don't. if one pops out while you are on the road God only knows what kind of damage it can do. go with cut coils.
i'd say they are bolts shaped like a j and cranked down to compress coil spring, like some of the spring compressors work. i'm sure if you have to lower it you could make some, or cut your coils, or enjoy the comfortable ride you have now.
Do it properly - get shorter coil springs rated for your ride. J bolts are pure 'Redneck Engineering' where safety is never a consideration....
J bolts or spring spacers either one aren't legal in several states anymore either. As the others said they can fail and usually fail at the wrong time. If you can afford it buy a pair of dropped spindles otherwise use a set of custom made lowering coils or cut the coils.
I agree with all the above, but if I may, a short story about J-bolts. It was 1959 when I ask my Dad if it would be Ok to lower my '57 Ford. His answer was "No! but Hell No!" They will ruin your ride! Months p***ed by and Christmas rolled around and under the tree was a small but heavy box. I couldn't imagine what it could be. You guess it, a set of J-bolts from my Dad, He got them from JC Whitney, I believe.....I do miss him, he was a good Dad...
I believe I used the term J-bolts in an earlier question regarding how cars were lowered in the 'olden days'. I concur with the wisdom proffered in this particular thread - don't do it. We were HS kids....all we wanted was a rake. J-bolts did the trick, but regularly broke or bent, or sometimes just popped out - each occasion resulting in great noise, unwanted thrills as the suspension recovered in various ways. This is NOT a good thing to do...but to us it was less permanent than heating the coils. Once we understood the term 'reversed spindles', things got safer. dj
J-bolts hazardous? If you pull the coils down 3 inches with j-bolts and one of them breaks, the result will be similar to going over a bump, hearing a "thump" and the front end of the car will hardly react at all. Ask me how I know. I guess if both of them should break simultaneously, the front end might jump up 3 inches?? Hazardous? I think-Not. (Unless you are under there and the broken piece happens to smack you). Ha.