A couple thoughts after watching your subframe connector video. It is REALLY not advisable to jack up the rear like that when welding a connector in. There is a good amount of flex in a unibody car like a Mustang. Ideally, the car should be sitting on its wheels, level to the ground. With the back up like you had it you may very well have locked in some unwanted rake or even twist in the body. If you needed more room underneath to work it would have been better to get a second set of those blocks and have all four wheels up on them to level the car out.
As far as your welds go, grind 'em off, clean up the metal and try again. All that porosity in the welds from the lack of shielding gas makes them worthless. They will be brittle and crack for sure. There is also likely very little penetration yielding a pretty worthless connection. The other welds look pretty "booger" too. Typically, welds like that also lack good penetration and are prone to failure. There will be a lot of stress on those connections and the body flexes and moves going down the road. You want to make sure your welds are up to it. Honestly, I'd be concerned right now. Do some practice welds on similar thicknesses of metal to get your welder dialed in up on a bench or table. Once you have that locked in concentrate on being comfortable and in good position when you go back and do the rewelding. In the video, it looks like you weren't holding consistent torch distance/angle as one reason your welds turned out as they did.
Not bashing or trying to be critical. Welding is not easy and I am by far not an expert but I have learned enough over the years to know that short of a good weld all you get are bad ones. Bad welds are not something you want when talking about frames and suspensions! They'll bite you every time.
As far as your welds go, grind 'em off, clean up the metal and try again. All that porosity in the welds from the lack of shielding gas makes them worthless. They will be brittle and crack for sure. There is also likely very little penetration yielding a pretty worthless connection. The other welds look pretty "booger" too. Typically, welds like that also lack good penetration and are prone to failure. There will be a lot of stress on those connections and the body flexes and moves going down the road. You want to make sure your welds are up to it. Honestly, I'd be concerned right now. Do some practice welds on similar thicknesses of metal to get your welder dialed in up on a bench or table. Once you have that locked in concentrate on being comfortable and in good position when you go back and do the rewelding. In the video, it looks like you weren't holding consistent torch distance/angle as one reason your welds turned out as they did.
Not bashing or trying to be critical. Welding is not easy and I am by far not an expert but I have learned enough over the years to know that short of a good weld all you get are bad ones. Bad welds are not something you want when talking about frames and suspensions! They'll bite you every time.
