Glad you asked
We offer a 1,000,000 mile warranty on all of our ball joints and steering linkage. The benchmark for quality of ball joints is the stud pullout rating. In our testing, the Moog K5208 upper S10 ball joint stud pulled out at 10,846 lbs. Our stud pulled out at 16,545 lbs. We accomplish this through use of superior metals and a forging process rather than a cast or stamping process like the competition.
The reason our price is so competitive is that we are manufacturer-direct, and we don't have 10 layers of executives and a fleet of private jets to support!
Below is a detailed technical explanation for those who are interested...
Ball joints:
The parts are made with highly polished stud and bearing surfaces with close tolerance clearances between the surfaces to reduce friction. The parts come factory packed with the highest quality molybdenum disulfide grease for performance regardless of temperature, pressure, or cycle frequency.
Mid-carbon steel (.43% carbon) is used whereas competitors use mild steel (.17%). The reason competitors use low carbon steel is because it's cheaper to buy and easier to work with. Low carbon steel allows them to produce shells and studs using cold forging rather than stronger, more expensive hot forging needed with mid-carbon steel. SAE1045 mid-carbon micro alloy steel is the particular steel used. Competition uses SAE4118 low carbon steel.
We used the higher carbon steel and hot forging method because we get a stronger, more durable part with less distortion from the severe heat-treating required to get the same hardness from low carbon steel.
The result of the cold forging is that size variations may be over +/- .010". Our part is CNC milled on all surfaces to produce virtually zero tolerance fit.
The S10 upper ball joints are made from hot forging rather than the metal stampings used by competition. This gave us a much stronger, more durable part with a much larger, stronger bearing surface and a pull-out rating almost double that of Moog.
Threads on studs and nuts are machine cut and matched to ensure greatest thread contact and smoothness of torques. CR rubber compound is used for the dust boots. It remains strong and flexible at the high and low temperatures encountered by North American vehicles. CR compound is also impermeable to brake fluid and road level ozone. The boots have a double lip seal to keep grease in and dirt out. The boots are anchored to the part to ensure boot retention. An accordion-type boot is used on the upper ball joints. This prevents the bottom of the boot from being pulled from its anchored base and prevents the stud sealing hole from becoming elliptical.
The ball joints come fully assembled and can be installed with the boot already installed on the ball joint.
They also feature forged ball studs (SAE4140 steel) and a knurled, press-fit diameter to accommodate both fresh and worn lower control arms. All mounting hardware is SAE grade-8.
When tested, the Moog K5208 ball joint (the upper ball joint) stud pulled out at 10,846 lbs. Our stud pulled out at 16,545 lbs. Here are the test results:
http://members.aol.com/powrperformance/moogtest.pdf
http://members.aol.com/powrperformance/ppmtest.pdf
Tie rod ends and idler arms have similar or superior features to Moog "T" series. Moog, on their non-"T" series, uses a double conical bearing (to the best of my knowledge) - the shape of an egg, and it starts to wear on the top and bottom and begins to rock.
Our bearings are like a top hat - straight down and flat across the bottom and rides on a thrust washer. It allows vertical movement when necessary but no lateral movement that would change toe and cause wear.
