Welding 35 VH chaincase

[nevhunter]

You will be flat out getting one that doesn't have SOME damage, or perhaps at all.. My first Ariel was a 1935 RH 350 in 1956. The chain case was cracked right down the middle vertically. They aren't very thick but It was repaired back then with Oxy. Apart from a slight change of the colour of the weld metal, it was undetectable when cleaned up and polished. Nev

[aljosa.kubaska]

It was the same problem with chaingard and crankcase on my Square from 1932. I have done it with MIG. First thing you have degreas material. This alloy is porous and it must be done well. When you are wellding you must heat complet chaincase (about 200 C). After wellding put it in the send. In this way temperature from complete part will slowly recede and you will disable new cracks.
Aljosa

[stuart.wilby]

I agree with nev, older cast aluminium needs the extra silicon as a deoxident agent to facilitate.removal of impurities in the molten weld pool, pure aluminium filler rods will not do this and cracks will appear during the contraction period, if the crack is away from an edge ie in the middle of the casting, it is usual to drill a hole each end of the crack line to prevent it propagating, grind out the crack line until cleanliness can be assured, the whole casting has to be heated to circa 400c a match leaves a black line at this temp, support it and surround the casting with temporary hearth made of fire bricks to keep it warm and perform the weld, cool it very slowly. Tig welding is best but doesn’t like dirt, mig is great again needs to be spotless, oxy acetylene is very good don’t trap the flux, if using a degreaser get rid of it before welding, the fumes are dangerous. Apply the same system for a crack with a “free” end where expansion and contraction is not restrained, good luck.