The bumper bolts always seem to break off when you try to remove them on the older cars (particularly the basket cases I tend to deal with most). I usually heat the hanger before and during the wrenching operation but the 1/2″-16 BSF screws are soft as puppy-poo and twist right in half. As with any other Morgan related project there is more than one way to fix this problem. The process I prefer is to remove and replace the tapped slug that Morgan brazed in the end of the hanger tube. The advantage is that when done the repair is indistinguishable from the original. The disadvantage is that it doesn’t look like you did anything so… no bragging rights. Clamp the tube in a vise and use a center drill to start a hole in the broken screw. Follow that with a #7 bit and drill all the way through; it will be about 3/4″ deep before it breaks through. Tap the hole 1/4″-20 and thread a 2″ or longer eye-screw into it. Turn the tube over in the vise so the eye-screw is pointing down and use wire or a hook to hang a heavy weight from it. Place a bucket of water directly below. Use an oxy/act torch to heat the end of the tube bright-bright red (hotter than you think it should take) and the slug/ eye-screw/ weight will fall into the bucket of water.
Never- never throw out old kingpins. If you have a few handy, as I usually do, chuck one in a lathe and turn the upper end, where the kingpin screw goes (coincidentally it is 1/2″-16 BSF) to the same diameter as the slug that fell in the water. Cut it off at about 1″ and braze it back in the tube. And there; Bob’s your uncle.
Three last comments regarding the front bumper hangers:
1. Drill a small hole on the bottom of the tube near the tapped slug to let water out. The reason these are so difficult to disassemble is probably because they spent most of their existence filled with water.
2: The clamps are not interchangeable or reversible. Keep the individual tube and its clamp together after disassembly. A plastic cable tie works fine.
3. Don’t for a second think you can pries the aluminum clamp open to help slide it off of the tube. It is a very porous casting and will break instantly. A better method is to clean the tube in front of it using sandpaper and/or a scraper and heat the clamp with a propane torch. Once warm you can put a Phillips head screwdriver in the cross-hole and rotate it on the tube to break it free. It will then slide off without breaking; well, maybe.