your input is much appreciated everyone. Thank you very much. I still find it hard to believe that it would break so easy. Surely it would endure much more stress when under the load of the vehicle taking bumps and turns?
I also used to think the same but as it turns out there is probably very little stress on the nut/threaded area . The majority of the load is vertical except when you turn a corner, even then the stress is spread over a large area (shackle). Then you have the rubber bushing to absorb and shock. I've never had one break once it was installed unless you over torque it and put a "crack" in the threads leaving it to break later. If you use lock tight or use a fiber locking nut you should be OK because then, even if you don't torque it down, it won't back off!!
PS - I totally agree with you about the threaded portion breaking so easy. It really shouldn't break with such little torque. The original factory shackles were probably better quality. Every time I do any spring work I always have a spare shackle...JUST IN CASE!!!
Don't forget to use plenty of silicone gel/lube (not the spray stuff) in the bushings so that you don't get that famous "squeek, squeek, squeek!!!"
treblig
