Developed for use in Formula Drift competition. ~ Forged steel with CNC finished mounting surfaces for strength and symmetry. ~ 45mm roll center and bump steer correction ~ Up to 70 degrees of angle when equipped with our full front end set of supporting parts ~ Designed for use with a low static caster setting, the railing spindle smooths out steering inputs & restores some of the self steer usually lost in low caster settings. ~ Slower steering than our standard super angle knuckle for consistency & stability during high speed drifting. ~ 6 settings of ackerman adjustment to suit your style whether its running faster through the course (more ackerman) or crab walking through the straightaway (zero ackerman) ~ S13 has a 30mm spindle and S14 is a 34mm spindle, They also differ in the FLCA taper, hub compatibility, and coilover hardware is M12 on S13, M14 on S14. If you put an S14 knuckle on S13 you'll drill your coilover lower mount holes bigger & you'll be mising a spindle nut washer we sell separately. ~ This is a brand new part ready to bolt on with no core charge, no modification to your OEM knuckle, no two way shipping fees, no down time. **Cannot be used with tapered outer tie rod. Must convert to 14mm straight through bolt and rod end outer tie rods (MAX part # OTR and OTRLB) **Must be paired with a highly adjustable front suspension system to properly position the wheels when using trail spindles. Our Limit Break Angle Kit is recommended along with forward steering rack relocation. Wheels will be moved back in the wheel wells. Recommened static caster setting is approx 4.5 degrees. See the gallery for side by side photos of the trail knuckle & our standard knuckle.