I repaired a frame that was literally ready for the front suspension to fall of. It was a 196? and the flanges had been cut with a torch for header clearance, then preceded to crack almost completely from top to bottom.
I ground the crack out completely, from both sides till them meet in the middle.
Then TIG welded the crack back together from both sides.
Dressed the welds flat, and also replaced the missing (torched) parts, welding the same way.
When done you could not tell it had ever been torched, cracked, or repaired.
Now that it is back on the road the welds have been inspected several now, no problems.
I would not MIG weld a frame, as it tends to create hard spots that can lead to more cracks. The weld is very hot, but the material around it stays relatively cold during welding.
TIG welding is a "softer" approach to welding, not as harsh as MIG welding because the heat is more gradually applied/ more time to soak in, so no hot/cold areas for stress cracks to form.
MIG welding may work for a while, but chances of failure down the line are greater, don't take that chance, TIG weld it.
Grigg
