Diagnosing a spring as faulty is simple is the spring is cracked, broken, or if the vehicle is leaning to one side, however, if the vehicle has excessive body roll, but the vehicle sits level, the ride height at all four wheels, the spring height on all four springs, and the tire pressure will all be recorded. This information will be compared to factory specifications, and diagnosis will recommend those outside of allowable tolerance to the specification be replaced. For rattles and squeaks, the pads will be diagnosed just by noting their appearance. If cracked, rotted, deteriorated, or heavily weathered, they will be recommended for replacement.
When changing independent coil springs, the job is just as involved, and just as dangerous as changing coil springs on a strut. Except independent coil springs are more cumbersome, as the tension is released from the spring while it is still in the car, instead of on the wall, or the bench. Once the vehicle is raised, and the wheel, brake caliper, brake caliper mount, brake rotor, and any other obstacles are removed, a safety chain is placed through the coil spring, and lower control arm, ensuring the spring can not take flight if stress is relieved suddenly. The technician then places a jack underneath the control arm, partially removes the castle nut for the lower ball joint, separates the ball joint from the steering knuckle, and raises the control arm to compress the spring enough to finish removing the castle nut on the ball joint. At that point, the jack is lowered slowly, and the spring gradually loses tension until it is observably loose. Installation is the reverse of removal, and new coil spring insulators (pads) should be installed.
The original springs for any vehicle were designed specifically for that vehicle, and have many properties besides their weight capacity and physical dimensions. Replacing springs with different properties will dramatically alter the driving feel of the vehicle, and handling characteristics. Before changing springs, we recommend consulting a professional technician to ensure the proper springs are selected. Cutting or heating springs to alter the vehicle's ride height is never recommended, and will create unpredictable, often uncontrollable driving conditions. When springs are altered, the characteristics of each spring will vary, producing undesirable conditions.
Coil springs integrated into struts can be replaced as part of the entire unit. There are many parts suppliers and manufacturers that offer pre-assembled struts including the coil spring. This method will lower the risk of replacing the strut or coil spring.
The coil springs can be replaced at home if the entire process, and all safety measures are understood. It is critical to understand coil springs are under tremendous tension, and releasing a compressed spring can result in injury, or death. If coil springs are not completely understood, as well as safety measures for disassembly, a professional technician should complete the repair.
I have done 2 mazda 3 and a mazda 5 front strut and coil replacements. Takes about 1.5 to 2 hours including torching out the pinch bolts and knocking out the old ones from the knuckle, cleaning up.the bores, installing new and cleaning threads. Doesn't include the alignment. Mazda quoted my buddy 600 for one side for just the shock replacement. If I tried to save the shocks it would have taken me longer as I just airhammered them out from the bottom.
I would recommend replacement of both shocks and springs with quickstruts. You save on the labor of replacing the coil. You Get new shocks and don't have to worry if they get damaged during removal.
I would also recommend replacing the sway bar links at the same time as half of it is unbolted during the repair and they are cheap.
Before you embark on a journey of revenge, dig two graves.Confucius