Suzuki 4WD Club of Victoria

welding steel mounts onto cast iron (diff)

Should I bother trying, get an expert, get a friend, or think of a non weld alternative?
I only got an arc welder and general purpose rods

welding to anything CAST is fraught with problems, i doubt that you'll find any "expert" that will tackle the job without shit-loads of cash and NO guarantee of success.

i suggest that you find an alternative method of holding the diff down, like a well constructed "strap"

I'm much better at making non weld brackets than I am at welding, so probly will do that.
searching welding tutorials has helped me realise I probly shouldn't try
cheers and thanks

I don't think there's any reason to design the mount to require welding. Having said that, you might be able to design a mount where welding is required to hold it in place but doesn't require welding to provide it with strength.

Preheating (even using a kitchen oven) and using low hydrogen electrodes (with stick welding) would provide adequate results assuming you weren't putting the bracket under extreme stress (which is a design issue, not a welding issue)

I've had surprisingly good results welding castings with normal mild steel MIG. I'd never recommend it, but it has held.
Steve.

A bracket to control up and down looks easy enough, but not sure if I should be controling twist.
Thinking of a wrap around bracket, not much room, but something will fit.
A look in daylight with a fresh mind is needed

No, it is not cast iron. It is weldable and others have done so but as I suggested to you have a look at a bracket that encircles it and attaches to the crossmember on both sides of the pinion. As an aside I have welded cast iron in the past with success but if you don't get it right ( prep, pre-heating, correct rods, correct technique etc.) it will end in tears and even if you a good job it will never be 100%.

I got a few ideas developing.

Keep running out of daylight and warmth
So it is all going slowly.
Getting started is good tho.

no one has mentioned cast iron. except Chris.

cast steel is not as good to weld as you might think, it generally has lots of inclusions and porosity just under the surface.
the best thing is to construct a bracket that encircles the housing and holds it, so that it's correctly held for the direction of the loads that its going to receive.