Removing front suspension on the 73 Vega. Spring compressor threaded rod dropped down through top shock hole and connected to the swing out armed part (one long and one short arm) of the compressor that is engaged on the lowest coil I can get it on. I tighten it up until I've compressed the spring enough to remove the ball joint nut. Nuts off and BANG!!! The spring unloaded and swatted my hand out of the way. Instance broken thumb and blood dripping out of the leather work gloves. Surgery, pins, and a cast later I go back to the scene of the crime to see WTF happened as I've been doing front coil springs for 40 years now.
The compressor is still engaged on the springs BUT it has moved up about 10" on the coil spring and still has some tension on it. I don't think the arms can jump off the coils and move way up on the spring and swing back out and back on the coils so the only thing I can think of is that the coil spring spun (or maybe the arms spun) to very quickly remove the tension on the spring. I'm very fortunate that I wasn't killed or lost my hand.
Drawn a few conclusions and suggestions from this:
1- I should have backed of the spring compressor as soon as I had the ball joint nut removed.
2. Mechanic friend said that I should have clipped a couple vise grips and the coil spring to prevent the arms from climing up the spring.
3. He also said that when he would compress a spring that he would give it a tap or two with a hammer to see if it was going to have a tendency to slip. Try to do that from a distance and out of the path that you would think it would go.
I hope you read this and remember it. We all know the dangers of a compressed coil springs and I have a great respect/fear of them. I've just never had one uncompress and still have the compressor engaged in an INSTANT! I have plenty one time to write now as it's 4 to 6 weeks before I can play in the garage or hold a wrench.
Roger