Always worked very well as long as the instructions are followed. Costs about £20 these days from Frost. I would be happy to use it to repair an alternator flange like you describe.

Just a thought.

[geoberni]

Equally, J-B Weld can be used for a lot of repairs. Although a snapped of mounting bracket might be too much sideways force when refitting. I think its perhaps best at holes or cracks.

An interesting Blog read here and it's only about £5 if you want to try it.: https://inboxq.com/jb-weld-for-aluminum/

[Classiccars]

Handy for future use thanks.Manage to get a replacement end thanks all.