Lowering Springs Comparisons

MaysEffect

Constantly riding on the bumpstops is NOT a good thing. Slamming the bumps can cause damage and premature failure to the damper. Also considering the low profiles tires, this will be exerting more load on the tire sidewall and ultimately the wheel rim. The miata for example had larger sidewalls, softer tires overall and softer bumpstops with more absorption.

There are however aftermarket bumpstops with tuned bump curves that will allow some further compression instead of hard stops in compression stroke.

I'm inclined to believe the jolt you are feeling is from the rear springs binding the "dead springs" Where as the fronts are already fully bound at normal ride height due to the weight bias. Next time you have car up in the air, check if you see scratches/indentations between the tightly bound coils


With regards to the halfshafts, the suspension geometry as factory is designed to keep the shafts relatively level during normal driving conditions. Increased camber, lower ride height. higher torque loads and blown out bushings can cause premature failure to the boots, the internal cages/races and the shaft itself. Ripped boots is a slower wear issue which usually leads to damaged bearings which is a noticeable failure. Damage to the cages and races would almost definitely be catastrophic failure. A snapped shaft is probably the most preferred failure, in a worse case it will bend and start playing hammer fist with the surrounding suspension pieces. This will probably fail at lowspeed.

There are plenty of details on how it all can fail like Rusty suggested.